The Effects of the Training in the Preparation Period on the Repetitive Strength Transformation with Cadet Level Football Players

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Jovan Gardašević

2016-06-01

Full Text Available The main aim of the research was to identify a level of quantitative changes of the repetitive strength with fifteen years old football players under the influence of the programmed football training of a six weeks preparation period. The training programme covered forty-four training units. The research was made on a sample of 120 cadet level football players. To estimate the repetitive strength three tests have been used: Lying-sed for 30 seconds, Push-ups and Lifting upper body while lying on stomach. In the area of comparative statistics, we used discriminant parametric procedure t-test for big paired samples. It can be concluded that there are statistically significant differences in all three variables to estimate the repetitive strength. This confirmed the hypothesis that the expected significant positive quantitative changes of basic-motor abilities influenced by the proposed model of training in preparation period with fifteen years old football players. The authors were guided by the fact that this kind of training program in preparation period is very effective in terms of raising the repetitive strength level with fifteen years old. The obtained results can be directed towards innovation plans and programs in the preparation period, and the adaptation of the same needs of the respective population.

SECRET SHARING SCHEMES WITH STRONG MULTIPLICATION AND A LARGE NUMBER OF PLAYERS FROM TORIC VARIETIES

DEFF Research Database (Denmark)

Hansen, Johan Peder

2017-01-01

This article consider Massey's construction for constructing linear secret sharing schemes from toric varieties over a finite field $\\Fq$ with $q$ elements. The number of players can be as large as $(q-1)^r-1$ for $r\\geq 1$. The schemes have strong multiplication, such schemes can be utilized in ...

Features of the training process of handball players of higher qualification between rounds in the competitive period

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V.A. Tyshchenko

2015-01-01

Full Text Available Purpose : the technology of preparation of athletes in accordance with the requirements of the system approach. Team management methodology disclosed in terms of the training process in the competitive period between rounds of the regular championship of Ukraine. Material : the experiment involved 85 athletes aged 18-32 years. Results : The recommended during pilot training to perform technical and tactical actions in lockstep future games. Testing and modeling training - at a more complete simulation of conditions of competition. Shock training to perform with significant excess volume and intensity. Shock-modeling training - close to a match where the simulated conditions and confounding factor. The most efficient and effective indicators to consider: the number of substitutions in one match - 8-12 times; residence time player on the court - 12-15 minutes; preferred time of travel players during replacement - 3-5 minutes; heart rate after a rest - 100-120 beats per minute. Conclusions : The developed model microcycle training process handball players between rounds of the Championship of Ukraine.

Multiple player tracking in sports video: a dual-mode two-way bayesian inference approach with progressive observation modeling.

Science.gov (United States)

Xing, Junliang; Ai, Haizhou; Liu, Liwei; Lao, Shihong

2011-06-01

Multiple object tracking (MOT) is a very challenging task yet of fundamental importance for many practical applications. In this paper, we focus on the problem of tracking multiple players in sports video which is even more difficult due to the abrupt movements of players and their complex interactions. To handle the difficulties in this problem, we present a new MOT algorithm which contributes both in the observation modeling level and in the tracking strategy level. For the observation modeling, we develop a progressive observation modeling process that is able to provide strong tracking observations and greatly facilitate the tracking task. For the tracking strategy, we propose a dual-mode two-way Bayesian inference approach which dynamically switches between an offline general model and an online dedicated model to deal with single isolated object tracking and multiple occluded object tracking integrally by forward filtering and backward smoothing. Extensive experiments on different kinds of sports videos, including football, basketball, as well as hockey, demonstrate the effectiveness and efficiency of the proposed method.

Effects of resistance training periodization on performance and salivary immune-endocrine responses of elite female basketball players.

Science.gov (United States)

Nunes, J A; Crewther, B T; Viveiros, L; De Rose, D; Aoki, M S

2011-12-01

The aim of this paper was to examine the effects of resistance training periodization on the performance and salivary hormone-immune responses of elite female basketball players. Twelve female athletes were monitored across a 50 day period of resistance training that emphasized strength, endurance and power. One repetition maximum (1RM) strength, maximal repetitions at 50% 1RM and vertical jump performance was assessed pre- and post-training. Saliva samples were also collected at 0700, 0930, 1100 and 1730 hours and analyzed for testosterone (T), cortisol (C) and immunoglobulin A (IgA). Improvements in 1RM strength, maximal repetitions and vertical jump performance were identified post-training (PTraining had no effect on salivary T and C concentrations, but the T:C ratio increased at 0730 hours (Ptraining) in strength and T concentrations were positively correlated at 0730 hours (Ptraining increased muscle performance in elite female basketball players, but only minor changes in the salivary T:C ratio and IgA were noted. Correlational analysis identified a possible role for early morning changes in T as a regulator of individual strength changes.

Effects of Pre - Season Short - Term Daily Undulating Periodized Training on Muscle Strength and Sprint Performance of Under - 20 Soccer Players

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Charles Ricardo L OPES

2015-06-01

Full Text Available The aim of this study was to evaluate the effects of daily undulating training periodization designed for maximal lower limb muscle strength and sprint performance in under - 20 soccer players. Twenty - four male athletes (age = 19.1 ± 1.2 yr; mass = 71.1 ± 6. 8 kg; height = 178.0 ± 0.1 cm participated in four weeks of a daily undulating periodized (DUP training soccer program. During the pre - and post - training periods the subjects performed a one repetition maximum (1 RM half back squat test and a 15 - meter s print. Significant training - induced changes were observed in sprint times (pre = 2.38 ± 0.01 s; post = 2.31 ± 0.02 s and 1 RM tests (pre = 107.0 ± 2.0 kg; post = 128.0 ± 2.2 kg. These results indicate that a DUP program is efficient in promoting positive neuromuscular adaptations in soccer players, even with a short - term preseason training period.

Improved nonparametric inference for multiple correlated periodic sequences

KAUST Repository

Sun, Ying

2013-08-26

This paper proposes a cross-validation method for estimating the period as well as the values of multiple correlated periodic sequences when data are observed at evenly spaced time points. The period of interest is estimated conditional on the other correlated sequences. An alternative method for period estimation based on Akaike\\'s information criterion is also discussed. The improvement of the period estimation performance is investigated both theoretically and by simulation. We apply the multivariate cross-validation method to the temperature data obtained from multiple ice cores, investigating the periodicity of the El Niño effect. Our methodology is also illustrated by estimating patients\\' cardiac cycle from different physiological signals, including arterial blood pressure, electrocardiography, and fingertip plethysmograph.

Wearable flex sensor system for multiple badminton player grip identification

Science.gov (United States)

Jacob, Alvin; Zakaria, Wan Nurshazwani Wan; Tomari, Mohd Razali Bin Md; Sek, Tee Kian; Suberi, Anis Azwani Muhd

2017-09-01

This paper focuses on the development of a wearable sensor system to identify the different types of badminton grip that is used by a player during training. Badminton movements and strokes are fast and dynamic, where most of the involved movement are difficult to identify with the naked eye. Also, the usage of high processing optometric motion capture system is expensive and causes computational burden. Therefore, this paper suggests the development of a sensorized glove using flex sensor to measure a badminton player's finger flexion angle. The proposed Hand Monitoring Module (HMM) is connected to a personal computer through Bluetooth to enable wireless data transmission. The usability and feasibility of the HMM to identify different grip types were examined through a series of experiments, where the system exhibited 70% detection ability for the five different grip type. The outcome plays a major role in training players to use the proper grips for a badminton stroke to achieve a more powerful and accurate stroke execution.

Nutritional intake and overall diet quality of female soccer players before the competition period

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Daniel dos SANTOS

Full Text Available ABSTRACT Objective: To assess the dietary intake and overall diet quality of female soccer players before the competitive games. Methods: This descriptive and cross-sectional study included 21 women aged 20.8±4.5 years from a professional soccer team. Their nutritional status and dietary adequacy during the training period, before competition season, were assessed. Dietary intake was assessed by three 24-hour recalls, one food frequency questionnaire, and the Healthy Eating Index, an overall diet quality index based on food group intake. Results: The athletes have shown proper nutritional status, but a diet deficient in energy due largely to low carbohydrate intake. On the other hand, the intakes of protein, fatty acids, and sodium were above the recommended intakes, even for athletes. Diet quality assessment by the Healthy Eating Index - 2010 resulted in a mean score of 54.6 points of a maximum of 100, indicating a need of improving the overall diet quality. Conclusion: The study found that the dietary patterns of female football players were both quantitatively and qualitatively inappropriate. A nutritional intervention is indicated to improve diet quality, with the inclusion of various foods, such as whole grains, fruits, vegetables, dairy products, and better protein quality, along with a reduction in saturated fats, sodium, and added sugar.

Discrepancy between exercise performance, body composition, and sex steroid response after a six-week detraining period in professional soccer players.

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Nikolaos E Koundourakis

Full Text Available PURPOSE: The aim of this study was to examine the effects of a six-week off-season detraining period on exercise performance, body composition, and on circulating sex steroid levels in soccer players. METHODS: Fifty-five professional male soccer players, members of two Greek Superleague Teams (Team A, n = 23; Team B, n = 22, participated in the study. The first two weeks of the detraining period the players abstained from any physical activity. The following four weeks, players performed low-intensity (50%-60% of VO2max aerobic running of 20 to 30 minutes duration three times per week. Exercise performance testing, anthropometry, and blood sampling were performed before and after the six-week experimental period. RESULTS: Our data showed that in both teams A and B the six-week detraining period resulted in significant reductions in maximal oxygen consumption (60,31±2,52 vs 57,67±2,54; p<0.001, and 60,47±4,13 vs 58,30±3,88; p<0.001 respectively, squat-jump (39,70±3,32 vs 37,30±3,08; p<0.001, and 41,05±3,34 vs 38,18±3,03; p<0.001 respectively, and countermovement-jump (41,04±3,99 vs 39,13±3,26; p<0.001 and 42,82±3,60 vs 40,09±2,79; p<0.001 respectively, and significant increases in 10-meters sprint (1,74±0,063 vs 1,79±0,064; p<0.001, and 1,73±0,065 vs 1,78±0,072; p<0.001 respectively, 20-meters sprint (3,02±0,05 vs 3,06±0,06; p<0.001, and 3,01±0,066 vs 3,06±0,063; p<0.001 respectively, body fat percentage (Team A; p<0.001, Team B; p<0.001, and body weight (Team A; p<0.001, Team B; p<0.001. Neither team displayed any significant changes in the resting concentrations of total-testosterone, free-testosterone, dehydroepiandrosterone-sulfate, Δ4-androstenedione, estradiol, luteinizing hormone, follicle-stimulating hormone, and prolactin. Furthermore, sex steroids levels did not correlate with exercise performance parameters. CONCLUSION: Our results suggest that the six-week detraining period resulted in a rapid loss of

How do professional Australian Football League (AFL) players utilise social media during periods of injury? A mixed methods analysis.

Science.gov (United States)

Nankervis, Brodie; Ferguson, Laura; Gosling, Cameron; Storr, Michael; Ilic, Dragan; Young, Mark; Maloney, Stephen

2018-07-01

The objective of this study was to explore how social media is used by a population of injured professional athletes, by comparing the content and frequency of posts on social media, pre and post-injury. A retrospective mixed methods design was utilised. Professional Australian Football League (AFL) players, injured during the 2015 season, were included in the study. Publicly accessible social media profiles for these players were identified on Twitter and Instagram. All posts published on verified profiles, from four weeks prior to injury until return to play, were extracted. Thematic analysis was used to investigate the content of these posts, while univariate and multivariate linear regression was used to investigate the frequency of posts during this time period. Two reoccurring themes were identified exclusively post-injury; 'supporting team from the sideline' and 'sharing information about injury and rehabilitation'. The frequency of total posts did not differ significantly pre and post-injury, but the frequency of injury related posts increased in the immediate post-injury phase, then decreased between 4-8 weeks and 8-12 weeks post-injury. The frequency of injury related posts was higher with more severe injuries. The findings of this study suggest that injured players use social media to seek social support from their followers, especially in the immediate post-injury period and after sustaining a severe injury. The role of social media in injury rehabilitation may warrant further investigation, to determine if it could be used to facilitate return to play. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Menstrual cycle disorders in female volleyball players.

Science.gov (United States)

Wodarska, M; Witkoś, J; Drosdzol-Cop, A; Dąbrowska, J; Dąbrowska-Galas, M; Hartman, M; Plinta, R; Skrzypulec-Plinta, V

2013-07-01

The aim of this study was to examine the relation between increased physical activity and menstrual disorders in adolescent female volleyball players. The study was conducted on 210 Polish female volleyball players, aged 13-17 years, the authorship questionnaire was used. The results of the study showed that irregular menstruation occurred in 19% of girls, spotting between menstrual periods in 27% and heavy menstruation was reported in 33% of girls. Out of all volleyball female players participating in the study, 94 girls (45%) declared absence of menstrual periods after regular cycles. Statistical analysis showed that the more training hours per week, the bigger probability of the occurrence of irregular menstruation. It was concluded that the number of hours of volleyball training per week affects regularity of menstrual cycles in female volleyball players. The absence of menstruation might be caused by the duration of training per week or years of training.

Musculoskeletal injuries among Malaysian badminton players.

Science.gov (United States)

Shariff, A H; George, J; Ramlan, A A

2009-11-01

The purpose of this study was to investigate the pattern of musculoskeletal injuries sustained by Malaysian badminton players. This is a retrospective case notes review of all badminton players who attended the National Sports Institute (NSI) Clinic, Kuala Lumpur, Malaysia, and were diagnosed with musculoskeletal injuries. In a two and a half year period, from January 2005 to June 2007, 469 musculoskeletal injuries were diagnosed among badminton players at the NSI Clinic. The mean age of the players who attended the clinic was 19.2 (range 13-52) years. Approximately 60 percent of the injuries occurred in players younger than 20 years of age. The majority of injuries (91.5 percent) were categorised as mild overuse injury and mostly involved the knee. The majority of the injuries sustained by badminton players in this study were due to overuse, primarily in the knee. The majority of the injuries were diagnosed in younger players and occurred during training/practice sessions. There was no difference in terms of incidence and types of injuries between the genders.

Changes in the level of motor skills of football players "Flisak" Złotoria club after the period of special preparation

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Łukasz Pabianek

2017-02-01

Full Text Available The main objective of the study was to analyze and assess the changes in motor skill level of football players after the period of special preparation. This goal was accomplished by discussing theoretical information on the above issues as well as the results of a study conducted jointly with a group of 54 trainers at Flisak Złotoria Club (18 football players aged 11-12, 13-17 and over 17 years. In the course of the research it was shown that the football training at Flisak Złotoria in the special subperiod contributed to a slight improvement in general level and special fitness. Irregularities have been observed in young men's swing and seniors' swing, but due to the marginal nature of negative changes they should not cause a negative assessment of the quality of training in the examined club (though an in-depth analysis of training programs is required for the preparatory period. It also seems reasonable to look for solutions that will increase the efficiency of special fitness training. There was no constant correlation between the age of the respondents and the results of the training. In the course of the research conducted among youngsters, juniors and seniors, it was stated above all that the special preparation sub-period had a very limited but positive impact on the overall fitness level of football players, as confirmed by the improvement in the average scores obtained in 7 out of 9 Exercises. The fact that, as the empirical data show, the marginal reduction of the Seniors' speed over short distances (a decrease of the average running time of 15 meters by 0.21% and the youthfulness (decrease of the length of the jump by 0.99 %.

The audiological health of horn players.

Science.gov (United States)

Wilson, Wayne J; O'Brien, Ian; Bradley, Andrew P

2013-01-01

Among orchestral musicians, horn players are one of the most at-risk groups for noise-induced hearing loss (NIHL). To investigate this group further, pure tone audiometry and a 14-item questionnaire were used to assess the hearing health, as well as attitudes and practices regarding hearing conservation, among 142 French horn players attending an international horn conference in Brisbane, Australia. Of this study's French horn players, 11.1% to 22.2%, and 17.7% to 32.9% of those aged ≤40 years, showed some form of hearing loss (corrected for age and gender) typical of NIHL, using conservative versus lenient criteria, respectively. Stepwise multiple regression analyses showed no obvious predictor of hearing loss in this study's participants. Of the 18% of participants who reported using hearing protection, 81% used this protection "sometimes" and 50% used generic, foam, or other inferior forms of protection. Continued efforts to better manage the hearing health of horn players is warranted particularly as any hearing loss will affect a horn player's ability to perform and therefore his or her livelihood. Managing the hearing health of horn players will be challenging, however, with no simple predictor of NIHL loss being identified in this study's sample.

MRI assessment of calf injuries in Australian Football League players: findings that influence return to play

International Nuclear Information System (INIS)

Waterworth, George; Wein, Sara; Rotstein, Andrew H.; Gorelik, Alexandra

2017-01-01

Calf muscle strains have become increasingly prevalent in recent seasons of the Australian Football League (AFL) and represent a significant cause of time lost from competition. The purpose of this study was to examine the association between MRI features of calf muscle strains and games missed and to thereby identify parameters that are of prognostic value. A retrospective analysis of MRI scans of AFL players with calf strains referred to a musculoskeletal radiology clinic over a 5-year period (2008-2012) was performed. The muscle(s) and muscle component affected, the site and size of strain, and the presence of an intramuscular tendon tear or intermuscular fluid were recorded. These data were cross-referenced with whether a player missed at least one game. Imaging features of prognostic value were thus identified. Sixty-three athletes had MRI scans for calf muscle strains. Soleus strains were more common than strains of other muscles. Players with soleus strains were more likely to miss at least one game if they had multiple muscle involvement (p = 0.017), musculotendinous junction strains (p = 0.046), and deep strains (p = 0.036). In a combined analysis of gastrocnemius and soleus strains, intramuscular tendon tears were observed in a significantly greater proportion of players who missed games (p = 0.010). Amongst AFL players with calf injuries, there is an association between missing at least one game and multiple muscle involvement, musculotendinous junction strains, deep strain location, and intramuscular tendon tears. In this setting, MRI may therefore provide prognostic information to help guide return-to-play decisions. (orig.)

MRI assessment of calf injuries in Australian Football League players: findings that influence return to play

Energy Technology Data Exchange (ETDEWEB)

Waterworth, George; Wein, Sara; Rotstein, Andrew H. [Victoria House Medical Imaging, Prahran, Victoria (Australia); Gorelik, Alexandra [Royal Melbourne Hospital, University of Melbourne, Melbourne Epicentre, Parkville (Australia)

2017-03-15

Calf muscle strains have become increasingly prevalent in recent seasons of the Australian Football League (AFL) and represent a significant cause of time lost from competition. The purpose of this study was to examine the association between MRI features of calf muscle strains and games missed and to thereby identify parameters that are of prognostic value. A retrospective analysis of MRI scans of AFL players with calf strains referred to a musculoskeletal radiology clinic over a 5-year period (2008-2012) was performed. The muscle(s) and muscle component affected, the site and size of strain, and the presence of an intramuscular tendon tear or intermuscular fluid were recorded. These data were cross-referenced with whether a player missed at least one game. Imaging features of prognostic value were thus identified. Sixty-three athletes had MRI scans for calf muscle strains. Soleus strains were more common than strains of other muscles. Players with soleus strains were more likely to miss at least one game if they had multiple muscle involvement (p = 0.017), musculotendinous junction strains (p = 0.046), and deep strains (p = 0.036). In a combined analysis of gastrocnemius and soleus strains, intramuscular tendon tears were observed in a significantly greater proportion of players who missed games (p = 0.010). Amongst AFL players with calf injuries, there is an association between missing at least one game and multiple muscle involvement, musculotendinous junction strains, deep strain location, and intramuscular tendon tears. In this setting, MRI may therefore provide prognostic information to help guide return-to-play decisions. (orig.)

MRI assessment of calf injuries in Australian Football League players: findings that influence return to play.

Science.gov (United States)

Waterworth, George; Wein, Sara; Gorelik, Alexandra; Rotstein, Andrew H

2017-03-01

Calf muscle strains have become increasingly prevalent in recent seasons of the Australian Football League (AFL) and represent a significant cause of time lost from competition. The purpose of this study was to examine the association between MRI features of calf muscle strains and games missed and to thereby identify parameters that are of prognostic value. A retrospective analysis of MRI scans of AFL players with calf strains referred to a musculoskeletal radiology clinic over a 5-year period (2008-2012) was performed. The muscle(s) and muscle component affected, the site and size of strain, and the presence of an intramuscular tendon tear or intermuscular fluid were recorded. These data were cross-referenced with whether a player missed at least one game. Imaging features of prognostic value were thus identified. Sixty-three athletes had MRI scans for calf muscle strains. Soleus strains were more common than strains of other muscles. Players with soleus strains were more likely to miss at least one game if they had multiple muscle involvement (p = 0.017), musculotendinous junction strains (p = 0.046), and deep strains (p = 0.036). In a combined analysis of gastrocnemius and soleus strains, intramuscular tendon tears were observed in a significantly greater proportion of players who missed games (p = 0.010). Amongst AFL players with calf injuries, there is an association between missing at least one game and multiple muscle involvement, musculotendinous junction strains, deep strain location, and intramuscular tendon tears. In this setting, MRI may therefore provide prognostic information to help guide return-to-play decisions.

Self-esteem and injury in competitive field hockey players.

Science.gov (United States)

Kolt, G S; Roberts, P D

1998-08-01

A volunteer sample of 50 competitive field hockey players completed the Coopersmith Self-esteem Inventory at pre- and postseason and prospectively collected injury data over a 20-wk. season. Multiple regression analysis showed no relationship between scores on Self-esteem and the number of injuries, the participation time affected due to injury, and sex of players. Further multiple regression analysis showed that frequency of the more severe injuries significantly predicted scores on Self-esteem. This finding can be interpreted as evidence of the relationship between low self-esteem and injury in sport.

The Brazilian electric power sector reformulation process: an analysis of the veto players; O processo de reforma do setor eletrico brasileiro: uma analise dos 'veto players'

Energy Technology Data Exchange (ETDEWEB)

Roxo, Leticia

2007-07-01

The electric power sector reformulation implemented in the Brazil makes evident the intrinsic difficulty to handle with complex set of veto players. The multiplicity of veto players characterized by distinct ideologies results in the multiplication of business rounds related to the elaboration and implementation of the new game rules, whose agreement involves conflicts on the presented proposal, resulting in the slowness pf reformulation process conclusion.

Bridging Media with the Help of Players

Science.gov (United States)

Nitsche, Michael; Drake, Matthew; Murray, Janet

We suggest harvesting the power of multiplayer design to bridge content across different media platforms and develop player-driven cross-media experiences. This paper first argues to partially replace complex AI systems with multiplayer design strategies to provide the necessary level of flexibility in the content generation for cross-media applications. The second part describes one example project - the Next Generation Play (NGP) project - that illustrates one practical approach of such a player-driven cross-media content generation. NGP allows players to collect virtual items while watching a TV show. These items are re-used in a multiplayer casual game that automatically generates new game worlds based on the various collections of active players joining a game session. While the TV experience is designed for the single big screen, the game executes on multiple mobile phones. Design and technical implementation of the prototype are explained in more detail to clarify how players carry elements of television narratives into a non-linear handheld gaming experience. The system describes a practical way to create casual game adaptations based on players' personal preferences in a multi-user environment.

Monitoring training load, recovery-stress state, immune-endocrine responses, and physical performance in elite female basketball players during a periodized training program.

Science.gov (United States)

Nunes, João A; Moreira, Alexandre; Crewther, Blair T; Nosaka, Ken; Viveiros, Luis; Aoki, Marcelo S

2014-10-01

This study investigated the effect of a periodized training program on internal training load (ITL), recovery-stress state, immune-endocrine responses, and physical performance in 19 elite female basketball players. The participants were monitored across a 12-week period before an international championship, which included 2 overloading and tapering phases. The first overloading phase (fourth to sixth week) was followed by a 1-week tapering, and the second overloading phase (eighth to 10th week) was followed by a 2-week tapering. ITL (session rating of perceived exertion method) and recovery-stress state (RESTQ-76 Sport questionnaire) were assessed weekly and bi-weekly, respectively. Pretraining and posttraining assessments included measures of salivary IgA, testosterone and cortisol concentrations, strength, jumping power, running endurance, and agility. Internal training load increased across all weeks from 2 to 11 (p ≤ 0.05). After the first tapering period (week 7), a further increase in ITL was observed during the second overloading phase (p ≤ 0.05). After the second tapering period, a decrease in ITL was detected (p ≤ 0.05). A disturbance in athlete stress-recovery state was noted during the second overloading period (p ≤ 0.05), before returning to baseline level in end of the second tapering period. The training program led to significant improvements in the physical performance parameters evaluated. The salivary measures did not change despite the fluctuations in ITL. In conclusion, a periodized training program evoked changes in ITL in elite female basketball players, which appeared to influence their recovery-stress state. The training plan was effective in preparing participants for competition, as indicated by improvements in recovery-stress state and physical performance after tapering.

Telemetry and Communication IP Video Player

Science.gov (United States)

OFarrell, Zachary L.

2011-01-01

Aegis Video Player is the name of the video over IP system for the Telemetry and Communications group of the Launch Services Program. Aegis' purpose is to display video streamed over a network connection to be viewed during launches. To accomplish this task, a VLC ActiveX plug-in was used in C# to provide the basic capabilities of video streaming. The program was then customized to be used during launches. The VLC plug-in can be configured programmatically to display a single stream, but for this project multiple streams needed to be accessed. To accomplish this, an easy to use, informative menu system was added to the program to enable users to quickly switch between videos. Other features were added to make the player more useful, such as watching multiple videos and watching a video in full screen.

Scintigraphic diagnosis of sport injuries: Multiple fractures of ribs by golf-players

International Nuclear Information System (INIS)

Pohle, W.; Schuemichen, C.; Hoffmann, G.; Keul, J.; Kluemper, A.

1981-01-01

Three untrained golf-players suffered from pain in the dorsal region of the left thorax after some training hours. Three to four weeks after the pains had begun serial fractures of ribs were diagnosed by sup(99m)Tc-MDP bonescan-examinations. All fractures were localized near the costal angulus (paravertebral) of these ribs. The fractures are caused by manual tensions. The difficulties in timing the bone-scan and in identifying the morphologic substrate are demonstrated. It is recommended, that golf-players suffering from thoracic pain ought to be examined by bone scan. (orig.) [de

Scintigraphic diagnosis of sport injuries: Multiple fractures of ribs by golf-players

Energy Technology Data Exchange (ETDEWEB)

Pohle, W; Schuemichen, C; Hoffmann, G; Keul, J; Kluemper, A

1981-02-01

Three untrained golf-players suffered from pain in the dorsal region of the left thorax after some training hours. Three to four weeks after the pains had begun serial fractures of ribs were diagnosed by sup(99m)Tc-MDP bonescan-examinations. All fractures were localized near the costal angulus (paravertebral) of these ribs. The fractures are caused by manual tensions. The difficulties in timing the bone-scan and in identifying the morphologic substrate are demonstrated. It is recommended, that golf-players suffering from thoracic pain ought to be examined by bone scan.

Head Impact Exposure in Junior and Adult Australian Football Players

Directory of Open Access Journals (Sweden)

Mark Hecimovich

2018-01-01

Full Text Available This study measured and compared the frequency, magnitude, and distribution of head impacts sustained by junior and adult Australian football players, respectively, and between player positions over a season of games. Twelve junior and twelve adult players were tracked using a skin-mounted impact sensor. Head impact exposure, including frequency, magnitude, and location of impacts, was quantified using previously established methods. Over the collection period, there were no significant differences in the impact frequency between junior and adult players. However, there was a significant increase in the frequency of head impacts for midfielders in both grades once we accounted for player position. A comparable amount of head impacts in both junior and adult players has implications for Australian football regarding player safety and medical coverage as younger players sustained similar impact levels as adult players. The other implication of a higher impact profile within midfielders is that, by targeting education and prevention strategies, a decrease in the incidence of sports-related concussion may result.

Two-phased DEA-MLA approach for predicting efficiency of NBA players

Directory of Open Access Journals (Sweden)

Radovanović Sandro

2014-01-01

Full Text Available In sports, a calculation of efficiency is considered to be one of the most challenging tasks. In this paper, DEA is used to evaluate an efficiency of the NBA players, based on multiple inputs and multiple outputs. The efficiency is evaluated for 26 NBA players at the guard position based on existing data. However, if we want to generate the efficiency for a new player, we would have to re-conduct the DEA analysis. Therefore, to predict the efficiency of a new player, machine learning algorithms are applied. The DEA results are incorporated as an input for the learning algorithms, defining thereby an efficiency frontier function form with high reliability. In this paper, linear regression, neural network, and support vector machines are used to predict an efficiency frontier. The results have shown that neural networks can predict the efficiency with an error less than 1%, and the linear regression with an error less than 2%.

Sex-specific differences in injury types among basketball players

OpenAIRE

Ito E; Iwamoto J; Azuma K; Matsumoto H

2014-01-01

Eri Ito, Jun Iwamoto, Koichiro Azuma, Hideo MatsumotoInstitute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, JapanAbstract: The purpose of the present study was to investigate sex-specific differences in injury types among basketball players. According to our database, during the 20-year period between October 1991 and June 2011, 1,219 basketball players (640 males and 579 females) consulted our sports medicine clinic; in total, 1,414 injuries in basketball player...

Evaluating and treating neurobehavioral symptoms in professional American football players

Science.gov (United States)

Possin, Katherine L.; Hess, Christopher P.; Huang, Eric J.; Grinberg, Lea T.; Nolan, Amber L.; Cohn-Sheehy, Brendan I.; Ghosh, Pia M.; Lanata, Serggio; Merrilees, Jennifer; Kramer, Joel H.; Berger, Mitchel S.; Miller, Bruce L.; Yaffe, Kristine; Rabinovici, Gil D.

2015-01-01

Summary In the aftermath of multiple high-profile cases of chronic traumatic encephalopathy (CTE) in professional American football players, physicians in clinical practice are likely to face an increasing number of retired football players seeking evaluation for chronic neurobehavioral symptoms. Guidelines for the evaluation and treatment of these patients are sparse. Clinical criteria for a diagnosis of CTE are under development. The contribution of CTE vs other neuropathologies to neurobehavioral symptoms in these players remains unclear. Here we describe the experience of our academic memory clinic in evaluating and treating a series of 14 self-referred symptomatic players. Our aim is to raise awareness in the neurology community regarding the different clinical phenotypes, idiosyncratic but potentially treatable symptoms, and the spectrum of underlying neuropathologies in these players. PMID:26336629

Are squash players protecting their eyes?

Science.gov (United States)

Eime, R M; Finch, C F; Sherman, C A; Garnham, A P

2002-09-01

To determine factors associated with adult squash players' protective eyewear behaviours. A survey of 303 players (aged >or =18 years) was conducted at three squash venues in Melbourne, Australia over a three week period in June 2000 to obtain information about protective eyewear use. Of 303 participants the response rate was 98.1%; 66.1% were males, with a mean age of 40.5 years. The majority (68.4%) had played squash for 10 years or more. Although 18.8% of players reported using protective eyewear, only 8.9% reported wearing approved eyewear. Both age group (peye injuries (50.0%) and knowledge of eye injury risk (33.9%). A commonly reported barrier was restriction of vision (34.2%). These findings demonstrate a low prevalence of voluntary use of appropriate protective eyewear. Future prevention strategies incorporating education campaigns should focus on increasing players' knowledge of risks. The barriers to use and misconceptions about which types of eyewear is most protective need to be addressed as a priority.

Investigating the Nutritional and Recovery Habits of Tennis Players

Directory of Open Access Journals (Sweden)

James A. Fleming

2018-04-01

Full Text Available In this study, the nutritional and recovery habits of tennis players pre-, during, and post-match-play were investigated. Seventy tennis players completed a bespoke nutrition and recovery habits questionnaire, with questions related to the following areas: match preparation, intra-match nutritional habits, situation dependent variables, and post-match nutrition and recovery. On match day-1, the consumption of balanced meals consisting of carbohydrate (CHO, fat and protein, with some micronutrient considerations were reported by 51% of players. On match-days, CHOs were prioritised prior to match-play with CHO dominant meals consumed by the majority of players. During matches, all players adopted a nutritional strategy, with water (94%, banana(s (86% and sports drinks (50% commonly used. Carbohydrate rich nutritional aids, including sports drinks (80% and energy gels (26% were utilised more readily during long matches (>2 h. The day after match-play, 39% of players reported the consumption of “nothing specific”. Multiple post-match recovery strategies were adopted by 80% of players, with foam rolling (77%, ice baths (40%, protein shake intake (37% and hot baths (26% most used. Findings indicate highly variable eating and recovery habits in tennis players pre-, during and post-match-play, with scope for improved practices.

Investigating the Nutritional and Recovery Habits of Tennis Players.

Science.gov (United States)

Fleming, James A; Naughton, Robert J; Harper, Liam D

2018-04-03

In this study, the nutritional and recovery habits of tennis players pre-, during, and post-match-play were investigated. Seventy tennis players completed a bespoke nutrition and recovery habits questionnaire, with questions related to the following areas: match preparation, intra-match nutritional habits, situation dependent variables, and post-match nutrition and recovery. On match day-1, the consumption of balanced meals consisting of carbohydrate (CHO), fat and protein, with some micronutrient considerations were reported by 51% of players. On match-days, CHOs were prioritised prior to match-play with CHO dominant meals consumed by the majority of players. During matches, all players adopted a nutritional strategy, with water (94%), banana(s) (86%) and sports drinks (50%) commonly used. Carbohydrate rich nutritional aids, including sports drinks (80%) and energy gels (26%) were utilised more readily during long matches (>2 h). The day after match-play, 39% of players reported the consumption of "nothing specific". Multiple post-match recovery strategies were adopted by 80% of players, with foam rolling (77%), ice baths (40%), protein shake intake (37%) and hot baths (26%) most used. Findings indicate highly variable eating and recovery habits in tennis players pre-, during and post-match-play, with scope for improved practices.

Does Testosterone Modulate Mood States and Physical Performance in Young Basketball Players?

Science.gov (United States)

Miloski, Bernardo; Aoki, Marcelo S; de Freitas, Camila G; Schultz de Arruda, Ademir F; de Moraes, Helena S; Drago, Gustavo; Borges, Thiago O; Moreira, Alexandre

2015-09-01

This study aimed to examine and compare mood states profile and physical performance during different training phases between 2 groups of adolescent basketball players that were differentiated according to baseline testosterone concentration (T). The basketball players were submitted to an intensified training period (OVL) followed by a tapering period (TP). Twenty-three young male basketball players initiated the study. Experimental criteria data were used to stratify 16 players into high-testosterone (HTC) or low-testosterone (LTC) concentration groups. All the 16 athletes undertook 5 weeks of OVL followed by a 3-week TP. Saliva sampling, Yo-Yo intermittent recovery level 1 (Yo-Yo IRL1) test and the T-test were conducted at the beginning (T1), after OVL (T2), and after TP (T3). A similar increase in internal training load was observed during OVL when compared with TP in both groups (p 0.05); however, LTC displayed a higher score for fatigue (p 0.05). In conclusion, these results suggest that LTC athletes may be more susceptible to changes in mood states during intensified training periods. In addition, data indicate that a periodized training program successfully improved the physical performance (endurance and agility) of young basketball players; however, this improvement was not affected by testosterone level.

Smith predictor-based multiple periodic disturbance compensation for long dead-time processes

Science.gov (United States)

Tan, Fang; Li, Han-Xiong; Shen, Ping

2018-05-01

Many disturbance rejection methods have been proposed for processes with dead-time, while these existing methods may not work well under multiple periodic disturbances. In this paper, a multiple periodic disturbance rejection is proposed under the Smith predictor configuration for processes with long dead-time. One feedback loop is added to compensate periodic disturbance while retaining the advantage of the Smith predictor. With information of the disturbance spectrum, the added feedback loop can remove multiple periodic disturbances effectively. The robust stability can be easily maintained through the rigorous analysis. Finally, simulation examples demonstrate the effectiveness and robustness of the proposed method for processes with long dead-time.

The effects of plyometric training followed by detraining and reduced training periods on explosive strength in adolescent male basketball players.

Science.gov (United States)

Santos, Eduardo J A M; Janeira, Manuel A A S

2011-02-01

The aims of this study were to determine the effects of (a) plyometric training on explosive strength indicators in adolescent male basketball players and (b) detraining and reduced training on previously achieved explosive strength gains. Two groups were formed: an experimental and a control group. The former was submitted to a 10-week in-season plyometric training program, twice weekly, along with regular basketball practice. Simultaneously, the control group participated in regular basketball practice only. At the end of this period, the experimental group was subdivided into 2 groups: a reduced training group and a detraining group. All participants were assessed on squat jump, countermovement jump, Abalakov test, depth jump, mechanical power, and medicine ball throw at the beginning and at the end of the 10-week in-season plyometric training and on weeks 4, 8, 12, and 16 of the in-season detraining and reduced training periods. In the first phase of the study, the experimental group significantly increased all the assessed indicators (p training showed positive effects on upper- and lower-body explosive strength in adolescent male basketball players. Moreover, we can state that both detraining and a reduced training program indistinctly contribute to maintenance of strength levels. These results highlight the unique power that basketball-specific training seems to have on the sustainability and maintenance of sport performance.

Improved nonparametric inference for multiple correlated periodic sequences

KAUST Repository

Sun, Ying; Hart, Jeffrey D.; Genton, Marc G.

2013-01-01

cross-validation method to the temperature data obtained from multiple ice cores, investigating the periodicity of the El Niño effect. Our methodology is also illustrated by estimating patients' cardiac cycle from different physiological signals

Repeated change-of-direction test for collegiate male soccer players.

Science.gov (United States)

Mizuguchi, S; Gray, H; Calabrese, L S; Haff, G G; Sands, W A; Ramsey, M W; Cardinale, M; Stone, M H

2014-08-01

The aim of the study was to investigate the applicability of a repeated change-of-direction (RCoD) test for NCAA Division-I male soccer players. The RCoD test consisted of 5 diagonal direction changes per repetition with a soccer ball to be struck at the end. Each player performed 15 repetitions with approximately 10 seconds to jog back between repetitions. Data were collected in two sessions. In the first session, 13 players were examined for heart rate responses and blood lactate concentrations. In the second session, 22 players were examined for the test's ability to discriminate the primary from secondary players (78.0±16.1 and 10.4±13.3 minutes per match, respectively). Heart rate data were available only from 9 players due to artifacts. The peak heart rate (200.2±6.6 beats∙min-1: 99.9±3.0% maximum) and blood lactate concentration (14.8±2.4 mmol∙L-1 immediately after) resulted in approximately 3.5 and 6.4-fold increases from the resting values, respectively. These values appear comparable to those during intense periods of soccer matches. In addition, the average repetition time of the test was found to discriminate the primary (4.85±0.23 s) from the secondary players (5.10±0.24 s) (P=0.02). The RCoD test appears to induce physiological responses similar to intense periods of soccer matches with respect to heart rate and blood lactate concentration. Players with better average repetition times tend to be those who play major minutes.

Period multiplication and chaotic phenomena in atmospheric dielectric-barrier glow discharges

International Nuclear Information System (INIS)

Wang, Y. H.; Zhang, Y. T.; Wang, D. Z.; Kong, M. G.

2007-01-01

In this letter, evidence of temporal plasma nonlinearity in which atmospheric dielectric-barrier discharges undergo period multiplication and chaos using a one-dimensional fluid model is reported. Under the conditions conducive for chaotic states, several frequency windows are identified in which period multiplication and secondary bifurcations are observed. Such time-domain nonlinearity is important for controlling instabilities in atmospheric glow discharges

An investigation of player to player character identification via personal pronouns

DEFF Research Database (Denmark)

Hichens, Michael; Drachen, Anders; Richards, Deborah

2012-01-01

The player character is an important feature of many games, where it is through the character that the player interacts with game world. There has been considerable interest in the relationship between the player and the player character. Much of this work has examined the identification of players......, third) as an indication of the relationship between player and character. Results indicate that the presence of story and information about the player character had no effect on identification with the plater character. However, characteristics of the players, particularly gender and general experience...... in playing video games, did have a statistically significant affect, indicating that different levels of identification are more dependent on the player than on the game. This indicates that players are not a homogeneous group with respect to player character identification and is an important consideration...

Body Image Amongst Elite Rugby Union Players.

Science.gov (United States)

Gibson, Claire; Hindle, Chloe; McLay-Cooke, Rebecca; Slater, Joanne; Brown, Rachel; Smith, Brett; Baker, Dane; Healey, Philip; Black, Katherine

2017-11-16

There is limited information on the risk of eating disorders and body image of elite male athletes. However, research suggests there are some athletes who have poor body image and they may be at increased risk of developing eating disorders. Therefore, the current study investigated risk of eating disorders, body image, and the relationship with age, in elite rugby union players during their pre-season training period.This cross-sectional study was undertaken at the start of the pre-season amongst elite rugby union players in New Zealand. Twenty-six professional rugby union players completed a 49-item questionnaire on body image and disordered eating. A 'body image score' was calculated from questionnaire subscales including 'drive for thinness', 'bulimia' and 'body dissatisfaction', with total scores above twenty indicative of poor body image.Body image scores varied from 8-39 out of a possible 0-100. Disordered eating behaviours were reported, including binge eating at least once a week (15%, n=4/26), pathogenic weight control use (4%, n=1/26) and avoidance of certain foods (77%, n=20/26). There was a statistically significant inverse association between the bulimia subscale and age (P = 0.034).At the start of the pre-season training period, many elite rugby union players experience disturbances in body image. The prevalence of disordered eating behaviours is of concern, and needs to be minimised due to the negative impact on health and performance. A focus on assessment and education of younger male rugby players may be required in order to reduce disordered eating patterns.

Are squash players protecting their eyes?

OpenAIRE

Eime, R; Finch, C; Sherman, C; Garnham, A

2002-01-01

Methods: A survey of 303 players (aged ≥18 years) was conducted at three squash venues in Melbourne, Australia over a three week period in June 2000 to obtain information about protective eyewear use.

Personality traits and life satisfaction among online game players.

Science.gov (United States)

Chen, Lily Shui-Lien; Tu, Hill Hung-Jen; Wang, Edward Shih-Tse

2008-04-01

The DFC Intelligence predicts worldwide online game revenues will reach $9.8 billion by 2009, making online gaming a mainstream recreational activity. Understanding online game player personality traits is therefore important. This study researches the relationship between personality traits and life satisfaction in online game players. Taipei, Taiwan, is the study location, with questionnaire surveys conducted in cyber cafe shops. Multiple regression analysis studies the causal relationship between personality traits and life satisfaction in online game players. The result shows that neuroticism has significant negative influence on life satisfaction. Both openness and conscientiousness have significant positive influence on life satisfaction. Finally, implications for leisure practice and further research are discussed.

Analysis of football player's motion in view of fractional calculus

Science.gov (United States)

Couceiro, Micael S.; Clemente, Filipe M.; Martins, Fernando M. L.

2013-06-01

Accurately retrieving the position of football players over time may lay the foundations for a whole series of possible new performance metrics for coaches and assistants. Despite the recent developments of automatic tracking systems, the misclassification problem ( i.e., misleading a given player by another) still exists and requires human operators as final evaluators. This paper proposes an adaptive fractional calculus (FC) approach to improve the accuracy of tracking methods by estimating the position of players based on their trajectory so far. One half-time of an official football match was used to evaluate the accuracy of the proposed approach under different sampling periods of 250, 500 and 1000 ms. Moreover, the performance of the FC approach was compared with position-based and velocity-based methods. The experimental evaluation shows that the FC method presents a high classification accuracy for small sampling periods. Such results suggest that fractional dynamics may fit the trajectory of football players, thus being useful to increase the autonomy of tracking systems.

Hip Arthroscopy in High-Level Baseball Players.

Science.gov (United States)

Byrd, J W Thomas; Jones, Kay S

2015-08-01

To report the results of hip arthroscopy among high-level baseball players as recorded by outcome scores and return to baseball. All patients undergoing hip arthroscopy were prospectively assessed with the modified Harris Hip Score. On review of all procedures performed over a 12-year period, 44 hips were identified among 41 intercollegiate or professional baseball players who had achieved 2-year follow-up. Among the 41 players, follow-up averaged 45 months (range, 24 to 120 months), with a mean age of 23 years (range, 18 to 34 years). There were 23 collegiate (1 bilateral) and 18 professional (2 bilateral) baseball players, including 10 Major League Baseball players. Of the 8 Major League Baseball pitchers, 6 (75%) also underwent ulnar collateral ligament elbow surgery. Improvement in the modified Harris Hip Score averaged 13 points (from 81 points preoperatively to 94 points postoperatively); a paired-samples t test determined that this mean improvement of 13 points was statistically significant (P arthroscopy. This study supports the idea that arthroscopic treatment for a variety of hip pathologies in high-level baseball players provides a successful return to sport and improvement in functional outcome scores. Level IV, therapeutic case series. Copyright © 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Individual analysis of creatine kinase concentration in Brazilian elite soccer players

Directory of Open Access Journals (Sweden)

Adriano Lima Alves

2015-04-01

Full Text Available OBJECTIVE: to determine the individual profile of blood concentration of creatine kinase CK in elite soccer players as well as to analyze the CK concentrations in different periods during the Professional Brazilian Championship. METHODS: resting CK of 17 soccer players was evaluated before the competition pre-season and after the matches 36 and 46 hours after the games CKGame for the individual blood CK. The Chi-square test was used to analyze the individual CK during the season. The competitive season was divided into three periods: initial, intermediate and final. The one-way ANOVA with repeated measurements followed by post hoc Student-Newman-Keuls test was used to compare the individual CK of each soccer player in each competitive period. The significance level was set at p<0.05. RESULTS: the highest frequency of individual CK was found in the second quartile 71 observations and the lowest frequency in the first 26 observations and the fourth quartile 40 observations compared to the expected number of 45.8 x2=22.21. CK concentrations were lower in the intermediate mean=66.99% and final mean=60.21% periods than in the initial period mean=89.33%. CONCLUSION: soccer players did not show elevated muscle damage and probably a muscle adaptation occurred in the competition, due to the reduction of CK concentrations observed.

The effects of acute creatine supplementation on multiple sprint cycling and running performance in rugby players.

Science.gov (United States)

Ahmun, Robert P; Tong, Richard J; Grimshaw, Paul N

2005-02-01

The benefits of creatine (CR) supplementation are well documented, particularly during repeated bouts of high-intensity muscular activity. Most published experiments use mass-supported (cycle ergometry) activities as a means of evaluating creatine's efficacy, therefore minimizing any possible adverse effects of increased body mass associated with CR supplementation. This study aims to use both mass-supported and mass-dependent activities to assess the effectiveness of acute CR supplementation on a group of highly trained rugby players. A randomized, double-blind, crossover research design was utilized, with subjects receiving 20 g.d(-1) x 5 d of both CR and a glucose placebo (PL). Subjects were assessed via 10 x 6-second Wingate test and a 10 x 40-m sprint test on separate days, presupplementation and postsupplementation. A 28-d washout period separated the two treatments. No significant treatment (p > 0.05) or treatment by test interaction effects (p > 0.05) were observed for peak or minimum power output (W), peak or minimum running velocity (m.s(-1)), or fatigue index (%). No significant differences (p > 0.05) were found postsupplementation for body mass and percentage body fat. Although statistical significance was not achieved for any of the measured parameters, there were small improvements in performance that may be of benefit to rugby players.

Match Performance and Physiological Capacity of Female Elite Team Handball Players

DEFF Research Database (Denmark)

Michalsik, L B; Madsen, K; Aagaard, Per

2014-01-01

The present study evaluated the physical demands imposed on female elite team handball players in relation to playing position. Female elite team handball field players were examined during match-play over a 5-year period using video based computerized locomotion analysis of tournament matches...

The premenstrual period and exacerbations in multiple sclerosis

NARCIS (Netherlands)

Zorgdrager, A; De Keyser, J

2002-01-01

The aim of this study was to assess whether an association exists between the premenstrual period and exacerbations of multiple sclerosis (MS). The subjects were 56 premenopausal patients with relapsing MS and a regular menstrual cycle. Data over the previous 2 years were gathered from a structured

Spinal mobility and trunk muscle strength in elite hockey players.

Science.gov (United States)

Lindgren, S; Twomey, L

1988-01-01

Elite hockey players of both sexes from the Australian Institute of Sport were assessed for lumbar spine mobility, trunk flexion and back extensor muscle strength, hamstring flexibility and postural characteristics over a two year period. All the athletes were more mobile in rotation than the 'normal' West Australian population, and demonstrated flexible hamstrings and powerful back extensor muscles; trunk flexion was less strong initially, but improved after intervention in the form of a specific exercise programme, over the measurement period. A questionnaire disclosed that low back pain is a common complaint of hockey players, but rarely required intensive physical and medical treatment. The term 'hockey player's back' has been coined in recognition of the long flat thoracolumbar spine frequently noted in these subjects. Copyright © 1988 Australian Physiotherapy Association. Published by . All rights reserved.

The NBA’s Maximum Player Salary and the Distribution of Player Rents

Directory of Open Access Journals (Sweden)

Kelly M. Hastings

2015-03-01

Full Text Available The NBA’s 1999 Collective Bargaining Agreement (CBA included provisions capping individual player pay in addition to team payrolls. This study examines the effect the NBA’s maximum player salary on player rents by comparing player pay from the 1997–1998 and 2003–2004 seasons while controlling for player productivity and other factors related to player pay. The results indicate a large increase in the pay received by teams’ second highest and, to a lesser extent, third highest paid players. We interpret this result as evidence that the adoption of the maximum player salary shifted rents from stars to complementary players. We also show that the 1999 CBA’s rookie contract provisions reduced salaries of early career players.

Sex-specific differences in injury types among basketball players.

Science.gov (United States)

Ito, Eri; Iwamoto, Jun; Azuma, Koichiro; Matsumoto, Hideo

2015-01-01

The purpose of the present study was to investigate sex-specific differences in injury types among basketball players. According to our database, during the 20-year period between October 1991 and June 2011, 1,219 basketball players (640 males and 579 females) consulted our sports medicine clinic; in total, 1,414 injuries in basketball players (729 injuries in males and 685 injuries in females) were recorded. The mean age of patients was 19.6 years. The most common injury site was the knee, followed by the foot and ankle, lower back, and upper extremities. There was a higher proportion of female players presenting with a knee injury, compared with male players (50.4% vs 41.7%), and a lower proportion of female players presenting with an upper extremity injury (5.1% vs 9.7%). The proportion of anterior cruciate ligament injury in the 10-19-year-old age group was higher among female players than among male players (45.9% vs 22.1%), while the proportions of Osgood-Schlatter disease in the 10-19-year-old age group and jumper's knee (patellar and femoral tendinopathy) in the 20-29-year-old age group were higher among male players than among female players (12.5% vs 1.8% and 14.6% vs 3.7%, respectively). However, the proportions of other injuries did not differ significantly between male and female players. The present observational study, which was performed using a retrospective case-series design, showed the existence of sex-specific differences in knee injuries sustained while participating in basketball.

Multiparametric MRI changes persist beyond recovery in concussed adolescent hockey players

Science.gov (United States)

Manning, Kathryn Y.; Schranz, Amy; Bartha, Robert; Dekaban, Gregory A.; Barreira, Christy; Brown, Arthur; Fischer, Lisa; Asem, Kevin; Doherty, Timothy J.; Fraser, Douglas D.; Holmes, Jeff

2017-01-01

Objective: To determine whether multiparametric MRI data can provide insight into the acute and long-lasting neuronal sequelae after a concussion in adolescent athletes. Methods: Players were recruited from Bantam hockey leagues in which body checking is first introduced (male, age 11–14 years). Clinical measures, diffusion metrics, resting-state network and region-to-region functional connectivity patterns, and magnetic resonance spectroscopy absolute metabolite concentrations were analyzed from an independent, age-matched control group of hockey players (n = 26) and longitudinally in concussed athletes within 24 to 72 hours (n = 17) and 3 months (n = 14) after a diagnosed concussion. Results: There were diffusion abnormalities within multiple white matter tracts, functional hyperconnectivity, and decreases in choline 3 months after concussion. Tract-specific spatial statistics revealed a large region along the superior longitudinal fasciculus with the largest decreases in diffusivity measures, which significantly correlated with clinical deficits. This region also spatially intersected with probabilistic tracts connecting cortical regions where we found acute functional connectivity changes. Hyperconnectivity patterns at 3 months after concussion were present only in players with relatively less severe clinical outcomes, higher choline concentrations, and diffusivity indicative of relatively less axonal disruption. Conclusions: Changes persisted well after players' clinical scores had returned to normal and they had been cleared to return to play. Ongoing white matter maturation may make adolescent athletes particularly vulnerable to brain injury, and they may require extended recovery periods. The consequences of early brain injury for ongoing brain development and risk of more serious conditions such as second impact syndrome or neural degenerative processes need to be elucidated. PMID:29070666

Player-Character Dynamics in Multi- Player Role Playing Games

DEFF Research Database (Denmark)

Tychsen, Anders; McIlwain, D.; Brolund, T.

2007-01-01

This paper presents the results of a comprehensive empirical study of the impact of integrating complex game characters in multi-player Role Playing Games across tabletop and digital formats. Players were provided with characters that had detailed background history, personality and goals. Player...

A four year prospective study of injuries in elite Ontario youth provincial and national soccer players during training and matchplay

Science.gov (United States)

Mohib, Milad; Moser, Nicholas; Kim, Richard; Thillai, Maathavan; Gringmuth, Robert

2014-01-01

Introduction: With over 200 million amateur players worldwide, soccer is one of the most popular and internationally recognized sports today. By understanding how and why soccer injuries occur we hope to reduce prevalent injuries amongst elite soccer athletes. Methods: Via a prospective cohort, we examined both male and female soccer players eligible to train with the Ontario Soccer Association provincial program between the ages of 13 to 17 during the period of October 10, 2008 and April 20, 2012. Data collection occurred during all player exposures to potential injury. Exposures occurred at the Soccer Centre, Ontario Training grounds and various other venues on multiple playing surfaces. Results: A total number of 733 injuries were recorded. Muscle strain, pull or tightness was responsible for 45.6% of all injuries and ranked as the most prevalent injury. Discussion: As anticipated, the highest injury reported was muscular strain, which warrants more suitable preventive programs aimed at strengthening and properly warming up the players’ muscles. PMID:25550661

Risk Factors for Injuries in Professional Football Players.

Science.gov (United States)

Haxhiu, Bekim; Murtezani, Ardiana; Zahiti, Bedri; Shalaj, Ismet; Sllamniku, Sabit

2015-01-01

The aim of this study was to identify risk factors related to the occurrence of injuries in football players. The study included 216 football players from 12 teams in the elite football league. Football-related injury data were collected prospectively during the 2012/2013 competitive season. At baseline the following information was collected for the players: anthropometric measurements (weight, height, BMI, subcutaneous skinfolds), playing experience, injury history, physical fitness performance test (agility run), peak oxygen uptake. The incidence, type and severity of injuries and training and game exposure times were prospectively documented for each player. Most of the players (n = 155, 71.7%) sustained the injures during the study period. The overall injury incidence during the regular season was 6.3 injuries per 1000 athlete-exposures (95% confidence interval, 4.31-9.67). Multivariate logistic regression analysis showed that playing experience (odds ratio [OR] = 0.44; 95% CI = 0.32-0.61, p football for more than 1 month, with knee injuries (25.42%) being the most severe type. The risk factors that increase injury rates in football players were previous injury, higher age and years of playing. Future research should include adequate rehabilitation program to reduce the risk of injuries.

Security Hi-tech Individual Extra-light Device Mask: a new protection for [soccer] players.

Science.gov (United States)

Cascone, Piero; Petrucci, Bernardino; Ramieri, Valerio; Marianetti, Titto Matteo; TitoMatteo, Marianetti

2008-05-01

Among professional [soccer] players, a relevant incidence of maxillofacial trauma has been reported. The main challenge in these particular patients is to give them the possibility of a very short convalescence period and to make possible their agonistic activity as soon as possible. The authors here present an innovative technique to realize this--the Security Hi-tech Individual Extra-Light Device Mask, a customizable protective shield based on the player's face cast. A completely customized mask was forged over the player's face cast to protect the injured area. This mask shortens convalescence period, and due to its realization, it is comfortable and easy fitting, thus allowing the player to perform at a professional level in his sport activity in the shortest time possible.

FMRI hypoactivation during verbal learning and memory in former high school football players with multiple concussions.

Science.gov (United States)

Terry, Douglas P; Adams, T Eric; Ferrara, Michael S; Miller, L Stephen

2015-06-01

Multiple concussions before the age of 18 may be associated with late-life memory deficits. This study examined neural activation associated with verbal encoding and memory retrieval in former athletes ages 40-65 who received at least two concussions (median = 3; range = 2-15) playing high school football and a group of former high school football players with no reported history of concussions matched on age, education, and pre-morbid IQ. Functional magnetic resonance imaging data collected during a modified verbal paired associates paradigm indicated that those with concussive histories had hypoactivation in left hemispheric language regions, including the inferior/middle frontal gyri and angular gyrus compared with controls. However, concussive history was not associated with worse memory functioning on neuropsychological tests or worse behavioral performance during the paradigm, suggesting that multiple early-life concussions may be associated with subtle changes in the verbal encoding system that limits one from accessing higher-order semantic networks, but this difference does not translate into measurable cognitive performance deficits. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Sex-specific differences in injury types among basketball players

Directory of Open Access Journals (Sweden)

Ito E

2014-12-01

Full Text Available Eri Ito, Jun Iwamoto, Koichiro Azuma, Hideo MatsumotoInstitute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, JapanAbstract: The purpose of the present study was to investigate sex-specific differences in injury types among basketball players. According to our database, during the 20-year period between October 1991 and June 2011, 1,219 basketball players (640 males and 579 females consulted our sports medicine clinic; in total, 1,414 injuries in basketball players (729 injuries in males and 685 injuries in females were recorded. The mean age of patients was 19.6 years. The most common injury site was the knee, followed by the foot and ankle, lower back, and upper extremities. There was a higher proportion of female players presenting with a knee injury, compared with male players (50.4% vs 41.7%, and a lower proportion of female players presenting with an upper extremity injury (5.1% vs 9.7%. The proportion of anterior cruciate ligament injury in the 10–19-year-old age group was higher among female players than among male players (45.9% vs 22.1%, while the proportions of Osgood–Schlatter disease in the 10–19-year-old age group and jumper's knee (patellar and femoral tendinopathy in the 20–29-year-old age group were higher among male players than among female players (12.5% vs 1.8% and 14.6% vs 3.7%, respectively. However, the proportions of other injuries did not differ significantly between male and female players. The present observational study, which was performed using a retrospective case-series design, showed the existence of sex-specific differences in knee injuries sustained while participating in basketball.Keywords: sports injury, sex, anterior cruciate ligament injury, Osgood–Schlatter disease, basketball

Multiple Criteria and Multiple Periods Performance Analysis: The Comparison of North African Railways

Science.gov (United States)

Sabri, Karim; Colson, Gérard E.; Mbangala, Augustin M.

2008-10-01

Multi-period differences of technical and financial performances are analysed by comparing five North African railways over the period (1990-2004). A first approach is based on the Malmquist DEA TFP index for measuring the total factors productivity change, decomposed into technical efficiency change and technological changes. A multiple criteria analysis is also performed using the PROMETHEE II method and the software ARGOS. These methods provide complementary detailed information, especially by discriminating the technological and management progresses by Malmquist and the two dimensions of performance by Promethee: that are the service to the community and the enterprises performances, often in conflict.

Drinking by professional Australian Football League (AFL) players: prevalence and correlates of risk.

Science.gov (United States)

Dietze, Paul M; Fitzgerald, John L; Jenkinson, Rebecca A

2008-11-03

To examine self-reported patterns of alcohol consumption and experience of alcohol-related harms among professional Australian Football League (AFL) players. Cross-sectional survey of player alcohol consumption and self-reported alcohol-related harms among members of all 16 professional AFL clubs. Data relating to the 2006 football year were collected between 25 July and 30 August 2006 at regular football training sessions using a self-administered structured questionnaire. Risky/high-risk drinking for long- and short-term harm at different times of the year; Alcohol Use Disorders Identification Test (AUDIT) score. 582 AFL players completed the questionnaire (an 83% response rate). Alcohol consumption varied at different times of the year. During the playing season (approximately 22 weeks), the level of risky/high-risk consumption for long-term harm in AFL players (11/564 [2%]) was typically lower than in age-matched Australian men in the general population (15%). However, risky/high-risk consumption for long-term harm was higher in AFL players during the end-of-season period (approximately 2 weeks) (303/561 [54%]) and vacation period (6-8 weeks) (231/559 [41%]) than in age-matched Australian men. Risky/high-risk drinking for short-term harm on a monthly basis was frequent at all times of the year (eg, 395/560 [71%] in the pre-season period). The mean AUDIT score was 8.8 (95% CI, 8.4 to 9.1; range, 0 to 36). Reports of harmful effects of drinking and negative consequences, such as getting involved in a fight (physical or verbal) while drinking (146/556 [26%]), were common. Risky/high-risk consumption for short-term harm on a monthly basis was associated with a variety of player characteristics, such as usually drinking in public locations (odds ratio, 1.55 [95% CI, 1.02 to 2.35]). AUDIT score was associated with variables such as marital status, with married players scoring more than two points lower (95% CI, - 3.58 to - 0.58) than single players. Formal club rules

Speed and countermovement-jump characteristics of elite female soccer players, 1995-2010.

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Haugen, Thomas A; Tønnessen, Espen; Seiler, Stephen

2012-12-01

The purpose of this investigation was to compare sprint and countermovement-jump (CMJ) performance among female competitive soccer players as a function of performance level, field position, and age. In addition, the authors wanted to quantify the evolution of these physical characteristics among elite players over a 15-y period. 194 female elite players (22± 4.1 y, 63 ± 5.6 kg), including an Olympic winning squad, tested 40-m sprint with electronic timing and CMJ on a force platform at the Norwegian Olympic training center from 1995 to 2010. Moderate to large velocity differences across performance levels and positions were observed. National-team players were 2% faster than 1st-division players (P = .027, d = 0.5) and 5% faster than 2nd-division players (P players jumped 8-9% higher than 1st-division players (P = .001, d = 0.6) and junior elite players (P = .023, d = 0.5). Forwards were 3-4% faster than midfielders (P Players from 2006-2010 were 2% faster (P players from 1995-1999 over 20 m, whereas no differences in 20- to 40-m velocity or CMJ performance were observed. This study provides effect-magnitude estimates for the influence of performance level, age, and player position on sprint and CMJ performance in female soccer players. While 20- to 40-m velocity and CMJ performance have remained stable over the time, there has been a moderate but positive development in 0- to 20-m velocity among elite performers.

Prevalent morphometric vertebral fractures in professional male rugby players.

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Karen Hind

Full Text Available There is an ongoing concern about the risk of injury to the spine in professional rugby players. The objective of this study was to investigate the prevalence of vertebral fracture using vertebral fracture assessment (VFA dual energy X-ray absorptiometry (DXA imaging in professional male rugby players. Ninety five professional rugby league (n = 52 and union (n = 43 players (n = 95; age 25.9 (SD 4.3 years; BMI: 29.5 (SD 2.9 kg.m2 participated in the research. Each participant received one VFA, and one total body and lumbar spine DXA scan (GE Lunar iDXA. One hundred and twenty vertebral fractures were identified in over half of the sample by VFA. Seventy four were graded mild (grade 1, 40 moderate (grade 2 and 6 severe (grade 3. Multiple vertebral fractures (≥2 were found in 37 players (39%. There were no differences in prevalence between codes, or between forwards and backs (both 1.2 v 1.4; p>0.05. The most common sites of fracture were T8 (n = 23, T9 (n = 18 and T10 (n = 21. The mean (SD lumbar spine bone mineral density Z-score was 2.7 (1.3 indicating high player bone mass in comparison with age- and sex-matched norms. We observed a high number of vertebral fractures using DXA VFA in professional rugby players of both codes. The incidence, aetiology and consequences of vertebral fractures in professional rugby players are unclear, and warrant timely, prospective investigation.

The Anthropometric Characteristics of Futsal Players Compared with Professional Soccer Players

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Burdukiewicz Anna

2014-08-01

Full Text Available Purpose. The aim of the study was to compare the morphological characteristics of experienced futsal players with professional soccer players. Methods. The research sample included 22 university futsal players and 22 professional soccer players. Parameters including body height and mass, skinfold thicknesses of the trunk and extremities, lower limb length, trunk width, humerus and femur bone breadths, and the circumferences of the chest, hips, thighs, and calves were used to calculate various somatic indices. Somatotyping was performed using the Heath–carter method. Differences in the characteristics between the futsal and soccer players were analyzed using Student’s t test. Intragroup analysis was also performed on futsal players depending on player position and compared with the arithmetic means and standard deviations of all variables of the entire sample. Results. compared with their soccer-playing peers, the futsal players were shorter, weighed less, had shorter lower limbs, narrower hips, and smaller hip circumference and bone breadth values. In contrast, higher levels of body fat and endomorphy were noted in this group. The proportion of mesomorphs and ectomorphs were similar in both groups. Futsal goalkeepers were differentiated by greater subcutaneous adiposity and body mass. Defenders had the slimmest body shape, with relatively narrower shoulders and hips, smaller bone breadths, and lower levels of adiposity. The body build of wingers was slightly larger. Pivoters were characterized by greater body height and larger values for the characteristics measuring the lateral trunk dimensions. Conclusions. The observed morphological differences between futsal and soccer players were mainly in body height and height-associated characteristics. This indicates that no specialized approach in futsal recruitment is currently used. This points to the need to develop a specialized approach in the player recruitment stage, as the tactical and

Multiple Off-Ice Performance Variables Predict On-Ice Skating Performance in Male and Female Division III Ice Hockey Players

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effrey M. Janot, Nicholas M. Beltz, Lance D. Dalleck

2015-09-01

Full Text Available The purpose of this study was to determine if off-ice performance variables could predict on-ice skating performance in Division III collegiate hockey players. Both men (n = 15 and women (n = 11 hockey players (age = 20.5 ± 1.4 years participated in the study. The skating tests were agility cornering S-turn, 6.10 m acceleration, 44.80 m speed, modified repeat skate, and 15.20 m full speed. Off-ice variables assessed were years of playing experience, height, weight and percent body fat and off-ice performance variables included vertical jump (VJ, 40-yd dash (36.58m, 1-RM squat, pro-agility, Wingate peak power and peak power percentage drop (% drop, and 1.5 mile (2.4km run. Results indicated that 40-yd dash (36.58m, VJ, 1.5 mile (2.4km run, and % drop were significant predictors of skating performance for repeat skate (slowest, fastest, and average time and 44.80 m speed time, respectively. Four predictive equations were derived from multiple regression analyses: 1 slowest repeat skate time = 2.362 + (1.68 x 40-yd dash time + (0.005 x 1.5 mile run, 2 fastest repeat skate time = 9.762 - (0.089 x VJ - (0.998 x 40-yd dash time, 3 average repeat skate time = 7.770 + (1.041 x 40-yd dash time - (0.63 x VJ + (0.003 x 1.5 mile time, and 4 47.85 m speed test = 7.707 - (0.050 x VJ - (0.01 x % drop. It was concluded that selected off-ice tests could be used to predict on-ice performance regarding speed and recovery ability in Division III male and female hockey players.

Cognitive pitfall! Videogame players are not immune to dual-task costs.

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Donohue, Sarah E; James, Brittany; Eslick, Andrea N; Mitroff, Stephen R

2012-07-01

With modern technological advances, we often find ourselves dividing our attention between multiple tasks. While this may seem a productive way to live, our attentional capacity is limited, and this yields costs in one or more of the many tasks that we try to do. Some people believe that they are immune to the costs of multitasking and commonly engage in potentially dangerous behavior, such as driving while talking on the phone. But are some groups of individuals indeed immune to dual-task costs? This study examines whether avid action videogame players, who have been shown to have heightened attentional capacities, are particularly adept multitaskers. Participants completed three visually demanding experimental paradigms (a driving videogame, a multiple-object-tracking task, and a visual search), with and without answering unrelated questions via a speakerphone (i.e., with and without a dual-task component). All of the participants, videogame players and nonvideogame players alike, performed worse while engaging in the additional dual task for all three paradigms. This suggests that extensive videogame experience may not offer immunity from dual-task costs.

Prospective Player-Reported Injuries in Female Youth Fast-Pitch Softball Players.

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Smith, Matthew V; Davis, Randi; Brophy, Robert H; Prather, Heidi; Garbutt, Jane; Wright, Rick W

2015-01-01

There is a scarcity of literature evaluating injuries in youth fast-pitch softball players. To perform a descriptive analysis of player-reported injuries in youth fast-pitch softball position players and pitchers during a single select-level season. Prospective observation cohort study. Level 3. Ninety-eight athletes (48 pitchers, 50 position players) were followed for a single select fast-pitch softball season. Study participants completed web-based surveys every 3 weeks reporting injuries related to participation in fast-pitch softball. Injury was defined as pain causing cessation of participation in the current game or practice that prevents the player's return to that session or any pain that causes cessation of a player's customary participation on the day after the day of onset. The median age of the study participants was 14 years (range, 9-18 years). There were 49 reported injuries in 98 athletes. The average age was 13 years for those not injured and 14 years for those who were injured (P softball players. Better off-season and preseason conditioning may be a key factor for reducing pitching injuries. Recognition of injury patterns in fast-pitch softball players is critical to developing strategies to keep these athletes competing safely. © 2015 The Author(s).

Association Between History of Multiple Concussions and Health Outcomes Among Former College Football Players: 15-Year Follow-up From the NCAA Concussion Study (1999-2001).

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Kerr, Zachary Y; Thomas, Leah C; Simon, Janet E; McCrea, Michael; Guskiewicz, Kevin M

2018-06-01

Previous research has examined associations between concussion history and adverse health outcomes among former professional football players. Less is known about the potential effects of concussion among former college football players without additional exposure at the professional level. To examine the association between concussion and adverse health outcomes in a cohort of former college football players without exposure to professional football, 15 years after their playing careers ended. Cross-sectional study; Level of evidence, 3. A sample of 204 former collegiate football players (23.4% of eligible athletes with available contact information)-all of whom played at least 1 season of football from 1999 to 2001 in the National Collegiate Athletic Association (NCAA) and had no professional football exposure-completed a general health survey that assessed lifetime concussion history and included the following: the Veterans RAND 36 Item Health Survey, containing a physical composite score (PCS) and mental composite score (MCS); the depression module of the Patient Health Questionnaire; and the 4-item CAGE alcohol dependence questionnaire (for "cutting down, annoyance by criticism, guilty feeling, and eye-openers"). Multivariable binomial regression models estimated adjusted prevalence ratios (PRs) with 95% CIs while controlling for demographics and playing history covariates through forward selection model building. Most participants reported a concussion history (84.3%). Overall, 22.1% and 39.2% of participants reported a PCS and an MCS history of multiple concussions and adverse health outcomes were found among former collegiate football players without professional football exposure but were limited to those reporting ≥3 prior concussions. Because only 23.4% of eligible athletes responded to the survey, the possibility of ascertainment bias exists, and our findings should thus be interpreted with some caution. Continued examination within nonprofessional

Investigation on the Effects of 12 Days Intensive Competition on Some Blood Parameters of Basketball Players

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Gencer, Yildirim Gokhan; Coskun, Funda; Sarikaya, Mucahit; Kaplan, Seyhmus

2018-01-01

The aim of this study is to investigate the effect of intensive basketball competitions (10 official basketball games in 12 days intensive competition period) on blood parameters of basketball players. Blood samples were taken from the basketball players of the university team. The players were training regularly and they had no regular health…

PARTICIPATION OF MINI-BASKETBALL PLAYERS DURING SMALL-SIDED COMPETITIONS

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M\\u00AA Isabel Pi\\u00F1ar

2009-01-01

Full Text Available This study presents the differences of competition between mini-basketball with the traditional rules (5-a-side and minibasket with rule modifications (3-a-side such as: reduced number of players on court, compulsory participation in 2 of the match's 4 periods, reduced court size, placing the free throw line at 3m from the basket, and including a three-point line. The sample that was selected included 47 mini-basketball players, and the study was carried out using a quasi-experimental design without a control group. The aim was to determine the effect of rule modifications on the participation of the player with the ball. It was demonstrated that the degree of individual participation is greater in mini-basketball with modified rules.

Absence of chronic traumatic encephalopathy in retired football players with multiple concussions and neurological symptomatology

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Hazrati, Lili-Naz; Tartaglia, Maria C.; Diamandis, Phedias; Davis, Karen D.; Green, Robin E.; Wennberg, Richard; Wong, Janice C.; Ezerins, Leo; Tator, Charles H.

2013-01-01

Background: Chronic traumatic encephalopathy (CTE) is the term coined for the neurodegenerative disease often suspected in athletes with histories of repeated concussion and progressive dementia. Histologically, CTE is defined as a tauopathy with a distribution of tau-positive neurofibrillary tangles (NFTs) that is distinct from other tauopathies, and usually shows an absence of beta-amyloid deposits, in contrast to Alzheimer's disease (AD). Although the connection between repeated concussions and CTE-type neurodegeneration has been recently proposed, this causal relationship has not yet been firmly established. Also, the prevalence of CTE among athletes with multiple concussions is unknown. Methods: We performed a consecutive case series brain autopsy study on six retired professional football players from the Canadian Football League (CFL) with histories of multiple concussions and significant neurological decline. Results: All participants had progressive neurocognitive decline prior to death; however, only 3 cases had post-mortem neuropathological findings consistent with CTE. The other 3 participants had pathological diagnoses of AD, amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD). Moreover, the CTE cases showed co-morbid pathology of cancer, vascular disease, and AD. Discussion: Our case studies highlight that not all athletes with history of repeated concussions and neurological symptomology present neuropathological changes of CTE. These preliminary findings support the need for further research into the link between concussion and CTE as well as the need to expand the research to other possible causes of taupathy in athletes. They point to a critical need for prospective studies with good sampling methods to allow us to understand the relationship between multiple concussions and the development of CTE. PMID:23745112

Absence of chronic traumatic encephalopathy in retired football players with multiple concussions and neurological symptomatology

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Lili-Naz eHazrati

2013-05-01

Full Text Available Background: Chronic traumatic encephalopathy (CTE is the term coined for the neurodegenerative disease often suspected in athletes with histories of repeated concussion and progressive dementia. Histologically, CTE is defined as a tauopathy with a distribution of tau-positive neurofibrillary tangles that is distinct from other tauopathies, and usually shows an absence of beta-amyloid deposits, in contrast to Alzheimer’s disease. Although the connection between repeated concussions and CTE-type neurodegeneration has been recently proposed, this causal relationship has not yet been firmly established. Also, the prevalence of CTE among athletes with multiple concussions is unknown. Methods: We performed a consecutive case series brain autopsy study on six retired professional football players from the Canadian Football League with histories of multiple concussions and significant neurological decline. Results: All participants had progressive neurocognitive decline prior to death; however, only 3 cases had post-mortem neuropathological findings consistent with CTE. The other 3 participants had pathological diagnoses of Alzheimer’s disease, amyotrophic lateral sclerosis and Parkinson’s disease. Moreover, the CTE cases showed co-morbid pathology of cancer, vascular disease and Alzheimer’s disease. Discussion: Our case studies highlight that not all athletes with history of repeated concussions and neurological symptomalogy present neuropathological changes of CTE. These preliminary findings support the need for further research into the link between concussion and CTE as well as the need to expand the research to other possible causes of taupathy in athletes. They point to a critical need for prospective studies with good sampling methods to allow us to understand the relationship between multiple concussions and the development of CTE.

Physical and physiological profiles of Boland netball players

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Netball, as a team sport, is an interval- ... intensity, short bursts of movement and less intense recovery periods. ... tiveness of a training programme can be evaluated. Feedback ..... the Boland players also had a higher body fat percentage than.

EFFECTS OF PLYOMETRIC TRAINING ON THE MOTOR ABILITIES OF TENNIS PLAYERS

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Miroslav Smajić

2015-05-01

Full Text Available Plyometrics is a training method that uses an overload (Chu, 1983, and the main purpose of plyometric training is the development of greater reactive force (Allerheiligen & Rogers, 1995. Sports physiologists agree that plyometrics includes specific exercises that cause significant stretching of muscles located below the eccentric contraction, and followed by a strong concentric contraction, which is used for the development of a strong movement in a short period of time (LaChance, 1995. The aim of the research is to identify and analyze the transformative effects of plyometric exercise program on the manifest dimension of strength, agility and speed running experimental group of players. Methods: The sample consisted of 50 players were aged 17.5 years (± 6 months, who were divided into two groups. One group consisted of 25 tennis players TK “Gemaks” from Belgrade who represented the experimental group, while the second group included 25 tennis players TK “AS” from Belgrade who represented the control group. For evaluation of motor abilities used 4 tests. In order to determine differences between groups of respondents in the initial and final measurement was applied univariate analysis of variance. In order to determine the effect of training programs between the two tests was applied univariate analysis of covariance. Results: This research has proven that plyometric training, which was applied to a group of tennis players from Belgrade for a period of three months, youth ages contributed to improving their motor abilities, primarily explosive strength and agility. Discussion: Practice plyometric program combined with regular training for the development and improvement of techniques tennis game showed excellent results in order to improve the explosive leg strength, agility tennis players eksperimenatlne groups, and proved to be positive in working with junior tennis players ages. Research have shown that the development of explosive

Adding Fish Oil to Whey Protein, Leucine, and Carbohydrate Over a Six-Week Supplementation Period Attenuates Muscle Soreness Following Eccentric Exercise in Competitive Soccer Players.

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Philpott, Jordan D; Donnelly, Chris; Walshe, Ian H; MacKinley, Elizabeth E; Dick, James; Galloway, Stuart D R; Tipton, Kevin D; Witard, Oliver C

2018-01-01

Soccer players often experience eccentric exercise-induced muscle damage given the physical demands of soccer match-play. Since long chain n-3 polyunsaturated fatty acids (n-3PUFA) enhance muscle sensitivity to protein supplementation, dietary supplementation with a combination of fish oil-derived n-3PUFA, protein, and carbohydrate may promote exercise recovery. This study examined the influence of adding n-3PUFA to a whey protein, leucine, and carbohydrate containing beverage over a six-week supplementation period on physiological markers of recovery measured over three days following eccentric exercise. Competitive soccer players were assigned to one of three conditions (2 × 200 mL): a fish oil supplement beverage (FO; n = 10) that contained n-3PUFA (1100 mg DHA/EPA-approximately 550 mg DHA, 550 mg EPA), whey protein (15 g), leucine (1.8 g), and carbohydrate (20 g); a protein supplement beverage (PRO; n = 10) that contained whey protein (15 g), leucine (1.8 g), and carbohydrate (20 g); and a carbohydrate supplement beverage (CHO; n = 10) that contained carbohydrate (24 g). Eccentric exercise consisted of unilateral knee extension/flexion contractions on both legs separately. Maximal force production was impaired by 22% during the 72-hour recovery period following eccentric exercise (p recovery, was less in FO (1948 ± 1091 mm × 72 h) than PRO (4640 ± 2654 mm × 72 h, p soccer performance, or blood c-reactive protein concentrations were observed between groups. In conclusion, the addition of n-3PUFA to a beverage containing whey protein, leucine, and carbohydrate ameliorates the increase in muscle soreness and blood concentrations of creatine kinase following eccentric exercise in competitive soccer players.

One-Year Prospective Study on Passion and Gambling Problems in Poker Players.

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Morvannou, Adèle; Dufour, Magali; Brunelle, Natacha; Berbiche, Djamal; Roy, Élise

2018-06-01

The concept of passion is relevant to understanding gambling behaviours and gambling problems. Longitudinal studies are useful to better understand the absence and development of gambling problems; however, only one study has specifically considered poker players. Using a longitudinal design, this study aims to determine the influence, 1 year later, of two forms of passion-harmonious and obsessive-on gambling problems in poker players. A total of 116 poker players was recruited from across Quebec, Canada. The outcome variable of interest was participants' category on the Canadian Pathological Gambling Index, and the predictive variable was the Gambling Passion Scale. Multiple logistic regression analyses were conducted to identify independent risk factors of at-risk poker players 1 year later. Obsessive passion at baseline doubled the risk of gambling problems 1 year later (p passion, there was no association. Number of gambling activities, drug problems, and impulsivity were also associated with at-risk gambling. This study highlights the links between obsessive passion and at-risk behaviours among poker players. It is therefore important to prevent the development of obsessive passion among poker players.

Morphological and maturational predictors of technical performance in young soccer players

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Marcelo de Oliveira Matta

2014-09-01

Full Text Available The purpose of the present study is to describe the association between chronological age, morphology, biological maturation and sport experience in relation to technical performance in young Brazilian soccer players. Technical, maturation and anthropometric variables were assessed in 119 soccer players, 74 and 45 in the under-15 and under-17 categories, respectively. Data were analyzed using a multiple linear regression model. Adiposity was negatively associated with technical performance regardless the age-category. Weight was negatively associated with technical performance in under-15 and positively with the under-17 category, respectively. In under-17 biological maturation was negatively related to the dribbling test and positively associated with the ball control test. Years of experience proved to be positively associated with technique taught to soccer player in the under-17 category. The explained variance was different between categories. The technical performance of Brazilian soccer players aged 14-to-17 seems to be related to biological maturation, adiposity, weight and years of experience.

Preseason physiological profile of soccer and basketball players in different divisions.

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Metaxas, Thomas I; Koutlianos, Nikos; Sendelides, Thomas; Mandroukas, Athanasios

2009-09-01

The purpose of this study was to examine and compare the cardiorespiratory performance and isokinetic muscle strength between Greek soccer and basketball players of different divisions before starting the training season. Study participants included 100 soccer players and 61 basketball players, who were assigned according to the kind of sport and division. All participants underwent anthropometric measurements and performed an exercise test on a treadmill to determine maximal oxygen uptake (VO2max). Peak torque for quadriceps and hamstring muscles was measured on isokinetic dynamometer at angular velocity of 60 degrees/s(-1), 180 degrees/s(-1), and 300 degrees/s(-1). The statistical p value was set at p duration of the maintenance period and to the effect of the training session on each sport, respectively. Finally, a higher level of muscle strength would be preferable in soccer and basketball and would reduce the risk for injuries in the maintenance and rebuilding training periods.

Effect of A 16 Week Combined Strength and Plyometric Training Program Followed by A Detraining Period on Athletic Performance in Pubertal Volleyball Players.

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Fathi, Abed; Hammami, Raouf; Moran, Jason; Borji, Rihab; Sahli, Sonia; Rebai, Haithem

2018-02-01

The purpose of this study was to determine the effects of 16 weeks of combined strength and plyometric training or plyometric training alone, and how a detraining program can modify adaptations in response to the training stimulus. Sixty male volleyball players (circa PHV:-1 to +1 years from PHV) were assigned to a Combined Training group (CTG) (n=20), a Plyometric Training group (PTG) (n=20) or a control group (CG) (n=20). The experimental groups (CTG and PTG) participated in training twice weekly for 16 weeks. Thigh muscle volume, body fat, flexibility, sprint, jump height and medicine ball throw were measured at pre-training, post-training and detraining. Respectively, the CTG and PTG showed increases in thigh muscle volume (Effect size: 0.71 and 0.42), and decreases in body fat (-0.42 and -0.34) as well as improvements in 5 m sprint (-0.69 and -0.46) 10 m sprint (-0.31 and -0.3), lower body muscle power (0.44 and 0.36) and upper body muscle power (1.32 and 0.7). After the detraining period, all groups maintained previously attained muscle power (6.79% to 9.87%; pplyometric training provided better improvements than plyometric training only. The combination of strength and plyometric training is a time-effective training modality that confers improvements in physical performance measures, muscle size and body fat. A temporary period of detraining may not undermine performance gains in pubertal volleyball players.

Violent video game players and non-players differ on facial emotion recognition.

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Diaz, Ruth L; Wong, Ulric; Hodgins, David C; Chiu, Carina G; Goghari, Vina M

2016-01-01

Violent video game playing has been associated with both positive and negative effects on cognition. We examined whether playing two or more hours of violent video games a day, compared to not playing video games, was associated with a different pattern of recognition of five facial emotions, while controlling for general perceptual and cognitive differences that might also occur. Undergraduate students were categorized as violent video game players (n = 83) or non-gamers (n = 69) and completed a facial recognition task, consisting of an emotion recognition condition and a control condition of gender recognition. Additionally, participants completed questionnaires assessing their video game and media consumption, aggression, and mood. Violent video game players recognized fearful faces both more accurately and quickly and disgusted faces less accurately than non-gamers. Desensitization to violence, constant exposure to fear and anxiety during game playing, and the habituation to unpleasant stimuli, are possible mechanisms that could explain these results. Future research should evaluate the effects of violent video game playing on emotion processing and social cognition more broadly. © 2015 Wiley Periodicals, Inc.

Dose estimate for personal music players including earphone sensitivity and characteristic

DEFF Research Database (Denmark)

Hammershøi, Dorte; Ordoñez Pizarro, Rodrigo Eduardo; Christensen, Anders Tornvig

2016-01-01

Personal music players can expose their listeners to high sound pressure levels over prolonged periods of time. The risk associated with prolonged listening is not readily available to the listener, and efforts are made to standardize dose estimates that may be displayed for the user. In the pres......Personal music players can expose their listeners to high sound pressure levels over prolonged periods of time. The risk associated with prolonged listening is not readily available to the listener, and efforts are made to standardize dose estimates that may be displayed for the user...... earphone measurements published in the past. The work is on-going....

Multiple Off-Ice Performance Variables Predict On-Ice Skating Performance in Male and Female Division III Ice Hockey Players.

Science.gov (United States)

Janot, Jeffrey M; Beltz, Nicholas M; Dalleck, Lance D

2015-09-01

The purpose of this study was to determine if off-ice performance variables could predict on-ice skating performance in Division III collegiate hockey players. Both men (n = 15) and women (n = 11) hockey players (age = 20.5 ± 1.4 years) participated in the study. The skating tests were agility cornering S-turn, 6.10 m acceleration, 44.80 m speed, modified repeat skate, and 15.20 m full speed. Off-ice variables assessed were years of playing experience, height, weight and percent body fat and off-ice performance variables included vertical jump (VJ), 40-yd dash (36.58m), 1-RM squat, pro-agility, Wingate peak power and peak power percentage drop (% drop), and 1.5 mile (2.4km) run. Results indicated that 40-yd dash (36.58m), VJ, 1.5 mile (2.4km) run, and % drop were significant predictors of skating performance for repeat skate (slowest, fastest, and average time) and 44.80 m speed time, respectively. Four predictive equations were derived from multiple regression analyses: 1) slowest repeat skate time = 2.362 + (1.68 x 40-yd dash time) + (0.005 x 1.5 mile run), 2) fastest repeat skate time = 9.762 - (0.089 x VJ) - (0.998 x 40-yd dash time), 3) average repeat skate time = 7.770 + (1.041 x 40-yd dash time) - (0.63 x VJ) + (0.003 x 1.5 mile time), and 4) 47.85 m speed test = 7.707 - (0.050 x VJ) - (0.01 x % drop). It was concluded that selected off-ice tests could be used to predict on-ice performance regarding speed and recovery ability in Division III male and female hockey players. Key pointsThe 40-yd dash (36.58m) and vertical jump tests are significant predictors of on-ice skating performance specific to speed.In addition to 40-yd dash and vertical jump, the 1.5 mile (2.4km) run for time and percent power drop from the Wingate anaerobic power test were also significant predictors of skating performance that incorporates the aspect of recovery from skating activity.Due to the specificity of selected off-ice variables as predictors of on-ice performance, coaches can

COMPARATIVE STUDY OF 4 WEEKS OF DYNAMIC B ALANCE TRAINING PROGRAM IN COLLEGIATE FOOTBALL PLAYERS: RANDOMIZED CLINICAL TRIAL

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Nisha

2015-03-01

Full Text Available BACKGROUND: Balance is highly integrative dynamic process involving coordination of multiple neurological pathways that allows for the maintenance of the COG over BOS . Football players often perform lower extremity passing , shooting , twisting , cutting and dribbling skills while wearing shoes , these actions require body to be in the equilibrium position to perform the task . This leads to t he conclusion of the great importance of the ability of balance in football . AIMS: 1 . To study the effect of 4 week multidirectional balance board training on dynamic balance in football players . 2 . To study the effect of 4 week Both Sides Up ball training on dynamic balance in football players . 3 . To compare the effect of multidirectional balance board training program and BOSU ball training program on dynamic balance in football players . STUDY DESIGN: Randomized Clinical trial . METHODS: Total of 60 competitive badminton players with age group between18 - 25 were recruited in this study . The participants were allocated into 2 groups viz ., Group A (multidirectional balance board training and Group B (BOSU ball Training for a period of 4 we eks . Participants were test for SEBT and vertical jump test on first day and after 4 weeks of balance training . STATISTICAL ANALYSIS: Student t test , Chi - Square Test . RESULTS: The data analysis and statistical inference showed that , after 4 weeks of balanc e training there was improvement in dynamic balance in both the groups but there was no significant difference in dynamic balance between two groups . As seen by difference in the SEBT and VJT scores pre and post training with p<0 . 001 . CONCLUSION: 4 weeks balance training using BOSU and multidirectional balance board is effective in improving dynamic balance and vertical jump performance in football players and also can be used as a component of multifaceted training to improve dynamic balance and game skills

The Effectiveness Evaluation among Different Player-Matching Mechanisms in a Multi-Player Quiz Game

Science.gov (United States)

Tsai, Fu-Hsing

2016-01-01

This study aims to investigate whether different player-matching mechanisms in educational multi-player online games (MOGs) can affect students' learning performance, enjoyment perception and gaming behaviors. Based on the multi-player quiz game, TRIS-Q, developed by Tsai, Tsai and Lin (2015) using a free player-matching (FPM) mechanism, the same…

Frontal lobe function in chess players.

Science.gov (United States)

Nejati, Majid; Nejati, Vahid

2012-01-01

Chess is considered as a cognitive game because of severe engagement of the mental resources during playing. The purpose of this study is evaluation of frontal lobe function of chess players with matched non-players. Wisconsin Card Sorting Test (WCST) data showed no difference between the player and non-player groups in preservation error and completed categories but surprisingly showed significantly lower grade of the player group in correct response. Our data reveal that chess players don't have any preference in any stage of Stroop test. Chess players don't have any preference in selective attention, inhibition and executive cognitive function. Chess players' have lower shifting abilities than non-players.

Heart Rate Variability Discriminates Competitive Levels in Professional Soccer Players.

Science.gov (United States)

Proietti, Riccardo; di Fronso, Selenia; Pereira, Lucas A; Bortoli, Laura; Robazza, Claudio; Nakamura, Fabio Y; Bertollo, Maurizio

2017-06-01

Heart rate variability (HRV) has been increasingly used to monitor team sports athletes. Besides the traditional time domain indices (i.e., the SD of successive RR intervals [SDNN] and the root mean square difference of successive normal RR intervals [RMSSD]), recently the use of the stress score (SS), which is an inverse function of the SD2 index derived from the Poincaré plot, and the sympathetic/parasympathetic ratio (S/PS) to monitor soccer players has been proposed. However, the reliability of these new indices and the ability of HRV to differentiate between soccer competitive levels are unknown. The aim of this study was to analyze the reliability of the different HRV-derived indices in professional soccer players during the competitive period and to compare HRV of professional soccer players from 3 teams of distinct competitive levels (i.e., Italian Second Division [2D], European League [EL], and Champions League [CL]). Fifty-four male professional soccer players from 3 different teams of 2 European countries (Italy and Germany) participated in the study. The intraclass correlation coefficient values of the HRV indices varied from 0.78 (very large) to 0.90 (near perfect). The coefficient of variation (CV) values for RMSSD and SDNN were all soccer players and is able to differentiate between international- and national-level players.

A comparison of static near stereo acuity in youth baseball/softball players and non-ball players.

Science.gov (United States)

Boden, Lauren M; Rosengren, Kenneth J; Martin, Daniel F; Boden, Scott D

2009-03-01

Although many aspects of vision have been investigated in professional baseball players, few studies have been performed in developing athletes. The issue of whether youth baseball players have superior stereopsis to nonplayers has not been addressed specifically. The purpose of this study was to determine if youth baseball/softball players have better stereo acuity than non-ball players. Informed consent was obtained from 51 baseball/softball players and 52 non-ball players (ages 10 to 18 years). Subjects completed a questionnaire, and their static near stereo acuity was measured using the Randot Stereotest (Stereo Optical Company, Chicago, Illinois). Stereo acuity was measured as the seconds of arc between the last pair of images correctly distinguished by the subject. The mean stereo acuity score was 25.5 +/- 1.7 seconds of arc in the baseball/softball players and 56.2 +/- 8.4 seconds of arc in the non-ball players. This difference was statistically significant (P softball players had significantly better static stereo acuity than non-ball players, comparable to professional ball players.

Veto players

NARCIS (Netherlands)

Warntjen, Andreas; Dowding, Keith

2010-01-01

Veto players are political actors whose consent is necessary to adopt a new policy. Put otherwise, they have veto power which allows them to prevent a change to the status quo. The concept is crucial to the influential veto player theory developed by George Tsebelis. Building on earlier work in

Role of force training in physical training of student basketball team players

Directory of Open Access Journals (Sweden)

S.S. Brynzak

2013-10-01

Full Text Available Presented results of the implementation of the program of strength training in the preparation of the annual cycle of student basketball team. The study involved 15 athletes. The testing program included the evaluation of home and remote speed (running 6 and 20 m with a high launch, speed and overall endurance (2x40 shuttle run test with and Cooper, speed-strength (high jump, strength (gets dynamometry. Strength training program was included in classes 3 times a week for two months before the start of the competition period. Found that the proposed program of strength training improves physical fitness of the players. Marked increase in the level of development of motor qualities of the players during the macrocycle. There was a significant increase in physical fitness of players on the team at the end of the competition period. Marked improvement in starting, telecommuting, speed and speed endurance. Increased overall endurance and strength, but the level of development is low.

The evaluation of small-sided games as a talent identification tool in highly trained prepubertal soccer players.

Science.gov (United States)

Fenner, Jonathan S J; Iga, John; Unnithan, Viswanath

2016-10-01

The aim of this study was to evaluate physiological and technical attributes of prepubertal soccer players during multiple small-sided games (SSGs), and determine if SSGs can act as a talent identification tool. Sixteen highly trained U10 soccer players participated and separated into two groups of eight. Each group played six small-sided (4 vs. 4) matches of 5-min duration. Each player was awarded total points for the match result and goals scored. A game technical scoring chart was used to rate each player's performance during each game. Time-motion characteristics were measured using micromechanical devices. Total points had a very large significant relationship with game technical scoring chart (r = 0.758, P talented prepubertal soccer players.

Player-Tracking Technology: Half-Full or Half-Empty Glass?

Science.gov (United States)

Buchheit, Martin; Simpson, Ben Michael

2017-04-01

With the ongoing development of microtechnology, player tracking has become one of the most important components of load monitoring in team sports. The 3 main objectives of player tracking are better understanding of practice (provide an objective, a posteriori evaluation of external load and locomotor demands of any given session or match), optimization of training-load patterns at the team level, and decision making on individual players' training programs to improve performance and prevent injuries (eg, top-up training vs unloading sequences, return to play progression). This paper discusses the basics of a simple tracking approach and the need to integrate multiple systems. The limitations of some of the most used variables in the field (including metabolic-power measures) are debated, and innovative and potentially new powerful variables are presented. The foundations of a successful player-monitoring system are probably laid on the pitch first, in the way practitioners collect their own tracking data, given the limitations of each variable, and how they report and use all this information, rather than in the technology and the variables per se. Overall, the decision to use any tracking technology or new variable should always be considered with a cost/benefit approach (ie, cost, ease of use, portability, manpower/ability to affect the training program).

Frontal Lobe Function in Chess Players

Directory of Open Access Journals (Sweden)

Vahid Nejati

2012-05-01

Full Text Available Chess is considered as a cognitive game because of severe engagement of the mental resources during playing. The purpose of this study is evaluation of frontal lobe function of chess players with matched non-players. Wisconsin Card Sorting Test (WCST data showed no difference between the player and non-player groups in preservation error and completed categories but surprisingly showed significantly lower grade of the player group in correct response. Our data reveal that chess players dont have any preference in any stage of Stroop test. Chess players dont have any preference in selective attention, inhibition and executive cognitive function. Chess players' have lower shifting abilities than non-players.

Optimal inventory policy in a closed loop supply chain system with multiple periods

International Nuclear Information System (INIS)

Sasi Kumar, A.; Natarajan, K.; Ramasubramaniam, Muthu Rathna Sapabathy.; Deepaknallasamy, K.K.

2017-01-01

Purpose: This paper aims to model and optimize the closed loop supply chain for maximizing the profit by considering the fixed order quantity inventory policy in various sites at multiple periods. Design/methodology/approach: In forward supply chain, a standard inventory policy can be followed when the product moves from manufacturer, distributer, retailer and customer but the inventory in the reverse supply chain of the product with the similar standard policy is very difficult to manage. This model investigates the standard policy of fixed order quantity by considering the three major types of return-recovery pair such as commercial returns, end- of- use returns, end –of- life returns and their inventory positioning at multiple periods. The model is configured as mixed integer linear programming and solved by IBM ILOG CPLEX OPL studio. Findings: To find the performance of the model a numerical example is considered for a product with three Parts (A which of 2nos, B and C) for 12 multiple periods. The results of the analysis show that the manufacturer can know how much should to be manufacture in multiple periods based on Variations of the demand by adopting the FOQ inventory policy at different sites considering its capacity constraints. In addition, it is important how much of parts should be purchased from the supplier at the given 12 periods. Originality/value: A sensitivity analysis is performed to validate the proposed model two parts. First part of the analysis will focus on the inventory of product and parts and second part of analysis focus on profit of the company. The analysis which provides some insights in to the structure of the model.

Optimal inventory policy in a closed loop supply chain system with multiple periods

Energy Technology Data Exchange (ETDEWEB)

Sasi Kumar, A.; Natarajan, K.; Ramasubramaniam, Muthu Rathna Sapabathy.; Deepaknallasamy, K.K.

2017-07-01

Purpose: This paper aims to model and optimize the closed loop supply chain for maximizing the profit by considering the fixed order quantity inventory policy in various sites at multiple periods. Design/methodology/approach: In forward supply chain, a standard inventory policy can be followed when the product moves from manufacturer, distributer, retailer and customer but the inventory in the reverse supply chain of the product with the similar standard policy is very difficult to manage. This model investigates the standard policy of fixed order quantity by considering the three major types of return-recovery pair such as commercial returns, end- of- use returns, end –of- life returns and their inventory positioning at multiple periods. The model is configured as mixed integer linear programming and solved by IBM ILOG CPLEX OPL studio. Findings: To find the performance of the model a numerical example is considered for a product with three Parts (A which of 2nos, B and C) for 12 multiple periods. The results of the analysis show that the manufacturer can know how much should to be manufacture in multiple periods based on Variations of the demand by adopting the FOQ inventory policy at different sites considering its capacity constraints. In addition, it is important how much of parts should be purchased from the supplier at the given 12 periods. Originality/value: A sensitivity analysis is performed to validate the proposed model two parts. First part of the analysis will focus on the inventory of product and parts and second part of analysis focus on profit of the company. The analysis which provides some insights in to the structure of the model.

Optimal inventory policy in a closed loop supply chain system with multiple periods

Directory of Open Access Journals (Sweden)

SasiKumar A.

2017-05-01

Full Text Available Purpose: This paper aims to model and optimize the closed loop supply chain for maximizing the profit by considering the fixed order quantity inventory policy in various sites at multiple periods. Design/methodology/approach: In forward supply chain, a standard inventory policy can be followed when the product moves from manufacturer, distributer, retailer and customer but the inventory in the reverse supply chain of the product with the similar standard policy is very difficult to manage. This model investigates the standard policy of fixed order quantity by considering the three major types of return-recovery pair such as commercial returns, end- of- use returns, end –of- life returns and their inventory positioning at multiple periods.  The model is configured as mixed integer linear programming and solved by IBM ILOG CPLEX OPL studio. Findings: To find the performance of the model a numerical example is considered for a product with three Parts (A which of 2nos, B and C for 12 multiple periods. The results of the analysis show that the manufacturer can know how much should to be manufacture in multiple periods based on Variations of the demand by adopting the FOQ inventory policy at different sites considering its capacity constraints. In addition, it is important how much of parts should be purchased from the supplier at the given 12 periods. Originality/value: A sensitivity analysis is performed to validate the proposed model two parts. First part of the analysis will focus on the inventory of product and parts and second part of analysis focus on profit of the company. The analysis which provides some insights in to the structure of the model.

Correspondence between training load executed by volleyball players and the one observed by coaches.

Science.gov (United States)

Rodríguez-Marroyo, Jose A; Medina, Javier; García-López, Juan; García-Tormo, José V; Foster, Carl

2014-06-01

The main aim of this study was to compare the training load (TL) executed by volleyball players with that observed by coaches. Second, we analyzed the influence of the coaches' experience in the estimated TL. Twelve female volleyball players and 4 male coaches participated in this study. During a period of 15 weeks, physical (PT) and technical-tactical training sessions and matches were monitored. In each session, the session rating of perceived exertion (sRPE) was recorded to analyze the players' exercise intensity and TL(RP)E. Coaches were present in all sessions and rated their estimate of sRPE at the same time as the players to calculate the coaches' TL(RPE). Both players' and coaches' mean sRPE (4.0 ± 1.1, 3.7 ± 1.1, and 3.8 ± 1.0 in players and expert and beginning coaches, respectively) and TLRPE (380.1 ± 106.8, 358.3 ± 110.5, and 359.7 ± 108.0 in players and expert and beginning coaches, respectively) were similar. However, a higher (p volleyball.

Prospective Player-Reported Injuries in Female Youth Fast-Pitch Softball Players

Science.gov (United States)

Smith, Matthew V.; Davis, Randi; Brophy, Robert H.; Prather, Heidi; Garbutt, Jane; Wright, Rick W.

2015-01-01

Background: There is a scarcity of literature evaluating injuries in youth fast-pitch softball players. Purpose: To perform a descriptive analysis of player-reported injuries in youth fast-pitch softball position players and pitchers during a single select-level season. Study Design: Prospective observation cohort study. Level of Evidence: Level 3. Methods: Ninety-eight athletes (48 pitchers, 50 position players) were followed for a single select fast-pitch softball season. Study participants completed web-based surveys every 3 weeks reporting injuries related to participation in fast-pitch softball. Injury was defined as pain causing cessation of participation in the current game or practice that prevents the player’s return to that session or any pain that causes cessation of a player’s customary participation on the day after the day of onset. Results: The median age of the study participants was 14 years (range, 9-18 years). There were 49 reported injuries in 98 athletes. The average age was 13 years for those not injured and 14 years for those who were injured (P softball players. Better off-season and preseason conditioning may be a key factor for reducing pitching injuries. Clinical Relevance: Recognition of injury patterns in fast-pitch softball players is critical to developing strategies to keep these athletes competing safely. PMID:26502442

Study on the Application of TOPSIS Method to the Introduction of Foreign Players in CBA Games

Science.gov (United States)

Zhongyou, Xing

The TOPSIS method is a multiple attribute decision-making method. This paper introduces the current situation of the introduction of foreign players in CBA games, presents the principles and calculation steps of TOPSIS method in detail, and applies it to the quantitative evaluation of the comprehensively competitive ability during the introduction of foreign players. Through the analysis of practical application, we found that the TOPSIS method has relatively high rationality and applicability when it is used to evaluate the comprehensively competitive ability during the introduction of foreign players.

Small-sided game training improves aerobic capacity and technical skills in basketball players.

Science.gov (United States)

Delextrat, A; Martinez, A

2014-05-01

The aim of this study was to compare the effects of 2 training interventions based on small-sided games (SGG) and high-intensity interval training (HIT) on physical and technical performance of male junior basketball players. A secondary objective was to investigate if these effects were similar in starting and bench players. 18 players participated in a pre-testing session, 6-weeks intervention period and a post-testing session. Pre- and post-sessions involved assessments of aerobic fitness, repeated sprint ability (RSA), defensive and offensive agility, upper and lower body power, shooting and passing skills. Mixed-design analysis of variance (ANOVA) with Bonferroni corrected pairwise comparisons examined the effects of time and type of intervention on physical and technical performances. The main results showed that both interventions resulted in similar improvements in aerobic capacity (+3.4% vs. +4.1%), with greater improvements in bench players compared to starting players (+7.1% vs. +1.1%, Pbasketball players during the season. However, when RSA is targeted, more specific training seems necessary. © Georg Thieme Verlag KG Stuttgart · New York.

A COMPARISON OF THE ANTHROPOMETRIC PARAMETERS BETWEEN BASKETBALL PLAYERS, HANDBALL PLAYERS AND VOLLEYBALL PLAYERS

OpenAIRE

Florian Miftari; Juel Jarani; Dhimitraq Stratoberdha; Hazir Salihu

2017-01-01

The purpose of this study was to compare the anthropometric measurement to the professional players of the three different disciplines of basketball, handball and volleyball. . For each player anthropometric measurements such as weight, body height, waist circumference, BMI and skinfold calculation on different sports are performed. Differences in terms of anthropometric measurements were assessed by independent static tests and the differences for each variable for each sport were evaluated ...

Multiple periodic solutions for a fourth-order discrete Hamiltonian system

Directory of Open Access Journals (Sweden)

Yongkun Li

2010-12-01

Full Text Available By means of a three critical points theorem proposed by Brezis and Nirenberg and a general version of Mountain Pass Theorem, we obtain some multiplicity results for periodic solutions of a fourth-order discrete Hamiltonian system Δ4u(t-2+∇ F(t,u(t=0 for all t∈ Z.

Nutritional Practices of National Female Soccer Players: Analysis and Recommendations

Science.gov (United States)

Martin, Louise; Lambeth, Anneliese; Scott, Dawn

2006-01-01

The aim of the study was to establish the nutritional practices and activity patterns of elite female soccer players. The nutritional intake of 16 female England Soccer players was self-reported over a seven-day period. Participants were provided with written and verbal guidelines for the completion of the diaries. Training details were also recorded, and used in combination with BMR predictions to calculate daily energy expenditure. Energy, macronutrient and micronutrient intakes were determined using DietMaster 4.0 software. Results suggest that energy intake was low (1904 ± 366.3 kcal) in relation to previous recommendations for soccer players. Energy expenditure (2153.5 ± 596.2 kcal) was not significantly different (p > 0.05) from intake, suggesting energy balance was achieved. Carbohydrate (53.8 ± 6.8%), protein (16.8 ± 2.1%) and fat (28.8 ± 6.6%) intakes were in line with recommendations. Fluid intake (2466 ± 1350.5ml·day-1) was sufficient to meet baseline recommendations, but would need to be higher to meet the additional requirement of training and competition. With the exception of vitamin A and iron, all micronutrient intakes were higher than the DRI. In conclusion, recommendations for female soccer players are to encourage consumption of carbohydrate-electrolyte beverages to enhance carbohydrate intake and increase fluid intake, and ensure sufficient iron rich foods are included in the diet to meet the DRI. Key points Female soccer players demonstrate a low energy intake in relation to predicted requirements, but were in energy balance in this study. Increased carbohydrate intake may be beneficial to both training and competition performance of elite female soccer players Fluid requirements should be addressed on an individual basis and matched to player requirements. The iron status of female soccer players may be compromised due to insufficient dietary intake to meet the DRV. PMID:24198690

Nutritional practices of national female soccer players: analysis and recommendations.

Science.gov (United States)

Martin, Louise; Lambeth, Anneliese; Scott, Dawn

2006-01-01

The aim of the study was to establish the nutritional practices and activity patterns of elite female soccer players. The nutritional intake of 16 female England Soccer players was self-reported over a seven-day period. Participants were provided with written and verbal guidelines for the completion of the diaries. Training details were also recorded, and used in combination with BMR predictions to calculate daily energy expenditure. Energy, macronutrient and micronutrient intakes were determined using DietMaster 4.0 software. Results suggest that energy intake was low (1904 ± 366.3 kcal) in relation to previous recommendations for soccer players. Energy expenditure (2153.5 ± 596.2 kcal) was not significantly different (p > 0.05) from intake, suggesting energy balance was achieved. Carbohydrate (53.8 ± 6.8%), protein (16.8 ± 2.1%) and fat (28.8 ± 6.6%) intakes were in line with recommendations. Fluid intake (2466 ± 1350.5ml·day(-1)) was sufficient to meet baseline recommendations, but would need to be higher to meet the additional requirement of training and competition. With the exception of vitamin A and iron, all micronutrient intakes were higher than the DRI. In conclusion, recommendations for female soccer players are to encourage consumption of carbohydrate-electrolyte beverages to enhance carbohydrate intake and increase fluid intake, and ensure sufficient iron rich foods are included in the diet to meet the DRI. Key pointsFemale soccer players demonstrate a low energy intake in relation to predicted requirements, but were in energy balance in this study.Increased carbohydrate intake may be beneficial to both training and competition performance of elite female soccer playersFluid requirements should be addressed on an individual basis and matched to player requirements.The iron status of female soccer players may be compromised due to insufficient dietary intake to meet the DRV.

Upper respiratory tract infection and mucosal immunity in young ice hockey players during the pre-tournament training period.

Science.gov (United States)

Orysiak, Joanna; Witek, Konrad; Malczewska-Lenczowska, Jadwiga; Zembron-Lacny, Agnieszka; Pokrywka, Andrzej; Sitkowski, Dariusz

2018-02-27

The aim of this study was to determine the effects of 17 days of training during preparation for the Ice Hockey Under 18 World Championship of the Polish ice hockey national team on the mucosal immune function and monitor upper respiratory tract infection (URTI) incidence before, during and after the competition. Twelve male ice hockey players (age 17.7±0.5 years) were recruited for this study. The first saliva/blood collection took place at the beginning of the training camp (without training at the training camp), the second one was conducted on the 9th day of the training camp immediately after the intensification of training, and the third collection was carried out on the 13th day of training (4 days before leaving for the World Championship) in the tapering phase. To assess the mucosal immune function, concentrations of secretory immunoglobulin A (sIgA), sIgA1, and sIgA2 were analyzed in saliva. Cortisol concentration and creatine kinase activity were determined in blood, as indicators of stress and muscle damage, respectively. The Wisconsin Upper Respiratory Symptom Survey-21 questionnaire was used to assess URTI symptoms. A significant increase in the sIgA1 and sIgA2 concentrations was observed in the third collection compared with the second time point (114.45±33.00 vs 77.49±27.29 and 88.97±25.33 vs 71.65±32.44 U, respectively). There were no statistically significant correlations between the URTI incidence and saliva variables. In conclusion, the tapering period positively affects the mucosal immune function, especially sIgA1 and sIgA2 concentrations, with no significant change in frequency of URTI in young ice hockey players.

Shoulder pain among high-level volleyball players and preseason features.

Science.gov (United States)

Forthomme, Benedicte; Wieczorek, Valerie; Frisch, Anne; Crielaard, Jean-Michel; Croisier, Jean-Louis

2013-10-01

The main goal of this prospective study was to identify the most significant intrinsic risk factors for shoulder pain by measuring strength developed by shoulder rotators and by carrying out various morphostatic assessments. Sixty-six players (mean ± SD age = 24 ± 5 yr) were recruited from nine volleyball teams from the first and second divisions (34 men and 32 women) to participate in the study. Before the start of the volleyball season, all the participants completed a preseason questionnaire and underwent both a bilateral isokinetic evaluation of the shoulders and morphostatic measurements. During the subsequent 6 months of the competition period, the players reported through a weekly questionnaire any shoulder pain experienced. During the ongoing season, 23% (15 of 66 players) of the volleyball players experienced dominant shoulder pain. Interestingly, participants who reported a history of dominant shoulder pain were found to have nine times higher risk of suffering further pain in their dominant shoulder. The eccentric maximal strength developed by the internal and external rotators was found to represent a protective factor in the volleyball players (respective odds ratios = 0.946, P = 0.01 and 0.94, P = 0.05). No risk factors were found among the shoulder morphostatic measurements. In our study, the evaluation of shoulder rotator muscle strength through isokinetic assessment, especially eccentric mode, appeared to be the most contributing parameter to identify risk factors for shoulder pain. This evaluation should allow to better identify players at risk.

Short-term auditory effects of listening to an MP3 player.

Science.gov (United States)

Keppler, Hannah; Dhooge, Ingeborg; Maes, Leen; D'haenens, Wendy; Bockstael, Annelies; Philips, Birgit; Swinnen, Freya; Vinck, Bart

2010-06-01

To determine the output levels of a commercially available MPEG layer-3 (MP3) player and to evaluate changes in hearing after 1 hour of listening to the MP3 player. First, A-weighted sound pressure levels (measured in decibels [dBA]) for 1 hour of pop-rock music on an MP3 player were measured on a head and torso simulator. Second, after participants listened to 1 hour of pop-rock music using an MP3 player, changes in hearing were evaluated with pure-tone audiometry, transient-evoked otoacoustic emissions, and distortion product otoacoustic emissions. Twenty-one participants were exposed to pop-rock music in 6 different sessions using 2 types of headphones at multiple preset gain settings of the MP3 player. Output levels of an MP3 player and temporary threshold and emission shifts after 1 hour of listening. The output levels at the full gain setting were 97.36 dBA and 102.56 dBA for the supra-aural headphones and stock earbuds, respectively. In the noise exposure group, significant changes in hearing thresholds and transient-evoked otoacoustic emission amplitudes were found between preexposure and postexposure measurements. However, this pattern was not seen for distortion product otoacoustic emission amplitudes. Significant differences in the incidence of significant threshold or emission shifts were observed between almost every session of the noise exposure group compared with the control group. Temporary changes in hearing sensitivity measured by audiometry and otoacoustic emissions indicate the potential harmful effects of listening to an MP3 player. Further research is needed to evaluate the long-term risk of cumulative noise exposure on the auditory system of adolescents and adults.

Cortical thickness and subcortical brain volumes in professional rugby league players

Directory of Open Access Journals (Sweden)

Magdalena Wojtowicz

Full Text Available Purpose: The purpose of this study was to examine cortical thickness and subcortical volumes in professional rugby players with an extensive history of concussions compared to control subjects. Method: Participants included 24 active and former professional rugby league players [Age M(SD = 33.3(6.3; Range = 21–44] with an extensive history of concussion and 18 age- and education-matched controls with no history of neurotrauma or participation in contact sports. Participants underwent T1-weighted imaging and completed a neuropsychological battery, including two tests of memory. Whole brain cortical thickness analysis and structural volume analysis was performed using FreeSurfer version 6.0. Results: Professional rugby league players reported greater alcohol consumption (p < .001 and had significantly worse delayed recall of a visually complex design (p = .04. They did not differ from controls on other clinical outcome measures. There were no differences in cortical thickness between the groups. Professional players had smaller whole brain (p = .003, bilateral hippocampi (ps = .03, and left amygdala volumes (p = .01 compared to healthy controls. Within the players group, there were significant associations between greater alcohol use and smaller bilateral hippocampi and left amygdala volumes. There were no associations between structural volumes and history of concussions or memory performance. Conclusions: The literature examining cortical thickness in athletes with a history of multiple concussions is mixed. We did not observe differences in cortical thickness in professional rugby league players compared to controls. However, smaller subcortical volumes were found in players that were, in part, associated with greater alcohol consumption. Keywords: Volumetric MRI, Cortical thickness, Concussion, Brain morphometry, Athletes, Rugby

Wireless nanosensors for monitoring concussion of football players

Science.gov (United States)

Ramasamy, Mouli; Harbaugh, Robert E.; Varadan, Vijay K.

2015-04-01

Football players are more to violent impacts and injuries more than any athlete in any other sport. Concussion or mild traumatic brain injuries were one of the lesser known sports injuries until the last decade. With the advent of modern technologies in medical and engineering disciplines, people are now more aware of concussion detection and prevention. These concussions are often overlooked by football players themselves. The cumulative effect of these mild traumatic brain injuries can cause long-term residual brain dysfunctions. The principle of concussion is based the movement of the brain in the neurocranium and viscerocranium. The brain is encapsulated by the cerebrospinal fluid which acts as a protective layer for the brain. This fluid can protect the brain against minor movements, however, any rapid movements of the brain may mitigate the protective capability of the cerebrospinal fluid. In this paper, we propose a wireless health monitoring helmet that addresses the concerns of the current monitoring methods - it is non-invasive for a football player as helmet is not an additional gear, it is efficient in performance as it is equipped with EEG nanosensors and 3D accelerometer, it does not restrict the movement of the user as it wirelessly communicates to the remote monitoring station, requirement of individual monitoring stations are not required for each player as the ZigBee protocol can couple multiple transmitters with one receiver. A helmet was developed and validated according to the above mentioned parameters.

The association between white-matter tract abnormalities, and neuropsychiatric and cognitive symptoms in retired professional football players with multiple concussions.

Science.gov (United States)

Multani, Namita; Goswami, Ruma; Khodadadi, Mozhgan; Ebraheem, Ahmed; Davis, Karen D; Tator, Charles H; Wennberg, Richard; Mikulis, David J; Ezerins, Leo; Tartaglia, Maria Carmela

2016-07-01

Retired professional athletes, who have suffered repetitive concussions, report symptoms of depression, anxiety, and memory impairment over time. Moreover, recent imaging data suggest chronic white-matter tract deterioration in sport-related concussion. The aim of this study is to evaluate the impact of repetitive concussions in retired professional football players on white-matter tracts, and relate these changes to neuropsychological function. All subjects (18 retired professional football players and 17 healthy controls) underwent imaging, neuropsychological assessment, and reported on concussion-related symptoms. Whole brain tract-based spatial statistics analysis revealed increased axial diffusivity in the right hemisphere of retired players in the (1) superior longitudinal fasciculus (SLF), (2) corticospinal tract, and (3) anterior thalamic radiations, suggesting chronic axonal degeneration in these tracts. Moreover, retired players report significantly higher neuropsychiatric and cognitive symptoms than healthy controls, and worsening of these symptoms since their last concussion. Loss of integrity in the right SLF significantly correlated with participants' visual learning ability. In sum, these results suggest that repetitive concussions in retired professional football players are associated with focal white-matter tract abnormalities that could explain some of the neuropsychiatric symptoms and cognitive deficits experienced by these retired athletes.

Adaptations to speed endurance training in highly trained soccer players

DEFF Research Database (Denmark)

Nyberg, Michael Permin; Fiorenza, Matteo; Lund, Anders

2016-01-01

PURPOSE: The present study examined whether a period of additional speed endurance training would improve intense intermittent exercise performance in highly trained soccer players during the season and whether the training changed aerobic metabolism and the level of oxidative enzymes in type I...... and II muscle fibers. METHODS: During the last nine weeks of the season, thirteen semi-professional soccer players performed additional speed endurance training sessions consisting of 2-3 sets of 8 - 10 repetitions of 30 m sprints with 10 s of passive recovery (SET). Before and after SET, subjects...... in type I and II fibers did not change. CONCLUSION: In highly trained soccer players, additional speed endurance training is associated with an improved ability to perform repeated high-intensity work. To what extent the training-induced changes in V˙O2 kinetics and mechanical efficiency in type I fibers...

High Speed Running and Sprinting Profiles of Elite Soccer Players

Directory of Open Access Journals (Sweden)

Miñano-Espin Javier

2017-08-01

Full Text Available Real Madrid was named as the best club of the 20th century by the International Federation of Football History and Statistics. The aim of this study was to compare if players from Real Madrid covered shorter distances than players from the opposing team. One hundred and forty-nine matches including league, cup and UEFA Champions League matches played by the Real Madrid were monitored during the 2001-2002 to the 2006-2007 seasons. Data from both teams (Real Madrid and the opponent were recorded. Altogether, 2082 physical performance profiles were examined, 1052 from the Real Madrid and 1031 from the opposing team (Central Defenders (CD = 536, External Defenders (ED = 491, Central Midfielders (CM = 544, External Midfielders (EM = 233, and Forwards (F = 278. Match performance data were collected using a computerized multiple-camera tracking system (Amisco Pro®, Nice, France. A repeated measures analysis of variance (ANOVA was performed for distances covered at different intensities (sprinting (>24.0 km/h and high-speed running (21.1-24.0 km/h and the number of sprints (21.1-24.0 km/h and >24.0 km/h during games for each player sectioned under their positional roles. Players from Real Madrid covered shorter distances in high-speed running and sprint than players from the opposing team (p 0.01 from Real Madrid covered shorter distances in high-intensity running and sprint and performed less sprints than their counterparts. Finally, no differences were found in the high-intensity running and sprint distances performed by players from Real Madrid depending on the quality of the opposition.

Variations in Star Excursion Balance Test Performance Between High School and Collegiate Football Players.

Science.gov (United States)

McCann, Ryan S; Kosik, Kyle B; Beard, Megan Q; Terada, Masafumi; Pietrosimone, Brian G; Gribble, Phillip A

2015-10-01

The Star Excursion Balance Test (SEBT) is a reliable inexpensive tool used to assess dynamic postural control deficits and efficacy in the prediction of musculoskeletal injuries, but with little previous consideration for performance differences across age and skill levels. The purpose of this study was to examine differences in SEBT scores between high school and collegiate football players. Three-hundred eighteen high school football players and 180 National Collegiate Athletic Association Division I collegiate football players volunteered to participate. Star Excursion Balance Test scores were obtained bilaterally for anterior (ANT), posterolateral (PL), and posteromedial (PM) directions, and for an overall composite (COMP) score. The mean of 3 trials from each leg was normalized to stance leg length and presented as a percentage score. Bilaterally averaged scores were compared between high school and collegiate football players using separate independent t-tests. A multiple linear backward regression determined the amount of variance in SEBT scores explained by age, mass, and height. Compared with collegiate athletes, high school athletes had lower PL (72.8 ± 11.4% vs. 77.1 ± 10.2%; p football players.

Phase transitions in multiplicative competitive processes

International Nuclear Information System (INIS)

Shimazaki, Hideaki; Niebur, Ernst

2005-01-01

We introduce a discrete multiplicative process as a generic model of competition. Players with different abilities successively join the game and compete for finite resources. Emergence of dominant players and evolutionary development occur as a phase transition. The competitive dynamics underlying this transition is understood from a formal analogy to statistical mechanics. The theory is applicable to bacterial competition, predicting novel population dynamics near criticality

Active Learning for Player Modeling

DEFF Research Database (Denmark)

Shaker, Noor; Abou-Zleikha, Mohamed; Shaker, Mohammad

2015-01-01

Learning models of player behavior has been the focus of several studies. This work is motivated by better understanding of player behavior, a knowledge that can ultimately be employed to provide player-adapted or personalized content. In this paper, we propose the use of active learning for player...... experience modeling. We use a dataset from hundreds of players playing Infinite Mario Bros. as a case study and we employ the random forest method to learn mod- els of player experience through the active learning approach. The results obtained suggest that only part of the dataset (up to half the size...... that the method can be used online during the content generation process where the mod- els can improve and better content can be presented as the game is being played....

A Multiple Period Problem in Distributed Energy Management Systems Considering CO2 Emissions

Science.gov (United States)

Muroda, Yuki; Miyamoto, Toshiyuki; Mori, Kazuyuki; Kitamura, Shoichi; Yamamoto, Takaya

Consider a special district (group) which is composed of multiple companies (agents), and where each agent responds to an energy demand and has a CO2 emission allowance imposed. A distributed energy management system (DEMS) optimizes energy consumption of a group through energy trading in the group. In this paper, we extended the energy distribution decision and optimal planning problem in DEMSs from a single period problem to a multiple periods one. The extension enabled us to consider more realistic constraints such as demand patterns, the start-up cost, and minimum running/outage times of equipment. At first, we extended the market-oriented programming (MOP) method for deciding energy distribution to the multiple periods problem. The bidding strategy of each agent is formulated by a 0-1 mixed non-linear programming problem. Secondly, we proposed decomposing the problem into a set of single period problems in order to solve it faster. In order to decompose the problem, we proposed a CO2 emission allowance distribution method, called an EP method. We confirmed that the proposed method was able to produce solutions whose group costs were close to lower-bound group costs by computational experiments. In addition, we verified that reduction in computational time was achieved without losing the quality of solutions by using the EP method.

Expert model of decision-making system for efficient orientation of basketball players to positions and roles in the game--empirical verification.

Science.gov (United States)

Dezman, B; Trninić, S; Dizdar, D

2001-06-01

The purpose of the research was to empirically verify the expert model system designed for more efficient orientation of basketball players to particular positions and /or roles in the game (specialization). Participants were 60 randomly chosen male basketball players (12 players per each position) from the 12 Croatian 1st league teams in season 1998/99. Data were gathered from 10 basketball coaches who estimated overall performance (actual quality) of players on defense (7 variables) and on offense (12 variables). Variables were established by Trninić, Perica and Dizdar. A measure of body height was added to the aforementioned group of variables. The results obtained suggest that the proposed decision-making system can be used as an auxiliary instrument in orienting players to the positions and roles in the game. It has been established that the players have attained the highest grades of overall performance exactly at their primary playing positions in the game. The largest differences were determined between point guards (position 1) and centers (position 5). The greatest difficulties have occurred in determining optimal position for small forwards (position 3), then for shooting guards (position 2) and, last, for power forwards (position 4), because all these basketball players are the most versatile ones. Therefore, reliability of the system is the lowest when it is applied for selecting and orientating players to these positions. Convenient body height significantly contributes to aptitude of these players to play multiple positions and to assume multiple roles in the game. This research has reinforced the thesis that body height is a variable with the greatest influence on orientation of players to particular positions and roles in the game.

The Diagnostic and Prognostic Value of Ultrasonography in Soccer Players With Acute Hamstring Injuries

DEFF Research Database (Denmark)

Petersen, Jesper; Thorborg, Kristian; Nielsen, Michael Bachmann

2014-01-01

BACKGROUND: An injury to the hamstring muscle complex is the most common injury in soccer. Ultrasound of acute hamstring injuries is often used as a clinical tool for diagnosing hamstring injuries and guiding players in when they can return to play. PURPOSE: To (1) investigate the characteristic......) to investigate if ultrasonography can be used as a prognostic indicator of time to return to play. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Players from 50 teams participating in 1 of the top 5 Danish soccer divisions were followed in the period from January to December 2008. Of 67 players...

Between-game variation of physical soccer performance measures in highly trained youth soccer players.

Science.gov (United States)

Doncaster, Greg; Unnithan, Viswanath

2017-07-12

To assess the between-game variation in measures of physical performance during 11 v 11 soccer match-play, over a short period of time, in highly trained youth soccer players. A single cohort observational study design was employed. Physical match performance data were collected from 17 male, highly trained youth soccer players (age: 13.3 ± 0.4 y) over three, 2 x 20min, 11 v 11 matches. Using 10 Hz GPS, the variables selected for analyses were total distance (TD), high-speed running (HSR), very high-speed running (VHSR), number of high-speed running efforts (HSReff) and number of very high-speed running efforts (VHSReff). Match data was also separated into cumulative 5 min epochs, to identify the peak 5 min epoch and the mean of the cumulative 5 min epochs for each match. Variability was quantified using the coefficient of variation (CV), Standard error of measurement (SEM) and intra-class correlation coefficient (ICC). Between- and within-player smallest worthwhile changes (SWC) were also calculated for each variable to aid in the interpretation of the data. Analysis of the variance between games reported a low CV for TD (3.8%) but larger CVs for HSR (33.3%), HSReff (35.4%) and VHSR and VHSReff (59.6 and 57.4 %, respectively). Analysis of 5 min epochs (peak and average) found an increase in the CVs beyond that of the values reported for the whole match. Between-player SWC in high intensity physical performance data ranged from 24.7 - 42.4 %, whereas within-player SWC ranged from 1.2 - 79.9%. The between-game variability of high and very high intensity activities in youth soccer players, across three soccer matches over a short period of time (2 weeks), is relatively 'large' and specific to the individual, thus highlighting the need for caution when interpreting physical performance data between games and players.

Task-specific kinetic finger tremor affects the performance of carrom players.

Science.gov (United States)

Kahathuduwa, Chanaka N; Weerasinghe, Vajira S; Dassanayake, Tharaka L; Priyadarshana, Rajeewa; Dissanayake, Arunika L; Perera, Christine

2016-01-01

We aimed to determine the effect of task-specific kinetic finger tremor, as indexed by surface electromyography (EMG), on the accuracy of a carrom stroke. Surface EMG of extensor digitorum communis muscle of the playing arm was recorded during rest, isometric contraction and stroke execution in 17 male carrom players with clinically observed finger tremor and 18 skill- and age-matched controls. Log-transformed power spectral densities (LogPSDs) of surface EMG activity (signifying tremor severity) at a 1-s pre-execution period correlated with angular error of the stroke. LogPSDs in 4-10 Hz range were higher in players with tremor than controls during pre-execution (P kinetic finger tremor in carrom players. This finger tremor during the immediate pre-execution phase appears to be a significant determinant of stroke accuracy.

The β Pictoris association low-mass members: Membership assessment, rotation period distribution, and dependence on multiplicity

Science.gov (United States)

Messina, S.; Lanzafame, A. C.; Malo, L.; Desidera, S.; Buccino, A.; Zhang, L.; Artemenko, S.; Millward, M.; Hambsch, F.-J.

2017-10-01

Context. Low-mass members of young loose stellar associations and open clusters exhibit a wide spread of rotation periods. Such a spread originates from the distributions of masses and initial rotation periods. However, multiplicity can also play a significant role. Aims: We aim to investigate the role played by physical companions in multiple systems in shortening the primordial disk lifetime, anticipating the rotation spin up with respect to single stars. Methods: We have compiled the most extensive list to date of low-mass bona fide and candidate members of the young 25-Myr β Pictoris association. We have measured from our own photometric time series or from archival time series the rotation periods of almost all members. In a few cases the rotation periods were retrieved from the literature. We used updated UVWXYZ components to assess the membership of the whole stellar sample. Thanks to the known basic properties of most members we built the rotation period distribution distinguishing between bona fide members and candidate members and according to their multiplicity status. Results: We find that single stars and components of multiple systems in wide orbits (>80 AU) have rotation periods that exhibit a well defined sequence arising from mass distribution with some level of spread likely arising from initial rotation period distribution. All components of multiple systems in close orbits (Pleiades shows that whereas the evolution of F-G stars is well reproduced by angular momentum evolution models, this is not the case for the slow K and early-M stars. Finally, we find that the amplitude of their light curves is correlated neither with rotation nor with mass. Conclusions: Once single stars and wide components of multiple systems are separated from close components of multiple systems, the rotation period distributions exhibit a well defined dependence on mass that allows us to make a meaningful comparison with similar distributions of either younger or older

Ultra-Short-Term Heart Rate Variability is Sensitive to Training Effects in Team Sports Players.

Science.gov (United States)

Nakamura, Fabio Y; Flatt, Andrew A; Pereira, Lucas A; Ramirez-Campillo, Rodrigo; Loturco, Irineu; Esco, Michael R

2015-09-01

The aim of this study was to test the possibility of the ultra-short-term lnRMSSD (measured in 1-min post-1-min stabilization period) to detect training induced adaptations in futsal players. Twenty-four elite futsal players underwent HRV assessments pre- and post-three or four weeks preseason training. From the 10-min HRV recording period, lnRMSSD was analyzed in the following time segments: 1) from 0-5 min (i.e., stabilization period); 2) from 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min and; 3) from 5-10 min (i.e., criterion period). The lnRMSSD was almost certainly higher (100/00/00) using the magnitude-based inference in all periods at the post- moment. The correlation between changes in ultra-short-term lnRMSSD (i.e., 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min) and lnRMSSDCriterion ranged between 0.45-0.75, with the highest value (p = 0.75; 90% CI: 0.55 - 0.85) found between ultra-short-term lnRMDSSD at 1-2 min and lnRMSSDCriterion. In conclusion, lnRMSSD determined in a short period of 1-min is sensitive to training induced changes in futsal players (based on the very large correlation to the criterion measure), and can be used to track cardiac autonomic adaptations. Key pointsThe ultra-short-term (1 min) natural log of the root-mean-square difference of successive normal RR intervals (lnRMSSD) is sensitive to training effects in futsal playersThe ultra-short-term lnRMSSD may simplify the assessment of the cardiac autonomic changes in the field compared to the traditional and lengthier (10 min duration) analysisCoaches are encouraged to implement the ultra-short-term heart rate variability in their routines to monitor team sports athletes.

Impact locations and concussion outcomes in high school football player-to-player collisions.

Science.gov (United States)

Kerr, Zachary Y; Collins, Christy L; Mihalik, Jason P; Marshall, Stephen W; Guskiewicz, Kevin M; Comstock, R Dawn

2014-09-01

Little research has examined concussion outcomes in terms of impact location (ie, the area on the head in which the impact occurred). This study describes the epidemiology of concussions resulting from player-to-player collision in high school football by impact location. National High School Sports-Related Injury Surveillance Study data (2008/2009-2012/2013) were analyzed to calculate rates and describe circumstances of football concussion (eg, symptomology, symptom resolution time, return to play) resulting from player-to-player collisions by impact location (ie, front-, back-, side-, and top-of-the-head). Most concussions resulting from player-to-player collisions occurred from front-of-the-head (44.7%) and side-of-the-head (22.3%) impacts. Number of symptoms reported, prevalence of reported symptoms, symptom resolution time, and length of time to return to play were not associated with impact location. However, a larger proportion of football players sustaining concussions from top-of-the-head impacts experienced loss of consciousness (8.0%) than those sustaining concussions from impacts to other areas of the head (3.5%) (injury proportion ratio 2.3; 95% confidence interval 1.2-4.2; P = .008). Players had their head down at the time of impact in a higher proportion of concussions caused by top-of-the-head impacts (86.4%) than concussions from impacts to other areas of the head (24.0%) (injury proportion ratio 3.6; 95% confidence interval 3.2-4.0; P impact location. Recommended strategies for reducing the proportion of top-of-the-head impacts include improved education regarding tackling with proper "head-up" technique. Copyright © 2014 by the American Academy of Pediatrics.

Multiple periodic-soliton solutions of the (3+1)-dimensional generalised shallow water equation

Science.gov (United States)

Li, Ye-Zhou; Liu, Jian-Guo

2018-06-01

Based on the extended variable-coefficient homogeneous balance method and two new ansätz functions, we construct auto-Bäcklund transformation and multiple periodic-soliton solutions of (3 {+} 1)-dimensional generalised shallow water equations. Completely new periodic-soliton solutions including periodic cross-kink wave, periodic two-solitary wave and breather type of two-solitary wave are obtained. In addition, cross-kink three-soliton and cross-kink four-soliton solutions are derived. Furthermore, propagation characteristics and interactions of the obtained solutions are discussed and illustrated in figures.

Secret Sharing Schemes with a large number of players from Toric Varieties

DEFF Research Database (Denmark)

Hansen, Johan P.

A general theory for constructing linear secret sharing schemes over a finite field $\\Fq$ from toric varieties is introduced. The number of players can be as large as $(q-1)^r-1$ for $r\\geq 1$. We present general methods for obtaining the reconstruction and privacy thresholds as well as conditions...... for multiplication on the associated secret sharing schemes. In particular we apply the method on certain toric surfaces. The main results are ideal linear secret sharing schemes where the number of players can be as large as $(q-1)^2-1$. We determine bounds for the reconstruction and privacy thresholds...

Physical fitness of elite Belgian soccer players by player position.

Science.gov (United States)

Boone, Jan; Vaeyens, Roel; Steyaert, Adelheid; Vanden Bossche, Luc; Bourgois, Jan

2012-08-01

The purpose of this study was to gain an insight into the physical and physiological profile of elite Belgian soccer players with specific regard to the player's position on the field. The sample consisted of 289 adult players from 6 different first division teams. The players were divided into 5 subgroups (goalkeepers, center backs, full backs, midfielders, and strikers) according to their self-reported best position on the field. The subjects performed anaerobic (10-m sprint, 5 × 10-m shuttle run [SR], squat jump [SJ], and countermovement jump [CMJ]) and aerobic (incremental running protocol) laboratory tests. The strikers had significantly shorter sprinting times (5-, 5- to 10-m time, and SR) compared with the midfielders, center backs, and goalkeepers, whereas the full backs were also significantly faster compared with the goalkeepers and the center backs. The goalkeepers and the center backs displayed higher jumping heights (total mean SJ = 40.7 ± 4.6 cm and CMJ = 43.1 ± 4.9 cm) compared with the other 3 positions, whereas the strikers also jumped higher than the full backs and the midfielders did. Regarding the aerobic performance, both full backs and the midfielders (61.2 ± 2.7 and 60.4 ± 2.8 ml · min(-1) · kg(-1), respectively) had a higher VO2max compared with the strikers, center backs, and goalkeepers (56.8 ± 3.1, 55.6 ± 3.5, and 52.1 ± 5.0 ml · min(-1) · kg(-1), respectively). From this study, it could be concluded that players in different positions have different physiological characteristics. The results of this study might provide useful insights for individualized conditional training programs for soccer players. Aside from the predominant technical and tactical skills, a physical profile that is well adjusted to the position on the field might enhance game performance.

High School Football Players Use Their Helmets to Tackle Other Players Despite Knowing the Risks.

Science.gov (United States)

Kuriyama, Andrew M; Nakatsuka, Austin S; Yamamoto, Loren G

2017-03-01

There is greater attention to head-related injuries and concussions in American football. The helmet's structural safety and the way that football players use their helmets are important in preventing head injuries. Current strategies include penalizing players for high-risk behavior such as leading with their helmet or hitting an opposing player above the shoulder. Passive strategies include helmet modification to better protect the head of the players or to change the playing style of the players. Hawai'i high school varsity football players were surveyed to determine how they use their helmets and how a new helmet design would affect their style of play. One hundred seventy-seven surveys were completed; 79% said that they used their helmet to hit an opposing player during a tackle and 46% said they made this contact intentionally. When asked about modifying helmets with a soft material on the outside, 48% said they thought putting a soft cover over a regular helmet would protect their head better. However, many participants said that putting a soft cover over their regular helmet was a bad idea for various reasons. Most young football players use their helmets to block or tackle despite being taught they would be penalized or potentially injured if they did so. By gaining a better understanding of why and how players use their helmets and how they would respond to new helmet designs, steps can be taken to reduce head injuries for all levels of play.

Concussions are associated with decreased batting performance among Major League Baseball players.

Science.gov (United States)

Wasserman, Erin B; Abar, Beau; Shah, Manish N; Wasserman, Daniel; Bazarian, Jeffrey J

2015-05-01

Concussions impair balance, visual acuity, and reaction time--all of which are required for high-level batting performance--but the effects of concussion on batting performance have not been reported. The authors examined this relationship between concussion and batting performance among Major League Baseball (MLB) players. Batting performance among concussed MLB players will be worse upon return to play than batting performance among players missing time for noninjury reasons. Cohort study; Level of evidence, 3. The authors identified MLB players who sustained a concussion between 2007 and 2013 through league disabled-list records and a Baseball Prospectus database. For a comparison group, they identified players who went on paternity or bereavement leave during the same period. Using repeated-measures generalized linear models, the authors compared 7 batting metrics between the 2 groups for the 2 weeks upon return, as well as 4 to 6 weeks after return, controlling for pre-leave batting metrics, number of days missed, and position. The authors identified 66 concussions and 68 episodes of bereavement/paternity leave to include in the analysis. In the 2 weeks after return, batting average (.235 vs .266), on-base percentage (.294 vs .326), slugging percentage (.361 vs .423), and on-base plus slugging (.650 vs .749) were significantly lower among concussed players relative to the bereavement/paternity leave players (time×group interaction, Pperformance after concussion is adversely affected and to identify better measures to use for return-to-play decisions. © 2015 The Author(s).

VO2 kinetics and performance in soccer players after intense training and inactivity

DEFF Research Database (Denmark)

Christensen, Peter Møller; Krustrup, Peter; Gunnarsson, Thomas P.

2011-01-01

18 elite soccer players were, for a two-week period, assigned to a high intensity training group (HI, n=7) performing 10 training sessions mainly consisting of aerobic high intensity training (8×2 min) and speed endurance training (10-12×30-s sprints) or a training cessation group (TC, n=11......PURPOSE:: To examine the effects of a short-term period with intensified training or training cessation of trained soccer players on VO2 kinetics at 75% maximal aerobic speed (MAS), oxidative enzymes and performance in repeated high intensity exercise. METHODS:: After the last match of the season......) that refrained from training. RESULTS:: For TC, VO2 kinetics became slower (P...

The Transition Period in Soccer: A Window of Opportunity.

Science.gov (United States)

Silva, Joao Renato; Brito, Joao; Akenhead, Richard; Nassis, George P

2016-03-01

The aim of this paper is to describe the physiological changes that occur during the transition period in soccer players. A secondary aim is to address the issue of utilizing the transition period to lay the foundation for the succeeding season. We reviewed published peer-reviewed studies if they met the following three selection criteria: (1) the studied population comprised adult soccer players (aged >18 years), (2) time points of physiological and performance assessments were provided, and (3) appropriate statistics for the calculation of effect sizes were reported. Following two selection phases, 12 scientific publications were considered, involving a total sample of 252 players. The transition period elicits small to moderate negative changes in body composition, a moderate decline in sprint performance with and without changes of direction, and small to moderate decrements in muscle power. Detraining effects are also evident for endurance-related physiological and performance outcomes: large decrements in maximal oxygen consumption V̇O2max) and time to exhaustion, and moderate to very large impairments have been observed in intermittent-running performance. Off-season programs should be characterized by clear training objectives, a low frequency of training sessions, and simple training tools in order to facilitate compliance. The program suggested here may constitute the 'minimum effective dose' to maintain or at least attenuate the decay of endurance- and neuromuscular-related performance parameters, as well as restore an adequate strength profile (reduce muscle strength imbalances). This periodization strategy may improve the ability of players to cope with the elevated training demands of pre-season training and therefore reduce the risk of injury. Moreover, this strategy will favor a more efficient development of other relevant facets of performance during the pre-competition phase (e.g., tactical organization). We contend that the transition period

Daily Fantasy Sports Players: Gambling, Addiction, and Mental Health Problems.

Science.gov (United States)

Nower, Lia; Caler, Kyle R; Pickering, Dylan; Blaszczynski, Alex

2018-01-19

Studies point to a relationship between fantasy sports/daily fantasy sports (DFS) play and gambling behavior. However, little is known about the nature of those relationships, particularly regarding the development of gambling problems. This study investigates the nature, frequency, and preferences of gambling behavior as well as problem gambling severity and comorbid conditions among DFS players. Data were collected from an epidemiologic survey of 3634 New Jersey residents on gambling and leisure activities. Participants were contacted by phone (land-line and cell) and online to obtain a representative, cross-sectional sample of non-institutionalized adults, aged 18 years or older. Excluding non-gamblers, the remaining 2146 participants, included in these analyses, indicated they had either played DFS (n = 299) or had gambled but not played DFS (1847) in the past year. Univariate comparisons and multiple logistic regression analyses were performed to identify the most significant characteristics and predictors of DFS players. Overall, a higher number of gambling activities, high frequency gambling, male gender, and reports of suicidal thoughts in the past year were most predictive of DFS players. Being Hispanic (vs. Caucasian) and/or single (vs. married or living with a partner) also doubled the odds of DFS play. Findings suggest that DFS players are characterized by high gambling frequency and problem severity and comorbid problems, notably suicidal ideation. Future research should examine the motivations and possible etiological sub-types of DFS players and the nature and course of DFS play, particularly in relation to gambling behavior and the development of gambling and other problems.

Adaptive Portfolio Optimization for Multiple Electricity Markets Participation

DEFF Research Database (Denmark)

Pinto, Tiago; Morais, Hugo; Sousa, Tiago M.

2016-01-01

as the most suitable solution to facilitate the small players' participation in electric power negotiations while improving energy efficiency. The opportunity for players' participation in multiple energy negotiation environments (smart grid negotiation in addition to the already implemented market types......, such as day-ahead spot markets, balancing markets, intraday negotiations, bilateral contracts, forward and futures negotiations, and among other) requires players to take suitable decisions on whether to, and how to participate in each market type. This paper proposes a portfolio optimization methodology......, which provides the best investment profile for a market player, considering different market opportunities. The amount of power that each supported player should negotiate in each available market type in order to maximize its profits, considers the prices that are expected to be achieved in each market...

Technical player profiles related to the physical fitness of young female volleyball players predict team performance.

Science.gov (United States)

Dávila-Romero, C; Hernández-Mocholí, M A; García-Hermoso, A

2015-03-01

This study is divided into three sequential stages: identification of fitness and game performance profiles (individual player performance), an assessment of the relationship between these profiles, and an assessment of the relationship between individual player profiles and team performance during play (in championship performance). The overall study sample comprised 525 (19 teams) female volleyball players aged 12-16 years and a subsample (N.=43) used to examine study aims one and two was selected from overall sample. Anthropometric, fitness and individual player performance (actual game) data were collected in the subsample. These data were analyzed through clustering methods, ANOVA and independence chi-square test. Then, we investigated whether the proportion of players with the highest individual player performance profile might predict a team's results in the championship. Cluster analysis identified three volleyball fitness profiles (high, medium, and low) and two individual player performance profiles (high and low). The results showed a relationship between both types of profile (fitness and individual player performance). Then, linear regression revealed a moderate relationship between the number of players with a high volleyball fitness profile and a team's results in the championship (R2=0.23). The current study findings may enable coaches and trainers to manage training programs more efficiently in order to obtain tailor-made training, identify volleyball-specific physical fitness training requirements and reach better results during competitions.

Somatotype and stress hormone levels in young soccer players.

Science.gov (United States)

Handziska, E; Handziski, Z; Gjorgoski, I; Dalip, M

2015-11-01

The relationship between somatotype and cortisol and adrenocorticotropic (ACTH) hormone concentrations at rest or after exercise in adolescent soccer players at different time points throughout a soccer season is not understood. Therefore, the aim of this study was to examine the relationship between somatotype and cortisol and ACTH concentrations at rest and after exercise in adolescent soccer players at different time points during a soccer season. During the first 4 months of the soccer season, 47 soccer players (between 15-17 years of age) were tested at three different time points including at baseline, after 6 weeks, and at the end of 4 months. Testing included anaerobic threshold (AnT, km/h) and maximal speed of running (Max, km/h) were measured with Conconi protocol on treadmill. Before and after a maximal exercise Test, plasma levels of cortisol (ug/dL) and ACTH (pg/ml) were assessed by chemiluminometry enzyme amplificated method. Heath-Carter anthropometric somatotype model was used to determine 13 elements of somatotype. Descriptive statistics and multiple regression were used for statistical analysis (Psoccer training process could indicate a stagnation of training process, accordingly with insignificant changes of AnT. The significant correlations of some somatotypes with stress hormonal responses could only suggest that the somatotype characteristics of young soccer players could be of interest in process of selection and planning of soccer training process with an essential need for more studies.

Seasonal Changes in Soccer Players' Body Composition and Dietary Intake Practices.

Science.gov (United States)

Devlin, Brooke L; Kingsley, Michael; Leveritt, Michael D; Belski, Regina

2017-12-01

Devlin, BL, Kingsley, M, Leveritt, MD, and Belski, R. Seasonal changes in soccer players' body composition and dietary intake practices. J Strength Cond Res 31(12): 3319-3326, 2017-The aims of this study were 2-fold: to determine seasonal changes in dietary intake and body composition in elite soccer players and to evaluate the influence of self-determined individual body composition goals on dietary intake and body composition. This longitudinal, observational study assessed body composition (total mass, fat-free soft tissue mass, and fat mass) using dual-energy x-ray absorptiometry and dietary intake (energy and macronutrients) via multiple-pass 24-hour recalls, at 4 time points over a competitive season in elite soccer players from one professional club in the Australian A-League competition. Self-reported body composition goals were also recorded. Eighteen elite male soccer players took part (25 ± 5 years, 180.5 ± 7.4 cm, 75.6 ± 6.5 kg). Majority (≥67%) reported the goal to maintain weight. Fat-free soft tissue mass increased from the start of preseason (55,278 ± 5,475 g) to the start of competitive season (56,784 ± 5,168 g; p nutrition recommendations. The self-reported body composition goals did not strongly influence dietary intake practices or changes in body composition. This study has demonstrated that body composition changes over the course of a soccer season are subtle in elite soccer players despite relatively low self-reported intake of energy and carbohydrate.

Rehabilitation protocol for patellar tendinopathy applied among 16- to 19-year old volleyball players.

Science.gov (United States)

Biernat, Ryszard; Trzaskoma, Zbigniew; Trzaskoma, Lukasz; Czaprowski, Dariusz

2014-01-01

The aim of the study was to investigate the efficacy of rehabilitation protocol applied during competitive period for the treatment of patellar tendinopathy. A total of 28 male volleyball players were divided into two groups. Fifteen from experimental group (E) and 13 from control group (C) fulfilled the same tests 3 times: before the training program started (first measurement), after 12 weeks (second measurement) and after 24 weeks (third measurement). The above-mentioned protocol included the following: USG imagining with color Doppler function, clinical testing, pain intensity evaluation with VISA-P questionnaire, leg muscle strength and power and jumping ability measurements. The key element of the rehabilitation program was eccentric squat on decline board with additional unstable surface. The essential factor of the protocol was a set of preventive functional exercises, with focus on eccentric exercises of hamstrings. Patellar tendinopathy was observed in 18% of the tested young volleyball players. Implementation of the presented rehabilitation protocol with eccentric squat on decline board applied during sports season lowered the pain level of the young volleyball players. Presented rehabilitation protocol applied without interrupting the competitive period among young volleyball players together with functional exercises could be an effective method for the treatment of patellar tendinopathy.

Protective Equipment and Player Characteristics Associated With the Incidence of Sport-Related Concussion in High School Football Players

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McGuine, Timothy A.; Hetzel, Scott; McCrea, Michael; Brooks, M. Alison

2015-01-01

Background The incidence of sport-related concussion (SRC) in high school football is well documented. However, limited prospective data are available regarding how player characteristics and protective equipment affect the incidence of SRC. Purpose To determine whether the type of protective equipment (helmet and mouth guard) and player characteristics affect the incidence of SRC in high school football players. Design Cohort study; Level of evidence, 2. Methods Certified athletic trainers (ATs) at each high school recorded the type of helmet worn (brand, model, purchase year, and recondition status) by each player as well as information regarding players’ demographics, type of mouth guard used, and history of SRC. The ATs also recorded the incidence and days lost from participation for each SRC. Incidence of SRC was compared for various helmets, type of mouth guard, history of SRC, and player demographics. Results A total of 2081 players (grades 9–12) enrolled during the 2012 and/or 2013 football seasons (2287 player-seasons) and participated in 134,437 football (practice or competition) exposures. Of these players, 206 (9%) sustained a total of 211 SRCs (1.56/1000 exposures). There was no difference in the incidence of SRC (number of helmets, % SRC [95% CI]) for players wearing Riddell (1171, 9.1% [7.6%–11.0%]), Schutt (680, 8.7% [6.7%–11.1%]), or Xenith (436, 9.2% [6.7%–12.4%]) helmets. Helmet age and recondition status did not affect the incidence of SRC. The rate of SRC (hazard ratio [HR]) was higher in players who wore a custom mouth guard (HR = 1.69 [95% CI, 1.20–2.37], P football players. Players who had sustained an SRC within the previous 12 months were more likely to sustain an SRC than were players without a history of SRC. Sports medicine providers who work with high school football players need to realize that factors other than the type of protective equipment worn affect the risk of SRC in high school players. PMID:25060072

The potential risk of personal stereo players

DEFF Research Database (Denmark)

Hammershøi, Dorte; Ordoñez, Rodrigo Pizarro; Reuter, Karen

2010-01-01

The technological development within personal stereo systems,such as MP3 players, e. g. iPods, has changed music listening habits from home entertainment to everyday and everywhere use. The technology has developed considerably, since the introduction of cassette players and CD walkmen. High......-level low-distortion music is produced by minimal devices which can play for long periods. In this paper, the existing literature on effects of personal stereo systems is reviewed, incl. studies of exposure levels, and effects on hearing. Generally, it is found that the levels being used are of concern......, which in one study is demonstrated to relate to the specific use in situations with high levels of background noise. Another study demonstrates that the effect of using personal stereo is comparable to that of being exposed to noise in industry. The results are discussed in view of the measurement...

Groin Problems in Male Soccer Players Are More Common Than Previously Reported

DEFF Research Database (Denmark)

Harøy, Joar; Clarsen, Ben; Thorborg, Kristian

2017-01-01

surveillance method developed to capture acute and overuse problems. STUDY DESIGN: Descriptive epidemiology study. METHODS: We registered groin problems during a 6-week period of match congestion using the Oslo Sports Trauma Research Center Overuse Injury Questionnaire. A total of 240 players from 15 teams......BACKGROUND: The majority of surveillance studies in soccer have used a time-loss injury definition, and many groin problems result from overuse, leading to gradually increasing pain and/or reduced performance without necessarily causing an absence from soccer training or match play. Thus......, the magnitude of groin problems in soccer has probably been underestimated in previous studies based on traditional injury surveillance methods. PURPOSE: To investigate the prevalence of groin problems among soccer players of both sexes and among male soccer players at different levels of play through a new...

Whole-body vibration training effects on the physical performance of basketball players.

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Colson, Serge S; Pensini, Manuela; Espinosa, Julien; Garrandes, Frederic; Legros, Patrick

2010-04-01

The aim of this study was to investigate the influence of 4 weeks of whole-body vibration training added to the conventional training of basketball players. Eighteen competitive basketball players (13 male symbol, 5 female symbol, 18-24 years old) were randomly assigned to a whole-body vibration group (WBVG, n = 10; 7 male symbol and 3 female symbol) or a control group (CG, n = 8; 6 male symbol and 2 female symbol). During the 4-week period, all subjects maintained their conventional basketball training program. The members of WBVG were additionally trained 3 times a week for 20 minutes on a vibration platform (10 unloaded static lower limb exercises, 40-Hz, 4-mm, Silverplate). Testing was performed before and after the 4-week period and comprised strength assessment, vertical jump performance, and a 10-m sprint test. The maximal voluntary isometric strength of the knee extensors significantly increased (p training, as did squat jump (SJ) height (p training program added to the conventional training of basketball players during the preseason is an effective short-term stimulus to enhance knee extensor strength and slightly SJ performance.

Ultra-Short-Term Heart Rate Variability is Sensitive to Training Effects in Team Sports Players

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Fabio Y. Nakamura, Andrew A. Flatt, Lucas A. Pereira, Rodrigo Ramirez-Campillo, Irineu Loturco, Michael R. Esco

2015-09-01

Full Text Available The aim of this study was to test the possibility of the ultra-short-term lnRMSSD (measured in 1-min post-1-min stabilization period to detect training induced adaptations in futsal players. Twenty-four elite futsal players underwent HRV assessments pre- and post-three or four weeks preseason training. From the 10-min HRV recording period, lnRMSSD was analyzed in the following time segments: 1 from 0-5 min (i.e., stabilization period; 2 from 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min and; 3 from 5-10 min (i.e., criterion period. The lnRMSSD was almost certainly higher (100/00/00 using the magnitude-based inference in all periods at the post- moment. The correlation between changes in ultra-short-term lnRMSSD (i.e., 0-1 min; 1-2 min; 2-3 min; 3-4 min; 4-5 min and lnRMSSDCriterion ranged between 0.45-0.75, with the highest value (p = 0.75; 90% CI: 0.55 – 0.85 found between ultra-short-term lnRMDSSD at 1-2 min and lnRMSSDCriterion. In conclusion, lnRMSSD determined in a short period of 1-min is sensitive to training induced changes in futsal players (based on the very large correlation to the criterion measure, and can be used to track cardiac autonomic adaptations.

Performance outcomes after repair of complete achilles tendon ruptures in national basketball association players.

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Amin, Nirav H; Old, Andrew B; Tabb, Loni P; Garg, Rohit; Toossi, Nader; Cerynik, Douglas L

2013-08-01

A complete rupture of the Achilles tendon is a devastating injury. Variables affecting return to competition and performance changes for National Basketball Association (NBA) players are not readily evident. Players in the NBA who ruptured their Achilles tendons and who underwent surgical repair would have more experience in the league, and the performance of those who were able to return to competition would be decreased when compared with their performance before injury and with their control-matched peers. Cohort study; Level of evidence, 3. Data for 18 basketball players with Achilles tendon repair over a 23-year period (1988-2011) were obtained from injury reports, press releases, and player profiles. Variables included age, body mass index (BMI), player position, and number of years playing in the league. Individual season statistics were obtained, and the NBA player efficiency rating (PER) was calculated for 2 seasons before and after injury. Controls were matched by playing position, number of seasons played, and performance statistics. Univariate and multivariate analyses were performed to assess the effect of each factor. At the time of injury, the average age was 29.7 years, average BMI was 25.6, and average playing experience was 7.6 years. Seven players never returned to play an NBA game, whereas 11 players returned to play 1 season, with 8 of those players returning for ≥2 seasons. Players who returned missed an average of 55.9 games. The PER was reduced by 4.57 (P = .003) in the first season and by 4.38 (P = .010) in the second season. When compared with controls, players demonstrated a significant decline in the PER the first season (P = .038) and second season (P = .081) after their return. The NBA players who returned to play after repair of complete Achilles tendon ruptures showed a significant decrease in playing time and performance. Thirty-nine percent of players never returned to play.

Observations on the treatment of lumbar disk disease in college football players.

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Day, A L; Friedman, W A; Indelicato, P A

1987-01-01

Over a 4 year period, 12 college players were treated for diskogenic injury. The most common position affected was down-lineman. Symptoms consisted of low back and/or radicular pain. No players could recall the onset of symptoms relative to football activity; weightlifting was associated with symptoms in three cases. Tentative clinical diagnosis was herniated disk disease. Method of diagnosis in the athletic population is presented along with results of surgical treatment. Percutaneous diskectomy appears to be successful for disk herniations occurring at the L4-5 space or higher.

Vascular Health in American Football Players: Cardiovascular Risk Increased in Division III Players

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Deborah L. Feairheller

2016-01-01

Full Text Available Studies report that football players have high blood pressure (BP and increased cardiovascular risk. There are over 70,000 NCAA football players and 450 Division III schools sponsor football programs, yet limited research exists on vascular health of athletes. This study aimed to compare vascular and cardiovascular health measures between football players and nonathlete controls. Twenty-three athletes and 19 nonathletes participated. Vascular health measures included flow-mediated dilation (FMD and carotid artery intima-media thickness (IMT. Cardiovascular measures included clinic and 24 hr BP levels, body composition, VO2 max, and fasting glucose/cholesterol levels. Compared to controls, football players had a worse vascular and cardiovascular profile. Football players had thicker carotid artery IMT (0.49 ± 0.06 mm versus 0.46 ± 0.07 mm and larger brachial artery diameter during FMD (4.3±0.5 mm versus 3.7±0.6 mm, but no difference in percent FMD. Systolic BP was significantly higher in football players at all measurements: resting (128.2±6.4 mmHg versus 122.4±6.8 mmHg, submaximal exercise (150.4±18.8 mmHg versus 137.3±9.5 mmHg, maximal exercise (211.3±25.9 mmHg versus 191.4±19.2 mmHg, and 24-hour BP (124.9±6.3 mmHg versus 109.8±3.7 mmHg. Football players also had higher fasting glucose (91.6±6.5 mg/dL versus 86.6±5.8 mg/dL, lower HDL (36.5±11.2 mg/dL versus 47.1±14.8 mg/dL, and higher body fat percentage (29.2±7.9% versus 23.2±7.0%. Division III collegiate football players remain an understudied population and may be at increased cardiovascular risk.

Use of Biotechnological Devices in the Quantification of Psychophysiological Workload of Professional Chess Players.

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Fuentes, Juan P; Villafaina, Santos; Collado-Mateo, Daniel; de la Vega, Ricardo; Gusi, Narcis; Clemente-Suárez, Vicente Javier

2018-01-19

Psychophysiological requirements of chess players are poorly understood, and periodization of training is often made without any empirical basis. For this reason, the aim of the present study was to investigate the psychophysiological response and quantify the player internal load during, and after playing a chess game. The participant was an elite 33 year-old male chess player ranked among the 300 best chess players in the world. Thus, cortical arousal by critical flicker fusion threshold, electroencephalogram by the theta Fz/alpha Pz ratio and autonomic modulation by heart rate variability were analyzed. Data revealed that cortical arousal by critical flicker fusion threshold and theta Fz/alpha Pz ratio increased and heart rate variability decreased during chess game. All these changes indicated that internal load increased during the chess game. In addition, pre-activation was detected in pre-game measure, suggesting that the prefrontal cortex might be preparatory activated. For these reasons, electroencephalogram, critical flicker fusion threshold and heart rate variability analysis may be highly applicable tools to control and monitor workload in chess player.

A Method for Using Player Tracking Data in Basketball to Learn Player Skills and Predict Team Performance.

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Skinner, Brian; Guy, Stephen J

2015-01-01

Player tracking data represents a revolutionary new data source for basketball analysis, in which essentially every aspect of a player's performance is tracked and can be analyzed numerically. We suggest a way by which this data set, when coupled with a network-style model of the offense that relates players' skills to the team's success at running different plays, can be used to automatically learn players' skills and predict the performance of untested 5-man lineups in a way that accounts for the interaction between players' respective skill sets. After developing a general analysis procedure, we present as an example a specific implementation of our method using a simplified network model. While player tracking data is not yet available in the public domain, we evaluate our model using simulated data and show that player skills can be accurately inferred by a simple statistical inference scheme. Finally, we use the model to analyze games from the 2011 playoff series between the Memphis Grizzlies and the Oklahoma City Thunder and we show that, even with a very limited data set, the model can consistently describe a player's interactions with a given lineup based only on his performance with a different lineup.

Short Duration Heat Acclimation in Australian Football Players

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Monica Kelly, Paul B. Gastin, Daniel B Dwyer, Simon Sostaric, Rodney J. Snow

2016-03-01

Full Text Available This study examined if five sessions of short duration (27 min, high intensity, interval training (HIIT in the heat over a nine day period would induce heat acclimation in Australian football (AF players. Fourteen professional AF players were matched for VO2peak (mL·kg-1·min-1 and randomly allocated into either a heat acclimation (Acc (n = 7 or Control (Con group (n = 7. The Acc completed five cycle ergometer HIIT sessions within a nine day period on a cycle ergometer in the heat (38.7 ± 0.5 °C; 34.4 ± 1.3 % RH, whereas Con trained in thermo-neutral conditions (22.3 ± 0.2 °C; 35.8 ± 0. % RH. Four days prior and two days post HIIT participants undertook a 30 min constant load cycling test at 60% VO2peak in the heat (37.9 ± 0.1 °C; 28.5 ± 0.7 % RH during which VO2, blood lactate concentration ([Lac-], heart rate (HR, rating of perceived exertion (RPE, thermal comfort, core and skin temperatures were measured. Heat acclimation resulted in reduced RPE, thermal comfort and [Lac-] (all p < 0.05 during the submaximal exercise test in the heat. Heart rate was lower (p = 0.007 after HIIT, in both groups. Heat acclimation did not influence any other measured variables. In conclusion, five short duration HIIT sessions in hot dry conditions induced limited heat acclimation responses in AF players during the in-season competition phase. In practice, the heat acclimation protocol can be implemented in a professional team environment; however the physiological adaptations resulting from such a protocol were limited.

Effects of volume-based overload plyometric training on maximal-intensity exercise adaptations in young basketball players.

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Asadi, Abbas; Ramirez-Campillo, Rodrigo; Meylan, Cesar; Nakamura, Fabio Y; Cañas-Jamett, Rodrigo; Izquierdo, Mikel

2017-12-01

The aim of the present study was to compare maximal-intensity exercise adaptations in young basketball players (who were strong individuals at baseline) participating in regular basketball training versus regular plus a volume-based plyometric training program in the pre-season period. Young basketball players were recruited and assigned either to a plyometric with regular basketball training group (experimental group [EG]; N.=8), or a basketball training only group (control group [CG]; N.=8). The athletes in EG performed periodized (i.e., from 117 to 183 jumps per session) plyometric training for eight weeks. Before and after the intervention, players were assessed in vertical and broad jump, change of direction, maximal strength and a 60-meter sprint test. No significant improvements were found in the CG, while the EG improved vertical jump (effect size [ES] 2.8), broad jump (ES=2.4), agility T test (ES=2.2), Illinois agility test (ES=1.4), maximal strength (ES=1.8), and 60-m sprint (ES=1.6) (Ptraining in addition to regular basketball practice can lead to meaningful improvements in maximal-intensity exercise adaptations among young basketball players during the pre-season.

Strength and Power Correlates of Throwing Velocity on Subelite Male Cricket Players.

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Freeston, Jonathan L; Carter, Thomas; Whitaker, Gary; Nicholls, Owen; Rooney, Kieron B

2016-06-01

Throwing velocity is an important aspect of fielding in cricket to affect run-outs and reduce the opponent's run-scoring opportunities. Although a relationship between strength and/or power and throwing velocity has been well established in baseball, water polo, and European handball, it has not been adequately explored in cricket. Consequently, this study aimed to determine the relationship between measures of strength and/or power and throwing velocity in cricket players. Seventeen male cricket players (mean ± SD; age, 21.1 ± 1.6 years; height, 1.79 ± 0.06 m; weight, 79.8 ± 6.4 kg) from an elite athlete program were tested for maximal throwing velocity from the stretch position and after a 3-meter shuffle. They were also assessed for strength and power using a range of different measures. Throwing velocity from the stretch position (30.5 ± 2.4 m·s) was significantly related to dominant leg lateral-to-medial jump (LMJ) distance (r = 0.71; p velocity and medicine ball chest pass (MB CP) distance (r = 0.67; p bench press strength (p = 0.90), height (p = 0.33), or weight (p = 0.29). Multiple regression analysis revealed that dominant MB Rot and MB CP explained 66% of the variance. The results were similar for velocity after a shuffle step (31.8 ± 2.1 m·s); however, VJ height reached statistical significance (r = 0.51; p ≤ 0.05). The multiple regression was also similar with MB Rot and MB CP explaining 70% of the variance. The cricketers in this study threw with greater velocity than elite junior and subelite senior cricketers but with lower velocities than elite senior cricketers and collegiate level and professional baseball players. This is the first study to demonstrate a link between strength and/or power and throwing velocity in cricket players and highlight the importance of power development as it relates to throwing velocity. Exercises that more closely simulated the speed (body weight jumps and medicine ball throws) or movement pattern (shoulder IR

Factors associated with deep tissue injury in male wheelchair basketball players of a Japanese national team

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Hirotaka Mutsuzaki

2014-04-01

Full Text Available Maintenance of the sporting activity of elite athletes in adapted sports can be difficult if a secondary disorder, such as a pressure ulcer, occurs. Pressure ulcers result from deep tissue injuries by external pressure. The purpose of this study was to use ultrasonography to investigate deep tissue injuries in male wheelchair basketball players of a Japanese national team, and to determine factors associated with the injuries (e.g., body mass index, class of wheelchair basketball, underlying disease, length of athletic career, and whether use of wheelchair is primarily for playing basketball. Twenty male Japanese wheelchair basketball players on the national team for the 2012 London Paralympic Games (12 representative players and eight candidate representative players participated in this study. The sacral region and bilateral ischial regions in each athlete were examined by ultrasonography to detect low-echoic lesions indicative of deep tissue injuries. Nine (45% players had low-echoic lesions, which were detected in 10 of 60 areas. Eight lesions were detected in the sacral region and two lesions were detected in the ischial region. More players with spinal cord injury had low-echoic lesions [9 (69.2% of 13 players], compared to players with skeletal system disease [0 (0% of 7 players, p = 0.002]. Players who used a wheelchair in daily life were more likely to have low-echoic lesions [8 (66.74% of 12 players], compared to players who primarily used a wheelchair for playing basketball [1 (12.5% of 8 players, p = 0.010]. Deep tissue injuries were detected in 45% of male Japanese wheelchair basketball players on the national team. Players with spinal cord injury and players who used a wheelchair in daily life were more likely to have deep tissue injuries, particularly in the sacral region. The lesions were small, but a periodic medical check should be performed to maintain athletes' sporting life.

Vitamin D Deficiency Among Professional Basketball Players.

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Fishman, Matthew P; Lombardo, Stephen J; Kharrazi, F Daniel

2016-07-01

Vitamin D plays an important role in several systems of the human body. Various studies have linked vitamin D deficiency to stress and insufficiency fractures, muscle recovery and function, and athletic performance. The prevalence of vitamin D deficiency in the elite athletic population has not been extensively studied, and very few reports exist among professional athletes. There is a high prevalence of vitamin D deficiency or insufficiency among players attending the National Basketball Association (NBA) Combine. Cross-sectional study; Level of evidence, 3. This is a retrospective review of data previously collected as part of the routine medical evaluation of players in the NBA Combines from 2009 through 2013. Player parameters evaluated were height, weight, body mass index (BMI), and vitamin D level. Statistical analysis using t tests and analysis of variance was used to detect any correlation between the player parameters and vitamin D level. Vitamin D levels were categorized as deficient (32 ng/mL). After institutional review board approval was submitted to the NBA, the NBA released deidentified data on 279 players who participated in the combines from 2009 through 2013. There were 90 players (32.3%) who were deficient, 131 players (47.0%) who were insufficient, and 58 players (20.8%) who were sufficient. A total of 221 players (79.3%) were either vitamin D deficient or insufficient. Among all players included, the average vitamin D level was 25.6 ± 10.2 ng/mL. Among the players who were deficient, insufficient, and sufficient, the average vitamin D levels were 16.1 ± 2.1 ng/mL, 25.0 ± 3.4 ng/mL, and 41.6 ± 8.6 ng/mL, respectively. Player height and weight were significantly increased in vitamin D-sufficient players compared with players who were not sufficient (P = .0008 and .009, respectively). Player age and BMI did not significantly differ depending on vitamin D status (P = .15 and .77, respectively). There is a high prevalence of vitamin D deficiency

Is the internal training load different between starters and nonstarters volleyball players submitted to the same external load training? A case study

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Thiago Andrade Goulart Horta

2017-11-01

Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2017v19n4p395   The same training stimulus can provide different physiological adaptations for athletes of the same team. Thus, the aim of this study was to analyze and compare the load training of starters and nonstarters players, athletes of a men’s volleyball team at different times of the season. The sample consisted of fifteen men’s volleyball superleague athletes who were divided into two groups of starters and nonstarters players. The training load of the ten weeks of the team’s preparation period for the main championship season in which no games were performed was selected for the study. The method of subjective perceived of effort (session-RPE proposed by Foster et al. (2001 was used to quantify the training load. The group of starters players had higher total weekly training load (TWTL and RPE values in the average of the ten weeks of training (p<0.05. Higher TWTL values for starters players in the preparatory and pre-competitive period compared to nonstarters players was also demonstrated (p<0.05. When different weeks were analyzed separately, weeks three and seven presented higher TWTL and RPE values for starters players compared with nonstarters players (p<0.05. The results presented in this study showed that starters players showed greater internal training load compared to nonstarters players.

Mechanical, Hormonal and Psychological Effects of a Non-Failure Short-Term Strength Training Program in Young Tennis Players

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Sarabia, Jose Manuel; Fernandez-Fernandez, Jaime; Juan-Recio, Casto; Hernández-Davó, Hector; Urbán, Tomás; Moya, Manuel

2015-01-01

This study examined the effects of a 6-week non-failure strength training program in youth tennis players. Twenty tennis players (age: 15.0 ± 1 years, body height: 170.9 ± 5.1 cm, body mass: 63.3 ± 9.1 kg) were divided into experimental and control groups. Pre and post-tests included half squats, bench press, squat jumps, countermovement-jumps and side-ball throws. Salivary cortisol samples were collected, and the Profile of Mood States questionnaire was used weekly during an anatomical adaptation period, a main training period and after a tapering week. The results showed that, after the main training period, the experimental group significantly improved (pvelocity in the half-squat power output test; Profile of Mood States (in total mood disturbance between the last week of the mean training period and the tapering week); and in squat-jump and countermovement-jump height. Moreover, significant differences were found between the groups at the post-tests in the total number of repetitions, mean and peak power during the half-squat endurance test, mean velocity in the half-squat power output test, salivary cortisol concentration (baselines, first and third week of the mean training period) and in the Profile of Mood States (in fatigue subscale: first and third week of the mean training period). In conclusion, a non-failure strength training protocol improved lower-limb performance levels and produced a moderate psychophysiological impact in youth elite tennis players, suggesting that it is a suitable program to improve strength. Such training protocols do not increase the total training load of tennis players and may be recommended to improve strength. PMID:25964812

Changes in sleep quantity and efficiency in professional rugby union players during home based training and match-play.

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Eagles, A; Mclellan, C; Hing, W; Carloss, N; Lovell, D

2014-11-04

Adequate sleep is paramount to athlete recovery and performance, however little is know about the typical sleep patterns of professional rugby union players during home based training and match-play in the competitive season. The aim of the present study was to monitor changes in sleep quantity and efficiency of elite male rugby union players over a twelve night period, which included training and two competitive matches. A total of ten elite male rugby union players from a selected team, participated in the study. Athletes sleep quantity and efficiency was monitored over a twelve night period using the Bodymedia sensewear units (BSU). There was a significant difference in sleep quantity (pwake over the twelve night period. Sleep efficiency is defined as a percentage score calculated by incorporating movement and physiological measures over the sleep duration as determined by the BSU. Also there was no significant difference between sleep parameters on the game nights. The findings show players have significantly (p<0.05) reduced sleep following a home game, which is of concern considering the established negative influence of sleep deprivation on cognitive and physical performance. This data may assist coaching, medical and performance staff to develop and implement team and individualised sleep monitoring regimes to optimise training and on-field performance.

Association between the training loads imposed to amateur rugby sevens players and burnout syndrome

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Alberto Sarly Coutinho Sobral

2014-06-01

Full Text Available Burnout syndrome has been shown to be increasingly prevalent in athletes, since it is related to factors that influence levels of stress during the preparation of sports. Therefore, it has been studied in several sports, but not in Rugby Seven. The aim of this study was to correlate the effects of training loads imposed on amateur Rugby Sevens players with the burnout questionnaire. Nine players (25 ± 5 years-old were evaluated before the preparatory period. Assessment included the measurement of the % fat percentage; nutritional status, stress, and aerobic power. During the preparatory period, once again, it was assessed the state of stress, aerobic power, and intensity of the training program. It was observed that there is no significant correlation between the intensity of the workout and Burnout scores (p> 0.05, nor between Burnout scores and aerobic capacity. However, there was significant a correlation between the intensity of training performed with aerobic power (p< 0.01. Therefore, it is concluded that a training program prescribed properly, prevents the onset of burnout syndrome in Rugby Sevens players.

Athletic performance outcomes following lumbar discectomy in professional basketball players.

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Anakwenze, Okechukwu A; Namdari, Surena; Auerbach, Joshua D; Baldwin, Keith; Weidner, Zachary D; Lonner, Baron S; Huffman, G R; Sennett, Brian J

2010-04-01

Retrospective case-control study. To quantify the athletic performance profiles after lumbar discectomy (LD) in a cohort of National Basketball Association (NBA) players in comparison with a control group of matched NBA players who did not undergo LD during the same study period. LD provides symptomatic relief and improved functional outcomes in the majority of patients as assessed by validated measures such as Oswestry Disability Index, Visual Analog Scale, and Short Form-36 (SF-36). Among professional athletes, however, the goal of lumbar HNP treated by discectomy is not only to improve functional status but also, ultimately, to return the player to preinjury athletic performance levels. No study to date has compared the athletic performance profiles before and after discectomy in professional athletes. An analysis of NBA games summaries, weekly injury reports, player profiles, and press releases was performed to identify 24 NBA players who underwent LD for symptomatic lumbar HNP between 1991 and 2007. A 1:2 case: control study was performed using players without history of lumbar HNP who were matched for age, position, experience, and body mass index as control subjects (n = 48). Paired t tests were conducted on the following parameters: games played, minutes per game, points per 40 minutes, rebounds per 40 minutes, assists per 40 minutes, steals per 40 minutes, blocks per 40 minutes, and shooting percentage. For each athletic performance outcome, between-group comparisons evaluating preindex to postindex season performance were done (index season = season of surgery). In the LD group, 18 of 24 players (75%) returned to play again in the NBA, compared with 42 of 48 players (88%, P = 0.31) in the control group. One year after surgery, between-group comparisons revealed statistically significant increase in blocked shots per 40 minutes in the LD (0.18) versus control group (-0.33; P = 0.008) and a smaller decrease in rebounds per 40 minutes in the LD (-0

Time-motion analysis of goalball players in attacks: differences of the player positions and the throwing techniques.

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Monezi, Lucas Antônio; Magalhães, Thiago Pinguelli; Morato, Márcio Pereira; Mercadante, Luciano Allegretti; Furtado, Otávio Luis Piva da Cunha; Misuta, Milton Shoiti

2018-03-26

In this study, we aimed to analyse goalball players time-motion variables (distance covered, time spent, maximum and average velocities) in official goalball match attacks, taking into account the attack phases (preparation and throwing), player position (centres and wings) and throwing techniques (frontal, spin and between the legs). A total of 365 attacks were assessed using a video based method (2D) through manual tracking using the Dvideo system. Inferential non-parametric statistics were applied for comparison of preparation vs. throwing phase, wings vs. centres and, among the throwing techniques, frontal, spin and between the legs. Significant differences were found between the attack preparation versus the throwing phase for all player time-motion variables: distance covered, time spent, maximum player velocity and average player velocity. Wing players performed most of the throws (85%) and covered longer distances than centres (1.65 vs 0.31 m). The between the legs and the spin throwing techniques presented greater values for most of the time-motion variables (distance covered, time spent and maximum player velocity) than did the frontal technique in both attack phases. These findings provide important information regarding players' movement patterns during goalball matches that can be used to plan more effective training.

A Method for Using Player Tracking Data in Basketball to Learn Player Skills and Predict Team Performance.

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Brian Skinner

Full Text Available Player tracking data represents a revolutionary new data source for basketball analysis, in which essentially every aspect of a player's performance is tracked and can be analyzed numerically. We suggest a way by which this data set, when coupled with a network-style model of the offense that relates players' skills to the team's success at running different plays, can be used to automatically learn players' skills and predict the performance of untested 5-man lineups in a way that accounts for the interaction between players' respective skill sets. After developing a general analysis procedure, we present as an example a specific implementation of our method using a simplified network model. While player tracking data is not yet available in the public domain, we evaluate our model using simulated data and show that player skills can be accurately inferred by a simple statistical inference scheme. Finally, we use the model to analyze games from the 2011 playoff series between the Memphis Grizzlies and the Oklahoma City Thunder and we show that, even with a very limited data set, the model can consistently describe a player's interactions with a given lineup based only on his performance with a different lineup.

Training Load, Physical Performance, Biochemical Markers, and Psychological Stress During A Short Preparatory Period in Brazilian Elite Male Volleyball Players.

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Horta, Thiago A G; Bara Filho, Maurício G; Coimbra, Danilo R; Miranda, R; Werneck, Francisco Z

2017-12-11

The aim of this study was to assess the relationship between training load (TL) and physical performance, biochemical markers, and psychological stress during a short preparatory period (PP) in Brazilian elite male volleyball players. Twelve volleyball players from a team competing in the Brazilian Men's Volleyball Super League were enrolled (26.9 ± 4.6 years). Countermovement Jump (CMJ), Creatine Kinase (CK), Testosterone (T), Cortisol (Cr), T/Cr ratio, and Recovery and Stress Questionnaire for Athletes (RESTQ-Sport) were collected at baseline, after 2, 4, and 6 week. TL was quantified daily using the Rating of Perceived Exertion (RPE). Differences were noted between Total Weekly TL (TWTL) (F3,33 = 50.907; p = 0.0001), CK (F3,33 = 16.157; p = 0.0001), and T (F3,33 = 3.283; p = 0.03). No differences were seen in CMJ (F3,33 = 1.821; p = 0.16), Cr (F3,33 = 2.409; p = 0.08), or T/Cr ratio (F3,33 = 1.527; p = 0.23). The RESTQ-Sport demonstrated differences between moments in Social Stress (F3,33 = 2.297; p = 0.04; Eta = 0.25), Success (F3,33 = 4.350; p = 0.01; Eta = 0.19), General Well-being (F3,33 = 4.465; p = 0.01; Eta = 0.36), and Injury (F3,33 = 2.792; p = 0.05; Eta = 0.62). The results showed a significant correlations of small to moderate magnitude between TWTL and CK (r = 0.32; p = 0.05). In conclusion, a short PP in volleyball leads to increased TL, CK level, and psychological stress. TL was related with the increase of CK, suggesting muscle damage without increased of physical performance.

Association of anthropometric qualities with vertical jump performance in elite male volleyball players.

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Aouadi, R; Jlid, M C; Khalifa, R; Hermassi, S; Chelly, M S; Van Den Tillaar, R; Gabbett, T

2012-02-01

The objective of this study was to examine the association between physical and anthropometric profiles and vertical jump performance in elite volleyball players. Thirty-three elite male volleyball players (21±1 y, 76.9±5.2 kg, 186.5±5 cm) were studied. Several anthropometric measurements (body mass, stature, body mass index, lower limb length and sitting height) together with jumping height anaerobic power of counter movement jump with arm swing (CMJarm) were obtained from all subjects. Forward stepwise multiple linear regression analysis was performed to determine if any of the anthropometric parameters were predictive of CMJarm. Anaerobic power was significantly higher (P≤0.05) in the tallest players relative to their shorter counterparts. A significant relationship was observed between CMJarm and lower limb length (r2=0.69; P0.05) predictors of CMJarm performance. This study demonstrates that lower limb length is correlated with CMJarm in elite male volleyball players. The players with longer lower limbs have the better vertical jump performances and their anaerobic power is higher. These results could be of importance for trained athletes in sports relying on jumping performance, such as basketball, handball or volleyball. Thus, the measurement of anthropometric characteristics, such as stature and lower limb length may assist coaches in the early phases of talent identification in volleyball.

Finite stage asymmetric repeated games: Both players' viewpoints

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Li, Lichun

2017-01-05

In asymmetric zero-sum games, one player has superior information about the game over the other. It is known that the informed players (maximizer) face the tradeoff of exploiting its superior information at the cost of revealing its superior information, but the basic point of the uninformed player (minimizer)\\'s decision making remains unknown. This paper studies the finite stage asymmetric repeated games from both players\\' viewpoints, and derives that not only security strategies but also the opponents\\' corresponding best responses depends only on the informed player\\'s history action sequences. Moreover, efficient LP formulations to compute both player\\'s security strategies are provided.

Shoulder instability in professional football players.

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Leclere, Lance E; Asnis, Peter D; Griffith, Matthew H; Granito, David; Berkson, Eric M; Gill, Thomas J

2013-09-01

Shoulder instability is a common problem in American football players entering the National Football League (NFL). Treatment options include nonoperative and surgical stabilization. This study evaluated how the method of treatment of pre-NFL shoulder instability affects the rate of recurrence and the time elapsed until recurrence in players on 1 NFL team. Retrospective cohort. Medical records from 1980 to 2008 for 1 NFL team were reviewed. There were 328 players included in the study who started their career on the team and remained on the team for at least 2 years (mean, 3.9 years; range, 2-14 years). The history of instability prior to entering the NFL and the method of treatment were collected. Data on the occurrence of instability while in the NFL were recorded to determine the rate and timing of recurrence. Thirty-one players (9.5%) had a history of instability prior to entering the NFL. Of the 297 players with no history of instability, 39 (13.1%) had a primary event at a mean of 18.4 ± 22.2 months (range, 0-102 months) after joining the team. In the group of players with prior instability treated with surgical stabilization, there was no statistical difference in the rate of recurrence (10.5%) or the timing to the instability episode (mean, 26 months) compared with players with no history of instability. Twelve players had shoulder instability treated nonoperatively prior to the NFL. Five of these players (41.7%) had recurrent instability at a mean of 4.4 ± 7.0 months (range, 0-16 months). The patients treated nonoperatively had a significantly higher rate of recurrence (P = 0.02) and an earlier time of recurrence (P = 0.04). The rate of contralateral instability was 25.8%, occurring at a mean of 8.6 months. Recurrent shoulder instability is more common in NFL players with a history of nonoperative treatment. Surgical stabilization appears to restore the rate and timing of instability to that of players with no prior history of instability.

Biochemical, physical and tactical analysis of a simulated game in young soccer players.

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Aquino, Rodrigo L; Gonçalves, Luiz G; Vieira, Luiz H; Oliveira, Lucas P; Alves, Guilherme F; Santiago, Paulo R; Puggina, Enrico F

2016-12-01

The objectives of this study were to describe and compare the displacement patterns and the tactical performance of the players in the first to the second game time and verify possible associations between indirect markers of muscle damage with displacement patterns in a simulated game played by young soccer players. Eighteen young soccer players were submitted to a simulated game and two blood collections, one before and another 30 minutes post-game to analyze the behavior of creatine kinase and lactate dehydrogenase enzymes. The patterns of displacement and tactics variables were obtained through functions developed in MATLAB environment (MathWorks, Inc., Natick, MA, USA). It is observed a significant increase in average speed (P=0.05), number of sprints (Ptactical variables (team surface area: P=0.002; spreading: P=0.001) in the second period of the simulated game. In addition, there was significant reduction in the percentage of the total distance at low intensity (P≤0.05) in the second period, and there was a strong association between the percentage of change delta of creatine kinase and lactate dehydrogenase with the displacement patterns in the simulated game. The results show that indirect markers of muscle damage have great association with displacement patterns in game performed in training conditions for young soccer players, evidencing a need for reflection on the post-training recovery sessions strategies, contributing to better planning of sessions throughout the macrocycle.

Perceptions of the Coach–Athlete Relationship Predict the Attainment of Mastery Achievement Goals Six Months Later: A Two-Wave Longitudinal Study among F. A. Premier League Academy Soccer Players

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Adam R. Nicholls

2017-05-01

Full Text Available All football teams that compete within the F. A. Premier League possess an academy, whose objective is to produce more and better home-grown players that are capable of playing professionally. These young players spend a large amount of time with their coach, but little is known about player’s perception of the coach–athlete relationship within F. A. Premier League Academies. The objectives of this study were to examine whether perceptions of the coach–athlete relationship changed over six months and if the coach–athlete relationship predicted self-reported goal achievement among F. A. Premier League academy players. This study included cross-sectional (n = 104 and longitudinal (n = 52 assessments, in which academy soccer players completed a measure of the coach–athlete relationship and goal achievement across either one or two time periods. The cross-sectional data were subjected to bivariate correlations, whereas the longitudinal data were analyzed using multiple regressions. Perceptions of the coach–athlete relationship remained stable over time. The coach–athlete relationship predicted the achievement of mastery goals six months later. Enhancing the quality of the coach–athlete relationship among elite adolescent athletes appears to be a suitable way of maximizing mastery achievement goals, particularly among developmental athletes who participate in team sports.

Variability of aerobic abilities of football players during competition season

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Novaković P.

2012-01-01

Full Text Available The purpose of this study is to determine whether there are differences in VO2max during one season in a team of semi-professional football players. This study will also determine the differences between groups, in relation to their position in the team, as well as in relation between the first team and the reserves. This study was conducted on a male football team, between 16 and 28 years of age and with no health problems, competing in a third-tier league. The technique employed is testing and the instrument is the Shuttle Run test that estimated their aerobic capacity. The testing was conducted indirectly during field tests at the beginning of the preparatory period, at the beginning of the competing period and at the end of the season. After a statistical analysis, it can be concluded that there are significant differences between the initial testing, control testing, and final testing. The initial testing was done at the beginning of the preparatory period and the results of the test ranged from 41.50 to 58.10 ml/kg/min. Then after six weeks, which was also right before the start of the competitive part of the season, the control testing was conducted and the results ranged from 46.90 to 62.30 ml/kg/min. Finally, at the end of the season, after all league matches had been played, the final testing was carried out and the results were obtained ranging from 43.80 to 62.00 ml/kg/min. All the testing was conducted on a sample of 31 players, where no relation was discovered between the status of the players at any of the three time points. However, there were some statistically significant differences from the aspect of the players' position but that is due to the goalkeepers being statistically different from the rest of the team. The cause of the differences in the obtained results are differences in intensity, volume and type of training depending on the stage of the season, as well as the specificity of training for the various positions in

Vertical jump in female and male basketball players--a review of observational and experimental studies.

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Ziv, Gal; Lidor, Ronnie

2010-05-01

The main purpose of this article was to review a series of studies (n=26; 15 observational and 11 experimental) examining vertical jump (VJ) performances in female and male basketball players. Information on the tests used in these studies and their specific protocols, and the training programs conducted to improve VJ ability in elite basketball players, was assessed. It was found that vertical jump values varied greatly, from 22 to 48 cm in female players and from 40 to 75 cm in male players. These large variations can be explained mostly by the differences in testing protocols (each VJ protocol examined different physiological pathways) and skill level of players. The variations in VJ values among studies were greatly reduced when they used the same protocol. In addition, short plyometric training sessions as part of the strength and conditioning program were found to enhance VJ performances in basketball players. Based on the reviewed studies, five limitations associated with the testing protocols and the strength and conditioning programs used in the studies were outlined, among them the use of multiple testing protocols and lack of experimental studies. Three recommendations for basketball and strength and conditioning coaches were suggested, for one of which was including plyometric training in the annual training program. 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Correlation between explosive strength, aerobic power and repeated sprint ability in elite basketball players.

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Stojanovic, M D; Ostojic, S M; Calleja-González, J; Milosevic, Z; Mikic, M

2012-08-01

The aim of this study was to examine the relationship between explosive strength and aerobic power with basketball-specific repeated sprint ability in elite male basketball players. Twenty-four elite basketball players (age 22.2±3.4 years, height 197.1±6.2 cm, weight 95.7±8.8 kg; training experience 11.0±3.1 years; mean±SD), participated in the study. Subjects performed countermovement jump (CMJ) test and incremental pseudo-ramp test protocol with measured CMJ height and VO2max, respectively. Specific repeated sprint ability (RSA) test was conducted, with total sprinting time (summation of 10 sprint times - RSAtot) and sprint decrement (fatigue index - RSAFI) calculated. Significant decrements in sprint performance from the eight 30-m sprint (Pbasketball players. It seems that coaches and strength and conditioning professionals should devote additional time for explosive strength development in elite basketball players during preparatory period to enhance RSA performance.

Developing Talented Soccer Players: An Analysis of Socio-Spatial Factors as Possible Key Constraints

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Serra-Olivares Jaime

2016-12-01

Full Text Available Most studies on the identification and development of soccer talent have been one-dimensional in nature. Although some multi-dimensional analyses have been conducted, few research studies have assessed in any depth the socio-spatial factors influencing talent development. The aim of this particular study was to analyse variations in the international representation of clubs (n = 821 and countries (n = 59 in the development of players who took part in the 2014 FIFA Soccer World Cup. Clubs and countries were ranked and divided into quartiles according to the number of players developed between the ages of 15 and 21 (clubs and countries that developed players for at least three years between these ages and the number of official league matches played by these players up to the age of 23. Significant variations were observed between clubs in terms of the number of developed players who took part in the World Cup and the number of official league matches played by these players up to the age of 23 (p < .05, and also between countries (p < .05. The findings reveal the need to carry out more in-depth studies into the type of training and competition engaged in by elite players in the period of development between the ages of 15 and 21. It may be the case that these factors are potentially decisive socio-spatial constraints in the development of soccer talent.

Low back pain in female elite football and handball players compared with an active control group.

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Tunås, Paula; Nilstad, Agnethe; Myklebust, Grethe

2015-09-01

The purpose of this cross-sectional study was to compare the prevalence of low back pain (LBP) among female elite football and handball players to a matched non-professional active control group. The participants were requested to answer a questionnaire based on standardized Nordic questionnaires for musculoskeletal symptoms to assess the prevalence of LBP. Included participants were elite female football (n = 277) and handball players (n = 190), and a randomly selected control group from the Norwegian population (n = 167). Fifty-seven percentage of the football players, 59 % of the handball players and 60 % of the control group had experienced LBP the previous year. There were no significant group differences in the prevalence of LBP ever (p = 0.62), the previous year (p = 0.85) or the previous 7 days (p = 0.63). For both sports, there was a significant increase in prevalence of LBP from the resting period to the competitive periods of the season (p ≤ 0.001). Seventy percent of the goalkeepers in both football and handball had experienced LBP the previous year. There were no difference in LBP among female elite football and handball players compared with the control group. However, female elite athletes in football and handball reported a high prevalence of LBP compared to previous studies. The variations in LBP and playing positions indicate that specific field positions, in football and handball, is a risk factor for developing LBP.

Strength and Conditioning Practices in Adolescent Rugby Players: Relationship with Changes in Physical Qualities.

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Weakley, Jonathon J S; Till, Kevin; Darrall-Jones, Joshua; Roe, Gregory A B; Phibbs, Padraic J; Read, Dale; Jones, Ben L

2017-01-30

Adolescent rugby players benefit from the implementation of resistance training. However resistance training practices and how they influence short-term physical change is unknown. Therefore the purpose of this study was to quantify resistance training practices, evaluate physical development, and relate these changes to resistance training variables across 12-weeks in adolescent rugby union players. Thirty-five male adolescent rugby union players participated in the study with subjects completing an anthropometric and physical testing battery pre- and post- a 12-week in-season mesocycle. Subjects recorded resistance training frequency, exercises, repetitions, load, minutes, and rating of perceived exertion for each session using weekly training diaries during the 12-week period. Paired sample t-tests and Cohen's d effect sizes were used to assess change, while Pearson correlation coefficients assessed relationships between variables. Resistance training practices were variable, while significant (p ≤0.05) improvements in body mass, countermovement jump (CMJ) height, front squat, bench press, and chin up strength were observed. Resistance training volume load had moderate to strong relationships with changes in CMJ (r =0.71), chin up (r =0.73) and bench press (r =0.45). Frequency of upper and lower body compound exercises had significant moderate to large relationships with changes in CMJ (r =0.68), chin up (r =0.65), and bench press (r =0.41). Across a 12-week in-season period, adolescent rugby union players have varying resistance training practices, while anthropometric and physical characteristics appear to improve. Given the observed relationships, increased volume loads through the implementation of free-weight compound exercises could be an effective method for improving physical qualities in young rugby players.

[Dietary behaviours of volleyball and basketball players].

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Szczepańska, Elzbieta; Spałkowska, Agnieszka

2012-01-01

In sports, such as basketball and volleyball, players must demonstrate the speed, strength, stamina and concentration. Correct nutrition affects the strength of the muscles and the extension of capacity. It is also necessary for the proper functioning of the nervous system and determines the rate of regeneration after physical effort. The aim of this study was to assess dietary behaviours of professional volleyball and basketball players and compare the prevalence of correct behaviours in both groups. 209 professional volleyball and basketball players from sports clubs localized in six Silesian cities were survived with the mean of author questionnaire. The chi-square test was used to examine differences in the prevalence of the correct behaviours among players. Analysis of the results obtained showed that 52% of the players had 4-5 meals a day. 35% of respondents had wholemeal bread and/or groats daily. Milk and dairy products daily ate 71% of surveyed players, meat and sausages 70% respectively. 41% of respondents had cottage cheese and 28% had fish several times a week. Vegetables and fruit were eaten by 21% and respectively 23% of respondents. Sweets were eaten daily by 40% of surveyed, while fast-food were eaten several times a week by 17% of players. Nutrients for athletes were used by 32%, and vitamin supplementation by 48% of respondents. Prevalence of correct dietary behaviour in the group of professional volleyball and basketball players differed. Basketball players statistically more frequently than volleyball players had 4-5 meals a day, had wholemeal bread and/or thick groats, milk and dairy products, meat and sausages, especially poultry. They had raw vegetables and fruit several times a day. They drank more than 2.5 liters of fluids per day. They also significantly more frequently than volleyball players consumed the fast-food occasionally or never. Dietary behaviours of surveyed players were incorrect. Comparison of prevalence of proper behaviours

Chess players' fame versus their merit.

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Simkin, M V; Roychowdhury, V P

2015-12-12

We investigate a pool of international chess title holders born between 1901 and 1943. Using Elo ratings, we compute for every player his expected score in a game with a randomly selected player from the pool. We use this figure as the player's merit. We measure players' fame as the number of Google hits. The correlation between fame and merit is 0.38. At the same time, the correlation between the logarithm of fame and merit is 0.61. This suggests that fame grows exponentially with merit.

Racism in soccer? Perception of challenges of black and white players by white referees, soccer players, and fans.

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Wagner-Egger, Pascal; Gygax, Pascal; Ribordy, Farfalla

2012-02-01

This experiment investigated challenge evaluations in soccer and their relation to prejudice: more precisely, whether skin colour may influence judgments of soccer tackles. Three groups of participants (soccer players, referees,and soccer fans) were asked to evaluate challenges, featuring Black and White players as aggressors and victims in a mixed-design study. Results showed that participants made some differentiations between Black and White players in a challenge evaluation task. Participants were more likely to consider within-group challenges as fouls and were faster to consider challenges made by Black players as fouls. On the other hand, fouls made by White players were seen as more severe. There were no major differences between the participating groups, suggesting that the observed effects were independent of how good players were or whether the participants were referees or not.

DIFFERENCES IN FUNCTIONAL AND MOTOR ABILITIES OFYOUNG FOOTBALL PLAYERS, BASKETBALL AND VOLLEYBALL PLAYERS

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Franja Fratrić

2009-11-01

Full Text Available The main goal of this research is to determine whether and what differences exist between the three groups of subjects (high-quality football, volleyball and basketball cadets and youth age, in the motoric and functional abilities, as well as to identify dif- ferences between subgroups within each sport. The sample consists of 61 volleyball, 31 basketball player and football player 31 (total n = 123 male, cadet and youth age are members of local clubs. Subjects were born between 01.01.1991 and 12.12.1994. The sample of variables are the values of 17 tests for the evaluation of functional and mobile status. The Motor-functional status on the basis of the results of secondary value of foot- ball, basketball and volleyball make a clear conclusion that the football players showed the best results in almost all the tests and that they had the smallest disbalance in the power of certain groups of muscles.The football players hve the highest homogeneity.

Mechanical, Hormonal and Psychological Effects of a Non-Failure Short-Term Strength Training Program in Young Tennis Players

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Sarabia Jose Manuel

2015-03-01

Full Text Available This study examined the effects of a 6-week non-failure strength training program in youth tennis players. Twenty tennis players (age: 15.0 ± 1 years, body height: 170.9 ± 5.1 cm, body mass: 63.3 ± 9.1 kg were divided into experimental and control groups. Pre and post-tests included half squats, bench press, squat jumps, countermovementjumps and side-ball throws. Salivary cortisol samples were collected, and the Profile of Mood States questionnaire was used weekly during an anatomical adaptation period, a main training period and after a tapering week. The results showed that, after the main training period, the experimental group significantly improved (p<0.05 in mean and peak power output and in the total number of repetitions during the half-squat endurance test; mean force, power and velocity in the half-squat power output test; Profile of Mood States (in total mood disturbance between the last week of the mean training period and the tapering week; and in squat-jump and countermovement-jump height. Moreover, significant differences were found between the groups at the post-tests in the total number of repetitions, mean and peak power during the half-squat endurance test, mean velocity in the half-squat power output test, salivary cortisol concentration (baselines, first and third week of the mean training period and in the Profile of Mood States (in fatigue subscale: first and third week of the mean training period. In conclusion, a non-failure strength training protocol improved lower-limb performance levels and produced a moderate psychophysiological impact in youth elite tennis players, suggesting that it is a suitable program to improve strength. Such training protocols do not increase the total training load of tennis players and may be recommended to improve strength.

Short Duration Heat Acclimation in Australian Football Players.

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Kelly, Monica; Gastin, Paul B; Dwyer, Daniel B; Sostaric, Simon; Snow, Rodney J

2016-03-01

This study examined if five sessions of short duration (27 min), high intensity, interval training (HIIT) in the heat over a nine day period would induce heat acclimation in Australian football (AF) players. Fourteen professional AF players were matched for VO2peak (mL·kg(-1)·min(-1)) and randomly allocated into either a heat acclimation (Acc) (n = 7) or Control (Con) group (n = 7). The Acc completed five cycle ergometer HIIT sessions within a nine day period on a cycle ergometer in the heat (38.7 ± 0.5 °C; 34.4 ± 1.3 % RH), whereas Con trained in thermo-neutral conditions (22.3 ± 0.2 °C; 35.8 ± 0. % RH). Four days prior and two days post HIIT participants undertook a 30 min constant load cycling test at 60% V̇O2peak in the heat (37.9 ± 0.1 °C; 28.5 ± 0.7 % RH) during which VO2, blood lactate concentration ([Lac(-)]), heart rate (HR), rating of perceived exertion (RPE), thermal comfort, core and skin temperatures were measured. Heat acclimation resulted in reduced RPE, thermal comfort and [Lac(-)] (all p competition phase. In practice, the heat acclimation protocol can be implemented in a professional team environment; however the physiological adaptations resulting from such a protocol were limited. Key pointsSome minor heat acclimation adaptations can be induced in professional AF players with five 27 min non-consecutive, short duration HIIT sessions in the heat.The heat acclimation protocol employed in this study was able to be implemented in a professional team sport environment during an actual competitive season.Elevating and maintaining a high core temperature sufficient for heat acclimation likely requires a longer heat training session or some pre-heating prior to exercise.

Arthroscopic rotator cuff repair in elite rugby players.

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Tambe, Amol; Badge, Ravi; Funk, Lennard

2009-01-01

Rugby is an increasingly popular collision sport. A wide spectrum of injuries can be sustained during training and match play. Rotator cuff injury is uncommon in contact sports and there is little published literature on the treatment of rotator cuff tears in rugby players. We therefore reviewed the results and functional outcomes of arthroscopic rotator cuff repair in elite rugby players. Eleven professional rugby players underwent arthroscopic rotator cuff repair at our hospital over a 2-year period. We collected data on these patients from the operative records. The patients were recalled for outcome scoring and ultrasound scans. There were seven rugby league players and four rugby union players, including six internationals. Their mean age was 25.7 years. All had had a traumatic episode during match play and could not return to the game after the injury. The mean time to surgery was 5 weeks. The mean width of the cuff tear was 1.8 cm. All were full- thickness cuff tears. Associated injuries included two Bankart lesions, one bony Bankart lesion, one posterior labral tear, and two 360 degrees labral tears. The biceps was involved in three cases. Two were debrided and a tenodesis was performed in one. Repair was with suture anchors. Following surgery, all patients underwent a supervised accelerated rehabilitation programme. The final follow-up was at 18 months (range: 6-31 months) post surgery. The Constant scores improved from 44 preoperatively to 99 at the last follow-up. The mean score at 3 months was 95. The Oxford shoulder score improved from 34 to 12, with the mean third month score being 18. The mean time taken to return to full match play at the preinjury level was 4.8 months. There were no complications in any of the patients and postoperative scans in nine patients confirmed that the repairs had healed. We conclude that full-thickness rotator cuff tears in the contact athlete can be addressed successfully by arthroscopic repair, with a rapid return to

Effect of low dose, short-term creatine supplementation on muscle power output in elite youth soccer players.

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Yáñez-Silva, Aquiles; Buzzachera, Cosme F; Piçarro, Ivan Da C; Januario, Renata S B; Ferreira, Luis H B; McAnulty, Steven R; Utter, Alan C; Souza-Junior, Tacito P

2017-01-01

To determine the effects of a low dose, short-term Creatine monohydrate (Cr) supplementation (0.03 g.kg.d -1 during 14 d) on muscle power output in elite youth soccer players. Using a two-group matched, double blind, placebo-controlled design, nineteen male soccer players (mean age = 17.0 ± 0.5 years) were randomly assigned to either Cr ( N  = 9) or placebo ( N  = 10) group. Before and after supplementation, participants performed a 30s Wingate Anaerobic Test (WAnT) to assess peak power output (PPO), mean power output (MPO), fatigue index (FI), and total work. There were significant increases in both PPO and MPO after the Cr supplementation period ( P  ≤ 0.05) but not the placebo period. There were also significant increases in total work, but not FI, after the Cr supplementation and placebo periods ( P  ≤ 0.05). Notably, there were differences in total work between the Cr and placebo groups after ( P  ≤ 0.05) but not before the 14 d supplementation period. There is substantial evidence to indicate that a low-dose, short-term oral Cr supplementation beneficially affected muscle power output in elite youth soccer players.

Comparative analysis of gameplay and players emotion in the most popular games from play store

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Riwinoto; Mahfud, N.; Lumombo, L.

2018-03-01

The development of the android mobile operating system and the presence of Play Store services poses challenges for developers to produce exciting mobile games. Although publishing games in Play Store is not difficult, in fact developers have to face tough competition to make homemade games can become popular. This study analyzes the gameplay of three popular paid-free games in Play Store that can survive for a period of one year from the top 10 positions in October 2015- November 2016. Analysis performed on 8 elements of the game based on the definition of Fullerton and emotional expression analysis of respondents who appeared while playing the three choosen games. The analysis shows that scarce resources are the main attraction of all three games because they create conflicts, giving constraints and challenges to players. The multiplayer game has a pattern of results and the result makes the opponent become more negative than the player to win. While the single player game is analyzed has a pattern to make the player get positive to win. There are 3 basic emotions that most often appear that is joy, disgust and surprise. Multiplayer games tend to emphasize the emotions of joy players, while single player games tend to bring disgust emotions.

Physique and Performance of Young Wheelchair Basketball Players in Relation with Classification.

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Valentina Cavedon

Full Text Available The relationships among physical characteristics, performance, and functional ability classification of younger wheelchair basketball players have been barely investigated to date. The purpose of this work was to assess anthropometry, body composition, and performance in sport-specific field tests in a national sample of Italian younger wheelchair basketball players as well as to evaluate the association of these variables with the players' functional ability classification and game-related statistics. Several anthropometric measurements were obtained for 52 out of 91 eligible players nationwide. Performance was assessed in seven sport-specific field tests (5m sprint, 20m sprint with ball, suicide, maximal pass, pass for accuracy, spot shot and lay-ups and game-related statistics (free-throw points scored per match, two- and three-point field-goals scored per match, and their sum. Association between variables, and predictivity was assessed by correlation and regression analysis, respectively. Players were grouped into four Classes of increasing functional ability (A-D. One-way ANOVA with Bonferroni's correction for multiple comparisons was used to assess differences between Classes. Sitting height and functional ability Class especially correlated with performance outcomes, but wheelchair basketball experience and skinfolds did not. Game-related statistics and sport-specific field-test scores all showed significant correlation with each other. Upper arm circumference and/or maximal pass and lay-ups test scores were able to explain 42 to 59% of variance in game-related statistics (P<0.001. A clear difference in performance was only found for functional ability Class A and D.In younger wheelchair basketball players, sitting height positively contributes to performance. The maximal pass and lay-ups test should be carefully considered in younger wheelchair basketball training plans. Functional ability Class reflects to a limited extent the actual

Effect of Hip-Focused Injury Prevention Training for Anterior Cruciate Ligament Injury Reduction in Female Basketball Players: A 12-Year Prospective Intervention Study.

Science.gov (United States)

Omi, Yorikatsu; Sugimoto, Dai; Kuriyama, Setsurou; Kurihara, Tomohisa; Miyamoto, Kenji; Yun, Songjo; Kawashima, Tatsuhiro; Hirose, Norikazu

2018-03-01

Programs to prevent anterior cruciate ligament (ACL) injuries in female basketball players are scarce. Also, ACL injury prevention training that focuses on hip joint function has not been reported. To determine the effectiveness of a hip-focused ACL injury prevention program in female basketball players. Cohort study; Level of evidence, 2. A prospective intervention study was conducted for 12 years. Incidence rates of ACL injuries were collected in the first 4 years (observation period) from college female basketball players. After the observation period, a hip-focused ACL injury prevention program was implemented for 8 years (intervention period). A total of 309 players (mean ± SD age, 19.6 ± 1.2 years; height, 163.7 ± 5.6 cm; weight, 59.1 ± 5.1 kg; body mass index, 22.0 ± 1.4) were tracked in the observation period and compared with 448 players (age, 19.6 ± 1.1 years; height, 162.6 ± 5.8 cm; weight, 58.0 ± 5.7 kg; body mass index, 21.9 ± 1.5) who participated in the intervention period. Athlete-exposures (AEs), ACL numbers and mechanisms of injury (MOIs), relative risk (RR), absolute risk reduction (ARR), numbers needed to treat (NNT), and compliance were analyzed. There were 16 ACL injuries (13 noncontact MOIs) in the 4-year observation period, whereas 9 ACL injuries (8 noncontact MOIs) were recorded in the 8-year intervention period. The overall ACL injury incidence was 0.25/1000 AEs in the 4-year observation period compared with 0.10/1000 AEs in the 8-year intervention period, respectively. Compared with the 4-year observation period, significant RR reduction was observed (0.38; 95% CI, 0.17-0.87; P = .017) with ARR and NNT of 0.032 (95% CI, 0.027-0.037) and 31.6 (95% CI, 27.1-37.7), respectively, in the 8-year intervention period. The noncontact ACL injury incidence was 0.21 per 1000 AEs during the 4-year observation period compared with 0.08/1000 AEs in the 8-year intervention period, which also showed significant RR reduction (0.37; 95% CI, 0

Comparative characteristics of psychophysiological features skilled basketball players-women with hearing and skilled basketball players healthy

Directory of Open Access Journals (Sweden)

Kozina Zh.L.

2013-06-01

Full Text Available A comparative analysis of the psychophysiological features of skilled basketball players with normal hearing and impaired hearing aid. The study involved two women's basketball team to 12 people each. The study used a complex computer psychodiagnosis. The complex includes 20 psychophysiological and 18 personal psychological tests. The indicators of the time simple and complex reaction and average tapping test healthy skilled basketball players and basketball players are hearing impaired. There was a significant higher rates of visual-motor speed and reaction-tapping test in basketball players with hearing compared to healthy athletes. This is explained by compensatory mechanisms that occur in connection with the violation of the audition.

Comparative characteristics of psychophysiological features skilled basketball players-women with hearing and skilled basketball players healthy

Directory of Open Access Journals (Sweden)

Zh.L. Kozina

2013-07-01

Full Text Available A comparative analysis of the psychophysiological features of skilled basketball players with normal hearing and impaired hearing aid. The study involved two women's basketball team to 12 people each. The study used a complex computer psychodiagnosis. The complex includes 20 psychophysiological and 18 personal psychological tests. The indicators of the time simple and complex reaction and average tapping test healthy skilled basketball players and basketball players are hearing impaired. There was a significant higher rates of visual-motor speed and reaction-tapping test in basketball players with hearing compared to healthy athletes. This is explained by compensatory mechanisms that occur in connection with the violation of the audition.

The consultation of rugby players in co-developing a player health study: feasibility and consequences of sports participants as research partners.

Science.gov (United States)

Davies, Madeleine A M; Balai, Edward; Adams, Jo; Carter, John-Henry; Judge, Andrew; Newton, Julia L; Arden, Nigel K

2017-01-01

Many funding bodies within the United Kingdom and globally have encouraged public involvement in research. The Department of Health has also called public involvement a sign of good research. Despite the wide acceptance of public involvement improving many aspects of research, from its design to its communication, involvement has varied levels of implementation across different fields of research. Sports people have rarely been involved in research, partly as this research tends not to be funded by mainstream funding bodies. This may lead to a lower research quality, not founded in player ('service user') experiences. When creating a study of former rugby player health, we were very keen to involve rugby players, understand their thoughts on player health, and their playing experiences. This article explains how rugby players were involved in several ways, but mainly in group discussions during the design stage. These groups helped to inform our study's aims and questionnaire, ensure the questionnaire would capture player experiences and answer questions relevant to players, that they would like to understand after their participation in rugby. We found that these groups were easy to arrange, and that in only one session with each group, we were given many ideas of how to improve the questionnaire and study. We believe that other studies in sports should involve sports people, and that this is a useful activity that will change data collection forms and processes, improving the research, helping researchers, and making studies more suitable for players who take part in them. Background Patient and public involvement ('involvement') in the UK has increased in accordance with funding requirements, patient-centered health policy initiatives and reporting of the positive impact of involvement for those involved, research and researchers. However, involvement has not been implemented equally across all disease areas and populations. The aim of this process was to

Arthroscopic Shoulder Surgery in Female Professional Tennis Players: Ability and Timing to Return to Play.

Science.gov (United States)

Young, Simon W; Dakic, Jodie; Stroia, Kathleen; Nguyen, Michael L; Safran, Marc R

2017-07-01

To assess the outcome and time to return to previous level of competitive play after shoulder surgery in professional tennis players. Retrospective case series. Tertiary academic centre. The records of all female tennis players on the Women's Tennis Association (WTA) professional circuit between January 2008 and June 2010 were reviewed to identify players who underwent shoulder surgery on their dominant (serving) shoulder. Primary outcomes were the ability and time to return to professional play and if they were able to return to their previous level of function as determined by singles ranking. Preoperative and postoperative singles rankings were used to determine rate and completeness of return to preoperative function. During the study period, 8 professional women tennis players from the WTA tour underwent shoulder surgery on their dominant arm. Indications included rotator cuff debridement or repair, labral reconstruction for instability or superior labral anterior posterior lesion, and neurolysis of the suprascapular nerve. Seven players (88%) returned to professional play. The mean time to return to play was 7 months after surgery. However, only 25% (2 of 8) players achieved their preinjury singles rank or better by 18 months postoperatively. In total, 4 players returned to their preinjury singles ranking, with their peak singles ranking being attained at a mean of 2.4 years postoperatively. In professional female tennis players, a high return to play rate after arthroscopic shoulder surgery is associated with a prolonged and often incomplete return to previous level of performance. Thus, counseling the patient to this fact is important to manage expectations. Level IV-Case Series.

Incidence of Stingers in Young Rugby Players.

Science.gov (United States)

Kawasaki, Takayuki; Ota, Chihiro; Yoneda, Takeshi; Maki, Nobukazu; Urayama, Shingo; Nagao, Masashi; Nagayama, Masataka; Kaketa, Takefumi; Takazawa, Yuji; Kaneko, Kazuo

2015-11-01

A stinger is a type of neurapraxia of the cervical roots or brachial plexus and represents a reversible peripheral nerve injury. The incidence of and major risk factors for stingers among young rugby players remain uninvestigated. To investigate the incidence, symptoms, and intrinsic risk factors for stingers in elite rugby union teams of young players. Descriptive epidemiology study. A total of 569 male rugby players, including 358 players from 7 high school teams and 211 players from 2 university teams, were investigated using self-administered preseason and postseason questionnaires. The prevalence of a history of stingers was 33.9% (95% CI, 30.3-37.9), and 20.9% (119/569) of players experienced at least 1 episode of a stinger during the season (34.2 [95% CI, 26.2-42.1] events per 1000 player-hours of match exposure). The reinjury rate for stingers per season was 37.3% (95% CI, 30.4-44.2). Using the multivariate Poisson regression method, a history of stingers in the previous season and the grade and position of the player were found to be risk factors for stingers during the current season. The mean severity of injury was 2.9 days, with 79.3% (191/241) of the players not losing any time from playing after sustaining a stinger injury and 5.8% (14/241) of the players recovering within more than 14 days. The most frequent symptom was numbness in the unilateral upper extremity, and the most severe symptom was weakness of grasping (mean severity, 6 days). A logistic regression analysis indicated that a history of stingers in the previous season and an injury with more than 3 symptoms, especially motor weakness, were correlated with the severity of injury. Young rugby players with a history of stingers have a significantly high rate of repeat injuries. Although nearly 80% of the players experienced only minimal (0-1 day) time loss injuries, neurological deficits sometimes last beyond 1 month. A history of stingers was identified to be the strongest risk factor for

Episodic memory in former professional football players with a history of concussion: an event-related functional neuroimaging study.

Science.gov (United States)

Ford, Jaclyn H; Giovanello, Kelly S; Guskiewicz, Kevin M

2013-10-15

Previous research has demonstrated that sport-related concussions can have short-term effects on cognitive processes, but the long-term consequences are less understood and warrant more research. This study was the first to use event-related functional magnetic resonance imaging (fMRI) to examine long-term differences in neural activity during memory tasks in former athletes who have sustained multiple sport-related concussions. In an event-related fMRI study, former football players reporting multiple sport-related concussions (i.e., three or more) were compared with players who reported fewer than three concussions during a memory paradigm examining item memory (i.e., memory for the particular elements of an event) and relational memory (i.e., memory for the relationships between elements). Behaviorally, we observed that concussion history did not significantly affect behavioral performance, because persons in the low and high concussion groups had equivalent performance on both memory tasks, and in addition, that concussion history was not associated with any behavioral memory measures. Despite demonstrating equivalent behavioral performance, the two groups of former players demonstrated different neural recruitment patterns during relational memory retrieval, suggesting that multiple concussions may be associated with functional inefficiencies in the relational memory network. In addition, the number of previous concussions significantly correlated with functional activity in a number of brain regions, including the medial temporal lobe and inferior parietal lobe. Our results provide important insights in understanding the long-term functional consequences of sustaining multiple sports-related concussions.

Rules of engagement : influence of co-player presence on player involvement in digital games

NARCIS (Netherlands)

Gajadhar, B.J.; Kort, de Y.A.W.; IJsselsteijn, W.A.

2009-01-01

This article presents an empirical study of social setting as a determinant of player involvement in competitive play. We conceptualize player experience as comprising of components of involvement and enjoyment. Involvement relates to the attentional pull of games encompassing feelings of immersion,

Positional interchanges influence the physical and technical match performance variables of elite soccer players.

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Schuth, G; Carr, G; Barnes, C; Carling, C; Bradley, P S

2016-01-01

Positional variation in match performance is well established in elite soccer but no information exists on players switching positions. This study investigated the influence of elite players interchanging from one position to another on physical and technical match performance. Data were collected from multiple English Premier League (EPL) seasons using a computerised tracking system. After adhering to stringent inclusion criteria, players were examined across several interchanges: central-defender to fullback (CD-FB, n = 11, 312 observations), central-midfielder to wide-midfielder (CM-WM, n = 7, 171 observations), wide-midfielder to central-midfielder (WM-CM, n = 7, 197 observations) and attacker to wide-midfielder (AT-WM, n = 4, 81 observations). Players interchanging from CD-FB covered markedly more high-intensity running and sprinting distance (effect size [ES]: -1.56 and -1.26), lost more possessions but made more final third entries (ES: -1.23 and -1.55). Interchanging from CM-WM and WM-CM resulted in trivial to moderate differences in both physical (ES: -0.14-0.59 and -0.21-0.39) and technical performances (ES: -0.48-0.64 and -0.36-0.54). Players interchanging from AT-WM demonstrated a moderate difference in high-intensity running without possession (ES: -0.98) and moderate-to-large differences in the number of clearances, tackles and possessions won (ES: -0.77, -1.16 and -1.41). The data demonstrate that the physical and technical demands vary greatly from one interchange to another but utility players seem able to adapt to these positional switches.

An embouchure aid for saxophone player

Directory of Open Access Journals (Sweden)

Ho-Jin Moon

2012-02-01

Full Text Available This study aims to introduce the method that can relieve vibrating forces to oral environment by making an embouchure aid. Thin plastic crown forms were fabricated to prevent tooth abrasion and irritation to lip mucosa for the saxophone player. After application to the player, the most comfort form was chosen and delivered to 3 professional saxophone players. After 5 mon, the players responded to the survey. This embouchure aid did not disturb playing and gave comfort to lower lip. In general, the players preferred thin soft type and thought it caused little effect on sound. Far too little attention has been paid to the problems encountered by single-reed wind instrumentalist who suffer from tooth abrasion and irritation to lip mucosa. The embouchure aid not only prevent tooth damage but also diminish the discomfort of tight embouchure.

Female adolescent elite handball players are more susceptible to shoulder problems than their male counterparts.

Science.gov (United States)

Asker, Martin; Holm, Lena W; Källberg, Henrik; Waldén, Markus; Skillgate, Eva

2018-02-10

Shoulder problems are frequent among senior elite handball players. The objective of this study was to assess the prevalence of shoulder problems among adolescent elite handball players and to investigate potential differences in gender, school grade, playing position and playing level. During the 2014 and 2015 pre-season periods, 471 players (age 15-18 years, 54% female) completed a comprehensive baseline questionnaire regarding history of any shoulder pain and shoulder problems experienced during the past season. The players were monitored weekly for one competition season (September-April) regarding shoulder problems and the amount of match and training. Generalised linear models with a binomial link function were used to calculate a prevalence ratio (PR) with 95% confidence interval (CI) to compare the subgroups of players. In total, 110 players (23%) reported having substantial shoulder problems (defined as moderate/severe reduction in training volume, or moderate/severe reduction in performance, or complete inability to participate) at some point during the follow-up season, of which almost half reported complete inability to participate. Of those players reporting substantial problems, 43% (95% CI 39-48) did so for at least 3 consecutive weeks during the season. The prevalence was significantly higher in female players (PR 1.46, 95% 1.04-2.06) and in backcourt players (PR 1.58, 95% CI 1.08-2.32), but no differences were found for school grade (PR 1.21 95% CI 0.88-1.67) or playing level (PR 1.09 95% CI 0.76-1.56). The prevalence of substantial shoulder problems in adolescent elite handball players is high, especially among females, and this warrants further studies on risk factors for shoulder injury and the development of prevention strategies in handball players already before the age of 15. These findings also highlight the importance of introducing a clinical monitoring programme on a routine basis and improving the medical support, taking gender

Effects of in-season low-volume high-intensity plyometric training on explosive actions and endurance of young soccer players.

Science.gov (United States)

Ramírez-Campillo, Rodrigo; Meylan, César; Alvarez, Cristian; Henríquez-Olguín, Carlos; Martínez, Cristian; Cañas-Jamett, Rodrigo; Andrade, David C; Izquierdo, Mikel

2014-05-01

Integrating specific training methods to improve explosive actions and endurance in youth soccer is an essential part of players' development. This study investigated the efficiency of short-term vertical plyometric training program within soccer practice to improve both explosive actions and endurance in young soccer players. Seventy-six players were recruited and assigned either to a training group (TG; n = 38; 13.2 ± 1.8 years) or a control group (CG; n = 38; 13.2 ± 1.8 years) group. All players trained twice per week, but the TG followed a 7-week plyometric program implemented within soccer practice, whereas the CG followed regular practice. Twenty-meter sprint time (20-m), Illinois agility test time, countermovement jump (CMJ) height, 20- (RSI20) and 40- (RSI40) cm drop jump reactive strength index, multiple 5 bounds distance (MB5), maximal kicking test for distance (MKD), and 2.4-km time trial were measured before and after the 7-week period. Plyometric training induced significant (p ≤ 0.05) and small to moderate standardized effect (SE) improvement in the CMJ (4.3%; SE = 0.20), RSI20 (22%; SE = 0.57), RSI40 (16%; SE = 0.37), MB5 (4.1%; SE = 0.28), Illinois agility test time (-3.5%, SE = -0.26), MKD (14%; SE = 0.53), 2.4-km time trial (-1.9%; SE = -0.27) performances but had a trivial and nonsignificant effect on 20-m sprint time (-0.4%; SE = -0.03). No significant improvements were found in the CG. An integrated vertical plyometric program within the regular soccer practice can substitute soccer drills to improve most explosive actions and endurance, but horizontal exercises should also be included to enhance sprinting performance.

Half-time re-warm up increases performance capacity in male elite soccer players

DEFF Research Database (Denmark)

Edholm, P; Krustrup, Peter; Randers, Morten Bredsgaard

2015-01-01

This study investigated the acute effects of a half-time re-warm up on performance and movement patterns in soccer match play. Using a crossover design, 22 professional male players performed traditional passive rest (CON) or a low-intensity re-warm up (RW) during the half-time period of two soccer.......01). Moreover, RW had more possession of the ball in the beginning of the second half. In conclusion, traditional passive half-time rest leads to impaired sprint and jump performance during the initial phase of the second half in professional soccer players whereas a re-warm up effectively attenuates...

Auditory memory function in expert chess players.

Science.gov (United States)

Fattahi, Fariba; Geshani, Ahmad; Jafari, Zahra; Jalaie, Shohreh; Salman Mahini, Mona

2015-01-01

Chess is a game that involves many aspects of high level cognition such as memory, attention, focus and problem solving. Long term practice of chess can improve cognition performances and behavioral skills. Auditory memory, as a kind of memory, can be influenced by strengthening processes following long term chess playing like other behavioral skills because of common processing pathways in the brain. The purpose of this study was to evaluate the auditory memory function of expert chess players using the Persian version of dichotic auditory-verbal memory test. The Persian version of dichotic auditory-verbal memory test was performed for 30 expert chess players aged 20-35 years and 30 non chess players who were matched by different conditions; the participants in both groups were randomly selected. The performance of the two groups was compared by independent samples t-test using SPSS version 21. The mean score of dichotic auditory-verbal memory test between the two groups, expert chess players and non-chess players, revealed a significant difference (p≤ 0.001). The difference between the ears scores for expert chess players (p= 0.023) and non-chess players (p= 0.013) was significant. Gender had no effect on the test results. Auditory memory function in expert chess players was significantly better compared to non-chess players. It seems that increased auditory memory function is related to strengthening cognitive performances due to playing chess for a long time.

THE MODEL CHARACTERISTICS OF JUMP ACTIONS STRUCTURE OF HIGH PERFORMANCE FEMALE VOLLEYBALL PLAYERS

Directory of Open Access Journals (Sweden)

Stech M.

2012-12-01

Full Text Available The purpose of this study was to develop generalized and individual models of the jump actions of skilled female volleyball players. The main prerequisite for the development of the jump actions models were the results of our earlier studies of factor structure of jump actions of 10 sportswomen of the Polish volleyball team "Gedania" (Premier League in the preparatory and competitive periods of the annual cycle of preparation. The athletes age was 22.0 +- 2.9 years, the sports experience - 8.1 +- 3.1 years, body height - 181.9 +- 8.4 years and body weight - 72.8 +- 10.8 kg. Mathematical and statistical processing of the data (the definition of M ± SD and significant differences between the samples was performed using a standard computer program "STATISTICA 7,0". Based on the analysis of the factor structure of 20 jump actions of skilled women volleyball players determined to within 5 of the most informative indexes and their tentative values recommended for the formation of a generalized model of this structure. Comparison of individual models of jump actions of skilled women volleyball players with their generalized models in different periods of preparation can be used for the rational choice of means and methods for the increasing of the training process efficiency.

Player Skill Decomposition in Multiplayer Online Battle Arenas

OpenAIRE

Chen, Zhengxing; Sun, Yizhou; El-nasr, Magy Seif; Nguyen, Truong-Huy D.

2017-01-01

Successful analysis of player skills in video games has important impacts on the process of enhancing player experience without undermining their continuous skill development. Moreover, player skill analysis becomes more intriguing in team-based video games because such form of study can help discover useful factors in effective team formation. In this paper, we consider the problem of skill decomposition in MOBA (MultiPlayer Online Battle Arena) games, with the goal to understand what player...

Changes in body mass, stature and BMI in South African elite U18 Rugby players from different racial groups from 2002-2012.

Science.gov (United States)

Durandt, Justin; Green, Mervin; Masimla, Herman; Lambert, Mike

2018-03-01

The purpose of this study was to determine whether there are differences between racial groups for body mass, stature and body mass index (BMI) in South African elite U18 rugby players and whether there were significant changes in these measurements between 2002 and 2012. Self-reported body mass and stature were obtained from U18 players (n = 4007) who attended the national tournament during this period. BMI was calculated for each player.White players were 9.8 kg heavier than black players, who were 2.3 kg heavier than coloured players (P body mass of all groups increased from 2002 to 2012 (P body mass, stature and BMI of elite under-18 rugby players in South Africa were significantly different between racial groups. This has implications for transforming the game to make it representative of the South African population.

Development of perceived competence, tactical skills, motivation, technical skills, and speed and agility in young soccer players.

Science.gov (United States)

Forsman, Hannele; Gråstén, Arto; Blomqvist, Minna; Davids, Keith; Liukkonen, Jarmo; Konttinen, Niilo

2016-07-01

The objective of this 1-year, longitudinal study was to examine the development of perceived competence, tactical skills, motivation, technical skills, and speed and agility characteristics of young Finnish soccer players. We also examined associations between latent growth models of perceived competence and other recorded variables. Participants were 288 competitive male soccer players ranging from 12 to 14 years (12.7 ± 0.6) from 16 soccer clubs. Players completed the self-assessments of perceived competence, tactical skills, and motivation, and participated in technical, and speed and agility tests. Results of this study showed that players' levels of perceived competence, tactical skills, motivation, technical skills, and speed and agility characteristics remained relatively high and stable across the period of 1 year. Positive relationships were found between these levels and changes in perceived competence and motivation, and levels of perceived competence and speed and agility characteristics. Together these results illustrate the multi-dimensional nature of talent development processes in soccer. Moreover, it seems crucial in coaching to support the development of perceived competence and motivation in young soccer players and that it might be even more important in later maturing players.

Age differences in change-of-direction performance and its subelements in female football players.

Science.gov (United States)

Hirose, Norikazu; Nakahori, Chikako

2015-05-01

To describe cross-sectional age differences in change-of-direction performance (CODp) in female football players and investigate the relationship between CODp and linear-sprint speed, muscle power, and body size. A sample of 135 well-trained female football players was divided into 8 age groups. Anthropometry (height, body mass, and lean body mass) and athletic performance (10-m sprint speed, 10-m×5-CODp, and 5-step bounding distance) were compared to determine interage differences using ANOVA. Then, the participants were divided into 3 age groups: 12- to 14-y-olds, 15- to 17-y-olds, and ≥18 y-olds. Simple- and multiple-regression analyses were conducted to determine the correlation between CODp and the other measurement variables in each age group. Age-related differences were found for CODp (F=10.41, Pfemale players. Linear-sprint speed, muscle power, and body size were weakly correlated with the age differences in CODp.

Identification af explosive power factors as predictors of player quality in young female volleyball players.

Science.gov (United States)

Grgantov, Zoran; Milić, Mirjana; Katić, Ratko

2013-05-01

With the purpose of determining the factor structure of explosive power, as well as the influence of each factor on situational efficiency, 56 young female volleyball players were tested using 14 tests for assessing nonspecific and specific explosive power. By factor analysis, 4 significant factors were isolated which explained the total of over 80% of the common variability in young female volleyball players. The first factor was defined as volleyball-specific jumping, the second factor as nonspecific jumping and sprinting, the third factor as throwing explosive power, while the fourth factor was interpreted as volleyball-specific throwing and spiking speed from the ground. Results obtained by regression analysis in the latent space of explosive power indicate that the identified factors are good predictors of player quality in young female volleyball players. The fourth factor defined as throwing and spiking speed from the ground had the largest influence on player quality, followed by volleyball-specific jumping and nonspecific jumping and sprinting, and to a much lesser extent, by throwing explosive power The results obtained in this age group bring to the fore the ability of spiking and serving a ball of high speed, which hinders the opponents from playing those balls in serve reception and field defence. This ability, combined with a high standing vertical jump reach and spike approach vertical jump reach (which is the basis of the 1st varimax factor) enables successful performance of all volleyball elements by which points are won in complex 1 (spike) and complex 2 (serve and block). Even though the 2nd factor (nonspecific jumping and sprinting) has a slightly smaller impact on situational efficiency in young players, this ability provides preconditions i.e. preparation for successful realisation of all volleyball elements, so greater attention must be paid to perfecting it in young female volleyball players.

Protective equipment and player characteristics associated with the incidence of sport-related concussion in high school football players: a multifactorial prospective study.

Science.gov (United States)

McGuine, Timothy A; Hetzel, Scott; McCrea, Michael; Brooks, M Alison

2014-10-01

The incidence of sport-related concussion (SRC) in high school football is well documented. However, limited prospective data are available regarding how player characteristics and protective equipment affect the incidence of SRC. To determine whether the type of protective equipment (helmet and mouth guard) and player characteristics affect the incidence of SRC in high school football players. Cohort study; Level of evidence, 2. Certified athletic trainers (ATs) at each high school recorded the type of helmet worn (brand, model, purchase year, and recondition status) by each player as well as information regarding players' demographics, type of mouth guard used, and history of SRC. The ATs also recorded the incidence and days lost from participation for each SRC. Incidence of SRC was compared for various helmets, type of mouth guard, history of SRC, and player demographics. A total of 2081 players (grades 9-12) enrolled during the 2012 and/or 2013 football seasons (2287 player-seasons) and participated in 134,437 football (practice or competition) exposures. Of these players, 206 (9%) sustained a total of 211 SRCs (1.56/1000 exposures). There was no difference in the incidence of SRC (number of helmets, % SRC [95% CI]) for players wearing Riddell (1171, 9.1% [7.6%-11.0%]), Schutt (680, 8.7% [6.7%-11.1%]), or Xenith (436, 9.2% [6.7%-12.4%]) helmets. Helmet age and recondition status did not affect the incidence of SRC. The rate of SRC (hazard ratio [HR]) was higher in players who wore a custom mouth guard (HR = 1.69 [95% CI, 1.20-2.37], P football players. Players who had sustained an SRC within the previous 12 months were more likely to sustain an SRC than were players without a history of SRC. Sports medicine providers who work with high school football players need to realize that factors other than the type of protective equipment worn affect the risk of SRC in high school players. © 2014 The Author(s).

Intrinsic risk factors of noncontact ankle sprains in soccer: a prospective study on 100 professional players.

Science.gov (United States)

Fousekis, Konstantinos; Tsepis, Elias; Vagenas, George

2012-08-01

Ankle sprain is an extremely common injury in soccer players. Despite extensive research, the intrinsic cause of this injury under noncontact conditions remains unclear. To identify intrinsic risk factors for noncontact ankle sprains in professional soccer players. Cohort study; Level of evidence, 2 One hundred professional soccer players were assessed in the preseason for potential risk factors of noncontact ankle sprains. The assessment included (A) ankle joint asymmetries (right-left) in isokinetic muscle strength, flexibility, proprioception, and stability; (B) somatometric asymmetries; (C) previous injuries; and (D) lateral dominance traits. Noncontact ankle sprains were prospectively recorded and diagnosed for a full competition period (10 months). Seventeen of the players sustained at least 1 noncontact ankle sprain. Logistic regression revealed that players with (A) eccentric isokinetic ankle flexion strength asymmetries (odds ratio [OR] = 8.88; 95% confidence interval [CI], 1.95-40.36, P = .005), (B) increased body mass index (OR = 8.16; 95% CI, 1.42-46.63, P = .018), and (C) increased body weight (OR = 5.72; 95% CI, 1.37-23.95, P = .017 ) each had a significantly higher risk of a noncontact ankle sprain. A trend for younger players (OR = 0.28; 95% CI, 0.061-1.24, P = .092) and for players with ankle laxity asymmetries (OR = 3.38; 95% CI, 0.82-14.00, P = .093) to be at greater risk for ankle sprain was also apparent to the limit of statistical significance (.05 ankle flexors and increased body mass index and body weight raise the propensity for ankle sprains in professional soccer players. Age and asymmetries in ankle laxity are potential factors worth revisiting, as there was an indication for younger players and players with ankle instability to be at higher risk for ankle injury. Proper preseason evaluation may improve prevention strategies for this type of injury in soccer.

Insights into relationships between body mass, composition and bone: findings in elite rugby players.

Science.gov (United States)

Hind, Karen; Gannon, Lisa; Brightmore, Amy; Beck, Belinda

2015-01-01

Recent reports indicate that bone strength is not proportional to body weight in obese populations. Elite rugby players have a similar body mass index (BMI) to obese individuals but differ markedly with low body fat, high lean mass, and frequent skeletal exposure to loading through weight-bearing exercise. The purpose of this study was to determine relationships between body weight, composition, and bone strength in male rugby players characterized by high BMI and high lean mass. Fifty-two elite male rugby players and 32 nonathletic, age-matched controls differing in BMI (30.2 ± 3.2 vs 24.1 ± 2.1 kg/m²; p = 0.02) received 1 total body and one total hip dual-energy X-ray absorptiometry scan. Hip structural analysis of the proximal femur was used to determine bone mineral density (BMD) and cross-sectional bone geometry. Multiple linear regression was computed to identify independent variables associated with total hip and femoral neck BMD and hip structural analysis-derived bone geometry parameters. Analysis of covariance was used to explore differences between groups. Further comparisons between groups were performed after normalizing parameters to body weight and to lean mass. There was a trend for a positive fat-bone relationship in rugby players, and a negative relationship in controls, although neither reached statistical significance. Correlations with lean mass were stronger for bone geometry (r(2): 0.408-0.520) than for BMD (r(2): 0.267-0.293). Relative to body weight, BMD was 6.7% lower in rugby players than controls (p Rugby players were heavier than controls, with greater lean mass and BMD (p rugby players (p rugby players was reduced in proportion to body weight and lean mass. However, their superior bone geometry suggests that overall bone strength may be adequate for loading demands. Fat-bone interactions in athletes engaged in high-impact sports require further exploration. Copyright © 2015. Published by Elsevier Inc.

Executive Functioning in Highly Talented Soccer Players

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Verburgh, Lot; Scherder, Erik J. A.; van Lange, Paul A.M.; Oosterlaan, Jaap

2014-01-01

Executive functions might be important for successful performance in sports, particularly in team sports requiring quick anticipation and adaptation to continuously changing situations in the field. The executive functions motor inhibition, attention and visuospatial working memory were examined in highly talented soccer players. Eighty-four highly talented youth soccer players (mean age 11.9), and forty-two age-matched amateur soccer players (mean age 11.8) in the age range 8 to 16 years performed a Stop Signal task (motor inhibition), the Attention Network Test (alerting, orienting, and executive attention) and a visuospatial working memory task. The highly talented soccer players followed the talent development program of the youth academy of a professional soccer club and played at the highest national soccer competition for their age. The amateur soccer players played at a regular soccer club in the same geographical region as the highly talented soccer players and play in a regular regional soccer competition. Group differences were tested using analyses of variance. The highly talented group showed superior motor inhibition as measured by stop signal reaction time (SSRT) on the Stop Signal task and a larger alerting effect on the Attention Network Test, indicating an enhanced ability to attain and maintain an alert state. No group differences were found for orienting and executive attention and visuospatial working memory. A logistic regression model with group (highly talented or amateur) as dependent variable and executive function measures that significantly distinguished between groups as predictors showed that these measures differentiated highly talented soccer players from amateur soccer players with 89% accuracy. Highly talented youth soccer players outperform youth amateur players on suppressing ongoing motor responses and on the ability to attain and maintain an alert state; both may be essential for success in soccer. PMID:24632735

Executive functioning in highly talented soccer players.

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Lot Verburgh

Full Text Available Executive functions might be important for successful performance in sports, particularly in team sports requiring quick anticipation and adaptation to continuously changing situations in the field. The executive functions motor inhibition, attention and visuospatial working memory were examined in highly talented soccer players. Eighty-four highly talented youth soccer players (mean age 11.9, and forty-two age-matched amateur soccer players (mean age 11.8 in the age range 8 to 16 years performed a Stop Signal task (motor inhibition, the Attention Network Test (alerting, orienting, and executive attention and a visuospatial working memory task. The highly talented soccer players followed the talent development program of the youth academy of a professional soccer club and played at the highest national soccer competition for their age. The amateur soccer players played at a regular soccer club in the same geographical region as the highly talented soccer players and play in a regular regional soccer competition. Group differences were tested using analyses of variance. The highly talented group showed superior motor inhibition as measured by stop signal reaction time (SSRT on the Stop Signal task and a larger alerting effect on the Attention Network Test, indicating an enhanced ability to attain and maintain an alert state. No group differences were found for orienting and executive attention and visuospatial working memory. A logistic regression model with group (highly talented or amateur as dependent variable and executive function measures that significantly distinguished between groups as predictors showed that these measures differentiated highly talented soccer players from amateur soccer players with 89% accuracy. Highly talented youth soccer players outperform youth amateur players on suppressing ongoing motor responses and on the ability to attain and maintain an alert state; both may be essential for success in soccer.

Muscle Power and Velocity During Trunk Rotations after 6 Weeks of Training in Ice-Hockey Players

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Poór Oliver

2017-05-01

Full Text Available The study evaluates changes of muscle power and velocity during trunk rotations in ice-hockey players after six weeks of training in competition period. A group of 15 ice-hockey players performed 2 trunk rotations to each direction in a standing position with barbell of 6, 10, 12, 16, 20, 22, 26 kg placed on the shoulders. Basic biomechanical parameters during the movement were monitored using the FiTRO Torso Dyne system. Results showed that mean velocity in acceleration phase of trunk rotation significantly increased after 6 weeks of training at 6 kg (from 259 to 282.6 deg/s, p = 0.003 and 12 kg (from 218.8 to 244.1 deg/s p = 0.004. However, its values did not changed significantly during rotations with 10, 16, 20, 22 and 26 kg. Mean power of trunk rotation did not changed significantly with any of used weight. These findings indicate that there are only small changes in muscle power in competition period of ice hockey-players.

Comparison of Angiotensin Converting Enzyme (ACE gene polymorphisms elite basketball players and volleyball players

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Emin Süel

2015-09-01

Full Text Available Aim: The purpose of this study is to research the differences of genotype polymorphism between the elite male and elite female basketball player, volleyball player and control group. Material and Methods: 58 basketball players (ages 24.25±4.99 years, height 188.22±12.31 cm and weight 80.62±16.34 kg, 64 volleyball players (ages 22.82±5.40 years, height 188.67±9.69 cm and weight 77.82±12.14 kg and 122 sedentary subjects (control group were participated randomly in the study. 5cc blood was taken control and control groups for measuring the ACE gene polymorphism. Chi-square and analysis of variance (ANOVA, Levene’s Tests, and frequencies of allele were used for statistical evaluation at significance level p0.05, basketball, volleyball and control group (p>0.05, male basketball, volleyball and control group (p>0.05, female basketball, volleyball and control group (p>0.05 and male and female athletes (p>0.05 respectively. There were no significance differences in male athletes between the genotype distribution and physical performance tests, such as 20m shuttle-run (F=1.31, vertical jump (F=0.22, and 20m sprint test (F=0.44. There were also no significance differences in female athletes between the genotype distribution and physical performance tests, such as 20m shuttle-run (F=2.03, vertical jump (F=0.10, and 20m sprint test (F=1.17. Conclusion: ACE polymorphism genotype distribution in terms of elite female and male volleyball players with elite female and male basketball players are the same.

Different Training Loads Partially Influence Physiological Responses to the Preparation Period in Basketball.

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Ferioli, Davide; Bosio, Andrea; La Torre, Antonio; Carlomagno, Domenico; Connolly, Darragh R; Rampinini, Ermanno

2018-03-01

Ferioli, D, Bosio, A, La Torre, A, Carlomagno, D, Connolly, DR, and Rampinini, E. Different training loads partially influence physiological responses to preparation period in basketball. J Strength Cond Res 32(3): 790-797, 2018-The aim of this study was to compare the session rating of perceived exertion training load (sRPE-TL), training volume (TV), and the changes in physical fitness between professional (n = 14) and semiprofessional (n = 18) basketball players during the preparation period. Furthermore, relationships between sRPE-TL and TV with changes in physical fitness level were investigated. The players performed the Yo-Yo intermittent recovery test-level 1 (Yo-Yo IR1) before and after the preparation period. In addition, physiological responses to a standardized 6-minute continuous running test (Mognoni's test) and to a standardized 5-minute high-intensity intermittent running test (HIT) were measured. Session rating of perceived exertion-TL and TV were greater for professional (5,241 ± 1787 AU; 914 ± 122 minutes) compared with semiprofessional players (2,408 ± 487 AU; 583 ± 65 minutes). Despite these differences, Yo-Yo IR1 performance improvements (∼30%) and physiological adaptations to the Mognoni's test were similar between the 2 groups. Furthermore, physiological adaptations to HIT were slightly greater for professional compared with semiprofessional players; however, the magnitude of these effects was only small/moderate. No clear relationships were found between sRPE-TL and changes in Yo-Yo IR1 performance and Mognoni's test (rs ± 90% confidence interval [CI]: Yo-Yo IR1, 0.18 ± 0.30; Mognoni's test, -0.14 ± 0.29). Only moderate relationships were found between sRPE-TL and changes in HIT (rs ± 90% CI: [La], -0.48 ± 0.23; [H], -0.42 ± 0.25). These results raise doubts on the effectiveness of using high sRPE-TL and TV during the preparation period to improve the physical fitness level of players. The Yo-Yo IR1 seems to be sensitive to

Translucent Players: Explaining Cooperative Behavior in Social Dilemmas

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Valerio Capraro

2016-06-01

Full Text Available In the last few decades, numerous experiments have shown that humans do not always behave so as to maximize their material payoff. Cooperative behavior when non-cooperation is a dominant strategy (with respect to the material payoffs is particularly puzzling. Here we propose a novel approach to explain cooperation, assuming what Halpern and Pass call translucent players. Typically, players are assumed to be opaque, in the sense that a deviation by one player in a normal-form game does not affect the strategies used by other players. But a player may believe that if he switches from one strategy to another, the fact that he chooses to switch may be visible to the other players. For example, if he chooses to defect in Prisoner's Dilemma, the other player may sense his guilt. We show that by assuming translucent players, we can recover many of the regularities observed in human behavior in well-studied games such as Prisoner's Dilemma, Traveler's Dilemma, Bertrand Competition, and the Public Goods game.

Exploring Self-regulation of More or Less Expert College-Age Video Game Players: A Sequential Explanatory Design.

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Yilmaz Soylu, Meryem; Bruning, Roger H

2016-01-01

This study examined differences in self-regulation among college-age expert, moderately expert, and non-expert video game players in playing video games for fun. Winne's model of self-regulation (Winne, 2001) guided the study. The main assumption of this study was that expert video game players used more processes of self-regulation than the less-expert players. We surveyed 143 college students about their game playing frequency, habits, and use of self-regulation. Data analysis indicated that while playing recreational video games, expert gamers self-regulated more than moderately expert and non-expert players and moderately expert players used more processes of self-regulation than non-experts. Semi-structured interviews also were conducted with selected participants at each of the expertise levels. Qualitative follow-up analyses revealed five themes: (1) characteristics of expert video gamers, (2) conditions for playing a video game, (3) figuring out a game, (4) how gamers act and, (5) game context. Overall, findings indicated that playing a video game is a highly self-regulated activity and that becoming an expert video game player mobilizes multiple sets of self-regulation related skills and processes. These findings are seen as promising for educators desiring to encourage student self-regulation, because they indicate the possibility of supporting students via recreational video games by recognizing that their play includes processes of self-regulation.

Exploring Self-regulation of More or Less Expert College-Age Video Game Players: A Sequential Explanatory Design

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Yilmaz Soylu, Meryem; Bruning, Roger H.

2016-01-01

This study examined differences in self-regulation among college-age expert, moderately expert, and non-expert video game players in playing video games for fun. Winne's model of self-regulation (Winne, 2001) guided the study. The main assumption of this study was that expert video game players used more processes of self-regulation than the less-expert players. We surveyed 143 college students about their game playing frequency, habits, and use of self-regulation. Data analysis indicated that while playing recreational video games, expert gamers self-regulated more than moderately expert and non-expert players and moderately expert players used more processes of self-regulation than non-experts. Semi-structured interviews also were conducted with selected participants at each of the expertise levels. Qualitative follow-up analyses revealed five themes: (1) characteristics of expert video gamers, (2) conditions for playing a video game, (3) figuring out a game, (4) how gamers act and, (5) game context. Overall, findings indicated that playing a video game is a highly self-regulated activity and that becoming an expert video game player mobilizes multiple sets of self-regulation related skills and processes. These findings are seen as promising for educators desiring to encourage student self-regulation, because they indicate the possibility of supporting students via recreational video games by recognizing that their play includes processes of self-regulation. PMID:27729881

Exploring Self-Regulation of More or Less Expert College-Age Video Game Players: A Sequential Explanatory Design

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Meryem YILMAZ SOYLU

2016-09-01

Full Text Available This study examined differences in self-regulation among college-age expert, moderately expert, and non-expert video game players in playing video games for fun. Winne’s model of self-regulation (Winne, 2001 guided the study. Main assumption of this study was that expert video game players used more processes of self-regulation than the less-expert players. We surveyed 143 college students about their game playing frequency, habits, and use of self-regulation. Data analysis indicated that while playing recreational video games, expert gamers self-regulated more than moderately expert and non-expert players and moderately expert players used more processes of self-regulation than non-experts. Semi-structured interviews also were conducted with selected participants at each of the expertise levels. Qualitative follow-up analyses revealed five themes: 1 characteristics of expert video gamers, 2 conditions for playing a video game, 3 figuring out a game, 4 how gamers act and, 5 game context. Overall, findings indicated that playing a video game is a highly self-regulated activity and that becoming an expert video game player mobilizes multiple sets of self-regulation related skills and processes. These findings are seen as promising for educators desiring to encourage student self-regulation, because they indicate the possibility of supporting students via recreational video games by recognizing that their play includes processes of self-regulation.

Impact of Psychological Variables on Playing Ability of University Level Soccer Players

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Ertan Tufekcioglu

2014-10-01

Full Text Available The purpose of the study was to find out the relationship between psychological variables and soccer playing ability among the university level male players. 42 soccer players representing different universities who participated in inter university competitions were selected as the subjects of the study. The dependent variable was soccer playing ability and independent variables were the selected psychological variables. Soccer playing ability was determined through a 10 point scale at the time of competitions. Psychological variables included achievement motivation, anxiety, self-concept and aggression. The data was statistically analyzed using Karl Pearson’s correlation coefficient and multiple regression analysis using SPSS. It was concluded that soccer playing ability has a positive correlation with achievement motivation and self-concept whereas anxiety and aggression have a negative correlation with soccer playing ability.

Basketball Performance Is Related to Maturity and Relative Age in Elite Adolescent Players.

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Torres-Unda, Jon; Zarrazquin, Idoia; Gravina, Leyre; Zubero, Jaime; Seco, Jesús; Gil, Susana M; Gil, Javier; Irazusta, Jon

2016-05-01

During a national championship, the anthropometric, physiological, and maturation characteristics of 13- to 14-year-old players of elite basketball teams and their association with sport performance were analyzed. Body parameters (weight, height, skinfold thicknesses, and lengths) were measured and physiological capacities assessed by sprint (20 m) and jump tests (i.e., countermovement jump with arm swing). Chronological age (CA) and maturity offset (years from age at peak height velocity; YAPHV) were calculated, and then predicted age at peak height velocity, as the difference between CA and YAPHV. Game performance was assessed with point averages and the performance index rating (PIR). The birth-date distribution of players was biased, those born early in the selection year outnumbering those born later. Anthropometric analysis indicated that players who performed better had longer body lengths. Physiological testing showed that semi-finalists had better sprint performance than quarter-finalists and those players with greater jump capacity scored more points. Early maturation and advanced maturity status were also associated with better PIR and scored points per game. Multiple blockwise regression analysis showed that, among the factors analyzed, YAPHV was the best predictor of basketball performance. In conclusion, around puberty, physical and physiological parameters associated with maturity and CA are important in determining the success of elite basketball players. Consequently, boys who are born in the second half of the year and/or late maturing tend to be marginalized or totally excluded, and not given the chance to play under equal conditions; their careers may then be held back by the relative disadvantage associated with inexperience.

The Prevalence of Injuries in Professional Turkish Soccer Players

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Yamaner, Faruk; Gumusdag, Hayrettin; Kartal, Alparslan; Gumus, M.; Gullu, A.; Imamoglu, O.

2011-01-01

Study aim: To assess the prevalence and anatomical sites of injuries in professional soccer players in one game season. Material and methods: A cohort of 510 professional male soccer players consisting of 48 goalkeepers, 194 defence players, 189 mid-field players and 79 forward players of the 1st and 2nd Turkish Professional Soccer Leagues in…

INFLUANCE OF TRAINING PROCESS ON DEVELOPMENT OF EXSPLOSIVE STRENGHT OF LEGS AT PIONEER BASKETBALL PLAYERS

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Vukašin Badža

2011-03-01

Full Text Available The research is trying to give an answer on a question whether the training process which lasted two years influenced on development of exsplosive strenght of legs (one of basic psysical abilities at pioneer basketball players. The sample in a research are basketball players from „Danubius - Vojvodina Srbijagas” team, from Novi Sad. The group counts 20 players who participated in training process and on who measuring was conducted. Data were collected per two years, and measuring were exert three times during this period. Tests that were used in this research are: long jump, high jump and running 20m. The obtained data will be processed statistically, using ANOVA for repeated measures and descriptive statistics. Research results will be represented in tables and discussed in text.

ANALYSIS AND COMPARISON OF ADOLESCENT ATHLETES' MOTIVATION: BASKETBALL PLAYERS VS. FOOTBALL PLAYERS

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Bartolom\\u00E9 J. Almagro

2009-01-01

Full Text Available The motivation of an athlete is determinant for the athletic engagement of the adolescent. The present study attempts to analyze the motivation of adolescent basketball and football players from the perspectives of Achievement Goal Theory (Nicholls, 1989 and Self-Determination Theory (Deci & Ryan, 1985. The study's sample was composed of 248 athletes from 12 to 17 years of age. Half were from basketball and half were from football. The instruments that were utilized were: the Spanish version of the Sport Motivation Scale (SMS (Núñez, Martín-Albo, Navarro, & González, 2006, the Spanish version of the Perceived Motivational Climate in Sport Questionnaire-2 (PMSCQ-2 (Balaguer, Mayo, Atienza, & Duda, 1997, and the adapted Spanish translation (Moreno, Moreno, & Cervelló, 2007 of the Intention to be Physically Active Scale (IPAS by Hein, Müür, and Koka (2004. The comparison of the means of the variables between football and basketball players was done utilizing the student t-test for independent samples. Significant differences were found for variables such as: intrinsic motivation (IM toward accomplishment, external regulation, amotivation, task, ego, and Self-Determination Index (SDI. Basketball players obtained higher values in the SDI, in task, and in IM toward accomplishment than football players. The search for premature performance in football and coaches' educations can help to explain these differences. The importance of these differences reside in the relationship between these motivational variables and the adherence to athletic practice. In conclusion, basketball demonstrated better values in motivational variables, which demonstrates that training sessions are more oriented toward task than ego, that players have more intrinsic and self-determined motivation, and therefore, the adherence of the young athletes will be greater in this sport.

Visual tracking speed is related to basketball-specific measures of performance in NBA players.

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Mangine, Gerald T; Hoffman, Jay R; Wells, Adam J; Gonzalez, Adam M; Rogowski, Joseph P; Townsend, Jeremy R; Jajtner, Adam R; Beyer, Kyle S; Bohner, Jonathan D; Pruna, Gabriel J; Fragala, Maren S; Stout, Jeffrey R

2014-09-01

The purpose of this study was to determine the relationship between visual tracking speed (VTS) and reaction time (RT) on basketball-specific measures of performance. Twelve professional basketball players were tested before the 2012-13 season. Visual tracking speed was obtained from 1 core session (20 trials) of the multiple object tracking test, whereas RT was measured by fixed- and variable-region choice reaction tests, using a light-based testing device. Performance in VTS and RT was compared with basketball-specific measures of performance (assists [AST]; turnovers [TO]; assist-to-turnover ratio [AST/TO]; steals [STL]) during the regular basketball season. All performance measures were reported per 100 minutes played. Performance differences between backcourt (guards; n = 5) and frontcourt (forward/centers; n = 7) positions were also examined. Relationships were most likely present between VTS and AST (r = 0.78; p basketball-specific performance measures. Backcourt players were most likely to outperform frontcourt players in AST and very likely to do so for VTS, TO, and AST/TO. In conclusion, VTS seems to be related to a basketball player's ability to see and respond to various stimuli on the basketball court that results in more positive plays as reflected by greater number of AST and STL and lower turnovers.

Competence-impeding electronic games and players' aggressive feelings, thoughts, and behaviors.

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Przybylski, Andrew K; Deci, Edward L; Deci, Edward; Rigby, C Scott; Ryan, Richard M

2014-03-01

[Correction Notice: An Erratum for this article was reported in Vol 106(3) of Journal of Personality and Social Psychology (see record 2014-07574-006). In the article, the name of author Edward Deci was missing his middle name initial and should have read as Edward L. Deci. In addition, an incorrect version of figure 1 was published.] Recent studies have examined whether electronic games foster aggression. At present, the extent to which games contribute to aggression and the mechanisms through which such links may exist are hotly debated points. In current research we tested a motivational hypothesis derived from self-determination theory-that gaming would be associated with indicators of human aggression to the degree that the interactive elements of games serve to impede players' fundamental psychological need for competence. Seven studies, using multiple methods to manipulate player competence and a range of approaches for evaluating aggression, indicated that competence-impeding play led to higher levels of aggressive feelings, easier access to aggressive thoughts, and a greater likelihood of enacting aggressive behavior. Results indicated that player perceived competence was positively related to gaming motivation, a factor that was, in turn, negatively associated with player aggression. Overall, this pattern of effects was found to be independent of the presence or absence of violent game contents. We discuss the results in respect to research focused on psychological need frustration and satisfaction and as they regard gaming-related aggression literature. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Suicide in professional American football players in the past 95 years.

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Webner, David; Iverson, Grant L

2016-01-01

To examine publicly-available information on all identified cases of suicide in active or former American professional football players between 1920 and the spring of 2015. Retrospective cohort study. Professional American Football in the US. A cohort of 26 702 athletes who had died, retired or were currently playing in the NFL from nfl.com since 1920 was identified. Internet queries identifying 26 professional football players who completed suicide. Obituaries and news reports were reviewed. The primary outcome measures included mortality, demographic characteristics and life circumstances in professional American football players completing suicide. From 1920-2015, the median age of the 26 men who completed suicide was 39.5 years (range = 23-85). The median number of years after retirement was 6.5 (range = 0-63). Most of the deaths since 1920 have occurred in the past 15 years (58.7%) and a large percentage have occurred since 2009 (42.3%). Most of the men suffered from multiple life stressors prior to their deaths, such as retirement from sport, loss of steady income, divorce, failed business ventures, estrangement from family members and medical, psychiatric and/or substance abuse problems. A disproportionate number of completed suicides in current and former professional football players have occurred since 2009 (42.3%). It is well established in the literature that the causes of depression and suicidality are diverse, often multifactorial and treatable. Providing at-risk retired athletes with mental health treatment will likely reduce their suffering and improve their quality-of-life.

Wearable nanosensor system for monitoring mild traumatic brain injuries in football players

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Ramasamy, Mouli; Varadan, Vijay K.

2016-04-01

Football players are more to violent impacts and injuries more than any athlete in any other sport. Concussion or mild traumatic brain injuries were one of the lesser known sports injuries until the last decade. With the advent of modern technologies in medical and engineering disciplines, people are now more aware of concussion detection and prevention. These concussions are often overlooked by football players themselves. The cumulative effect of these mild traumatic brain injuries can cause long-term residual brain dysfunctions. The principle of concussion is based the movement of the brain in the neurocranium and viscerocranium. The brain is encapsulated by the cerebrospinal fluid which acts as a protective layer for the brain. This fluid can protect the brain against minor movements, however, any rapid movements of the brain may mitigate the protective capability of the cerebrospinal fluid. In this paper, we propose a wireless health monitoring helmet that addresses the concerns of the current monitoring methods - it is non-invasive for a football player as helmet is not an additional gear, it is efficient in performance as it is equipped with EEG nanosensors and 3D accelerometer, it does not restrict the movement of the user as it wirelessly communicates to the remote monitoring station, requirement of individual monitoring stations are not required for each player as the ZigBee protocol can couple multiple transmitters with one receiver. A helmet was developed and validated according to the above mentioned parameters.

Neuromuscular and technical abilities related to age in water-polo players.

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De Siati, Fabio; Laffaye, Guillaume; Gatta, Giorgio; Dello Iacono, Antonio; Ardigò, Luca Paolo; Padulo, Johnny

2016-08-01

Testing is one of the important tasks in any multi-step sport programme. In most ball games, coaches assess motor, physical and technical skills on a regular basis in early stages of talent identification in order to further athletes' development. The purpose of the study was to investigate anthropometric variables and vertical jump heights as a free throw effectiveness predictor in water-polo players of different age groups. Two hundred and thirty-six young (10-18 years) male water-polo players partitioned into three age groups underwent anthropometric variables' measures and squat- and countermovement-jump tests, and performed water-polo free throws. Anthropometric variables, vertical jump heights and throw speed - as a proxy for free throw effectiveness - resulted different over age groups. Particularly, throw speed changed from 9.28 to 13.70 m · s(-1) (+48%) from younger to older players. A multiple-regression model indicated that body height, squat-jump height and throw time together explain 52% of variance of throw speed. In conclusion, tall height, high lower limb power and throwing quickness appeared to be relevant determinants for effective free throws. Such indications can help coaches during talent identification and development processes, even by means of novel training strategies. Further research is needed over different maturity statuses.

N-player quantum games in an EPR setting.

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James M Chappell

Full Text Available The N-player quantum games are analyzed that use an Einstein-Podolsky-Rosen (EPR experiment, as the underlying physical setup. In this setup, a player's strategies are not unitary transformations as in alternate quantum game-theoretic frameworks, but a classical choice between two directions along which spin or polarization measurements are made. The players' strategies thus remain identical to their strategies in the mixed-strategy version of the classical game. In the EPR setting the quantum game reduces itself to the corresponding classical game when the shared quantum state reaches zero entanglement. We find the relations for the probability distribution for N-qubit GHZ and W-type states, subject to general measurement directions, from which the expressions for the players' payoffs and mixed Nash equilibrium are determined. Players' N x N payoff matrices are then defined using linear functions so that common two-player games can be easily extended to the N-player case and permit analytic expressions for the Nash equilibrium. As a specific example, we solve the Prisoners' Dilemma game for general N ≥ 2. We find a new property for the game that for an even number of players the payoffs at the Nash equilibrium are equal, whereas for an odd number of players the cooperating players receive higher payoffs. By dispensing with the standard unitary transformations on state vectors in Hilbert space and using instead rotors and multivectors, based on Clifford's geometric algebra (GA, it is shown how the N-player case becomes tractable. The new mathematical approach presented here has wide implications in the areas of quantum information and quantum complexity, as it opens up a powerful way to tractably analyze N-partite qubit interactions.

Player Modeling for Intelligent Difficulty Adjustment

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Missura, Olana; Gärtner, Thomas

In this paper we aim at automatically adjusting the difficulty of computer games by clustering players into different types and supervised prediction of the type from short traces of gameplay. An important ingredient of video games is to challenge players by providing them with tasks of appropriate and increasing difficulty. How this difficulty should be chosen and increase over time strongly depends on the ability, experience, perception and learning curve of each individual player. It is a subjective parameter that is very difficult to set. Wrong choices can easily lead to players stopping to play the game as they get bored (if underburdened) or frustrated (if overburdened). An ideal game should be able to adjust its difficulty dynamically governed by the player’s performance. Modern video games utilise a game-testing process to investigate among other factors the perceived difficulty for a multitude of players. In this paper, we investigate how machine learning techniques can be used for automatic difficulty adjustment. Our experiments confirm the potential of machine learning in this application.

Secure Multi-Player Protocols

DEFF Research Database (Denmark)

Fehr, Serge

While classically cryptography is concerned with the problem of private communication among two entities, say players, in modern cryptography multi-player protocols play an important role. And among these, it is probably fair to say that secret sharing, and its stronger version verifiable secret...... sharing (VSS), as well as multi-party computation (MPC) belong to the most appealing and/or useful ones. The former two are basic tools to achieve better robustness of cryptographic schemes against malfunction or misuse by “decentralizing” the security from one single to a whole group of individuals...... (captured by the term threshold cryptography). The latter allows—at least in principle—to execute any collaboration among a group of players in a secure way that guarantees the correctness of the outcome but simultaneously respects the privacy of the participants. In this work, we study three aspects...

Daily Distribution of Carbohydrate, Protein and Fat Intake in Elite Youth Academy Soccer Players Over a 7-Day Training Period.

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Naughton, Robert J; Drust, Barry; O'Boyle, Andy; Morgans, Ryland; Abayomi, Julie; Davies, Ian G; Morton, James P; Mahon, Elizabeth

2016-10-01

While traditional approaches to dietary analysis in athletes have focused on total daily energy and macronutrient intake, it is now thought that daily distribution of these parameters can also influence training adaptations. Using 7-day food diaries, we quantified the total daily macronutrient intake and distribution in elite youth soccer players from the English Premier League in U18 (n = 13), U15/16 (n = 25) and U13/14 squads (n = 21). Total energy (43.1 ± 10.3, 32.6 ± 7.9, 28.1 ± 6.8 kcal·kg -1 ·day -1 ), CHO (6 ± 1.2, 4.7 ± 1.4, 3.2 ± 1.3 g·kg - 1 ·day -1 ) and fat (1.3 ± 0.5, 0.9 ± 0.3, 0.9 ± 0.3 g·kg- 1 ·day -1 ) intake exhibited hierarchical differences (p U15/16 > U18. In addition, CHO intake in U18s was lower (p lunch (~0.5 g·kg -1 ) > breakfast (~0.3 g·kg -1 ). We conclude elite youth soccer players do not meet current CHO guidelines. Although daily protein targets are achieved, we report a skewed daily distribution in all ages such that dinner > lunch > breakfast. Our data suggest that dietary advice for elite youth players should focus on both total daily macronutrient intake and optimal daily distribution patterns.

Analysis of Injury Incidences in Male Professional Adult and Elite Youth Soccer Players: A Systematic Review.

Science.gov (United States)

Pfirrmann, Daniel; Herbst, Mark; Ingelfinger, Patrick; Simon, Perikles; Tug, Suzan

2016-05-01

The incidence of injury for elite youth and professional adult soccer players is an important concern, but the risk factors for these groups are different. To summarize and compare the injury incidences and injury characteristics of male professional adult and elite youth soccer players. We searched MEDLINE and Web of Science using the search terms elite, international, European, soccer, football, injury, injuries, epidemiology, incidence, prevalence, not female, not American football, and not rugby. We also used the search terms professional for studies on professional adult soccer players and high-level, soccer academy, youth, adolescent, and young for studies on elite youth soccer players. Eligible studies were published in English, had a prospective cohort design, and had a minimum study period of 6 months. To ensure that injury data were assessed in relationship to the athlete's individual exposure, we included only studies that reported on injuries and documented exposure volume. Two independent reviewers applied the selection criteria and assessed the quality of the studies. A total of 676 studies were retrieved from the literature search. Eighteen articles met the inclusion criteria: 6 for elite youth and 12 for professional adult soccer players. Injury rates were higher for matches than for training for both youth and adult players. Youth players had a higher incidence of training injuries than professionals. Efforts must be made to reduce the overall injury rate in matches. Therefore, preventive interventions, such as adequately enforcing rules and focusing on fair play, must be analyzed and developed to reduce match-related injury incidences. Reducing training injuries should be a particular focus for youth soccer players.

Development of a virtual power market model to investigate strategic and collusive behavior of market players

International Nuclear Information System (INIS)

Shafie-khah, Miadreza; Parsa Moghaddam, Mohsen; Sheikh-El-Eslami, Mohamad Kazem

2013-01-01

In this paper, a virtual power market model is proposed to investigate the behavior of power market players from regulator's point of view. In this approach, strategic players are modeled in a multi-agent environment. These agents which are virtual representative of actual players forecast the prices and participate in the markets, exactly the same as real world situation. In addition, the role of ISO is encountered by using security constraint unit commitment (SCUC) and security constraint economic dispatch (SCED) solutions. Moreover, the interaction between market players is modeled using a heuristic dynamic game theory algorithm based on the supply function equilibria (SFE). In addition to the collusive behavior, using the proposed model, the short-term strategic behavior of players, which their effects will appear in long-term, can be simulated. The proposed model enables the market regulators to make decision before implementing new market rules with the confidence of their results. To represent the effectiveness of the proposed method, a case study including wind power plants is considered and the impact of various market rules on players’ behavior is simulated and discussed. Numerical studies indicate that simulating the strategic and collusive behavior prior to any change in the market rules is necessary. - Highlights: • A virtual power market model is proposed using a heuristic dynamic game theory. • The proposed model can simulate the behavior of market players in a certain period. • This model can evaluate the oligopoly, collusive and strategic behavior of players. • The price uncertainty and security constraint are considered. • Neglecting strategic behavior of players can cause adverse consequences

Comparison of Shoulder Strength in Routinely Trained Badminton Players and Non-Badminton Players

Directory of Open Access Journals (Sweden)

Wong Zhen Feng

2017-06-01

Full Text Available Background: Shoulder pain is a common reason for patients to seek medical help in any healthcare center. Shoulder pain is influenced by a few factors such as gender, posture during daily activities, aging and psychological factors. Based on the study of Epidemiology of Injuries and Prevention Strategies in Competitive Swimmers, shoulder pain due to shoulder injuries can be reduced by strengthening the shoulder muscle. Badminton has become one of the most popular sports in Asia, especially in Indonesia. This study was conducted to determine if badmintonis able to strengthen the shoulder muscle group. Methods: A cross-sectional analytic experimental study was conducted on September 2015 at Lodaya Badminton Training Center and Bale Padjadjaran of Universitas Padjadjaran. Subjects were 30 healthy male routinely trained badminton players and 30 non-badminton players who voluntarily follow the rstudy procedures. Strength measurement procedures were provided to the subjects after getting informed consent.  Data analysis was performed using T-test. Results: The shoulder strength  in routinely trained badminton players was significantly different from  non-badminton players (P<0.05. Conclusions: Shoulder strength can be improved through routine training of badminton to reduce risk of shoulder injury.   DOI: 10.15850/amj.v4n2.1083

Basketball ability testing and category for players with mental retardation: 8-month training effect.

Science.gov (United States)

Franciosi, Emanuele; Gallotta, Maria Chiara; Baldari, Carlo; Emerenziani, Gian Pietro; Guidetti, Laura

2012-06-01

Although sport for athletes with mental retardation (MR) is achieving an important role, the literature concerning basketball tests and training is still poor. The aims of this study were to verify whether the basketball test battery could be an appropriate modality to classify the players in the Promotion (Pro) category, to assess basketball abilities before (PRE) and after (POST) an 8-month training in players with MR in relation to Competitive (Comp) and Pro categories, to analyze the variation of specific basketball abilities based on subjects' MR diagnosis. Forty-one male basketball players with MR (17 Comp and 24 Pro; age range 18-45 years; MR: 15% mild, 54% moderate, 29% severe, and 2% profound) were assessed PRE and POST training through the basketball test battery, which assessed 4 ability levels of increasing difficulty (from I to IV), each one characterized by the analysis of fundamental areas (ball handling, reception, passing, and shooting). Level I was significantly changed after the intervention period regardless of the Category, whereas shooting was affected by the interaction between Category and Intervention. The results showed significant differences between categories in the scores of individual global, level I, level II, level III, and in all fundamental areas. Individual global score in both categories significantly increased. The players of Comp significantly improved in level III, in ball handling, reception, passing, and shooting scores. The players of Pro improved significantly in level II, in ball handling, reception, and passing scores. Individual global, ability levels I-III, and fundamental area scores were negatively correlated to the MR level indicating that the players with a lower MR obtained higher ability scores. In conclusion, it was found that the basketball test battery could be useful for improving and monitoring training in both Comp and Pro players.

The posture of adolescent male handball players: A two-year study.

Science.gov (United States)

Grabara, Małgorzata

2018-02-06

Young athletes at the stage of growth acceleration tend to exhibit increased susceptibility to postural abnormalities, especially in the trunk region. The aim of this study was to assess and compare the posture in male adolescent handball players over two years of regular training sessions. The study group comprised 21 handball players. At the start of the study 15 participants were aged 14 and 6 participants were aged 15 (mean 14.25 ± 0.58). The measurements were repeated three times. Posture was assessed with a photogrammetric method based on the moiré phenomenon. The analysis of posture relative to symmetry in the frontal and transverse planes did not reveal any significant differences between posture indicators obtained during the successive measurements. Sagittal plane posture indicators revealed significant changes in torso forward inclination angle and the shape of anteroposterior spinal curvatures. The latter consisted of significant deepening of the upper thoracic curve (angle α) and flattening of the lumbosacral curve (angle γ). A two-year period of handball training did not result in posture asymmetries in young male handball players. The observed changes in the shape of anteroposterior spinal curvatures might be related both to sports training and somatic parameters.

Vitamin D and exercise performance in professional soccer players.

Directory of Open Access Journals (Sweden)

Nikolaos E Koundourakis

Full Text Available The current study had two aims. The primary purpose was to examine the association between serum vitamin D levels and the ergometric evaluation of muscle strength, aerobic capacity, and speed in professional soccer players. The secondary aim was to evaluate the effects of the soccer off-season period on serum vitamin D levels.Sixty-seven Caucasian male soccer players (age 25.6 ± 6.2 and height 1.81 ± 0.08 m, members of two Greek Superleague Soccer teams and one Football-league championship team participated in this study. Exercise performance testing for the determination of squat jump (SJ, countermovement jump (CMJ, 10 (10 m and 20 meters (20 m sprint performance, maximal oxygen consumption (VO2max, anthropometry, and blood sampling were performed before (pre and after (post the six-week off-season period.Analysis of our results showed the following: (a a significant correlations between serum vitamin D levels and performance parameters in both pre (SJ; P < 0.001, CMJ; P < 0.001, VO2max; P < 0.001, 10 m; P < 0.001, and 20 m; P < 0.001 and post (SJ; P < 0.001, CMJ; P<0.001, VO2max; P = 0.006, 10 m; P < 0.001, and 20 m; P < 0.001 experimental sessions. (b Vitamin D concentration increased significantly (P < 0.001 following the six-week off-season period compared to baseline, while at the same time all measured performance parameters decreased (SJ; P < 0.001, CMJ; P < 0.001, 10 m; P < 0.001, 20 m; P < 0.001, VO2max; P<0.001.Our findings suggest that vitamin D levels are associated with the ergometric evaluation of muscle strength, as expressed by SJ and CMJ, sprinting capacity, and VO2max in professional soccer players, irrespective the levels of performance. Furthermore, our data reaffirm the importance of UVB on serum vitamin D levels. Moreover, reductions in exercise training stress may also have beneficial effects on vitamin D levels, suggesting a possible association of its levels and the training-induced stress. Our results indicate a

How Players Lose Interest in Playing a Game

DEFF Research Database (Denmark)

Bauckhage, Christian; Kersting, Kristian; Sifa, Rafet

2012-01-01

introduce methods from random process theory into game data mining in order to draw inferences about player engagement. Given large samples (over 250,000 players) of behavioral telemetry data from five different action-adventure and shooter games, we extract information as to how long individual players......Analyzing telemetry data of player behavior in computer games is a topic of increasing interest for industry and research, alike. When applied to game telemetry data, pattern recognition and statistical analysis provide valuable business intelligence tools for game development. An important problem...... in this area is to characterize how player engagement in a game evolves over time. Reliable models are of pivotal interest since they allow for assessing the long-term success of game products and can provide estimates of how long players may be expected to keep actively playing a game. In this paper, we...

Effect of coach change on professional tennis players

OpenAIRE

Nekolová, Barbora

2014-01-01

Title: Effect of coach change on professional tennis players Objectives of work: The aim of the thesis is to analyze the impact of coach change on professional tennis players from the psychology perspective, social relationship and player's attitude to the sport itself. The impact of the coach change on player's approach to tennis, game results, personal life and interpersonal relationships will be examined. Method: The methods that will be used are narrative interviews - annotated transcript...

The effects of a six-week training program on motor and functional skills of female basketball players

OpenAIRE

Zarić Ivan

2014-01-01

The aim of the study was to determine changes in motor and functional skills of women basketball players caused by the influence of six-week training process. Six-week training process (pre-season period of the junior female national basketball team of Serbia for European Championship) lasted 43 days, involved 53 workouts and 8 matches. The subjects sample included 13 basketball players, average age 17.76 (±0.43). The first testing was conducted at the beginning of the training program and th...

Comparison of shock transmission and forearm electromyography between experienced and recreational tennis players during backhand strokes.

Science.gov (United States)

Wei, Shun-Hwa; Chiang, Jinn-Yen; Shiang, Tzyy-Yuang; Chang, Hsiao-Yun

2006-03-01

To test the hypothesis that recreational tennis players transmit more shock impact from the racket to the elbow joint than experienced tennis players during the backhand stroke. Also, to test whether recreational tennis players used higher electromyographic (EMG) activities in common wrist extensor and flexor around epicondylar region at follow-through phase. A repeated-measure, cross-sectional study. National College of Physical Education and Sports at Taipei, Taiwan. Twenty-four male tennis players with no abnormal forearm musculoskeletal injury participated in the study. According to performance level, subjects were categorized into 2 groups: experienced and recreational. Impact transmission and wrist extensor-flexor EMG for backhand acceleration, impact, and follow-through phases were recorded for each player. An independent t test with a significance level of 0.05 was used to examine mean differences of shock impact and EMG between the 2 test groups. One-way ANOVA associated with Tukey multiple comparisons was used to identify differences among different impact locations and EMG phases. Experienced athletes reduced the racket impact to the elbow joint by 89.2%, but recreational players reduced it by only 61.8%. The largest EMG differences were found in the follow-through phase (Pelbow joint and use larger wrist flexor and extensor EMG activities at follow-through phase of the backhand stroke. Follow-through control is proposed as a critical factor for reduction of shock transmission. Clinicians or trainers should instruct beginners to quickly release their grip tightness after ball-to-racket impact to reduce shock impact transmission to the wrist and elbow.

Optical orthogonal code-division multiple-access system - Part 2: Multibits/sequence-period OOCDMA

Science.gov (United States)

Kwon, Hyuck M.

1994-08-01

In a recently proposed optical orthogonal code division multiple-access (OOCDMA) system, one bit of user's data is transmitted per sequence-period, and a threshold is employed for the final bit decision. In this paper, a system that can transmit multibits per sequence-period is introduced, and avalanche photodiode (APD) noise, thermal noise, and interference, are included. This system, derived by exploiting orthogonal properties of the OOCDMA code sequence and using a maximum search (instead of a threshold) in the final decision, is log(sub 2) F times higher in throughput, where F is sequence-period. For example, four orders of magnitude are better in bit error probability at - 56 dBW received laser power, with F = 1000 chips, 10 'marks' in a sequence, and 10 users of 30 Mb/s data rate for one-bit/sequence-period and 270 Mb/s data rate for multibits/sequence-period system. Furthermore, an exact analysis is performed for the log(sub 2)F bits/sequence-period system with a hard-limiter placed before the receiver, and its performance is compared to the performance without hard-limiter, for the chip-synchronous case. The improvement from using a hard-limiter is significant in the log(sub 2)F bits/sequence-period OCCDMA system.

Vitamin D profile in National Football League players.

Science.gov (United States)

Maroon, Joseph C; Mathyssek, Christina M; Bost, Jeffrey W; Amos, Austin; Winkelman, Robert; Yates, Anthony P; Duca, Mark A; Norwig, John A

2015-05-01

By maintaining phosphate and calcium homeostasis, vitamin D is critical for bone health and possibly physical performance. Hence, vitamin D is important to athletes. Few studies have investigated vitamin D levels in relation to fractures and performance in athletes, and no published study has included a multiracial sample of professional American football players. To assess vitamin D levels, including the prevalence of vitamin D deficiency/insufficiency, in professional American football players and to evaluate the association of vitamin D levels with race, fracture history, and the ability to obtain a contract position, which may be a marker for athletic performance. Cohort study; Level of evidence, 3. Serum vitamin D levels of 80 professional football players from a single team in the National Football League were obtained during the 2011 off-season (mean age, 26.5±3.7 years; black, n=67 [84%]). These levels were used to compare injury reports from the 2011-2012 and 2012-2013 seasons. Statistical analyses were performed to test if vitamin D levels were related to race, fracture history, and the ability to obtain a contract position. Mean vitamin D level was 27.4±11.7 ng/mL, with significantly lower levels for black players (25.6±11.3 ng/mL) versus white players (37.4±8.6 ng/mL; F 1,78=13.00, P=.001). All athletes who were vitamin D deficient were black. When controlling for number of professional years played, vitamin D levels were significantly lower in players with at least 1 bone fracture when compared with no fractures. Players who were released during the preseason because of either injury or poor performance had significantly lower vitamin D levels than did players who played in the regular season. Black professional football players have a higher rate of vitamin D deficiency than do white players. Furthermore, professional football players with higher vitamin D levels were more likely to obtain a contract position in the National Football League

Multiple periodic solutions for a class of second-order nonlinear neutral delay equations

Directory of Open Access Journals (Sweden)

2006-01-01

Full Text Available By means of a variational structure and Z 2 -group index theory, we obtain multiple periodic solutions to a class of second-order nonlinear neutral delay equations of the form0, au>0$"> x ″ ( t − τ + λ ( t f ( t , x ( t , x ( t − τ , x ( t − 2 τ = x ( t , λ ( t > 0 , τ > 0 .

Outcomes of microfracture in professional basketball players.

Science.gov (United States)

Cerynik, Douglas L; Lewullis, Gabriel E; Joves, Brian C; Palmer, Michael P; Tom, James A

2009-09-01

Surgical treatment for chondral defects of the knee in competitive running and jumping athletes remains controversial. This study evaluated the performance outcomes of professional basketball players in the National Basketball Association (NBA) who underwent microfracture. Data from 24 professional basketball players from 1997 to 2006 was obtained and analyzed. NBA player efficiency ratings (PER) were calculated for two seasons before and after injury. A control group of 24 players was used for comparison. Study group and control group demographics including age, NBA experience, and minutes per game demonstrated no statistical difference. Mean time to return to an NBA game was 30.0 weeks from the time of surgery. The first season after returning to competition PER and minutes per game decreased by 3.5 (P 0.05) and 3.0 min (P NBA game. On return to competition player performance and minutes per game are diminished.

Injuries in Spanish female soccer players

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Juan Del Coso

2018-04-01

Full Text Available Background: Epidemiologic research to learn the incidence, type, location, and severity of female soccer injuries and the risk factors for sustaining a sport injury is the first step in developing preventive policies. The aim of this study was to analyze the incidence of injuries in the population of female soccer players in Spain. Methods: The injuries incurred by 25,397 female soccer players were registered by the medical staff of the Spanish Football Federation during 1 season. A standardized medical questionnaire was used to classify the injury according to type, severity, location, and injury mechanism. A total of 2108 injuries was reported with an incidence of 0.083 injuries per player per season. Most injuries were in the lower limbs (74.0%, mainly affecting knee (30.4% and ankle joints (17.9%. Results: The proportion of injuries derived from contact with another player was higher during matches (33.7% than during training (11.4%; p  0.05. Conclusion: Most female soccer injuries were located at the knee and ankle; the injury mechanism determined the playing time lost; and the player's age did not affect injury characteristics. Keywords: Ankle, Epidemiology, Knee, Sport injuries, Women

Variational Approaches for the Existence of Multiple Periodic Solutions of Differential Delay Equations

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Rong Cheng

2010-01-01

Full Text Available The existence of multiple periodic solutions of the following differential delay equation (=−((− is established by applying variational approaches directly, where ∈ℝ, ∈(ℝ,ℝ and >0 is a given constant. This means that we do not need to use Kaplan and Yorke's reduction technique to reduce the existence problem of the above equation to an existence problem for a related coupled system. Such a reduction method introduced first by Kaplan and Yorke in (1974 is often employed in previous papers to study the existence of periodic solutions for the above equation and its similar ones by variational approaches.

The effects of 6 weeks of preseason skill-based conditioning on physical performance in male volleyball players.

Science.gov (United States)

Trajković, Nebojša; Milanović, Zoran; Sporis, Goran; Milić, Vladan; Stanković, Ratko

2012-06-01

The purpose of this study was to determine the changes in physical performance after a 6-week skill-based conditioning training program in male competitive volleyball players. Sixteen male volleyball players (mean ± SD: age 22.3 ± 3.7 years, body height 190.7 ± 4.2 cm, and body mass 78.4 ± 4.5 kg) participated in this study. The players were tested for sprinting (5- and 10-m sprint), agility, and jumping performance (the vertical-jump test, the spike-jump test, and the standing broad jump [SBJ]). Compared with pretraining, there was a significant improvement in the 5- and 10-m speed. There were no significant differences between pretraining and posttraining for lower-body muscular power (vertical-jump height, spike-jump height, and SBJ) and agility. Based on our results, it could be concluded that a preseason skill-based conditioning program does not offer a sufficient stimulus for volleyball players. Therefore, a general conditioning and hypertrophy training along with specific volleyball conditioning is necessary in the preseason period for the development of the lower-body strength, agility and speed performance in volleyball players.

Towards Player-Driven Procedural Content Generation

DEFF Research Database (Denmark)

Shaker, Noor; Yannakakis, Georgios N.; Togelius, Julian

2012-01-01

Generating immersive game content is one of the ultimate goals for a game designer. This goal can be achieved by realizing the fact that players’ perception of the same game differ according to a number of factors including: players’ personality, playing styles, expertise and culture background....... While one player might find the game immersive, others may quit playing as a result of encountering a seemingly insoluble problem. One promising avenue towards optimizing the gameplay experience for individual game players is to tailor player experience in real-time via automatic game content generation......-driven content generation....

Whole-Person Impairment in Younger Retired NFL Players: The Orthopaedic Toll of a Professional Football Career.

Science.gov (United States)

Domb, Benjamin G; Carter, Chris; Finch, Nathan A; Hammarstedt, Jon E; Dunne, Kevin F; Stake, Christine E

2014-05-01

Professional American football is a physically demanding, high-impact sport with an elevated risk of injury. Orthopaedic injuries may impose acute, short-term or cumulative consequences throughout a player's lifetime. Several studies have addressed health and psychosocial concerns of an older, retired population of players in the National Football League (NFL); however, minimal research has examined the orthopaedic toll on younger, retired players. This study reports total whole-person impairment (WPI) percentages in a cohort of younger, retired NFL players who presented for disability evaluations based on the use of standardized American Medical Association (AMA) impairment guidelines. Case series; Level of evidence, 4. During the study period of February 2011 to August 2013, 65 younger retired NFL players presented for impairment evaluations. The mean time between retirement and impairment evaluation was 3.1 years (range, 0.3-16.4 years). A complete history and physical examination was performed on all symptomatic joints. A retrospective chart review was conducted on 100% of presenting players to assess orthopaedic burden. Body-part impairment (BPI) percentage for each affected joint was generated. The impairment data for each extremity were then combined with spine impairment data to create WPI percentage. Player demographics, including age, position, and playing time, were also recorded. The average WPI percentage was 37% (range, 19%-53%). Players participating in >30 games (n = 54) had a higher mean WPI percentage (38%) than those playing in 5 seasons (n = 46) were 2.4 times more likely to have a WPI of at least 37% (P = .007). The most common joints players reported as symptomatic were lumbar (n = 63; 97%) and cervical spine (n = 58; 89%). The mean age at evaluation was 33.5 years (range, 27-42 years), and the mean number of seasons played was 7.5 (range, 3-14 seasons). The mean number of games played was 98.4 (range, 2-236 games). This study demonstrated

The Effects of Individualized Resistance Strength Programs on Knee Muscular Imbalances in Junior Elite Soccer Players

Science.gov (United States)

Śliwowski, Robert; Jadczak, Łukasz; Hejna, Rafał; Wieczorek, Andrzej

2015-01-01

The purpose of this study was to investigate the effects of a resistance training program on the muscular strength of soccer players’ knees that initially presented unilateral and bilateral differences. For this study, a team of 24 male well-trained junior soccer players was divided into two strength program training groups: a Resistance Training Control Group (RTCG) composed of 10 players that did not have muscular imbalances and a Resistance Training Experimental Group (RTEG) composed of 14 players that had muscular imbalances. All players followed a resistance training program for six weeks, two times per week, during the transition period. The program of individualized strength training consisted of two parts. The first part, which was identical in terms of the choice of training loads, was intended for both training groups and contained two series of exercises including upper and lower body exercises. The second part of the program was intended only for RTEG and consisted of two additional series for the groups of muscles that had identified unilateral and bilateral differences. The applied program showed various directions in the isokinetic profile of changes. In the case of RTCG, the adaptations related mainly to the quadriceps muscle (the peak torque (PT) change for the dominant leg was statistically significant (p soccer players. PMID:26630271

The El Dorado of Handball? Foreign Female Players Stay, while Domestic Players Return from Abroad

Science.gov (United States)

Topič, Mojca Doupona; Šibila, Marko

2016-01-01

Abstract The main purpose of this research was to study the characteristics of migration in European women’s handball based on the Slovenian example and to find the differences between the foreigners coming to Slovenia and the Slovenians transferring to foreign clubs. The research was based on 16 open face-to-face semi-structured interviews (8 Slovenians (age 29.5 ± 6.2 years) and 8 foreigners (age 35.5 ± 8.7 years)). We found out that the most powerful factor in foreigners was the financial one, while within Slovenian players it was their personal desire for progression within their sport, the club’s reputation and poor conditions in their previous club. The results confirm that when making a decision on transfer, all players had the support of family and friends, while the clubs of foreign players were not as supportive. Most interviewees considered their careers successful and did not regret going abroad. The research indicates that the largest differences discovered between Slovenians and foreigners were that foreign female players chose to stay in the new country (Slovenia), while domestic players returned home after few years playing abroad. In conclusion, the results show that in top-level handball there are important differences between migration models which are based on nationality and also that the migration models change throughout time, which is largely connected with the socioeconomic events in the country of origin or transfer. PMID:28149349

The El Dorado of Handball? Foreign Female Players Stay, while Domestic Players Return from Abroad

Directory of Open Access Journals (Sweden)

Bon Marta

2016-04-01

Full Text Available The main purpose of this research was to study the characteristics of migration in European women’s handball based on the Slovenian example and to find the differences between the foreigners coming to Slovenia and the Slovenians transferring to foreign clubs. The research was based on 16 open face-to-face semi-structured interviews (8 Slovenians (age 29.5 ± 6.2 years and 8 foreigners (age 35.5 ± 8.7 years. We found out that the most powerful factor in foreigners was the financial one, while within Slovenian players it was their personal desire for progression within their sport, the club’s reputation and poor conditions in their previous club. The results confirm that when making a decision on transfer, all players had the support of family and friends, while the clubs of foreign players were not as supportive. Most interviewees considered their careers successful and did not regret going abroad. The research indicates that the largest differences discovered between Slovenians and foreigners were that foreign female players chose to stay in the new country (Slovenia, while domestic players returned home after few years playing abroad. In conclusion, the results show that in top-level handball there are important differences between migration models which are based on nationality and also that the migration models change throughout time, which is largely connected with the socioeconomic events in the country of origin or transfer.

Efficiently detecting outlying behavior in video-game players.

Science.gov (United States)

Kim, Young Bin; Kang, Shin Jin; Lee, Sang Hyeok; Jung, Jang Young; Kam, Hyeong Ryeol; Lee, Jung; Kim, Young Sun; Lee, Joonsoo; Kim, Chang Hun

2015-01-01

In this paper, we propose a method for automatically detecting the times during which game players exhibit specific behavior, such as when players commonly show excitement, concentration, immersion, and surprise. The proposed method detects such outlying behavior based on the game players' characteristics. These characteristics are captured non-invasively in a general game environment. In this paper, cameras were used to analyze observed data such as facial expressions and player movements. Moreover, multimodal data from the game players (i.e., data regarding adjustments to the volume and the use of the keyboard and mouse) was used to analyze high-dimensional game-player data. A support vector machine was used to efficiently detect outlying behaviors. We verified the effectiveness of the proposed method using games from several genres. The recall rate of the outlying behavior pre-identified by industry experts was approximately 70%. The proposed method can also be used for feedback analysis of various interactive content provided in PC environments.

Operative shoulder instability injury management in Australian Football League players: A case series.

Science.gov (United States)

Bonacci, Jason; Manson, Brent; Bowe, Steven J; Gill, Stephen; Seward, Hugh; Hoy, Greg; Page, Richard

2017-11-27

The purpose of this study was to review the surgical management procedures of shoulder instability injuries in Australian Football League (AFL) players, and determine outcomes regarding return to sport and injury recurrence. Retrospective cohort study. Elite AFL players with shoulder instability resulting in surgery were assessed in a retrospective cohort design (72 players/77 shoulders). Type of initial injury, surgical management, return to sport and injury recurrence were obtained. The mean follow-up period post-surgery was 2.9 years. Return to sport outcomes were compared between arthroscopic and open surgery using a Kaplan-Meier survival analysis. Logistic regression modelling was used to determine associations between injury recurrence, type of injury, participant age and method of surgery. Shoulder instability injuries occurred most frequently during tackling (40%). Arthroscopic surgery was preferred for primary shoulder instability. Nine (16%) recurrences occurred in those who underwent arthroscopic surgery compared to two (9%) following open surgery. Return to the elite level was slightly but significantly (2 weeks, p=0.049) longer for open compared to arthroscopic surgery. Recurrence was 5 times more likely if the primary injury was a dislocation and more likely in players who were younger at the time of surgery. Tackling was the predominant mechanism for shoulder instability injuries in AFL players and arthroscopic surgery was more commonly performed for primary injuries. Sustaining a dislocation as the primary injury and younger age increased the likelihood of recurrent instability. Careful consideration should be given to the operative management of these individuals. Copyright © 2017. Published by Elsevier Ltd.

The Effects of Playing Multiple High School Sports on National Basketball Association Players' Propensity for Injury and Athletic Performance.

Science.gov (United States)

Rugg, Caitlin; Kadoor, Adarsh; Feeley, Brian T; Pandya, Nirav K

2018-02-01

Athletes who specialize in their sport at an early age may be at risk for burnout, overuse injury, and reduced attainment of elite status. Timing of sport specialization has not been studied in elite basketball athletes. National Basketball Association (NBA) players who played multiple sports during adolescence would be less likely to experience injury and would have higher participation rates in terms of games played and career length compared with single-sport athletes. Descriptive epidemiology study. First-round draft picks from 2008 to 2015 in the NBA were included in the study. From publically available records from the internet, the following data were collected for each athlete: participation in high school sports, major injuries sustained in the NBA, percentage of games played in the NBA, and whether the athlete was still active in the NBA. Athletes who participated in sports in addition to basketball during high school were defined as multisport athletes and were compared with athletes who participated only in basketball in high school. Two hundred thirty-seven athletes were included in the study, of which 36 (15%) were multisport athletes and 201 (85%) were single-sport athletes in high school. The multisport cohort played in a statistically significantly greater percentage of total games (78.4% vs 72.8%; P NBA (94% vs 81.1%; P = .03). While a minority of professional basketball athletes participated in multiple sports in high school, those who were multisport athletes participated in more games, experienced fewer major injuries, and had longer careers than those who participated in a single sport. Further research is needed to determine the reasons behind these differences.

Isokinetic Strength Profile of Elite Female Handball Players

Directory of Open Access Journals (Sweden)

Xaverova Zuzana

2015-12-01

Full Text Available Systematic assessment of muscle strength of the lower extremities throughout the annual training cycle in athletes is crucial from a performance perspective for the optimization of the training process, as well as a health perspective with regard to injury prevention. The main aim of the present study was to determine isokinetic muscle strength of the knee flexors and extensors in female handball players at the beginning of a preparatory period and to assess whether there were any differences between players of different performance levels. The performance level was expressed by means of membership of the Women’s Junior National Handball Team (JNT, n=8 or the Women’s National Handball Team (NT, n=9. The isokinetic peak torque during concentric and eccentric single-joint knee flexion and extension was measured at angular velocities of 60, 180, 240°/s (concentric and 60°/s (eccentric. The Mann- Whitney test showed no significant differences in the peak torques or ipsilateral ratios between the two groups. The bilateral force deficit (BFD for concentric extension at 240°/s was significantly higher in the JNT compared with the NT (p=0.04; d=1.02. However, the results of individual evaluation show that the BFD was more frequent in the NT in most measurements. A high BFD was evident in the eccentric mode in both groups highlighting a need for particular strengthening. With regard to low strength ratios a prevention programme should be suggested for both observed groups of professional female handball players to reduce the risk of injury.

Isokinetic Strength Profile of Elite Female Handball Players.

Science.gov (United States)

Xaverova, Zuzana; Dirnberger, Johannes; Lehnert, Michal; Belka, Jan; Wagner, Herbert; Orechovska, Karolina

2015-12-22

Systematic assessment of muscle strength of the lower extremities throughout the annual training cycle in athletes is crucial from a performance perspective for the optimization of the training process, as well as a health perspective with regard to injury prevention. The main aim of the present study was to determine isokinetic muscle strength of the knee flexors and extensors in female handball players at the beginning of a preparatory period and to assess whether there were any differences between players of different performance levels. The performance level was expressed by means of membership of the Women's Junior National Handball Team (JNT, n=8) or the Women's National Handball Team (NT, n=9). The isokinetic peak torque during concentric and eccentric single-joint knee flexion and extension was measured at angular velocities of 60, 180, 240°/s (concentric) and 60°/s (eccentric). The Mann-Whitney test showed no significant differences in the peak torques or ipsilateral ratios between the two groups. The bilateral force deficit (BFD) for concentric extension at 240°/s was significantly higher in the JNT compared with the NT (p=0.04; d=1.02). However, the results of individual evaluation show that the BFD was more frequent in the NT in most measurements. A high BFD was evident in the eccentric mode in both groups highlighting a need for particular strengthening. With regard to low strength ratios a prevention programme should be suggested for both observed groups of professional female handball players to reduce the risk of injury.

Morphological evolution of Springbok rugby players: Implications for ...

African Journals Online (AJOL)

The physique of rugby players has evolved over the course of the Twentieth Century. A novel morphological dataset was constructed of all Springbok rugby players until 2014. Although most of the change in body structure, particularly body weight, occurs during the era of professionalism, white Springbok rugby players ...

Elite female soccer players perform more high-intensity running when playing in international games compared with domestic league games.

Science.gov (United States)

Andersson, Helena A; Randers, Morten B; Heiner-Møller, Anja; Krustrup, Peter; Mohr, Magni

2010-04-01

The purpose of this study was to compare movement pattern, fatigue development, and heart rate (HR) for top-class elite female players when playing international (INT) vs. domestic league games (DOM). Video-based time-motion analyses and HR recordings were performed on 17 players during INT and DOM. The distances covered in high-intensity running (HIR) and sprinting were longer (p game types, the amount of HIR was reduced by 24-27% (p game. The midfielders covered longer (p game and in the most intense 5-minute period of the games, whereas no differences were observed between the game types for defenders. No difference in the HR response was found between INT and DOM. In conclusion, more HIR and sprinting occur in international compared with domestic games, which may affect the fatigue development for players in physically demanding roles. Thus, our results are important to coaches to prepare players to meet the challenges of international soccer games and show that the ability to perform intense intermittent exercise should be trained regularly in elite female players.

Football players, asset management & the unexploited potential of enhanced player engagement in football management & marketing

DEFF Research Database (Denmark)

Cortsen, Kenneth

2016-01-01

This article gives insights into why and how football brands (e.g. clubs and governing bodies) can benefit from enhancing the activation of players in football management and football marketing initiatives.......This article gives insights into why and how football brands (e.g. clubs and governing bodies) can benefit from enhancing the activation of players in football management and football marketing initiatives....

Football players, asset management & the unexploited potential of enhanced player engagement in football management & marketing

DEFF Research Database (Denmark)

Cortsen, Kenneth

2014-01-01

This article gives insights into why and how football brands (e.g. clubs and governing bodies) can benefit from enhancing the activation of players in football management and football marketing initiatives.......This article gives insights into why and how football brands (e.g. clubs and governing bodies) can benefit from enhancing the activation of players in football management and football marketing initiatives....

Locomotion characteristics and match-induced impairments in physical performance in male elite team handball players.

Science.gov (United States)

Michalsik, L B; Aagaard, P; Madsen, K

2013-07-01

The purpose of this study was to determine the physical demands and match-induced impairments in physical performance in male elite Team Handball (TH) players in relation to playing position. Male elite TH field players were closely observed during 6 competitive seasons. Each player (wing players: WP, pivots: PV, backcourt players: BP) was evaluated during match-play using video recording and subsequently performing locomotion match analysis. A total distance of 3 627±568 m (group means±SD) was covered per match with a total effective playing time (TPT) of 53:51±5:52 min:s, while full-time players covered 3 945±538 m. The mean speed was 6.40±1.01 km · h - 1. High-intensity running constituted only 1.7±0.9% of TPT per match corresponding to 7.9±4.9% of the total distance covered. An average of 1 482.4±312.6 activity changes per player (n=82) with 53.2±14.1 high-intensity runs were observed per match. Total distance covered was greater in BP (3 765±532 m) and WP (3 641±501 m) than PV (3 295±495 m) (pteam sport that comprises several types of movement categories, which during match-play place moderate-to-high demands on intermittent endurance running capacity and where the amount of high-intensity running may be high during brief periods of the match. Signs of fatigue-related changes were observed in terms of temporary impaired physical performance, since the amount of high-intensity running was reduced in the second half. Notably, physical demands differed between playing positions, with WP demonstrating a more intensive activity pattern than BP and PV, respectively. © Georg Thieme Verlag KG Stuttgart · New York.

High School Rugby Players' Perception of Coaching Effectiveness

Science.gov (United States)

Broodryk, Retief; van den Berg, Pieter Hendrick

2011-01-01

The aims of this study were firstly to determine the players' perceptions of their respective coaches' coaching effectiveness and secondly, determine the difference between big and small schools of the players' perceptions of their respective coaches' coaching effectiveness. Four hundred and seventy six players from 22 schools were asked to fill…

Swimming literacy field hockey woman player ground.

OpenAIRE

Baštová, Miroslava

2012-01-01

Title: Swimming literacy field hockey woman player ground. Objectives: To obtain and analyze data on the level ground swimming literacy field hockey woman player. Their perception swimming literacy for life, the use of non-specific regeneration and as a training resource. Methods: Analysis of scientific literature, survey, case study, data analysis and graphical presentation of results. Results of the work: field hockey player as swimming literate, benefits swimming but not used as a means of...

Effects of prolonged intensive training on the resting levels of salivary immunoglobulin A and cortisol in adolescent volleyball players.

Science.gov (United States)

Li, T L; Lin, H C; Ko, M H; Chang, C K; Fang, S H

2012-10-01

Concerns have been raised regarding the effects of prolonged intensive training on adolescent athletes. This study investigated the differences in mucosal immune functions and stress responses between intensively trained male adolescent volleyball players and age-matched sedentary controls. Twelve male volleyball players (16.5 [0.7] years of age) and sixteen healthy sedentary male volunteers (17.1 [0.6] years of age) participated in this study. Volleyball players were engaged in regular and year-round training. Unstimulated saliva samples were collected from volleyball players during the high-intensity training period and from the counterparts at the same timepoints after at least 18 hours of rest. Concentrations of salivary total protein, secretory immunoglobulin A (SIgA), cortisol, and lactoferrin were measured. Results of this study revealed that the SIgA concentrations and the ratio of SIgA/total protein in volleyball players were significantly lower compared with those in sedentary controls. However, the salivary cortisol concentrations and the ratio of cortisol/total protein in volleyball players were markedly higher compared with those in sedentary controls. No significant difference was observed in lactoferrin levels between volleyball players and sedentary controls. The findings of this study suggest that the prolonged intensive training may elicit a sustained stress and induce a suppressive effect on mucosal immunity in regularly and intensively trained adolescent athletes.

Fatigue Responses in Various Muscle Groups in Well-Trained Competitive Male Players after a Simulated Soccer Game.

Science.gov (United States)

Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G; Krustrup, Peter; Mohr, Magni

2018-03-01

We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12) participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement ( p ≤ 0.05) at 0 h post-match with knee flexors (14 ± 3%) and hip abductors (6 ± 1%) demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05) for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin) and 24 h into recovery (creatine kinase), respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02). In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery.

Fatigue Responses in Various Muscle Groups in Well-Trained Competitive Male Players after a Simulated Soccer Game

Directory of Open Access Journals (Sweden)

Fransson Dan

2018-03-01

Full Text Available We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12 participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement (p ≤ 0.05 at 0 h post-match with knee flexors (14 ± 3% and hip abductors (6 ± 1% demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05 for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin and 24 h into recovery (creatine kinase, respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02. In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery.

Protective equipment use among female rugby players.

Science.gov (United States)

Comstock, R Dawn; Fields, Sarah K; Knox, Christy L

2005-07-01

Our objective was to assess the prevalence of protective equipment use and the motivation for using protective equipment among a sample of US female rugby players. We surveyed a convenience sample of 234 current US female rugby players from 14 teams participating in a US women's rugby tournament, obtaining self-reported demographic, rugby exposure, and protective equipment use information. Mouthguards were the most commonly used piece of protective equipment: 90.8% of players reported having always worn a mouthguard while playing or practicing rugby within their most recent 3 months of play. Fewer than 15% of players reported having always worn other types of protective equipment. Equipment use varied by playing position. Whereas over 80% of players in all other positions always wore a mouthguard, 66.7% of scrum halves reported always wearing one. Both backs and forwards reported wearing shoulder pads, but only forwards reported always wearing padded headgear. Mouthguards, padded headgear, and shoulder pads were worn "to prevent injury," whereas ankle braces, neoprene sleeves, and athletic tape on joints were worn "to protect a current/recent injury." This is the first study of female rugby players to assess the prevalence of protective equipment use by playing position and the motivation for using protective equipment. With the exception of mouthguards, US female rugby players infrequently use protective equipment. Protective equipment use varies by playing position. Some types of protective equipment appear to be used as primary prevention mechanisms, whereas others are used as secondary or tertiary prevention mechanisms.

A location-routing problem model with multiple periods and fuzzy demands

Directory of Open Access Journals (Sweden)

Ali Nadizadeh

2014-08-01

Full Text Available This paper puts forward a dynamic capacitated location-routing problem with fuzzy demands (DCLRP-FD. It is given on input a set of identical vehicles (each having a capacity, a fixed cost and availability level, a set of depots with restricted capacities and opening costs, a set of customers with fuzzy demands, and a planning horizon with multiple periods. The problem consists of determining the depots to be opened only in the first period of the planning horizon, the customers and the vehicles to be assigned to each opened depot, and performing the routes that may be changed in each time period due to fuzzy demands. A fuzzy chance-constrained programming (FCCP model has been designed using credibility theory and a hybrid heuristic algorithm with four phases is presented in order to solve the problem. To obtain the best value of the fuzzy parameters of the model and show the influence of the availability level of vehicles on final solution, some computational experiments are carried out. The validity of the model is then evaluated in contrast with CLRP-FD's models in the literature. The results indicate that the model and the proposed algorithm are robust and could be used in real world problems.

Strength asymmetry of the shoulders in elite volleyball players.

Science.gov (United States)

Hadzic, Vedran; Sattler, Tine; Veselko, Matjaž; Markovic, Goran; Dervisevic, Edvin

2014-01-01

Volleyball players are reported to have shoulder strength imbalances. Previous authors have primarily investigated small samples of male players at a single skill level, without considering playing position, and with inconsistent findings. To evaluate shoulder strength asymmetry and a history of shoulder injury in a large sample of professional volleyball players of both sexes across different playing positions and skill levels. Descriptive laboratory study. A sample of 183 volleyball players (99 men, 84 women). We assessed shoulder internal-rotator and external-rotator concentric strength at 60°/s using an isokinetic dynamometer and dominant-nondominant differences in shoulder strength and strength ratios using repeated-measures analyses of variance. Peak torque was normalized for body mass and external-rotation/internal-rotation concentric strength. Internal-rotation strength was asymmetric in favor of the dominant side in both sexes, regardless of previous shoulder injury status. Male volleyball players had a lower shoulder strength ratio on the dominant side, regardless of previous shoulder injury status. However, this finding was valid only when hand dominance was taken into account. Female volleyball players playing at a higher level (ie, first versus second division) were 3.43 times more likely to have an abnormal strength ratio. Playing position was not associated with an abnormal shoulder strength ratio or strength asymmetry. In male volleyball players, the external-rotation/internal-rotation strength ratio of the dominant shoulder was lower, regardless of playing position, skill level, or a previous shoulder injury. In female players, the ratio was less only in those at a higher skill level. Although speculative, these findings generally suggest that female volleyball players could have a lower risk of developing shoulder-related problems than male volleyball players. Isokinetic shoulder testing may reveal important information about the possible risk

Current reversal in a continuously periodic system driven by an additive noise and a multiplicative noise

International Nuclear Information System (INIS)

Wang Canjun; Chen Shibo; Mei Dongcheng

2006-01-01

We study the noise-induce transport and current reversal of Brownian particles in a continuously periodic potential driven by cross correlation between a multiplicative white noise and an additive white noise. We find that directed motion of the Brownian particles can be induced by the correlation between the additive noise and the multiplicative noise. The current reversal and the direction of the current is controlled by the values of the intensity (λ) of the correlated noises and a dimensionless parameter R (R=α/D, D is the intensity of multiplicative noise and α is the intensity of additive noise)

Importance of physical qualities for speed and change of direction ability in elite female soccer players.

Science.gov (United States)

Emmonds, Stacey; Nicholson, G; Beggs, C; Jones, B; Bissas, A

2017-07-17

The purpose of this study was to determine the importance of physical qualities for speed and change of direction (CoD) ability in female soccer players. Data were collected on 10 female soccer players who were part of a professional English Women's Super League team. Player assessments included anthropometric (stature and body mass), body composition (dual-energy X-ray absorptiometry), speed (10m, 30m sprint), CoD ability (505 agility), aerobic (Yo-Yo Intermittent Recovery Test), lower-body strength (bilateral knee extensions) and power (countermovement jump [CMJ], squat jump [SJ], 30cm drop jump [DJ]) measures. The relationships between the variables were evaluated using eigenvector analysis and Pearson correlation analysis. Multiple linear regression revealed that the performance variables (10 and 20m speed, mean 505, and CoD deficit mean) can be predicted with almost 100% accuracy (i.e. adjusted R > 0.999) using various combinations of the predictor variables (DJ height, CMJ height, SJ height, lean body mass). An increase of one standard deviation (SD) in DJ height was associated with reductions of -5.636 and -9.082 SD in 10 m and 20 m sprint times. A one SD increase in CMJ also results in a reduction of -3.317 and -0.922 SD respectively in mean 505 and CoD deficit mean values. This study provides comparative data for professional English female soccer players that can be used by strength and conditioning coaches when monitoring player development and assessing the effectiveness of training programmes. Findings highlight the importance of developing reactive strength to improve speed and CoD ability in female soccer players.

Talented football players' development of achievement motives, volitional components, and self-referential cognitions: A longitudinal study.

Science.gov (United States)

Feichtinger, Philip; Höner, Oliver

2015-01-01

Adolescence is regarded as a key developmental phase in the course of talented football players' careers. The present study focuses on early adolescent players' development of achievement motives, volitional components, and self-referential cognitions. Based on the multidimensional and dynamic nature of talent, the development of multifaceted personality characteristics is an important issue in the context of sports talent research. According to previous findings in psychology, personality characteristics' development is defined by both stability and change, and the current study analyses four different types: differential stability (I), mean-level change (II), individual-level change (III), and structural stability (IV). The sample consists of 151 male players in the talent development programme of the German Football Association. Psychological diagnostics of the personality characteristics are implemented across longitudinal sections over a time period of three seasons, from the U12 to U14 age classes. The results reveal that the personality characteristics show (I) moderate test-retest correlations over one-year intervals (.43 ≤ rtt ≤ .62), and lower coefficients for a two-year period (.26 ≤ rtt ≤ .53). (II) Most of the personality characteristics' mean values differ significantly across the age classes with small effect sizes (.01 ≤ [Formula: see text] ≤ .03). (III) Only minor individual-level changes in the football players' development are found. (IV) The personality characteristics' associations within a two-factor structure do not stay invariant over time. From the results of the present study, conclusions are drawn regarding the talent identification and development process.

Effects of type of tapering on anaerobic capacity in young basketball players

Directory of Open Access Journals (Sweden)

Hugo Augusto Alvares da Silva Lira

2017-11-01

Full Text Available The aim of this study was to analyze the effect of the type of tapering on anaerobic capacity in male young basketball players. This was an experimental research with 12 weeks, developed with 47 basketball players, randomly divided into three groups: linear tapering (LG, tapering by step (SG and control group (CG. All groups participated of the same planning training until the last three weeks of periodization (the tapering phase. Only the CG did not perform tapering. Anaerobic Running Speed Test was carried in the last week of each mesocycle to assess the anaerobic capacity. The findings revealed that anaerobic capacity attenuated from the competitive to tapering phase in LG (p= .01 and SG (p= .01, which was not verified for the CG (p= .29. Significant difference of anaerobic capacity was found between LG and CG (p= .01, SG and CG (p= .01 and between LG and SG (p= .04 in the tapering phase. It was concluded that the tapering strategies were efficient to maximize anaerobic capacity in young basketball players, although linear tapering strategy has been revealed the best strategy for improvement the anaerobic capacity.

Effect of 2-wk intensified training and inactivity on muscle Na+/K+ pump expression, phospholemman (FXYD1) phosphorylation and performance in soccer players

DEFF Research Database (Denmark)

Thomassen, Martin; Christensen, Peter Møller; Gunnarsson, Thomas Gunnar Petursson

2010-01-01

The present study examined muscle adaptations and alterations in performance of highly trained soccer players with intensified training or training cessation. Eighteen elite soccer players were for a 2-wk period assigned to either a group which performed high intensity training with a reduction....... The present data suggest that short-term intensified training even for trained soccer players can increase muscle Na(+)/K(+) pump alpha2 isoform expression and that cessation of training for two weeks does not affect the expression of Na(+)/K(+) pump isoforms. Resting phosphorylation status of the Na...

Player behavioural modelling for video games

NARCIS (Netherlands)

van Lankveld, G.; Spronck, P.H.M.; Bakkes, S.C.J.

2012-01-01

Player behavioural modelling has grown from a means to improve the playing strength of computer programs that play classic games (e.g., chess), to a means for impacting the player experience and satisfaction in video games, as well as in cross-domain applications such as interactive storytelling. In

Self-determined motivation in rehabilitating professional rugby union players

OpenAIRE

Carson, F.; Polman, Remco C.J.

2017-01-01

Background The aim of the present study was to explore the views of professional rugby union players during the early rehabilitation, late rehabilitation and return to play stages, following anterior cruciate ligament (ACL) injury. Methods A qualitative dominant, mixed methodological approach was utilized with five players who had suffered an ACL injury requiring reconstructive surgery. A longitudinal approach, concurrent with each player?s rehabilitation, consisting of twice monthly intervie...

Physical Characteristics and Performance of Japanese Top-Level American Football Players.

Science.gov (United States)

Yamashita, Daichi; Asakura, Masaki; Ito, Yoshihiko; Yamada, Shinzo; Yamada, Yosuke

2017-09-01

Yamashita, D, Asakura, M, Ito, Y, Yamada, S, and Yamada, Y. Physical characteristics and performance of Japanese top-level American football players. J Strength Cond Res 31(9): 2455-2461, 2017-This study aimed to compare the physical characteristics and performance between top-level nonprofessional football players in Japan and National Football League (NFL) Combine invited players and between top-level and middle-level players in Japan to determine the factors that enhance performance in international and national competitions. A total of 168 American football players (>20 years) in Japan participated in an anthropometric (height and weight) and physical (vertical jump, long jump, 40-yard dash, pro-agility shuttle, 3-cone drill, and bench press repetition test) measurement program based on the NFL Combine program to compete in the selection of candidates for the Senior World Championship. All players were categorized into 1 of the 3 position groups based on playing position: skill players, big skill players, and linemen. Japanese players were additionally categorized into selected and nonselected players for the second tryout. The NFL Combine candidates had significantly better performance than selected Japanese players on all variables except on performance related to quickness among the 3 position groups. Compared with nonselected players, selected Japanese skill players had better performance in the 40-yard dash and bench press test and big skill players had better performance in the vertical jump, broad jump, and 40-yard dash. Selected and nonselected Japanese linemen were not different in any measurements. These results showed the challenges in American football in Japan, which include not only improving physical performance of top-level players, but also increasing the number of football players with good physical performance.

Training Patterns of Wheelchair Basketball Players in Turkey

Science.gov (United States)

Tatar, Yasar

2008-01-01

The aim of this study was to analyze technical drills, warm-up and cool-down exercises used by wheelchair basketball players of the Turkish league in relation to training sessions. 33 male wheelchair basketball players participated in the study (mean age 26.6[plus or minus]5,95 years). All players reported that they used warm-up exercises before…

Integration of the thiol redox status with cytokine response to physical training in professional basketball players.

Science.gov (United States)

Zembron-Lacny, A; Slowinska-Lisowska, M; Ziemba, A

2010-01-01

The present study was designed to evaluate the plasma markers of reactive oxygen species (ROS) activity and cytokines, and their relationship with thiol redox status of basketball players during training. Sixteen professional players of the Polish Basketball Extraleague participated in the study. The study was performed during the preparatory period and the play-off round. Markers of ROS activity (lipid peroxidation TBARS, protein carbonylation PC) and reduced glutathione (GSH) demonstrated regularity over time, i.e. TBARS, PC and GSH were elevated at the beginning and decreased at the end of training periods. Oxidized glutathione (GSSG) was not affected by exercise training. Thiol redox status (GSH(total)-2GSSG/GSSG) correlated with TBARS and PC in both training periods. The level of interleukin-6 (IL-6) was increased and positively correlated with thiol redox (r=0.423) in the preparatory period, whereas tumor necrosis factor alpha (TNFalpha) was increased and inversely correlated with thiol redox (r= 0.509) in the play-off round. The present study showed significant shifts in markers of ROS activity, thiol redox status and inflammatory mediators (IL-6, TNFalpha) following professional sport training as well as correlation between changes in thiol redox and cytokine response.

Prospective study of injury in volleyball players: 6 year results.

Science.gov (United States)

Pastor, M F; Ezechieli, M; Classen, L; Kieffer, O; Miltner, O

2015-01-01

The volleyball game has a high complexity and thus entails a lot of strain to the players. Due to this high and different training and competition strain comprehensive and individual training plans should be developed with competing training objectives in order to prevent injuries. The aim of the study was to analyse prospectively over six seasons the acute and overuse injuries of a German male professional volleyball team. The study included 34 male national league players from season the 2007/08 to 2012/13. All players received a sport medicine examination and a functional diagnosis before each season. Based on the results the players received an individual training plan. The players suffered 186 injuries. The prevalence of acute injuries was 1.94 per player and overuse injuries 0.64 per player. The incidence of acute injuries was 3.3/1000 h volleyball and overuse injuries 1.08/1000 h volleyball. The largest number of injuries was found in the spine. The players had most likely minor injuries. The players had significantly fewer injuries in their second season (1.92) than in their first season (3.25; p= 0.004). It could be concluded that volleyball is a sport with a relative low prevalence of injuries compared to other team sports. The prevalence of injury is 2.58 per player. Due to an injury a player dropped out 16.91 days per season. An individual training program seems to reduce the incidence of injury.

Short-term Outcomes Following Concussion in the NFL: A Study of Player Longevity, Performance, and Financial Loss.

Science.gov (United States)

Navarro, Sergio M; Sokunbi, Olumide F; Haeberle, Heather S; Schickendantz, Mark S; Mont, Michael A; Figler, Richard A; Ramkumar, Prem N

2017-11-01

A short-term protocol for evaluation of National Football League (NFL) athletes incurring concussion has yet to be fully defined and framed in the context of the short-term potential team and career longevity, financial risk, and performance. To compare the short-term career outcomes for NFL players with concussions by analyzing the effect of concussions on (1) franchise release rate, (2) career length, (3) salary, and (4) performance. Cohort study; Level of evidence, 3. NFL player transaction records and publicly available injury reports from August 2005 to January 2016 were analyzed. All players sustaining documented concussions were evaluated for a change to inactive or DNP ("did not participate") status. A case-control design compared franchise release rates and remaining NFL career span. Career length was analyzed via survival analysis. Salary and performance differences were analyzed with publicly available contract data and a performance-scoring algorithm based on position/player level. Of the 5894 eligible NFL players over the 11-year period, 307 sustained publicly reported concussions resulting in the DNP injury protocol. Analysis of the probability of remaining in the league demonstrated a statistically significantly shorter career length for the concussion group at 3 and 5 years after concussion. The year-over-year change in contract value for the concussion group resulted in a mean overall salary reduction of $300,000 ± $1,300,000 per year (interquartile range, -$723,000 to $450,000 per year). The performance score reduction for all offensive scoring players sustaining concussions was statistically significant. This retrospective study demonstrated that NFL players who sustain a concussion face a higher overall franchise release rate and shorter career span. Players who sustained concussions may incur significant salary reductions and perform worse after concussion. Short-term reductions in longevity, performance, and salary after concussion exist and

When pain brings gain: Soccer players behaviour and admissions suggest feigning injury to maintain a favourable scoreline

Directory of Open Access Journals (Sweden)

Stuart W G Derbyshire

2016-04-01

Full Text Available The rules of soccer dictate that play, once halted, cannot continue if a player is injured. Players may take advantage of this rule by feigning injury to preserve beneficial match positions. Thirty Euro 2008 matches, 90 Premier League matches and 63 World Cup 2010 matches were reviewed for the timing and severity of injuries. The number of injuries was compared between teams that benefited from stopping the game and those that did not benefit. The number of low-level injuries, not resulting in substitution or subsequent problems, was directly compared for benefit and non-benefit teams for each 15-minute period following kick off. Statistical significance was assessed using appropriate non-parametric tests. In addition, seven current players and three managers were interviewed and were asked about feigning injury. Teams that benefited from game stoppages suffered significantly more minor injuries in the last 15 minutes of matches compared with those that did not benefit. Four of the players directly admitted feigning injury. When it is beneficial, soccer players can and do successfully feign injury to stop the game. Consequently it is possible that others might also successfully feign injury, pain or disease when motivated to do so.

Do Australian Football players have sensitive groins? Players with current groin pain exhibit mechanical hyperalgesia of the adductor tendon.

Science.gov (United States)

Drew, Michael K; Lovell, Gregory; Palsson, Thorvaldur S; Chiarelli, Pauline E; Osmotherly, Peter G

2016-10-01

This is the first study to evaluate the mechanical sensitivity, clinical classifications and prevalence of groin pain in Australian football players. Case-control. Professional (n=66) and semi-professional (n=9) Australian football players with and without current or previous groin injuries were recruited. Diagnoses were mapped to the Doha Agreement taxonomy. Point and career prevalence of groin pain was calculated. Pressure pain thresholds (PPTs) were assessed at regional and distant sites using handheld pressure algometry across four sites bilaterally (adductor longus tendon, pubic bone, rectus femoris, tibialis anterior muscle). To assess the relationship between current groin pain and fixed effects of hyperalgesia of each site and a history of groin pain, a mixed-effect logistic regression model was utilised. Receiver Operator Characteristic (ROC) curve were determined for the model. Point prevalence of groin pain in the preseason was 21.9% with a career prevalence of 44.8%. Adductor-related groin pain was the most prevalent classification in the pre-season period. Hyperalgesia was observed in the adductor longus tendon site in athletes with current groin pain (OR=16.27, 95% CI 1.86 to 142.02). The ROC area under the curve of the regression model was fair (AUC=0.76, 95% CI 0.54 to 0.83). Prevalence data indicates that groin pain is a larger issue than published incidence rates imply. Adductor-related groin pain is the most common diagnosis in pre-season in this population. This study has shown that hyperalgesia exists in Australian football players experiencing groin pain indicating the value of assessing mechanical pain sensitivity as a component of the clinical assessment. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Generative Agents for Player Decision Modeling in Games

DEFF Research Database (Denmark)

Holmgård, Christoffer; Liapis, Antonios; Togelius, Julian

2014-01-01

This paper presents a method for modeling player decision making through the use of agents as AI-driven personas. The paper argues that artificial agents, as generative player models, have properties that allow them to be used as psyhometrically valid, abstract simulations of a human player......’s internal decision making processes. Such agents can then be used to interpret human decision making, as personas and playtesting tools in the game design process, as baselines for adapting agents to mimic classes of human players, or as believable, human-like opponents. This argument is explored...... in a crowdsourced decision making experiment, in which the decisions of human players are recorded in a small-scale dungeon themed puzzle game. Human decisions are compared to the decisions of a number of a priori defined “archetypical” agent-personas, and the humans are characterized by their likeness...

Seasonal variation in isokinetic strength of knee flexors and extensors in soccer players

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Michal Lehnert

2015-06-01

Full Text Available BACKGROUND: Muscle strength is an important factor in soccer from the performance and health perspective. There is a lack of knowledge about changes in muscle strength of the knee flexors and extensors and their ratios during annual training cycle. OBJECTIVES: The aim of this study was to evaluate the seasonal variability of the observed parameters of isokinetic strength of the knee flexors and extensors in soccer players, U19, from the performance and health perspective. METHODS: The strength of the knee flexors and extensors was measured in players U19 category (n = 9; the average age 18.5 ±0.4 years on the isokinetic dynamometer IsoMed 2000 in angular velocity 60° × s-1. Measurement was performed in concentric/concentric and excentric/excentric mode of muscle action at the beginning of the winter preparatory period, at the end of the preparatory period and at the end of the spring competitive period. Monitored parameters were absolute peak torque (PT, conventional H/Q ratio (H/QCON, functional H/Q ratio (H/QFUN and functional H/Q ratio in range 10-30° of knee flexion (H/QFUN_10-30. RESULTS: Significant change in PT (p < .05 was noted only in cases of the knee extensors of the nondominant leg in the concentric mode. The evaluation of imbalance of the knee flexors and extensors by H/QCON and H/QFUN ratios did not show any significant changes, but there was found a significant decrease of the H/QFUN_10-30 ratio in the dominant leg between measurements at the beginning and at the end of the winter preparatory period. CONCLUSIONS: The results of the current study indicate that throughout the monitored periods of the annual training cycle desirable changes in knee flexors and extensors strength did not occur. The values suggest the disruption of the dynamic stabilization of the knee joint and increase in injury risk. Different dynamics of the three observed ratios confirmed that they provide different information about the physical fitness of

A study of static, kinetic, and dynamic visual acuity in 102 Japanese professional baseball players

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Hoshina K

2013-03-01

Full Text Available Kohji Hoshina,1 Yuichi Tagami,2 Osamu Mimura,3 Hiroshi Edagawa,4 Masao Matsubara,5 Teiichi Nakayama6 1Hoshina Eye Clinic, Nishinomiya, Japan; 2Department of Ophthalmology, Kobe Century Memorial Hospital, Kobe, Japan; 3Department of Ophthalmology, Hyogo College of Medicine, Nishinomiya, Japan; 4Edagawa Eye Clinic, Tokyo, Japan; 5Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan; 6Ritsumeikan University, Kyoto, Japan Background: It seemed that visual functions might have some effects on the performance of baseball players. We measured static, kinetic, and dynamic visual acuity (SVA, KVA, and DVA, respectively of Japanese professional baseball players to ascertain whether there would be any difference in SVA, KVA, and DVA among player groups stratified according to their performance level. Methods: The subjects were 102 male professional baseball players with a mean age of 26 years who were members of a Japanese professional baseball club from 2000 to 2009. They were stratified into three groups according to their performance level: A (players who were on the roster of the top-level team all the time throughout the study period, B (players who were on the roster of the top-level team sometimes but not all the time, and C (players who were never on the roster of the top-level team. They were interviewed for the use of corrective visual aids, and examined for SVA, KVA, and DVA. The measurements of these parameters were compared among groups A, B, and C. We also investigated and analyzed the association of KVA or DVA with player position (pitchers or fielders and with hand dominance for batting. KVA was compared between the pitchers and the fielders because they each require different playing skills. DVA was compared between the right-handed and the left-handed batters. Results: There was no statistically significant difference among groups A, B, and C. There was a statistically significant difference in

Beneficial Long Communication in the Multi-Player Electronic Mail Game

NARCIS (Netherlands)

De Jaegher, K.J.M.

2015-01-01

In the two-player electronic mail game (EMG), as is well-known, the probability of collective action is lower the more confirmations and re-confirmations are made available to players. In the multi-player EMG, however, as we show players may coordinate on equilibria where they require only few of

Presence of the relative age effect and its effect on playing time among under-20 players in the Norwegian premier league Tippeligaen – a four-year follow up

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Stig Arve Sæther

2016-03-01

Full Text Available European top-level soccer clubs are continually looking for talented players. Few clubs, however, are willing to let youth players play at the highest senior level. Perhaps as a consequence, the search for talented players has resulted in an imbalance in the characteristics of these players, towards an overrepresentation of players born early in the selection year, an effect called the relative age effect (RAE. The RAE has been documented to be present among senior top-level players. Even so, few studies have investigated the effect among youth players at the senior level. The aim of this study is to examine RAE among U17-U20 players in the Norwegian premier league Tippeligaen in the 2009-2012 seasons. Participants were 315 male players born in 1990-1996. The results showed that 68% of the players were born in the two first quartiles of the year. The effect was even increasing in the four-year period. As we could expect based on the literature, the oldest players are given more playing time. However, the connection between playing time and RAE was inconsistent. Norwegian top-level soccer seems to be affected by the RAE when selecting their players. These players are not however guaranteed playing time because of the RAE.

Talent identification and early development of elite water-polo players: a 2-year follow-up study.

Science.gov (United States)

Falk, Bareket; Lidor, Ronnie; Lander, Yael; Lang, Benny

2004-04-01

The processes of talent detection and early development are critical in any sport programme. However, not much is known about the appropriate strategies to be implemented during these processes, and little scientific inquiry has been conducted in this area. The aim of this study was to identify variables of swimming, ball handling and physical ability, as well as game intelligence, which could assist in the selection process of young water-polo players. Twenty-four players aged 14-15 years underwent a battery of tests three times during a 2-year period, before selection to the junior national team. The tests included: freestyle swim for 50, 100, 200 and 400 m, 100-m breast-stroke, 100-m 'butterfly' (with breast-stroke leg motion), 50-m dribbling, throwing at the goal, throw for distance in the water, vertical 'jump' from the water, and evaluation of game intelligence by two coaches. A comparison of those players eventually selected to the team and those not selected demonstrated that, 2 years before selection, selected players were already superior on most of the swim tasks (with the exception of breast-stroke and 50-m freestyle), as well as dribbling and game intelligence. This superiority was maintained throughout the 2 years. Two-way tabulation revealed that, based on baseline scores, the prediction for 67% of the players was in agreement with the final selection to the junior national team. We recommend that fewer swim events be used in the process of selecting young water-polo players, and that greater emphasis should be placed on evaluation of game intelligence.

Level of Transformation of Motor Skills in Female Volleyball Players Influenced by Training Operators

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Ifet Mahmutović

2016-06-01

Full Text Available The aim of this paper is to determine the level of improvement of motor skills of female volleyball players influenced by kinesiology operators in a period of 6 months. Research was conducted on sample subject of 130 female volleyball players aged from 13±0.6 (mean±SD. Sample variables are divided in two groups: 9 variables of assessment of basic motor skills and 5 variables of assessment of situational motor skills. Analysing difference of arithmetic means between of initial and final measures of treated variables it is determined that there is statistically significant difference on the level Sig=0.001, except for variables of Jelka test which determinates speed duration of female volleyball players. Analysis of quantity changes of basic motor skills, shows that the most important projections on selected discriminative function of basic motor skills have the following variables: body lifting in 30 sec; dynamometry of a hand, hand tapping; pull-up; throwing a 1 kg ball from lying position; side defence movement; push-up on bars and situational motor skill are the variables: precision of tactic serving; consecutive bumping; wall-spikes. Comprehensive development of female volleyball players and diversity in the level of volleyball specialization of the development will depend on systematic work on treated motor skills. This program appeared to be efficient. However, it is necessary to gradually increase the demands for the female volleyball players and to put the accent on performance of acquired situational motor skills in future work.

Decomposition of Multi-player Games

Science.gov (United States)

Zhao, Dengji; Schiffel, Stephan; Thielscher, Michael

Research in General Game Playing aims at building systems that learn to play unknown games without human intervention. We contribute to this endeavour by generalising the established technique of decomposition from AI Planning to multi-player games. To this end, we present a method for the automatic decomposition of previously unknown games into independent subgames, and we show how a general game player can exploit a successful decomposition for game tree search.

Dynamic balance ability in young elite soccer players: implication of isometric strength.

Science.gov (United States)

Chtara, Moktar; Rouissi, Mehdi; Bragazzi, Nicola L; Owen, Adam L; Haddad, Monoem; Chamari, Karim

2018-04-01

Soccer requires maintaining unilateral balance when executing movement with the contralateral leg. Despite the fact that balance requires standing with maintaining isometric posture with the support leg, currently there is a lack of studies regarding the implication of isometric strength on dynamic balance's performance among young soccer players. Therefore, the aim of this study was to examine the relationship between the Y-Balance Test and 12 lower limbs isometric strength tests. Twenty-six right footed soccer players (mean±SD, age=16.2±1.6 years, height=175±4.2 cm, body mass=68.8±6.1 kg) performed a dynamic balance test (star excursion balance-test with dominant- (DL) and nondominant-legs (NDL). Furthermore, maximal isometric contraction tests of 12 lower limb muscle groups were assessed in DL and NDL. Correlations analysis reported a significant positive relationship between some of isometric strength tests (with DL and NDL) and the Y-Balance Test. Furthermore, stepwise multiple regression analysis showed that maximal isometric strength explained between 21.9% and 49.4% of the variance of the Y-Balance Test. Moreover, maximal isometric strength was dependent upon the reaching angle of the Y-Balance Test and the leg used to support body weight. This study showed a significant implication of maximal isometric strength of the lower limb and the Y-Balance Test. Moreover, the present investigation suggests the implementation of specific lower limb strengthening exercises depending on players' deficit in each reaching direction and leg. This result suggests that further studies should experiment if increasing lower limbs isometric strength could improve dynamic balance ability among young soccer players.

Validation of the FAST skating protocol to predict aerobic power in ice hockey players.

Science.gov (United States)

Petrella, Nicholas J; Montelpare, William J; Nystrom, Murray; Plyley, Michael; Faught, Brent E

2007-08-01

Few studies have reported a sport-specific protocol to measure the aerobic power of ice hockey players using a predictive process. The purpose of our study was to validate an ice hockey aerobic field test on players of varying ages, abilities, and levels. The Faught Aerobic Skating Test (FAST) uses an on-ice continuous skating protocol on a course measuring 160 feet (48.8 m) using a CD to pace the skater with a beep signal to cross the starting line at each end of the course. The FAST incorporates the principle of increasing workload at measured time intervals during a continuous skating exercise. Step-wise multiple regression modelling was used to determine the estimate of aerobic power. Participants completed a maximal aerobic power test using a modified Bruce incremental treadmill protocol, as well as the on-ice FAST. Normative data were collected on 406 ice hockey players (291 males, 115 females) ranging in age from 9 to 25 y. A regression to predict maximum aerobic power was developed using body mass (kg), height (m), age (y), and maximum completed lengths of the FAST as the significant predictors of skating aerobic power (adjusted R2 = 0.387, SEE = 7.25 mL.kg-1.min-1, p < 0.0001). These results support the application of the FAST in estimating aerobic power among male and female competitive ice hockey players between the ages of 9 and 25 years.

Mental Toughness Attributes of Junior Level Medalist Badminton Players

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Varghese C. Antony

2016-10-01

Full Text Available The study aims to compare the mental toughness attributes between medalist and non-medalist badminton players and between male and female players. Participants were 15 male and 15 female badminton players aged between 13-19 years (M= 15.71, SD=2.82. Mental toughness questionnaire of Tiwari and Sharma was administered and the data were analyzed by using descriptive statistics and t-test. Medalist players have exhibited higher mean values on self-confidence, attention control, motivation and goal setting attributes. Overall mental toughness of medalists was higher 180.80±17.15 than non-medalists 170.25±20.10. Comparison analysis showed significant difference between medalists and non-medalists on mental toughness attributes: Self-confidence (SCO: p=0.001<0.05, medalists scored (M±SD=31.33±2.10 higher than non-medalists; motivation (MOT: p=0.006<0.05, medalist scored higher (M±SD=33.50±4.07; goal setting (GSE: p=0.044<0.05, medalists scored significantly higher (M±SD=33.55±4.11 than non-medalists. Other attributes did not show any significant difference between medalist and non-medalist players. When compared with gender, no significant difference was observed on mental toughness attributes except attention control (ATNCON: p=0.044<0.05, female players scored (M±SD=38.97±3.08 higher than male players. The findings confirm that mental toughness is a desired attribute which differentiates a medalist and non-medalist player. Connaughton et al., (2007 stated that elite competitive athletes possess better mental toughness. Medalist players displayed better self-confidence than the non-medalists as supported by Kuan and Roy (2007, Loehr (1986. Motivation helps players to achieve their best and enhance mental toughness (Connaughton et al., 2008; Mohammad et al., 2009. Goal setting determines successful performance Weinberg and Weigand (1993, Weinberg (2003. It was concluded that medalist badminton players showed better mental toughness

A Survey on Common Injuries in Recreational Badminton Players

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A Muttalib

2009-11-01

Full Text Available The aim of this descriptive study is to determine the incidence of injuries among recreational badminton players. We evaluated 86 recreational badminton players in the city of Malacca; 35 were excluded for fitting the exclusion criteria. The average recreational badminton player was 36.13 years old and had been playing badminton for the past 17.84 years at a frequency of 2.11 times per week. 39.21% of the recreational badminton players complained of recent injuries in relation to playing badminton. Our data showed that the most common injury sustained by recreational badminton players was pain and stiffness at the shoulder joint. None of the injuries sustained by the players in our data were serious enough to warrant any form of surgical intervention. We conclude that badminton is a sport of relatively low risk and that the majority of related injuries were chronic overuse injuries.

Incidence of tinnitus in mp3 player users.

Science.gov (United States)

Figueiredo, Ricardo Rodrigues; Azevedo, Andreia Aparecida de; Oliveira, Patrícia Mello de; Amorim, Sandro Pereira Vasconcellos; Rios, Artur Guedes; Baptista, Vanderlei

2011-06-01

Exposure to loud noise is one of the main causes of tinnitus. To analyze the incidence of tinnitus in mp3 player users and non-users. One hundred subjects aged from 15 to 30 years were enrolled, 54 of them were regular mp3 player users and 46 were not. Patients with continuous tinnitus for at least 6 months completed the Tinnitus Handicap Inventory (THI) and were tested with high frequency audiometry and transient-evoked otoacoustic emissions (TAOE). A cross-sectional cohort study. The incidence of tinnitus in non-users was about 8 %; in mp3 player users it was about 28 %, a statistically significant difference. Hearing thresholds at 8 kHz were significantly higher in tinnitus patients that used mp3 portable players.TAOE were reduced at 2 kHz in the users group. No statistically significant difference was found in the THI scores between the two groups. Tinnitus was more frequent in teenagers and young adults who regularly listen to mp3 music in players. Moreover, the incidence of tinnitus among mp3 player users was associated with higher hearing thresholds at 8 kHz and lower TOAE at 2 kHz.

Female Chess Players Outperform Expectations When Playing Men.

Science.gov (United States)

Stafford, Tom

2018-03-01

Stereotype threat has been offered as a potential explanation of differential performance between men and women in some cognitive domains. Questions remain about the reliability and generality of the phenomenon. Previous studies have found that stereotype threat is activated in female chess players when they are matched against male players. I used data from over 5.5 million games of international tournament chess and found no evidence of a stereotype-threat effect. In fact, female players outperform expectations when playing men. Further analysis showed no influence of degree of challenge, player age, nor prevalence of female role models in national chess leagues on differences in performance when women play men versus when they play women. Though this analysis contradicts one specific mechanism of influence of gender stereotypes, the persistent differences between male and female players suggest that systematic factors do exist and remain to be uncovered.

Physiological Responses of Water-Polo Players Under Different Tactical Strategie

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Petros G. Botonis, Argyris G. Toubekis

2015-01-01

Full Text Available The aim of this study was to investigate the effect of defense tactical strategy on physiological responses characterizing playing intensity in water-polo game. In the first part of the study, fourteen players were assigned to defending (n = 7 and offending (n = 7 groups and participated in nine 4-min plays applying three different defending systems: press, static-zone and zone-press, in front of the defense court of one goalpost. In the second part, 18 players participated in nine different real full court water-polo games consisting of 3X15min of live-time playing periods. Both in defense court plays and real games, the three defense systems were played in a counterbalanced order and heart rate (HR was continuously recorded. Additionally, in defense court plays, blood lactate concentration (La was measured at the end of each 4-min period. Mean HR within defense court plays was higher in press (153 ± 10 beats.min-1 than in static-zone (140 ± 11 beats.min-1 and zone-press (143 ± 16 beats.min-1, p 0.05. Defenders and offenders showed similar HR and La responses across the tactical modes. In conclusion, defense tactical strategies affect physiological responses within a part of the game but do not affect the overall playing intensity of a real water-polo game. Tactical strategies similarly affect offenders and defenders.

Motivational profiles in table tennis players: Relations with performance anxiety and subjective vitality.

Science.gov (United States)

Chu, Tsz Lun Alan; Zhang, Tao; Hung, Tsung-Min

2018-06-27

Research has suggested the need to use a person-centred approach to examine multidimensionality of motivation. Guided by self-determination theory (Deci & Ryan, 1985), the primary aim of the present study was to examine the motivational profiles in table tennis players and their composition by gender, country, training status, and competition levels (from recreational to international). The secondary aim was to examine the differences in performance anxiety and subjective vitality across the motivational profiles. Participants were 281 table tennis players from multiple countries, mostly the U.S. and China. Hierarchical and nonhierarchical cluster analyses were conducted and showed three motivational profiles with distinct quantity and quality: "low", "controlled", and "self-determined". Chi-square tests of independence demonstrated significant differences in their cluster membership by country, formal training with a coach, and competition levels, but not gender. MANCOVA results indicated differences in performance anxiety and subjective vitality across the motivational profiles, in which the controlled profile had the greatest anxiety symptoms. These differences are attributed to the quality over quantity of motivation, which have meaningful implications for table tennis coaches and sport psychology consultants to diagnose and intervene with players in order to reduce their performance anxiety and improve their well-being.

Perceptions of football players regarding injury risk factors and prevention strategies.

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Astrid Zech

Full Text Available Current approaches regarding injury prevention focus on the transfer of evidence into daily practice. One promising approach is to influence attitudes and beliefs of players. The objective of this study was to record player's perceptions on injury prevention. A survey was performed among players of one German high-level football (soccer club. 139 professional and youth players between age 13 and 35 years completed a standardized questionnaire (response rate = 98%. It included categories with (1 history of lower extremity injuries, (2 perceptions regarding risk factors and (3 regularly used prevention strategies. The majority of players (84.2% had a previous injury. 47.5% of respondents believe that contact with other players is a risk factor, followed by fatigue (38.1% and environmental factors (25.9%. The relevance of previous injuries as a risk factor is differently perceived between injured (25% and uninjured players (0.0%. Nearly all players (91.5% perform stretching to prevent injuries, followed by neuromuscular warm up exercises (54.0%. Taping is used by 40.2% of previously injured players and 13.6% of players without a history of injuries. In conclusion, the perception of risk factors and performed preventive strategies are inconsistent with scientific evidence. Future transfer strategies should incorporate the players beliefs and attitudes.

Performance following a first professional concussion among National Basketball Association players.

Science.gov (United States)

Yengo-Kahn, Aaron M; Zuckerman, Scott L; Stotts, Jeff; Zalneraitis, Brian H; Gardner, Ryan M; Kerr, Zachary Y; Solomon, Gary S

2016-09-01

Basketball is a physical game played on a hardwood floor among high-jumping athletes at risk for injury. It is currently unknown how sport-related concussion (SRC) affects player performance after injury among professional basketball players. The objective of this study was to explore the impact of SRC on basketball performance among National Basketball Association (NBA) players. A retrospective, archival cohort study was performed that compared NBA player performance following concussion to pre-concussive performance. A comprehensive NBA injury database, compiled from publically available sources, was queried for NBA players who suffered concussion from 2005-06 to 2014-15 (10 seasons). Intra-and inter-player analyses were performed against a matched control group of players who missed playing time for personal reasons. Following application of inclusion/exclusion criteria and a matching process, 51 concussed players and 51 control players were included in analysis. There were no statistically significant decrements in baseline to post-concussion performance metrics in intra-player or player vs. controls after 5 return games. Our findings suggest that at the NBA level, an athlete's performance in the initial 5 games following injury does not suffer from the after-effects of concussive injury. These results may be useful in counseling professional athletes following a concussion.

Big Data for Business Ecosystem Players

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Perko Igor

2016-06-01

Full Text Available In the provided research, some of the Big Data most prospective usage domains connect with distinguished player groups found in the business ecosystem. Literature analysis is used to identify the state of the art of Big Data related research in the major domains of its use-namely, individual marketing, health treatment, work opportunities, financial services, and security enforcement. System theory was used to identify business ecosystem major player types disrupted by Big Data: individuals, small and mid-sized enterprises, large organizations, information providers, and regulators. Relationships between the domains and players were explained through new Big Data opportunities and threats and by players’ responsive strategies. System dynamics was used to visualize relationships in the provided model.

Test-retest reliability and agreement of the SPI-Questionnaire to detect symptoms of digital ischemia in elite volleyball players.

Science.gov (United States)

van de Pol, Daan; Zacharian, Tigran; Maas, Mario; Kuijer, P Paul F M

2017-06-01

The Shoulder posterior circumflex humeral artery Pathology and digital Ischemia - questionnaire (SPI-Q) has been developed to enable periodic surveillance of elite volleyball players, who are at risk for digital ischemia. Prior to implementation, assessing reliability is mandatory. Therefore, the test-retest reliability and agreement of the SPI-Q were evaluated among the population at risk. A questionnaire survey was performed with a 2-week interval among 65 elite male volleyball players assessing symptoms of cold, pale and blue digits in the dominant hand during or after practice or competition using a 4-point Likert scale (never, sometimes, often and always). Kappa (κ) and percentage of agreement (POA) were calculated for individual symptoms, and to distinguish symptomatic and asymptomatic players. For the individual symptoms, κ ranged from "poor" (0.25) to "good" (0.63), and POA ranged from "moderate" (78%) to "good" (97%). To classify symptomatic players, the SPI-Q showed "good" reliability (κ = 0.83; 95%CI 0.69-0.97) and "good" agreement (POA = 92%). The current study has proven the SPI-Q to be reliable for detecting elite male indoor volleyball players with symptoms of digital ischemia.

EVALUATING AUSTRALIAN FOOTBALL LEAGUE PLAYER CONTRIBUTIONS USING INTERACTIVE NETWORK SIMULATION

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Jonathan Sargent

2013-03-01

Full Text Available This paper focuses on the contribution of Australian Football League (AFL players to their team's on-field network by simulating player interactions within a chosen team list and estimating the net effect on final score margin. A Visual Basic computer program was written, firstly, to isolate the effective interactions between players from a particular team in all 2011 season matches and, secondly, to generate a symmetric interaction matrix for each match. Negative binomial distributions were fitted to each player pairing in the Geelong Football Club for the 2011 season, enabling an interactive match simulation model given the 22 chosen players. Dynamic player ratings were calculated from the simulated network using eigenvector centrality, a method that recognises and rewards interactions with more prominent players in the team network. The centrality ratings were recorded after every network simulation and then applied in final score margin predictions so that each player's match contribution-and, hence, an optimal team-could be estimated. The paper ultimately demonstrates that the presence of highly rated players, such as Geelong's Jimmy Bartel, provides the most utility within a simulated team network. It is anticipated that these findings will facilitate optimal AFL team selection and player substitutions, which are key areas of interest to coaches. Network simulations are also attractive for use within betting markets, specifically to provide information on the likelihood of a chosen AFL team list "covering the line".

Coping strategies of soccer players | Plaatjie | South African Journal ...

African Journals Online (AJOL)

This study focused on coping strategies used by soccer (football) players by exploring the role of the environment, ethnicity and culture in players' response to stressful situations. An interpretive-qualitative research methodology was applied with a sample of 33 professional soccer players. The subjects were representative ...

Time-motion analysis and physiological responses of small-sided team handball games in youth male players: Influence of player number

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Jan Bělka

2016-12-01

Full Text Available Background: Effective training depends on knowledge of a sport's requirements. Small-sided games (SSG are a spontaneous form of specific training, where exercise intensity can be manipulated mainly by modifying external factors. In SSG the players develop technical and tactical skills in the similar situations, such as during a match and can also develop their physical skills. Objective: The purpose of this study was to examine the distance covered and physiological response of altering the number of youth male players during small-sided team handball games with modified rules. Methods: The subjects consisted of 12 male youth team handball players (age 16.6 ± 0.5 years playing the first league for youth male players in the Czech Republic. The study was conducted during six weeks (one training session per week. Only three SSG were played in each training session. The SSG were played, first with five players on each side (5 vs. 5, then four (4 vs. 4, then three (3 vs. 3. Each game was four minutes long, followed by three minutes of passive rest. Results: The players covered the greatest distance (520.6 ± 61.4 m in the SSG 3 vs. 3. There was a difference in the distance covered between players in the 3 vs. 3 SSG and the other SSG (4 vs. 4 and 5 vs. 5 (p = .041 and p = .043, respectively. In individual speed zones a difference occurred only in the first and third speed zone and always among the 3 vs. 3 and 5 vs. 5 SSG (p = .034 and p = .044, respectively. The highest average intensity (87.9 ± 4.8% HRmax was in 3 vs. 3 SSG. Loading of the players in 5 vs. 5 was lower compared to 4 vs. 4 (p = .035 and 3 vs. 3 (p < .001. There was a difference in zone load intensity (> 90% HRmax between 3 vs. 3 and 5 vs. 5 SSG (p = .041. Conclusions: These results indicate that changing the number of players during SSG with modified rules in youth team handball may be used to manipulate the physiological response

Efficiently detecting outlying behavior in video-game players

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Young Bin Kim

2015-12-01

Full Text Available In this paper, we propose a method for automatically detecting the times during which game players exhibit specific behavior, such as when players commonly show excitement, concentration, immersion, and surprise. The proposed method detects such outlying behavior based on the game players’ characteristics. These characteristics are captured non-invasively in a general game environment. In this paper, cameras were used to analyze observed data such as facial expressions and player movements. Moreover, multimodal data from the game players (i.e., data regarding adjustments to the volume and the use of the keyboard and mouse was used to analyze high-dimensional game-player data. A support vector machine was used to efficiently detect outlying behaviors. We verified the effectiveness of the proposed method using games from several genres. The recall rate of the outlying behavior pre-identified by industry experts was approximately 70%. The proposed method can also be used for feedback analysis of various interactive content provided in PC environments.

Upper extremity sensorimotor control among collegiate football players.

Science.gov (United States)

Laudner, Kevin G

2012-03-01

Injuries stemming from shoulder instability are very common among athletes participating in contact sports, such as football. Previous research has shown that increased laxity negatively affects the function of the sensorimotor system potentially leading to a pathological cycle of shoulder dysfunction. Currently, there are no data detailing such effects among football players. Therefore, the purpose of this study was to examine the differences in upper extremity sensorimotor control among football players compared with that of a control group. Forty-five collegiate football players and 70 male control subjects with no previous experience in contact sports participated. All the subjects had no recent history of upper extremity injury. Each subject performed three 30-second upper extremity balance trials on each arm. The balance trials were conducted in a single-arm push-up position with the test arm in the center of a force platform and the subjects' feet on a labile device. The trials were averaged, and the differences in radial area deviation between groups were analyzed using separate 1-way analyses of variance (p football players showed significantly more radial area deviation of the dominant (0.41 ± 1.23 cm2, p = 0.02) and nondominant arms (0.47 ± 1.63 cm2, p = 0.03) when compared with the control group. These results suggest that football players may have decreased sensorimotor control of the upper extremity compared with individuals with no contact sport experience. The decreased upper extremity sensorimotor control among the football players may be because of the frequent impacts accumulated during football participation. Football players may benefit from exercises that target the sensorimotor system. These findings may also be beneficial in the evaluation and treatment of various upper extremity injuries among football players.

Finite stage asymmetric repeated games: Both players' viewpoints

KAUST Repository

Li, Lichun; Feron, Eric; Shamma, Jeff S.

2017-01-01

the opponents' corresponding best responses depends only on the informed player's history action sequences. Moreover, efficient LP formulations to compute both player's security strategies are provided.

Badminton injuries in youth competitive players.

Science.gov (United States)

Goh, S L; Mokhtar, A H; Mohamad Ali, M R

2013-02-01

The aim of the study was to examine sports injury pattern and establish cost of injuries in relation to training of 58 competitive badminton players in a Malaysian National Sports School. This one-year prospective observational study recruited all the 13-16 year old students after obtaining informed consent from their appointed guardian. All participants were requested to report any injuries, which were pain or disabilities that occur within the study period (September 1, 2008 to August 31, 2009) either during training or competition. Injured students were to seek treatment from the researcher(s) who made weekly visits and they were then followed up accordingly until they return to full training. Details and progress of the injuries were documented during each visit. Sixty-three injuries were recorded. Soft tissue sprains/strains were the commonest injury (64%). About one third of the injuries occurred in the lower limb especially the knees and was followed by back injuries; 38% of the injuries did not require training modification, half of these injuries resumed training within one week. Upon full training, half of them were still symptomatic. Injury risk was 57%; injury rate was 0.9 injuries/ player/1000 training hours. Badminton injuries mostly involved the lower limb and almost all overuse injuries occurred in the lower limb. However, badminton injuries as a whole were predominantly sprains and strains, and not overuse in nature as widely believed.

I Fought the Law: Transgressive Play and The Implied Player

DEFF Research Database (Denmark)

Aarseth, Espen J.

2007-01-01

This paper is an attempt to understand Game Studies through the contested notion of the “player” both inside and outside “the game object” – that is the object that game users perceive and respond to when they play. Building on Hans-Georg Gadamer’s notion of games as a subject that “masters...... the players”, the paper will go beyond the traditional split between the social sciences’ real players and the aesthetics/humanities critical author-as-player, and present a theory of the player and player studies that incorporates the complex tensions between the real, historical player and the game’s human...... components. Since games are both aesthetic and social phenomena, a theory of the player must combine both social and aesthetic perspectives to be successful. The tension between the humanities and the social sciences over who controls the idea of the player can be found mirrored also in the struggle between...

How should "hot" players in basketball be defended? The use of fast-and-frugal heuristics by basketball coaches and players in response to streakiness.

Science.gov (United States)

Csapo, Peter; Avugos, Simcha; Raab, Markus; Bar-Eli, Michael

2015-01-01

Previous research has shown that changes in shot difficulty may have rendered the hot-hand effect in basketball unobservable and are potentially a result of defensive adjustments. However, it has not been directly analysed whether strategic changes indeed take place in response to streakiness and whether they are effective with respect to winning games. The current work consists of an experimental study with 18 professional coaches and 20 players based on video sequences from National Basketball Association games, where the shown player displayed a streaky performance in half of the sequences. While coaches were asked to devise a defensive strategy after each viewed sequence, players had to assume the role of the shown player and decide whether to shoot or pass the ball. We find that coaches tended to increase the defensive pressure significantly more often on presumably hot players and thus make use of the hot-hand heuristic. Meanwhile, players chose to shoot more frequently in low-pressure and streaky situations but selected "pass" regardless of the previous performance when they faced increased defensive pressure. Assuming that a streaky player's performance is indeed elevated during hot phases, hot-hand behaviour can be considered adaptive in certain situations as it led hot players to pass instead of shoot.

The Evolving Treatment Patterns of NCAA Division I Football Players by Orthopaedic Team Physicians Over the Past Decade, 2008-2016.

Science.gov (United States)

Carver, Trevor J; Schrock, John B; Kraeutler, Matthew J; McCarty, Eric C

Previous studies have analyzed the treatment patterns used to manage injuries in National Collegiate Athletic Association (NCAA) Division I football players. Treatment patterns used to manage injuries in NCAA Division I football players will have changed over the study period. Descriptive epidemiology study. Level 5. The head orthopaedic team physicians for all 128 NCAA Division I football teams were asked to complete a survey containing questions regarding experience as team physician, medical coverage of the team, reimbursement issues, and treatment preferences for some of the most common injuries occurring in football players. Responses from the current survey were compared with responses from the same survey sent to NCAA Division I team physicians in 2008. Responses were received from 111 (111/119, 93%) NCAA Division I orthopaedic team physicians in 2008 and 115 (115/128, 90%) orthopaedic team physicians between April 2016 and April 2017. The proportion of team physicians who prefer a patellar tendon autograft for primary anterior cruciate ligament reconstruction (ACLR) increased from 67% in 2008 to 83% in 2016 ( P football players over the study period. In particular, physicians have changed their preferred techniques for ACLR, anterior shoulder stabilization, and PCL reconstruction. Physicians have also become more conservative with pregame Toradol injections. These opinions may help guide treatment decisions and lead to better care of all athletes.

Soccer player recognition by pixel classification in a hybrid color space

Science.gov (United States)

Vandenbroucke, Nicolas; Macaire, Ludovic; Postaire, Jack-Gerard

1997-08-01

Soccer is a very popular sport all over the world, Coaches and sport commentators need accurate information about soccer games, especially about the players behavior. These information can be gathered by inspectors who watch the soccer match and report manually the actions of the players involved in the principal phases of the game. Generally, these inspectors focus their attention on the few players standing near the ball and don't report about the motion of all the other players. So it seems desirable to design a system which automatically tracks all the players in real- time. That's why we propose to automatically track each player through the successive color images of the sequences acquired by a fixed color camera. Each player which is present in the image, is modelized by an active contour model or snake. When, during the soccer match, a player is hidden by another, the snakes which track these two players merge. So, it becomes impossible to track the players, except if the snakes are interactively re-initialized. Fortunately, in most cases, the two players don't belong to the same team. That is why we present an algorithm which recognizes the teams of the players by pixels representing the soccer ground which must be withdrawn before considering the players themselves. To eliminate these pixels, the color characteristics of the ground are determined interactively. In a second step, dealing with windows containing only one player of one team, the color features which yield the best discrimination between the two teams are selected. Thanks to these color features, the pixels associated to the players of the two teams form two separated clusters into a color space. In fact, there are many color representation systems and it's interesting to evaluate the features which provide the best separation between the two classes of pixels according to the players soccer suit. Finally, the classification process for image segmentation is based on the three most

The effect of assisted jumping on vertical jump height in high-performance volleyball players.

Science.gov (United States)

Sheppard, Jeremy M; Dingley, Andrew A; Janssen, Ina; Spratford, Wayne; Chapman, Dale W; Newton, Robert U

2011-01-01

Assisted jumping may be useful in training higher concentric movement speed in jumping, thereby potentially increasing the jumping abilities of athletes. The purpose of this study was to evaluate the effects of assisted jump training on counter-movement vertical jump (CMVJ) and spike jump (SPJ) ability in a group of elite male volleyball players. Seven junior national team volleyball players (18.0±1.0 yrs, 200.4±6.7 cm, and 84.0±7.2 kg) participated in this within-subjects cross-over counter-balanced training study. Assisted training involved 3 sessions per week of CMVJ training with 10 kg of assistance, applied through use of a bungee system, whilst normal jump training involved equated volume of unassisted counter-movement vertical jumps. Training periods were 5 weeks duration, with a 3-week wash-out separating them. Prior to and at the conclusion of each training period jump testing for CMVJ and SPJ height was conducted. Assisted jump training resulted in gains of 2.7±0.7 cm (pSports Medicine Australia. All rights reserved.

Effects of Unloaded vs. Loaded Plyometrics on Speed and Power Performance of Elite Young Soccer Players

Directory of Open Access Journals (Sweden)

Ronaldo Kobal

2017-09-01

Full Text Available The purpose of this study was to investigate the effects of loaded and unloaded plyometric training strategies on speed and power performance of elite young soccer players. Twenty-three under-17 male soccer players (age: 15.9 ± 1.2 years, height: 178.3 ± 8.1 cm, body-mass (BM: 68.1 ± 9.3 kg from the same club took part in this study. The athletes were pair-matched in two training groups: loaded vertical and horizontal jumps using an haltere type handheld with a load of 8% of the athletes' body mass (LJ; n = 12 and unloaded vertical and horizontal plyometrics (UJ; n = 11. Sprinting speeds at 5-, 10-, and 20-m, mean propulsive power (MPP relative to the players' BM in the jump squat exercise, and performance in the squat jump (SJ and countermovement jump (CMJ were assessed pre- and post-training period. During the experimental period, soccer players performed 12 plyometric training sessions across a 6-week preseason period. Magnitude based inferences and standardized differences were used for statistical analysis. A very likely increase in the vertical jumps was observed for the LJ group (99/01/00 and 98/02/00 for SJ and CMJ, respectively. In the UJ group a likely increase was observed for both vertical jumps (83/16/01 and 90/10/00, for SJ and CMJ, respectively. An almost certainly decrease in the sprinting velocities along the 20-m course were found in the LJ group (00/00/100 for all split distances tested. Meanwhile, in the UJ likely to very likely decreases were observed for all sprinting velocities tested (03/18/79, 01/13/86, and 00/04/96, for velocities in 5-, 10-, and 20-m, respectively. No meaningful differences were observed for the MPP in either training group (11/85/04 and 37/55/08 for LJ and UJ, respectively. In summary, under-17 professional soccer players increased jumping ability after a 6-week preseason training program, using loaded or unloaded jumps. Despite these positive adaptations, both plyometric strategies failed to

[Muscular trunk stability in professional and amateur volleyball players].

Science.gov (United States)

Miltner, O; Siebert, C; Tschaepe, R; Maus, U; Kieffer, O

2010-03-01

The aim of this study was to analyse the efficiency of muscular activity in the trunk stabilisation of professional volleyball players compared to a group of amateur hobby players. The results were compared amongst the groups as well as with a reference group consisting of asymptomatic individuals. The question to be answered was whether or not professional volleyball players possess a characteristic strength profile in their trunk musculature and if differences exist with regard to the individuals' competitive playing level. In this comparative study 12 professional volleyball players (German Bundesliga) and 18 non-professional volleyball players were analysed with regard to their isometric strength profile in all three planes. The reference group was provided by the Proxomed company, which had previously analysed healthy untrained individuals (n = 1045) of various age groups. A sports-specific profile for the musculature of volleyball players revealed a significant reduction in the flexion and rotation strength as well as a well-developed lateral flexion strength (highly significant when compared to the reference group). With reference to the level played, better strength values in flexion and lateral flexion were found among the professional athletes. Professional volleyball players present with a characteristic trunk musculature strength profile. A detailed analysis of the muscle strength of the spine as part of a sports medicine work-up could prove helpful in preventing injuries and overuse problems in professional and hobby volleyball players.

Method for the measurement of media player use

Science.gov (United States)

Webb, Graham

There has been ongoing concern that prolonged use of MP3 players can lead to noise-induced hearing loss. Acoustic exposure is the product of intensity and duration of exposure. Previous work has utilised measurements of maximum headphone output and output during listening tests to determine acoustic intensity; whilst duration of use is currently assessed with questionnaires and interviews. The subjective nature of these latter methods has led to a wide variation in figures for device use, restricting the scope of media player risk assessment. A need was therefore identified for an improved method of acquiring data of users' listening habits. This need was addressed with the design of a new data-logging device that discretely measures voltage output from the media player, whilst in use. A calibration method is proposed to implement the headphone transfer function into the data-logger, to relate output voltage to exposed pressure. It is proposed that the headphone transfer function is measured using an acoustic manikin, representative of the population of interest. The real ear measurement is put forward as an appropriate tool for validating results gained using this approach. A data-logger was designed and a proof of concept has been demonstrated in a software program written for this purpose. The proposed method has the advantages that an objective measurement can be made of the user's natural listening habits, over a long period of time, with a resolution comparable to personal acoustic dosimetry. A number of practical steps are required to further this work before data can be collected. A software graphic equaliser was used to implement the transfer function, but the chosen filter topology gave an unsatisfactory response, an investigation is required for further work. The device requires migration to hardware and the experimental calibration and validation of the system are also required. The worldwide population of MP3 player users is in the region of hundreds

Bone Mineral Density of Adolescent Female Tennis Players and Nontennis Players

Directory of Open Access Journals (Sweden)

Kevser Ermin

2012-01-01

Full Text Available The purpose of this study was to determine differences in bone mineral density (BMD among adolescent female tennis players (TPs and nontennis players (NTPs and to assess body composition as a predictor variable of BMD. Nineteen female TPs and 19 female NTPs, ages 14 to 18 years, participated in this study. Lumbar spine, total hip, femoral neck, forearms BMD, and body composition were assessed using dual-energy X-ray absorptiometry (DXA. Lumbar spine and total hip BMD measurements for TP were greater than NTP. However, these differences were not statistically significant (=0.37 and 0.12, resp.. TP had significantly greater femoral neck BMD than NTPs (=0.02. This difference might play an important role in preventing osteoporosis and decreasing the risk of fractures at the hip later in life.

Effect of Concussion on Performance of National Football League Players.

Science.gov (United States)

Reams, Nicole; Hayward, Rodney A; Kutcher, Jeffrey S; Burke, James F

2017-09-01

Lingering neurologic injury after concussion may expose athletes to increased risk if return to play is premature. The authors explored whether on-field performance after concussion is a marker of lingering neurologic injury. Retrospective cohort study on 1882 skill-position players who played in the National Football League (NFL) during 2007-2010. Players with concussion based on the weekly injury report were compared with players with other head and neck injuries (controls) on measures of on-field performance using Football Outsiders' calculation of defense-adjusted yards above replacement (DYAR), a measure of a player's contribution controlling for game context. Changes in performance, relative to a player's baseline level of performance, were estimated before and after injury using fixed-effects models. The study included 140 concussed players and 57 controls. Players with concussion performed no better or worse than their baseline on return to play. However, a decline in DYAR relative to their prior performance was noted 2 wk and 1 wk before appearing on the injury report. Concussed players performed slightly better than controls in situations where they returned to play the same week as appearing on the injury report. On return, concussed NFL players performed at their baseline level of performance, suggesting that players have recovered from concussion. Decline in performance noted 2 wk and 1 wk before appearing on the injury report may suggest that concussion diagnosis was delayed or that concussion can be a multihit phenomenon. Athletic performance may be a novel tool for assessing concussion injury and recovery.

The influence of game duration and playing position on intensity of exercise during match-play in elite water polo players.

Science.gov (United States)

Platanou, T; Geladas, N

2006-11-01

In this study, we assessed exercise intensity in 20 water polo games of different duration. The hypothesis that right wing players perform at a higher intensity than back and forward central players was also tested. Thirty water polo players, equally split between three field positions, participated in the study. Initially, their performance-related physiological capabilities were evaluated. Subsequently, during water polo games of short (4 x 7-min periods) or long duration (4 x 9-min periods), heart rate was monitored continuously and blood lactate concentration was measured at the end of each period. Activity patterns were also recorded using a video camera. Mean heart rate over the entire game was 156 +/- 18 beats x min(-1). Overall exercise intensity fluctuated around a value corresponding to the lactate threshold (4.03 +/- 0.96 mmol x l(-1), 86 +/- 5% of peak heart rate) and decreased (P game time (4.22 +/- 1.8 and 3.47 +/- 1.9 mmol x l(-1) in the second and fourth quarter, respectively). During the last 6 min, heart rate was higher (P games of short duration (156 +/- 3 beats x min(-1)) than in games of long duration (152 +/- 8 beats x min(-1)). Video analysis showed that the percentage of time spent in low-intensity activities (i.e. "out of game") was lower (23 vs. 26%), whereas that in high-intensity activities (i.e. "sprinting crawl") was higher (21 vs. 19%), in games of short compared with long duration. No difference was observed among players of various field positions in any of the variables examined. Thus during match-play, games of long duration produced significantly lower heart rate responses than games of short duration, and the physiological response exhibited by the players was not affected by field position. The water polo authorities should consider these results before changing game duration and coaches should prepare their athletes accordingly.

Relative age effect and its relationship with morphological characteristics and performance in young soccer players

Directory of Open Access Journals (Sweden)

Augusto Pedretti

2015-05-01

Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n3p367   In soccer, the relative age effect (RAE was observed in both adult and young players. The RAE appears to be more pronounced in elite sports, probably by the need to select the best players to compete internationally. This study review: (1 the prevalence of RAE in soccer players, (a considering competitive level (b and specific position and (2 association between RAE (a and anthropometric characteristics, (b physical fitness components and technical skills. A total of 12 studies met all inclusion criteria for this review. One trial (meta-analysis was included after the eligibility process. Overall, 77675 young soccer players were analysed. In all studies, significance level of 0.05 was set for the type I error. There is a consensus about the presence of an RAE in men’s soccer, and the percentage of players born in the first quarter in the selection year for professionals is high, with peak values found for elite young athletes, and a large decrease is evident throughout the regional and school representation. The relationship between RAE and the specific position is controversial, according to few studies. It is likely that players born in the first quarter differ in a variety of anthropometric characteristics and physical fitness components compared with peers born in the last quarter. Researchers need to understand the mechanisms by which RAE increase and decrease in order, to reduce and eliminate this social inequality that influence the experiences of athletes, especially in periods of development. Organizational and practical intervention is required.

Tracking of ball and players in beach volleyball videos.

Directory of Open Access Journals (Sweden)

Gabriel Gomez

Full Text Available This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points.

Linking performance decline to choking: players' perceptions in basketball.

Science.gov (United States)

Fryer, Ashley Marie; Tenenbaum, Gershon; Chow, Graig M

2018-02-01

This study was aimed at examining how basketball players view unexpected performance errors in basketball, and under what conditions they perceive them as choking. Fifty-three basketball players were randomly assigned into 2 groups (game half) to evaluate the linkage between performance decline and choking as a function of game-time, score gap and game half. Within each group, players viewed 8 scenario clips, which featured a different player conducting an error, and subsequently rated the extent of performance decline, the instance of choking and the salience of various performance attributions regarding the error. The analysis revealed that choking was most salient in the 2nd half of the game, but an error was perceived as choking more saliently in the beginning of the 2nd half. This trend was also shown for players' perception of performance decline. Players' ratings of the attributions assigned to errors, however, revealed that during the end of the 2nd half, time pressure and lack of concentration were the causes of errors. Overall, the results provide evidence towards a conceptual framework linking performance decline to the perception of choking, and that errors conducted by players are perceived as choking when there is not a salient reason to suggest its occurrence.

Differences in energy capacities between tennis players and runners.

Science.gov (United States)

Novak, Dario; Vucetić, Vlatko; Zugaj, Sanja

2013-05-01

The primary purpose of this study was to determine differences between elite athletes and tennis players in order to provide a clearer picture regarding the energy demands in modern tennis. Forty-eight (48) athletes and 24 tennis players from Croatian national leagues were compared in morphological and physiological parameters of an all-out incremental treadmill test with gas exchange measurements. Tennis players' HRmax (192.96+/-7.75 bpm) shows values that are most different to 400-meters sprinters (200.13+/-6.95 bpm). Maximum running speed of tennis players on the treadmill (vmax) is no different with the speed achieved by sprinters, while there are significant differences among other athletes. Values in running speed at anaerobic threshold (vAnT) show no statistically significant difference with the values for athlete sprinters and 400-m sprinters. Values of RvO2max for tennis players indicate significant similarities with athlete sprinters and 400-m sprinters while the values of RvO2AnT are nearly identical with the values for sprinters and show no statistically significant differences (psprint endurance in tennis players. Knowing these characteristics is the basis for planning and implementing training systems that will enable the increase and optimal usage of energy capacities of tennis players in possibly improving sports results.

Tracking of Ball and Players in Beach Volleyball Videos

Science.gov (United States)

Gomez, Gabriel; Herrera López, Patricia; Link, Daniel; Eskofier, Bjoern

2014-01-01

This paper presents methods for the determination of players' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points. PMID:25426936

Arthroscopic rotator cuff repair in elite rugby players

OpenAIRE

Tambe, Amol; Badge, Ravi; Funk, Lennard

2009-01-01

Background: Rugby is an increasingly popular collision sport. A wide spectrum of injuries can be sustained during training and match play. Rotator cuff injury is uncommon in contact sports and there is little published literature on the treatment of rotator cuff tears in rugby players. Aims: We therefore reviewed the results and functional outcomes of arthroscopic rotator cuff repair in elite rugby players. Materials and Methods: Eleven professional rugby players underwent arthroscopic ...

An Optimized Player Taxonomy Model for Mobile MMORPGs with Millions of Users

Directory of Open Access Journals (Sweden)

Fang You

2011-01-01

Full Text Available Massively multiplayer online role-playing games (MMORPGs have great potential as sites for research within the social and human-computer interaction. In the MMORPGs, a stability player taxonomy model is very important for game design. It helps to balance different types of players and improve business strategy of the game. The players in mobile MMORPGs are also connected with social networks; many studies only use the player's own attributes statistics or questionnaire survey method to predict player taxonomy, so lots of social network relations' information will be lost. In this paper, by analyzing the impacts of player's social network, commercial operating data from mobile MMORPGs is used to establish our player taxonomy model (SN model. From the model results, social network-related information in mobile MMORPGs will be considered as important factors to pose this optimized player taxonomy model. As experimental results showed, compared with another player taxonomy model (RA model, our proposed player taxonomy model can achieve good results: classification is more stable.

Exploring Online Game Players' Flow Experiences and Positive Affect

Science.gov (United States)

Chiang, Yu-Tzu; Lin, Sunny S. J.; Cheng, Chao-Yang; Liu, Eric Zhi-Feng

2011-01-01

The authors conducted two studies to explore online game players' flow experiences and positive affect. Our findings indicated that online game are capable of evoking flow experiences and positive affect, and games of violent or nonviolent type may not arouse players' aggression. The players could be placed into four flow conditions: flow,…

Foot morphology of Turkish football players according to foot ...

African Journals Online (AJOL)

Football is the most popular sport in the world. Foot morphology and foot preference are important factors in football player's performance. The aim of this cross-sectional study was to evaluate the foot morphology of elite football players with different foot preferences. 407 male football players participated in this study. 328 of ...

Short-term Outcomes following Concussion in the NFL: An 11-year Retrospective Study of Player Release Rate and Financial Loss

Science.gov (United States)

Ramkumar, Prem; Navarro, Sergio Michael

2017-01-01

Objectives: The primary goal of this study was to assess the short-term outcomes among National Football League (NFL) players following concussion in terms of: (1) DNP protocol activation, (2) release rate at one and three years, and (3) mean salary reduction. A secondary goal of the study was to stratify the post-concussive release rate by franchise and player position. Methods: NFL player transaction records and publicly available weekly injury reports from August 2005 to January 2016 for NFL players were analyzed. All players immediately sustaining recorded concussions were evaluated for a change to inactive or do-not-play (DNP) status. The one-year and three-year release rate following concussion was defined as any player transitioning to inactivation, retirement, free agency, or any failure to return for a successive season on the same team’s active roster after one or three years from the initial concussion. Student’s t-test was used to compare release rates between non-concussed and concussed players at one and three years. Mean salary reduction per year following concussion was calculated using publicly available player contracts. Additionally, franchise-level and position-based analyses of the release rate were performed. Results: Of the total 5,451 NFL players retrospectively analyzed over the 11-year period, 373 sustained publicly reported concussions resulting in DNP protocol activation. The release rate of the post-concussive versus non-concussive player was 26% vs. 20% at 1 year (pfranchise to release an athlete following concussion within one and three years. Table 1 reports a position-based analysis in terms of concussion rate, mean salary reduction, and NFL career longevity. Conclusion: Our retrospective study demonstrates that NFL concussions resulting in DNP protocol activation leads to a statistically greater release rate among concussed NFL players than non-concussed players. Released players suffered reduction in year-over-year accumulated

Soccer and Relative Age Effect: A Walk among Elite Players and Young Players

Directory of Open Access Journals (Sweden)

Manuel Jacob Sierra-Díaz

2017-01-01

Full Text Available Grouping people according to chronological age is popular in fields such as education and sport. Athletes who are born in the first months of the year usually have cognitive and physical development differences in contrast to those born in the last months of the same year. That is why competitive teams tend to select older players more often than youngsters. Age differences between athletes born in the same year as well as an over-representation of older players are known as the Relative Age Effect. This effect is extensively described in young and elite team sports such as basketball, volleyball or, ice-hockey, as well as in soccer. The purpose of this study is to examine the state-of-the-art of the Relative Age Effect in youth and elite soccer players. This review summarizes recent research articles on the Relative Age Effect related to competitive soccer from 2010 to 2016. The systematic literature search was conducted in four databases: SPORTDiscus, Medline, EBSCO host and Google Scholar. Although causes and final solutions have not been clearly achieved yet, it is necessary to continue investigating this phenomenon in order to provide a starting point for future research.

Adaptive Portfolio Optimization for Multiple Electricity Markets Participation.

Science.gov (United States)

Pinto, Tiago; Morais, Hugo; Sousa, Tiago M; Sousa, Tiago; Vale, Zita; Praca, Isabel; Faia, Ricardo; Pires, Eduardo Jose Solteiro

2016-08-01

The increase of distributed energy resources, mainly based on renewable sources, requires new solutions that are able to deal with this type of resources' particular characteristics (namely, the renewable energy sources intermittent nature). The smart grid concept is increasing its consensus as the most suitable solution to facilitate the small players' participation in electric power negotiations while improving energy efficiency. The opportunity for players' participation in multiple energy negotiation environments (smart grid negotiation in addition to the already implemented market types, such as day-ahead spot markets, balancing markets, intraday negotiations, bilateral contracts, forward and futures negotiations, and among other) requires players to take suitable decisions on whether to, and how to participate in each market type. This paper proposes a portfolio optimization methodology, which provides the best investment profile for a market player, considering different market opportunities. The amount of power that each supported player should negotiate in each available market type in order to maximize its profits, considers the prices that are expected to be achieved in each market, in different contexts. The price forecasts are performed using artificial neural networks, providing a specific database with the expected prices in the different market types, at each time. This database is then used as input by an evolutionary particle swarm optimization process, which originates the most advantage participation portfolio for the market player. The proposed approach is tested and validated with simulations performed in multiagent simulator of competitive electricity markets, using real electricity markets data from the Iberian operator-MIBEL.

Exploring the Relation between the Theory of Multiple Intelligences and Games for the Purpose of Player-Centred Game Design

Science.gov (United States)

Sajjadi, Pejman; Vlieghe, Joachim; De Troyer, Olga

2017-01-01

A large body of research work demonstrates the importance and effectiveness of adapting a learning game to its players. This process is driven by understanding the differences between individuals in terms of abilities and preferences. One of the rather interesting but least explored approaches for understanding individual differences among…

A study of the effectiveness of MP3 players to support family carers of people living with dementia at home.

Science.gov (United States)

Lewis, Virginia; Bauer, Michael; Winbolt, Margaret; Chenco, Carol; Hanley, Francine

2015-03-01

Music can be therapeutic to people with dementia; however, little is known about its effect on the family carers. This project aimed to (1) assess the effects of MP3 player use by a person with dementia on caregivers' mental health and wellbeing, including their self-care and health-promoting behavior and (2) determine whether MP3 player use increases caregivers' self-reported capacity to cope with their role. A pre-post quantitative and qualitative design was used. Carers completed a survey prior to commencing and four weeks after using the player. The survey included validated measures to assess the level of stress and coping among carers. Carers also kept a diary of the way they used the MP3 player. Half of the carers were interviewed about their experiences at the end of the study. Of 59 people who started using the MP3 player, 51 carers completed the four-week study period and surveys. Use of the MP3 player significantly decreased psychological distress, significantly improved the mental health and wellbeing of carers, significantly increased caregiver self-efficacy to manage symptoms of dementia, and was reported to provide valued respite from the high level of vigilance required for caring for a person with dementia. An MP3 player loaded with music can be a low cost and relatively simple and effective additional strategy to support families caring for people with dementia in the community.

The impact of neuromuscular electrical stimulation on recovery after intensive, muscle damaging, maximal speed training in professional team sports players.

Science.gov (United States)

Taylor, Tom; West, Daniel J; Howatson, Glyn; Jones, Chris; Bracken, Richard M; Love, Thomas D; Cook, Christian J; Swift, Eamon; Baker, Julien S; Kilduff, Liam P

2015-05-01

During congested fixture periods in team sports, limited recovery time and increased travel hinder the implementation of many recovery strategies; thus alternative methods are required. We examined the impact of a neuromuscular electrical stimulation device on 24-h recovery from an intensive training session in professional players. Twenty-eight professional rugby and football academy players completed this randomised and counter-balanced study, on 2 occasions, separated by 7 days. After baseline perceived soreness, blood (lactate and creatine kinase) and saliva (testosterone and cortisol) samples were collected, players completed a standardised warm-up and baseline countermovement jumps (jump height). Players then completed 60 m × 50 m maximal sprints, with 5 min recovery between efforts. After completing the sprint session, players wore a neuromuscular electrical stimulation device or remained in normal attire (CON) for 8 h. All measures were repeated immediately, 2 and 24-h post-sprint. Player jump height was reduced from baseline at all time points under both conditions; however, at 24-h neuromuscular electrical stimulation was significantly more recovered (mean±SD; neuromuscular electrical stimulation -3.2±3.2 vs. CON -7.2±3.7%; P0.05). Neuromuscular electrical stimulation improves recovery from intensive training in professional team sports players. This strategy offers an easily applied recovery strategy which may have particular application during sleep and travel. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Training habits and injuries of masters' level football players: a preliminary report.

Science.gov (United States)

Newsham-West, R; Button, C; Milburn, P D; Mündermann, A; Sole, G; Schneiders, A G; Sullivan, S J

2009-05-01

To profile training habits and injuries in football players participating in a national Masters tournament. A cross-sectional retrospective study design was used to survey male football players attending the 2008 New Zealand Masters Games. Information regarding player demographics, football injuries, football related training, and risk factors for injury were collected. 199 Players were recruited, with a median age of 44 yrs (range 35-73) and a median football playing history of 15 yrs (range 0-66). Irrespective of age, 112 (84%) players included a warm-up and 104 (78%) included a stretching regime in their regular training programme. In the 12 months prior to the tournament, 128 football related injuries were reported by 93 players (64 injuries/100 players or 46 injured players/100 players). The most frequently injured region was the lower limb; specifically the lower leg (n=23), ankle (n=18), hamstring (n=17), knee (n=15), and Achilles tendon (n=15). This study provides a preliminary insight into the training habits and injury profiles of Masters football players. Despite all players including some form of injury prevention strategy in their training, a significant number of players experienced an injury in the 12 months prior to the tournament.

High-intensity stepwise conditioning programme for improved exercise responses and agility performance of a badminton player with knee pain.

Science.gov (United States)

Chen, Bob; Mok, Damon; Lee, Winson C C; Lam, Wing Kai

2015-02-01

To examine the effect of a high-intensity stepwise conditioning programme combined with multiple recovery measures on physical fitness, agility, and knee pain symptoms of an injured player. A single case study. University-based conditioning training laboratory. One 26-year-old male world-class badminton player (height, 190.0 cm; weight, 79.3 kg; left dominant hand; playing experience, 16 years; former world champion) with patellar tendinosis and calcification of his left knee. The player received seven conditioning sessions over three weeks. During the programme, there was a gradual increase in training duration and load across sessions while cold therapy, manual stretches and massage were administered after each session to minimise inflammation. The training outcome was evaluated with three different testing methods: standard step test, badminton-specific agility test, and tension-pain rating. The conditioning programme reduced knee pain symptoms and improved actual performance and cardiopulmonary fitness during the agility task. The player was able to return to sport and compete within a month. A high-intensity stepwise conditioning programme improved the physical fitness while sufficient recovery measures minimised any possible undesirable effects and promoted faster return to elite level competition. Copyright © 2014 Elsevier Ltd. All rights reserved.

Relations of competitive state anxiety and efficacy of young volleyball players.

Science.gov (United States)

Milavić, Boris; Jurko, Damir; Grgantov, Zoran

2013-05-01

With the aim of validating the Competitive State Anxiety Inventory on a population of young Croatian volleyball players, 286 examinees, 106 male and 180 female volleyball players (average age of 16.09+/-1.83), filled out the CSAI-2, constructed by Martens, Vealey, Burton, Bump and Smith (1990)1. Given the fact that all scales of the Competitive State Anxiety Inventory have good homogeneity, reliability and sensitivity, it can be concluded that they represent high-quality measuring instruments for measuring psychological characteristics of young volleyball players. Young male and female volleyball players generally have a moderate level of self-confidence, and their cognitive anxiety is more prominent that somatic anxiety. In order to determine the age and gender differences in somatic and cognitive anxiety and self-confidence, parametric analysis of differences was performed and coefficients of the independent samples t-test were calculated. By analysis of differences according to age, it has been established that female junior players, in relation to female youth players, express a significantly lower level of somatic and cognitive anxiety and a significantly higher level of self-confidence. As opposed to female players, male youth and junior players do not differ in any of the analysed variables. By analysis of differences according to gender, it has been established that male youth players have a significantly higher level of self-confidence in comparison to female youth players. No significant differences were found in the level of competitive anxiety and self-confidence by analysis of variance between different player roles. No significant differences were found by discriminant analysis in somatic and cognitive anxiety, and self-confidence of female volleyball players of different situational efficacy. The group of least efficient male volleyball players is characterized by a very low level of self-confidence, while the most efficient group of volleyball

Cardiovascular health profile of elite female football players compared to untrained controls before and after short-term football training

DEFF Research Database (Denmark)

Randers, Morten Bredsgaard; Andersen, Lars Juel; Ørntoft, Christina Øyangen

2013-01-01

Abstract This study examined the intermittent exercise performance and cardiovascular health profile in elite female football players in comparison to untrained young women, as well as a subgroup subjected to football training 2x1 h · week(-1) for 16 weeks. Twenty-seven Danish national team players...... weeks of football training with 26 and 46% increases in TAPSE and E/A ratio, respectively, reaching levels comparable to ET. In summary, elite female football players have a superior cardiovascular health profile and intermittent exercise performance compared to untrained controls, but short...... (elite trained, ET) and 28 untrained women (UT) underwent dual-energy X-ray absorptiometry-scanning (DXA), comprehensive transthoracic echocardiography, treadmill and Yo-Yo Intermittent Endurance level 2 (IE2) testing. Eight women in UT were also tested after the football training period. Maximal oxygen...

Preventing musculoskeletal injuries among recreational adult volleyball players: design of a randomised prospective controlled trial.

Science.gov (United States)

Gouttebarge, Vincent; Zwerver, Johannes; Verhagen, Evert

2017-08-02

Both acute and overuse injuries are common among recreational volleyball players, especially finger/wrist, ankle, shoulder and knee injuries. Consequently, an intervention ('VolleyVeilig') was developed to prevent or reduce the occurrence of finger/wrist, shoulder, knee and ankle injuries among recreational volleyball players. This article describes the design of a study evaluating the effectiveness of the developed intervention on the one-season occurrence of finger/wrist, shoulder, knee and ankle injuries among recreational adult volleyball players. A randomized prospective controlled trial with a follow-up period of one volleyball season will be conducted. Participants will be healthy recreational adult volleyball players (18 years of age or older) practicing volleyball (training and/or match) at least twice a week. The intervention ('VolleyVeilig') consists of a warm-up program based on more than 50 distinct exercises (with different variations and levels). The effect of the intervention programme on the occurrence of injuries will be compared to volleyball as usual. Outcome measures will be incidence of acute injury (expressed as number of injuries per 1000 h of play) and prevalence of overuse injuries (expressed as percentage). This study will be one of the first randomized prospective controlled trials evaluating the effectiveness of an intervention on the occurrence of both acute and overuse injuries among recreational adult volleyball players. Outcome of this study could possibly lead to the nationwide implementation of the intervention in all volleyball clubs in The Netherlands, ultimately resulting in less injuries. Dutch Trial Registration NTR6202 , registered February 1st 2017. Version 3, February 2017.

Computing Decoupled Residuals for Compact Disc Players

DEFF Research Database (Denmark)

Odgaard, Peter Fogh; Stoustrup, Jakob; Andersen, Palle

2006-01-01

a pair of residuals generated by Compact Disc Player. However, these residuals depend on the performance of position servos in the Compact Disc Player. In other publications of the same authors a pair of decoupled residuals is derived. However, the computation of these alternative residuals has been...

Physiological characteristics of elite soccer players.

Science.gov (United States)

Tumilty, D

1993-08-01

Soccer is one of the most popular sports in the world. There is still much uncertainty and debate surrounding its physiological requirements because emphasis is on skills to the neglect of fitness, conservative training methods and the difficulty of studying the sport scientifically. The frequently found values for total distance covered in a game of about 10 km and an above-average, though not outstanding, maximum oxygen uptake of 60 ml/kg/min suggest a moderate overall aerobic demand. A comparison of top teams and players with less able participants indicates that the components of anaerobic fitness-speed, power, strength and the capacity of the lactic acid system may differentiate better between the 2 groups. Generally, there is a reduction in the level of activity in the second half of games compared with the first. There is some evidence that increased aerobic fitness may help counteract this. Progressively lower muscle glycogen stores are one likely cause of reduction in activity, and nutrition also appears to be a key factor in minimising performance deterioration, both in terms of overall diet and, more particularly, the ingestion of carbohydrates immediately before, during and after a game. There are evolutionary trends in the sport such as greater frequency of games, changes in the roles of players, and new strategies and tactics which are placing increasing demands on the all-round fitness of players. Many studies indicate scope for improvement in player fitness. The challenge for coaches and players is to meet these fitness requirements without sacrificing the skill work which makes the sport unique.

Case Study: Nutritional and Lifestyle Support to Reduce Infection Incidence in an International-Standard Premier League Soccer Player.

Science.gov (United States)

Ranchordas, Mayur K; Bannock, Laurent; Robinson, Scott L

2016-04-01

Professional soccer players are exposed to large amounts of physiological and psychological stress, which can increase infection risk and threaten availability for training and competition. Accordingly, it is important for practitioners to implement strategies that support player well-being and prevent illness. This case study demonstrates how a scientifically supported and practically applicable nutrition and lifestyle strategy can reduce infection incidence in an illness-prone professional soccer player. In the 3 months before the intervention, the player had 3 upper-respiratory tract infections (URTIs) and subsequently missed 3 competitive matches and 2 weeks' training. He routinely commenced morning training sessions in the fasted state and was estimated to be in a large daily energy deficit. Throughout the 12-week intervention, the amount, composition, and timing of energy intake was altered, quercetin and vitamin D were supplemented, and the player was provided with a daily sleep and hygiene protocol. There was a positive increase in serum vitamin D 25(OH) concentration from baseline to Week 12 (53 n·mol-1 to 120 n·mol-1) and salivary immunoglobulin-A (98 mg·dl-1 to 135 mg·dl-1), as well as a decline in the number of URTI symptoms (1.8 ± 2.0 vs. 0.25 ± 0.5 for Weeks 0-4 and Weeks 8-12, respectively). More important, he maintained availability for all training and matches over the 12-week period. We offer this case study as a real-world applied example for other players and practitioners seeking to deploy nutrition and lifestyle strategies to reduce risk of illness and maximize player availability.

Clustering Professional Basketball Players by Performance

OpenAIRE

Patel, Riki

2017-01-01

Basketball players are traditionally grouped into five distinct positions, but these designationsare quickly becoming outdated. We attempt to reclassify players into new groupsbased on personal performance in the 2016-2017 NBA regular season. Two dimensionalityreduction techniques, t-Distributed Stochastic Neighbor Embedding (t-SNE) and principalcomponent analysis (PCA), were employed to reduce 18 classic metrics down to two dimensionsfor visualization. k-means clustering discovered four grou...

Exploring Stereotypical Perceptions of Female Players in Digital Gaming Contexts.

Science.gov (United States)

Kaye, Linda K; Gresty, Claire E; Stubbs-Ennis, Natasha

2017-12-01

Gender stereotypes are still reported to exist in digital gaming contexts, despite the fact that participation of females is relatively equal to that of males. The current research explored a number of factors and their impact upon stereotypical perceptions and attitudes toward female players. This included avatar gender, gender identity by gaming context, as well as more general gender-role beliefs. We undertook two studies, each utilizing an online questionnaire targeted toward online players. Study 1 recruited online gamers (N = 489) and compared competence perceptions of players, which varied by player gender (male, female) and avatar gender (male, female), whereby four conditions were established. Overall, player competence was perceived to be highest when male avatars were used, specifically when female players were depicted in this way. Study 2 explored the relationships between male social identity and gender-role beliefs, with sexist attitudes in gaming, and whether this varied by gaming context (massively multiplayer online [MMO] vs. first-person shooter [FPS]). Male online gamers (N = 193) were recruited, of which 112 were MMO players, and 81 were FPS players. It was found that identifying as male social identity was not related to sexist attitudes in either gaming context. However, more general gender-role beliefs were related to sexist attitudes. The findings indicate that although certain stereotypes exist (e.g., competence perceptions), these are not necessarily harvested by players' identities within communities, but may derive through more operational functions such as avatar gender.

Physical and physiological attributes of female volleyball players--a review.

Science.gov (United States)

Lidor, Ronnie; Ziv, Gal

2010-07-01

The main objective of this article was to review a series of studies (n = 31) on physical attributes, physiological attributes, and on-court performances of female volleyball players. Empirical and practical knowledge emerging from studies on training-related issues in volleyball, such as body mass, fat-free mass, aerobic profile, strength, and agility and speed, should be integrated and applied when planning annual training programs for volleyball players. Based on our review, it was found that (a) players of a higher skill level are taller, somewhat heavier, and have higher vertical jump values than players of a lower level; (b) the aerobic profile of female volleyball players is similar to that of female basketball players; (c) ballistic resistance training can increase vertical jump values in female volleyball players; and (d) preseason conditioning should be conducted to prevent fatigue and reduced performance at the beginning of the season. Among the research concerns discussed in the article are that there is a lack data for on-court performance and time-motion analysis in female volleyball players and that more experimental/manipulative studies are needed to examine the effectiveness of different training programs on physiological attributes of female volleyball players. Two practical implications are suggested for volleyball and strength and conditioning coaches: (a) functional and nonfunctional overreaching should be carefully monitored when planning strength and conditioning programs, and (b) volleyball programs should include ballistic-type training.

A Profile of Fitness Parameters and Performance of Volleyball Players

Directory of Open Access Journals (Sweden)

Govind B. Taware

2013-07-01

Full Text Available Background: Ball games require comprehen-sive ability including physical, technical, men-tal and tactical abilities. Among them, physicalabilities of players exert marked effects on theskill of the players themselves and the tacticsof the team. Therefore players must have thephysical abilities to meet the demand of thesport. Volleyball is one of the most popularlyplayed games in the world. Unfortunately, thelevel of performance of the Indian volleyballplayers lags far behind the international stan-dards. Aim of the Study: The present study wasaimed to assess flexibility, muscular endurance,power and cardio-respiratory endurance of vol-leyball players and to compare the results withage matched controls. Also, to compare thefindings of the volleyball players with that ofthe international norms from the available lit-erature and to make some suggestions for theimprovement in their performance level. Ma-terial and Methods: The study was carried outin 40 male volleyball players aged between 17to 26 years and 40 ages matched male controls.Physical fitness parameters namely flexibility,muscular endurance, power and cardio-respi-ratory endurance were measured, data was ana-lyzed using unpaired ‘t’-test. Results: It was ob-served that all physical fitness parameters weresignificantly more in players as compared totheir aged-matched controls but when values ofthe subjects were compared to internationalstandards; our subjects were behind the recom-mended norms for the elite volleyball players.Conclusion: The volleyball players have moreadvantage of flexibility muscular endurance,power and cardio-respiratory endurance.

Sports hernia in National Hockey League players: does surgery affect performance?

Science.gov (United States)

Jakoi, Andre; O'Neill, Craig; Damsgaard, Christopher; Fehring, Keith; Tom, James

2013-01-01

Athletic pubalgia is a complex injury that results in loss of play in competitive athletes, especially hockey players. The number of reported sports hernias has been increasing, and the importance of their management is vital. There are no studies reporting whether athletes can return to play at preinjury levels. The focus of this study was to evaluate the productivity of professional hockey players before an established athletic pubalgia diagnosis contrasted with the productivity after sports hernia repair. Cohort study; Level of evidence, 3. Professional National Hockey League (NHL) players who were reported to have a sports hernia and who underwent surgery from 2001 to 2008 were identified. Statistics were gathered on the players' previous 2 full seasons and compared with the statistics 2 full seasons after surgery. Data concerning games played, goals, average time on ice, time of productivity, and assists were gathered. Players were divided into 3 groups: group A incorporated all players, group B were players with 6 or fewer seasons of play, and group C consisted of players with 7 or more seasons of play. A control group was chosen to compare player deterioration or improvement over a career; each player selected for the study had a corresponding control player with the same tenure in his career and position during the same years. Forty-three hockey players were identified to have had sports hernia repairs from 2001 to 2008; ultimately, 80% would return to play 2 or more full seasons. Group A had statistically significant decreases in games played, goals scored, and assists. Versus the control group, the decreases in games played and assists were supported. Statistical analysis showed significant decreases in games played, goals scored, assists, and average time on ice the following 2 seasons in group C, which was also seen in comparison with the control group. Group B (16 players) showed only statistical significance in games played versus the control group

Sports injuries in Plus League volleyball players.

Science.gov (United States)

Cieśla, E; Dutkiewicz, R; Mgłosiek, M; Nowak-Starz, G; Markowska, M; Jasiński, P; Dudek, J

2015-06-01

Although physical activity brings a range of lifelong health benefits, it may also lead to injuries that pose a significant threat to health. It is particularly noticeable in people involved in professional sports where sport-related injuries commonly occur and are associated with intense exercise which aims to improve physical fitness. The article attempts to determine incidence of sports injuries reported by Plus League volleyball players, as well as to identify their most common types and causes. The research project involved 90 Plus League volleyball players aged 18-37 with the average age of 25.11 (SD±5.378). A method of diagnostic survey was applied to collect empirical data by means of questionnaire developed by the authors (researchers). The results were statistically analysed and verified with the analysis of variance (ANOVA) and χ2 test at the significance level (or critical P-value) of P≤0.05. Over 87% of the respondents suffered from at least one sport-related injury. In total, 362 injuries occurred, on average 4.02 injuries per one volleyball player. The most common sports injuries involved ankle or talocrural joint (46 injuries), knee and lower leg muscles (30), interphalangeal articulations of fingers (30) as well as shoulder joint. More than half of the injuries (57%) occurred twice or three times. Volleyball players commonly sustain injuries through contact with an opposing player in competition. Sport-specific injuries may also occur due to exhaustion, lack of rest and undertreated injuries. The most common volleyball-related injuries are primarily talocrural joint, hand and shoulder injuries. Common types of injuries that can affect volleyball players include muscles, joints and ligaments injuries, sprains and strains as well as bruises. Most of these injuries are caused by exhaustion, contact with an opposing player during competition and fatigue. The incidence of sport-related injuries seems to be influenced by such factors as somatic

High-Intensity Training Improves Exercise Performance in Elite Women Volleyball Players During a Competitive Season.

Science.gov (United States)

Purkhús, Elisabeth; Krustrup, Peter; Mohr, Magni

2016-11-01

Purkhús, E, Krustrup, P, and Mohr, M. High-intensity training improves exercise performance in elite women volleyball players during a competitive season. J Strength Cond Res 30(11): 3066-3072, 2016-Elite women volleyball players (n = 25; mean ± SD: age, 19 ± 5 years; height, 171 ± 7 cm; weight, 63 ± 10 kg) volunteered to participate in the study. They were randomized into a high-intensity training (HIT; n = 13) group and a control (CON; n = 12) group. In addition to the normal team training and games, HIT performed 6-10 × 30-seconds all-out running intervals separated by 3-minute recovery periods 3 times per week during a 4-week in-season period whereas CON only completed the team training sessions and games. Preintervention and postintervention, all players completed the arrowhead agility test (AAT), a repeated sprint test (RST; 5 × 30 meters separated by 25 seconds of recovery), and the Yo-Yo Intermittent Recovery level 2 test (Yo-Yo IR2) followed by a-10 minute rest period and the Yo-Yo IR1 test. Mean running distance during HIT in week 1 was 152 ± 4 m and increased (p ≤ 0.05) by 4.6% (159 ± 3 m) in week 4. The AAT performance improved (p ≤ 0.05) by 2.3% (18.87 ± 0.97-18.44 ± 1.06 seconds) and RST by 4.3% postintervention in the HIT group only. Baseline RST fatigue index was 7.0 ± 2.9 and 6.2 ± 5.0% in HIT and CON, respectively, but was lowered (p ≤ 0.05) to 2.7 ± 3.0% posttraining in HIT and remained unaltered in CON (5.5 ± 5.0%). In HIT, Yo-Yo IR2 and Yo-Yo IR1 performance improved by 12.6 and 18.3% postintervention, respectively, with greater (p ≤ 0.05) Yo-yo IR1 change scores than in CON. In conclusion, additional high-intensity in-season training performed as interval running improved agility, repeated sprint ability, and high-intensity intermittent exercise performance in elite women volleyball players.

How to know and choose online games: differences between current and potential players.

Science.gov (United States)

Teng, Ching-I; Lo, Shao-Kang; Wang, Pe-Cheng

2007-12-01

This study investigated how different adolescent players acquire game information and the criteria they use in choosing online games and found that (1) current players generally use comprehensive information sources more than potential players do; (2) current players rely on free trials and smooth display of motion graphics as choice criteria more than potential players do; (3) potential players rely on the look of advertisements more than current players do; (4) both current and potential players most likely use word-of-mouth and gaming programs on TV as information sources; and (5) endorser attractiveness is ranked the least important among six choice criteria by both current and potential players.

Fitness Profiles of Elite Portuguese Rugby Union Players

Science.gov (United States)

Vaz, Luís; Morais, Tomaz; Rocha, Henrique; James, Nic

2014-01-01

The aim of this study was to describe the fitness profiles of senior elite Portuguese rugby players. Forty-six senior Portuguese rugby players, classified as backs (n=22; age 26.2±2.8) and forwards (n=24; age 26.7±2.9) were assessed during physical testing sessions carried out for the Portuguese National rugby team. The body composition, maximum strength and anaerobic capacity of players are hypothesized to be important physical characteristics as successful performance in rugby is predicated on the ability to undertake skilled behaviours both quickly and whilst withstanding large forces when in contact situations. No absolute differences were found between the backs and forwards for the speed performance variables although positional differences were found across all speeds when assessed relative to body mass since the forwards were significantly heavier. Coaches and the management team can use this information for monitoring progressive improvements in the physiological capacities of rugby players. These physical characteristics of elite rugby players provide normative profiles for specific positions and should form the basis of developmental programmes for adolescents. PMID:25114750

Fitness Profiles of Elite Portuguese Rugby Union Players

Directory of Open Access Journals (Sweden)

Vaz Luís

2014-07-01

Full Text Available The aim of this study was to describe the fitness profiles of senior elite Portuguese rugby players. Forty-six senior Portuguese rugby players, classified as backs (n=22; age 26.2±2.8 and forwards (n=24; age 26.7±2.9 were assessed during physical testing sessions carried out for the Portuguese National rugby team. The body composition, maximum strength and anaerobic capacity of players are hypothesized to be important physical characteristics as successful performance in rugby is predicated on the ability to undertake skilled behaviours both quickly and whilst withstanding large forces when in contact situations. No absolute differences were found between the backs and forwards for the speed performance variables although positional differences were found across all speeds when assessed relative to body mass since the forwards were significantly heavier. Coaches and the management team can use this information for monitoring progressive improvements in the physiological capacities of rugby players. These physical characteristics of elite rugby players provide normative profiles for specific positions and should form the basis of developmental programmes for adolescents.

Cricket club looking for new players

CERN Multimedia

Cricket Club

2016-01-01

The CERN Cricket Club, having lost several key players, has had a very difficult season so far and is desperately in need of new players. Having qualified for the Cricket Switzerland semi-finals for the last two years (unfortunately losing both), this year we are bottom of the Western Pool, having played the last two league matches with only 10 players. If you are interested in playing cricket please join us at net practice, which takes place on the Prevessin site each Thursday evening from 18:00 to around 20:00 (weather permitting) or send me an e-mail (see below). Please have a look at the Cricket Club web site for more information: http://cern.ch/Club-Cricket/ Chris Onions, President of the CERN Cricket Club   (christopher.onions@gmail.com)

Fault Predictive Control of Compact Disk Players

DEFF Research Database (Denmark)

Odgaard, Peter Fogh; Wickerhauser, Mladen Victor

2006-01-01

Optical disc players such as CD-players have problems playing certain discs with surface faults like scratches and fingerprints. The problem is to be found in the servo controller which positions the optical pick-up, such that the laser beam is focused on the information track. A scheme handling...

Hamstring muscle strains in professional football players: a 10-year review.

Science.gov (United States)

Elliott, Marcus C C W; Zarins, Bertram; Powell, John W; Kenyon, Charles D

2011-04-01

Investigations into hamstring strain injuries at the elite level exist in sports such as Australian Rules football, rugby, and soccer, but no large-scale study exists on the incidence and circumstances surrounding these injuries in the National Football League (NFL). Injury rates will vary between different player positions, times in the season, and across different playing situations. Descriptive epidemiology study. Between 1989 and 1998, injury data were prospectively collected by athletic trainers for every NFL team and recorded in the NFL's Injury Surveillance System. Data collected included team, date of injury, activity the player was engaged in at the time of injury, injury severity, position played, mechanism of injury, and history of previous injury. Injury rates were reported in injuries per athlete-exposure (A-E). An athlete-exposure was defined as 1 athlete participating in either 1 practice or 1 game. Over the 10-year study period 1716 hamstring strains were reported for an injury rate (IR) of 0.77 per 1000 A-E. More than half (51.3%) of hamstring strains occurred during the 7-week preseason. The preseason practice IR was significantly elevated compared with the regular-season practice IR (0.82/1000 A-E and 0.18/1000 A-E, respectively). The most commonly injured positions were the defensive secondary, accounting for 23.1% of the injuries; the wide receivers, accounting for 20.8%; and special teams, constituting 13.0% of the injuries in the study. Hamstring strains are a considerable cause of disability in football, with the majority of injuries occurring during the short preseason. In particular, the speed position players, such as the wide receivers and defensive secondary, as well as players on the special teams units, are at elevated risk for injury. These positions and situations with a higher risk of injury provide foci for preventative interventions.

Single season changes in resting state network power and the connectivity between regions distinguish head impact exposure level in high school and youth football players

Science.gov (United States)

Murugesan, Gowtham; Saghafi, Behrouz; Davenport, Elizabeth; Wagner, Ben; Urban, Jillian; Kelley, Mireille; Jones, Derek; Powers, Alex; Whitlow, Christopher; Stitzel, Joel; Maldjian, Joseph; Montillo, Albert

2018-02-01

The effect of repetitive sub-concussive head impact exposure in contact sports like American football on brain health is poorly understood, especially in the understudied populations of youth and high school players. These players, aged 9-18 years old may be particularly susceptible to impact exposure as their brains are undergoing rapid maturation. This study helps fill the void by quantifying the association between head impact exposure and functional connectivity, an important aspect of brain health measurable via resting-state fMRI (rs-fMRI). The contributions of this paper are three fold. First, the data from two separate studies (youth and high school) are combined to form a high-powered analysis with 60 players. These players experience head acceleration within overlapping impact exposure making their combination particularly appropriate. Second, multiple features are extracted from rs-fMRI and tested for their association with impact exposure. One type of feature is the power spectral density decomposition of intrinsic, spatially distributed networks extracted via independent components analysis (ICA). Another feature type is the functional connectivity between brain regions known often associated with mild traumatic brain injury (mTBI). Third, multiple supervised machine learning algorithms are evaluated for their stability and predictive accuracy in a low bias, nested cross-validation modeling framework. Each classifier predicts whether a player sustained low or high levels of head impact exposure. The nested cross validation reveals similarly high classification performance across the feature types, and the Support Vector, Extremely randomized trees, and Gradboost classifiers achieve F1-score up to 75%.

Periodicity, chaos, and multiple attractors in a memristor-based Shinriki's circuit

Energy Technology Data Exchange (ETDEWEB)

Kengne, J. [Laboratory of Automation and Applied Computer (LAIA), Department of Electrical Engineering, IUT-FV Bandjoun, University of Dschang, Dschang (Cameroon); Njitacke Tabekoueng, Z.; Kamdoum Tamba, V.; Nguomkam Negou, A. [Laboratory of Automation and Applied Computer (LAIA), Department of Electrical Engineering, IUT-FV Bandjoun, University of Dschang, Dschang (Cameroon); Department of Physics, Laboratory of Electronics and Signal Processing (LETS), Faculty of Science, University of Dschang, Dschang (Cameroon)

2015-10-15

In this contribution, a novel memristor-based oscillator, obtained from Shinriki's circuit by substituting the nonlinear positive conductance with a first order memristive diode bridge, is introduced. The model is described by a continuous time four-dimensional autonomous system with smooth nonlinearities. The basic dynamical properties of the system are investigated including equilibria and stability, phase portraits, frequency spectra, bifurcation diagrams, and Lyapunov exponents' spectrum. It is found that in addition to the classical period-doubling and symmetry restoring crisis scenarios reported in the original circuit, the memristor-based oscillator experiences the unusual and striking feature of multiple attractors (i.e., coexistence of a pair of asymmetric periodic attractors with a pair of asymmetric chaotic ones) over a broad range of circuit parameters. Results of theoretical analyses are verified by laboratory experimental measurements.

Can Perceptuo-Motor Skills Assessment Outcomes in Young Table Tennis Players (7-11 years) Predict Future Competition Participation and Performance? An Observational Prospective Study.

Science.gov (United States)

Faber, Irene R; Elferink-Gemser, Marije T; Faber, Niels R; Oosterveld, Frits G J; Nijhuis-Van der Sanden, Maria W G

2016-01-01

Forecasting future performance in youth table tennis players based on current performance is complex due to, among other things, differences between youth players in growth, development, maturity, context and table tennis experience. Talent development programmes might benefit from an assessment of underlying perceptuo-motor skills for table tennis, which is hypothesized to determine the players' potential concerning the perceptuo-motor domain. The Dutch perceptuo-motor skills assessment intends to measure the perceptuo-motor potential for table tennis in youth players by assessing the underlying skills crucial for developing technical and tactical qualities. Untrained perceptuo-motor tasks are used as these are suggested to represent a player's future potential better than specific sport skills themselves as the latter depend on exposure to the sport itself. This study evaluated the value of the perceptuo-motor skills assessment for a talent developmental programme by evaluating its predictive validity for competition participation and performance in 48 young table tennis players (7-11 years). Players were tested on their perceptuo-motor skills once during a regional talent day, and the subsequent competition results were recorded half-yearly over a period of 2.5 years. Logistic regression analysis showed that test scores did not predict future competition participation (p >0.05). Yet, the Generalized Estimating Equations analysis, including the test items 'aiming at target', 'throwing a ball', and 'eye-hand coordination' in the best fitting model, revealed that the outcomes of the perceptuo-motor skills assessment were significant predictors for future competition results (R2 = 51%). Since the test age influences the perceptuo-motor skills assessment's outcome, another multivariable model was proposed including test age as a covariate (R2 = 53%). This evaluation demonstrates promising prospects for the perceptuo-motor skills assessment to be included in a talent

Can Perceptuo-Motor Skills Assessment Outcomes in Young Table Tennis Players (7-11 years Predict Future Competition Participation and Performance? An Observational Prospective Study.

Directory of Open Access Journals (Sweden)

Irene R Faber

Full Text Available Forecasting future performance in youth table tennis players based on current performance is complex due to, among other things, differences between youth players in growth, development, maturity, context and table tennis experience. Talent development programmes might benefit from an assessment of underlying perceptuo-motor skills for table tennis, which is hypothesized to determine the players' potential concerning the perceptuo-motor domain. The Dutch perceptuo-motor skills assessment intends to measure the perceptuo-motor potential for table tennis in youth players by assessing the underlying skills crucial for developing technical and tactical qualities. Untrained perceptuo-motor tasks are used as these are suggested to represent a player's future potential better than specific sport skills themselves as the latter depend on exposure to the sport itself. This study evaluated the value of the perceptuo-motor skills assessment for a talent developmental programme by evaluating its predictive validity for competition participation and performance in 48 young table tennis players (7-11 years. Players were tested on their perceptuo-motor skills once during a regional talent day, and the subsequent competition results were recorded half-yearly over a period of 2.5 years. Logistic regression analysis showed that test scores did not predict future competition participation (p >0.05. Yet, the Generalized Estimating Equations analysis, including the test items 'aiming at target', 'throwing a ball', and 'eye-hand coordination' in the best fitting model, revealed that the outcomes of the perceptuo-motor skills assessment were significant predictors for future competition results (R2 = 51%. Since the test age influences the perceptuo-motor skills assessment's outcome, another multivariable model was proposed including test age as a covariate (R2 = 53%. This evaluation demonstrates promising prospects for the perceptuo-motor skills assessment to be

MONITORING TRAINING LOADS, STRESS, IMMUNE-ENDOCRINE RESPONSES AND PERFORMANCE IN TENNIS PLAYERS

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Rodrigo Vitasovic Gomes

2013-06-01

Full Text Available The study aim was to investigate the effect of a periodised pre-season training plan on internal training load and subsequent stress tolerance, immune-endocrine responses and physical performance in tennis players. Well-trained young tennis players (n = 10 were monitored across the pre-season period, which was divided into 4 weeks of progressive overloading training and a 1-week tapering period. Weekly measures of internal training load, training monotony and stress tolerance (sources and symptoms of stress were taken, along with salivary testosterone, cortisol and immunoglobulin A. One repetition maximum strength, running endurance, jump height and agility were assessed before and after training. The periodised training plan led to significant weekly changes in training loads (i.e. increasing in weeks 3 and 4, decreasing in week 5 and post-training improvements in strength, endurance and agility (P < 0.05. Cortisol concentration and the symptoms of stress also increased in weeks 3 and/or 4, before returning to baseline in week 5 (P < 0.05. Conversely, the testosterone to cortisol ratio decreased in weeks 3 and 4, before returning to baseline in week 5 (P < 0.05. In conclusion, the training plan evoked adaptive changes in stress tolerance and hormonal responses, which may have mediated the improvements in physical performance.

Effect of core stability training on throwing velocity in female handball players.

Science.gov (United States)

Saeterbakken, Atle H; van den Tillaar, Roland; Seiler, Stephen

2011-03-01

The purpose was to study the effect of a sling exercise training (SET)-based core stability program on maximal throwing velocity among female handball players. Twenty-four female high-school handball players (16.6 ± 0.3 years, 63 ± 6 kg, and 169 ± 7 cm) participated and were initially divided into a SET training group (n = 14) and a control group (CON, n = 10). Both groups performed their regular handball training for 6 weeks. In addition, twice a week, the SET group performed a progressive core stability-training program consisting of 6 unstable closed kinetic chain exercises. Maximal throwing velocity was measured before and after the training period using photocells. Maximal throwing velocity significantly increased 4.9% from 17.9 ± 0.5 to 18.8 ± 0.4 m·s in the SET group after the training period (p core stability training using unstable, closed kinetic chain movements can significantly improve maximal throwing velocity. A stronger and more stable lumbopelvic-hip complex may contribute to higher rotational velocity in multisegmental movements. Strength coaches can incorporate exercises exposing the joints for destabilization force during training in closed kinetic chain exercises. This may encourage an effective neuromuscular pattern and increase force production and can improve a highly specific performance task such as throwing.

Evaluation of microfracture of traumatic chondral injuries to the knee in professional football and rugby players.

Science.gov (United States)

Riyami, Masoud; Rolf, Christer

2009-05-07

Traumatic chondral lesions of the knee are common in football and rugby players. The diagnosis is often confirmed by arthroscopy which can be therapeutic by performing microfracture. Prospective information about the clinical results after microfracture is still limited. To evaluate the short-term outcome of microfractured lesions in professional football ad rugby players in terms of healing and ability to return to play. Twenty-four consecutive professional male players with isolated full-thickness articular cartilage defects on weight-bearing surface of femoral condyles were treated with microfracture. Clinical assessment of healing was done at three, six, 12 and at 18 months by using modified Cincinnati subjective and objective functional scoring. All 24 subjects were periodically scanned by 3-Tesla MRI on the day of the clinical evaluations and scored by the Henderson MRI classification for cartilage healing. A second look arthroscopy was carried out in 10 players five to seven months after surgery to evaluate lesion healing by using ICRS scoring system. This was done due to presence of discrepancy between a "normal" MRI and persistent clinical symptoms. This study showed that 83.3% of players' resume full training between five to seven months (mean: 6.2) after microfracture of full-thickness chondral lesions of weight-bearing surface of the knee. Function and MRI knee scores of the 24 subjects gradually improved over 18 months, and showed good correlation in assessing healing after microfracture at six, 12 and 18 months (r2 = 0.993, 0.986 and 0.993, respectively) however, the second look arthroscopy score proved to have stronger strength of association with function score than MRI score. We confirmed that microfracture is a safe and effective procedure in treating isolated traumatic chondral lesions of the load-bearing areas of the knee. Healing as defined by subjective symptoms and evaluated by MRI and a modified knee function score occurred between 5 to 7

Multiple periodic solutions for a discrete time model of plankton allelopathy

OpenAIRE

Zhang Jianbao; Fang Hui

2006-01-01

We study a discrete time model of the growth of two species of plankton with competitive and allelopathic effects on each other N1(k+1) = N1(k)exp{r1(k)-a11(k)N1(k)-a12(k)N2(k)-b1(k)N1(k)N2(k)}, N2(k+1) = N2(k)exp{r2(k)-a21(k)N2(k)-b2(k)N1(k)N1(k)N2(k)}. A set of sufficient conditions is obtained for the existence of multiple positive periodic solutions for this model. The approach is based on Mawhin's continuation theorem of coincidence degree theory as well as some a priori estimates. Some...

Thermoregulation, Fluid Balance, and Sweat Losses in American Football Players.

Science.gov (United States)

Davis, Jon K; Baker, Lindsay B; Barnes, Kelly; Ungaro, Corey; Stofan, John

2016-10-01

Numerous studies have reported on the thermoregulation and hydration challenges athletes face in team and individual sports during exercise in the heat. Comparatively less research, however, has been conducted on the American Football player. Therefore, the purpose of this article is to review data collected in laboratory and field studies and discuss the thermoregulation, fluid balance, and sweat losses of American Football players. American Football presents a unique challenge to thermoregulation compared with other sports because of the encapsulating nature of the required protective equipment, large body size of players, and preseason practice occurring during the hottest time of year. Epidemiological studies report disproportionately higher rates of exertional heat illness and heat stroke in American Football compared with other sports. Specifically, larger players (e.g., linemen) are at increased risk for heat ailments compared with smaller players (e.g., backs) because of greater body mass index, increased body fat, lower surface area to body mass ratio, lower aerobic capacity, and the stationary nature of the position, which can reduce heat dissipation. A consistent finding across studies is that larger players exhibit higher sweating rates than smaller players. Mean sweating rates from 1.0 to 2.9 L/h have been reported for college and professional American Football players, with several studies reporting 3.0 L/h or more in some larger players. Sweat sodium concentration of American Football players does not seem to differ from that of athletes in other sports; however, given the high volume of sweat loss, the potential for sodium loss is higher in American Football than in other sports. Despite high sweating rates with American Football players, the observed disturbances in fluid balance have generally been mild (mean body mass loss ≤2 %). The majority of field-based studies have been conducted in the northeastern part of the United States, with limited

Pre-training perceived wellness impacts training output in Australian football players.

Science.gov (United States)

Gallo, Tania F; Cormack, Stuart J; Gabbett, Tim J; Lorenzen, Christian H

2016-08-01

The impact of perceived wellness on a range of external load parameters, rating of perceived exertion (RPE) and external load:RPE ratios, was explored during skill-based training in Australian footballers. Fifteen training sessions involving 36 participants were analysed. Each morning before any physical training, players completed a customised perceived wellness questionnaire (sleep quality, fatigue, stress, mood and muscle soreness). Microtechnology devices provided external load (average speed, high-speed running distance, player load and player load slow). Players provided RPE using the modified Borg category-ratio 10 RPE scale. Mixed-effect linear models revealed significant effects of wellness Z-score on player load and player load slow. Effects are reported with 95% confidence limits. A wellness Z-score of -1 corresponded to a -4.9 ± 3.1 and -8.6 ± 3.9% reduction in player load and player load slow, respectively, compared to those without reduced wellness. Small significant effects were also seen in the average speed:RPE and player load slow:RPE models. A wellness Z-score of -1 corresponded to a 0.43 ± 0.38 m·min(-1) and -0.02 ± 0.01 au·min(-1) change in the average speed:RPE and player load slow:RPE ratios, respectively. Magnitude-based analysis revealed that the practical size of the effect of a pre-training perceived wellness Z-score of -1 would have on player load slow was likely negative. The results of this study suggests that monitoring pre-training perceived wellness may provide coaches with information about the intensity of output that can be expected from individual players during a training session.

Prevalence and variance of shoulder injuries in elite collegiate football players.

Science.gov (United States)

Kaplan, Lee D; Flanigan, David C; Norwig, John; Jost, Patrick; Bradley, James

2005-08-01

Shoulder injuries are the fourth most common musculoskeletal injury encountered in American football players. There is little information in the literature on the role of playing position in the type of shoulder injuries seen. There is a high prevalence of shoulder injuries in elite collegiate American football players, with type of injury varying by playing position. Cohort study (prevalence); Level of evidence, 3. A total of 336 elite collegiate American football players were invited to the National Football League Combine for physical testing and medical evaluation. Current and historical data were evaluated for the purpose of this study, and all players underwent radiographic examinations, including plain radiographs and/or magnetic resonance imaging when necessary. All shoulder pathological conditions and shoulder surgical procedures were recorded. Players were categorized by position for the analysis of position-specific trends. Of the players, 50% had a history of shoulder injuries, with a total of 226 shoulder injuries (1.3 injuries per player injured); 56 players (34%) had a total of 73 surgeries. The most common injuries were acromioclavicular separation (41%), anterior instability (20%), rotator cuff injury (12%), clavicle fracture (4%), and posterior instability (4%). The most common surgeries performed were anterior instability reconstruction (48%), Mumford/Weaver-Dunn surgery (15%), posterior instability surgery (10%), and rotator cuff surgery (10%). Shoulder injuries were more common in quarterbacks and defensive backs. Surgery was more common in linebackers or linemen. A history of anterior instability was more common in defensive players, with surgery required 76% of the time. Linemen had more rotator cuff injuries and posterior instability than players in other positions. Shoulder injuries are common injuries in elite collegiate football players, with one-third undergoing surgical procedures. There are definitive trends in the types of injuries

Shuttle-Run Sprint Training in Hypoxia for Youth Elite Soccer Players: A Pilot Study

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Hannes Gatterer

2014-12-01

Full Text Available The purposes of the present study were to investigate if a shuttle-run sprint training performed in a normobaric hypoxia chamber of limited size (4.75x2.25m is feasible, in terms of producing the same absolute training load, when compared to training in normoxia, and b if such training improves the repeated sprint ability (RSA and the Yo-Yo intermittent recovery (YYIR test outcome in young elite soccer players. Players of an elite soccer training Centre (age: 15.3 ± 0.5 years, height: 1.73 ± 0.07 m, body mass: 62.6 ± 6.6 kg were randomly assigned to a hypoxia or a normoxia training group. Within a 5-week period, players, who were not informed about the hypoxia intervention, performed at least 7 sessions of identical shuttle-run sprint training either in a normal training room (FiO2 = 20.95% or in a hypoxic chamber (FiO2 = 14.8%; approximately 3300m, both equipped with the same floor. Each training session comprised 3 series of 5x10s back and forth sprints (4.5m performed at maximal intensity. Recovery time between repetitions was 20s and between series 5min. Before and after the training period the RSA (6 x 40m shuttle sprint with 20 s rest between shuttles and the YYIR test were performed. The size of the chamber did not restrict the training intensity of the sprint training (both groups performed approximately 8 shuttles during 10s. Training in hypoxia resulted in a lower fatigue slope which indicates better running speed maintenance during the RSA test (p = 0.024. YYIR performance increased over time (p = 0.045 without differences between groups (p > 0.05. This study showed that training intensity of the shuttle-run sprint training was not restricted in a hypoxic chamber of limited size which indicates that such training is feasible. Furthermore, hypoxia compared to normoxia training reduced the fatigue slope during the RSA test in youth soccer players.

Ranking benchmarks of top 100 players in men's professional tennis.

Science.gov (United States)

Reid, Machar; Morris, Craig

2013-01-01

In men's professional tennis, players aspire to hold the top ranking position. On the way to the top spot, reaching the top 100 can be seen as a significant career milestone. National Federations undertake extensive efforts to assist their players to reach the top 100. However, objective data considering reasonable ranking yardsticks for top 100 success in men's professional tennis are lacking. Therefore, it is difficult for National Federations and those involved in player development to give empirical programming advice to young players. By taking a closer look at the ranking history of professional male tennis players, this article tries to provide those involved in player development a more objective basis for decision-making. The 100 names, countries, birthdates and ranking histories of the top 100 players listed in the Association of Tennis Professionals (ATP) at 31 December 2009 were recorded from websites in the public domain. Descriptive statistics were reported for the ranking milestones of interest. Results confirmed the merits of the International Tennis Federation's junior tour with 91% of the top 100 professionals earning a junior ranking, the mean peak of which was 94.1, s=148.9. On average, top 100 professionals achieved their best junior rankings and earned their first ATP point at similar ages, suggesting that players compete on both the junior and professional tours during their transition. Once professionally ranked, players took an average 4.5, s=2.1 years to reach the ATP top 100 at the mean age of 21.5, s=2.6 years, which contrasts with the mean current age of the top 100 of 26.8, s=3.2. The best professional rankings of players born in 1982 or earlier were positively related to the ages at which players earned their first ATP point and then entered the top 100, suggesting that the ages associated with these ranking milestones may have some forecasting potential. Future work should focus on the change in top 100 demographics over time as well

Kinanthropometric and performance characteristics of elite and non-elite female softball players.

Science.gov (United States)

Singh, S; Singh, M; Rathi, B

2013-12-01

The purpose of the present study was to compare the kinanthropometric and performance characteristics of elite and non-elite female softball players. A total forty elite and non-elite level female softball players were selected from the different colleges affiliated to the Guru Nanak Dev University, Amritsar, for the present study. The height of subjects was measured by using the standard anthropometric rod. Weight was measured with portable weighing machine. Widths and diameters of body parts were measured by using digital caliper. Girths and lengths were taken with steel tape. Skinfold thickness measurements were taken using the Slimguide skinfold caliper. All subjects were also assessed for performance tests i.e. vertical jump, 50m sprint, medicine ball throw, 10×4m shuttle run and reaction time. Independent samples t-test reveals that elite female softball players were significantly taller (Psoftball players also had significantly greater biacromial (Psoftball players. The non-elite female softball players were found to have significantly greater thigh circumference (Psoftball players. The non-elite players were also found to have significantly higher percentage body fat (Psoftball players. The elite female softball players had significantly greater kinanthropometric characteristics, body composition and performance characteristics than the non-elite female softball players.

Decreased shoulder function and pain common in recreational badminton players.

Science.gov (United States)

Fahlström, M; Söderman, K

2007-06-01

The aim of this study was to describe the prevalence and consequences of painful conditions in the shoulder region in recreational badminton players. A questionnaire study was performed on 99 players, of whom 57 were also assessed with Constant score. Previous or present pain in the dominant shoulder was reported by 52% of the players. Sixteen percent of the players had on-going shoulder pain associated with badminton play. A majority of these players reported that their training habits were affected by the pain. Total Constant score was lower in the painful shoulders. Furthermore, range of active pain-free shoulder abduction was decreased. However, isometric shoulder strength test showed no differences when compared with pain-free shoulders. Even though the pain caused functional problems, the players were still playing with on-going symptoms. The diagnoses were mostly unknown, although history and clinical tests indicate problems resembling subacromial impingement.

Little League Baseball and Players' Self-Esteem.

Science.gov (United States)

Hawkins, Donna B.; Gruber, Joseph J.

1982-01-01

The effect of a season of little league baseball on the self-esteem of 94 pre-adolescent players was investigated. The Coopersmith Self-esteem Inventory and a newly devised Baseball-Self scale were administered. Significant improvements in players' total Self-esteem, Home-Parents and School-Academic scores were found. (Author/PN)

Incidence of injuries in high school softball and baseball players.

Science.gov (United States)

Shanley, Ellen; Rauh, Mitchell J; Michener, Lori A; Ellenbecker, Todd S

2011-01-01

Participation in high school sports has grown 16.1% over the last decade, but few studies have compared the overall injury risks in girls' softball and boys' baseball. To examine the incidence of injury in high school softball and baseball players. Cohort study. Greenville, South Carolina, high schools. Softball and baseball players (n = 247) from 11 high schools. Injury rates, locations, types; initial or subsequent injury; practice or game setting; positions played; seasonal trends. The overall incidence injury rate was 4.5/1000 athlete-exposures (AEs), with more injuries overall in softball players (5.6/1000 AEs) than in baseball players (4.0/1000 AEs). Baseball players had a higher initial injury rate (75.9/1000 AEs) than softball players (66.4/1000 AEs): rate ratio (RR) = 0.88, 95% confidence interval (CI) = 0.4, 1.7. The initial injury rate was higher than the subsequent injury rate for the overall sample (P softball (P Softball players were more likely to be injured in a game than were baseball players (RR = 1.92, 95% CI = 0.8, 4.3). Most injuries (77%) were mild (3.5/1000 AEs). The upper extremity accounted for the highest proportion of injuries (63.3%). The incidence of injury for pitchers was 37.3% and for position players was 15.3%. The rate of injury was highest during the first month of the season (7.96/1000 AEs). The incidence of injury was low for both softball and baseball. Most injuries were minor and affected the upper extremity. The injury rates were highest in the first month of the season, so prevention strategies should be focused on minimizing injuries and monitoring players early in the season.

Match activities of elite women soccer players at different performance levels

DEFF Research Database (Denmark)

Mohr, Magni; Krustrup, Peter; Andersson, Helena

2008-01-01

, (2) fatigue develops temporarily during and towards the end of a game, and (3) defenders have lower work rates than midfielders and attackers. The difference in high-intensity running between the 2 levels demonstrates the importance of intense intermittent exercise for match performance in women......We sought to study the physical demands and match performance of women soccer players. Nineteen top-class and 15 high-level players were individually videotaped in competitive matches, and time-motion analysis were performed. The players changed locomotor activity >1,300 times in a game...... fewer (P women soccer players (1) top-class international players perform more intervals of high-intensity running than elite players at a lower level...

Nutritional analysis of dietary intake of professional female volleyball players during the competitive phase of the regular season

Directory of Open Access Journals (Sweden)

Juan Mielgo-Ayuso

2013-03-01

Full Text Available Introduction: nutritional aspects women’s volleyball has been little studied and more in a specific period of training as the competitive period. The aim is to assess and know the caloric and macronutrients intake by professional volleyball players of the Spanish Superliga for 16 weeks of training for the competition phase and compare with the references marked for athlete population.Material and methods: the study included 10 female volleyball players (JVF (26.6±5.9 years and height 178.05±8.7cm, for a total of 16 weeks of training and competition. They all gave written informed consent. They completed a food intake frequency questionary of the 16 week study, data corroborated by a dietary record (CFCA of 7 consecutive days in week 9 and 16. We were calculated daily nutritional intake from CFCA with the food composition table of CESNID by Easy Diet software, the Spanish Association of Dietitians-Nutritionists (AEDN.Results: the energy and nutritional analysis of the female professional volleyball players shows that the amount of energy and macronutrients does not meet to the recommendations for sports collective.Conclusions: it is observed low energy and carbohydrates intake and high intake of protein and lipids. Recommended practical aspects for improving nutrition education in this professional sports group.

Performance Outcomes After Metacarpal Fractures in National Basketball Association Players.

Science.gov (United States)

Guss, Michael S; Begly, John P; Ramme, Austin J; Hinds, Richard M; Karia, Raj J; Capo, John T

2016-12-01

Background: The aim was to determine whether players in the National Basketball Association (NBA) who sustain metacarpal fractures demonstrate decreased performance upon return to competition when compared with their performance before injury and that of their control-matched peers. Methods: Data for 32 NBA players with metacarpal fractures incurred over 11 seasons (2002-2003 to 2012-2013) were obtained from injury reports, press releases, and player profiles (www.nba.com and www.basketballreference.com). Player age, body mass index (BMI), position, shooting hand, number of years in the league, and treatment (surgical vs nonsurgical) were recorded. Individual season statistics for the 2 seasons immediately prior to injury and the 2 seasons after injury, including player efficiency rating (PER), were obtained. Thirty-two controls matched by player position, age, and performance statistics were identified. A performance comparison of the cohorts was performed. Results: Mean age at the time of injury was 27 years with an average player BMI of 24. Players had a mean 5.6 seasons of NBA experience prior to injury. There was no significant change in PER when preinjury and postinjury performances were compared. Neither injury to their shooting hand nor operative management of the fracture led to a decrease in performance during the 2 seasons after injury. When compared with matched controls, no significant decline in performance in PER the first season and second season after injury was found. Conclusion: NBA players sustaining metacarpal fractures can reasonably expect to return to their preinjury performance levels following appropriate treatment.

Physiological characteristics of elite and sub-elite badminton players.

Science.gov (United States)

Ooi, Cheong Hwa; Tan, Albert; Ahmad, Azwari; Kwong, Kien Weng; Sompong, Ruji; Ghazali, Khairul Aswadi Mohd; Liew, Swee Lee; Chai, Wen Jin; Thompson, Martin William

2009-12-01

The aims of this study were to establish the physical and physiological attributes of elite and sub-elite Malaysian male badminton players and to determine whether these attributes discriminate elite players from sub-elite players. Measurements and tests of basic anthropometry, explosive power, anaerobic recovery capacity, badminton-specific movement agility, maximum strength, and aerobic capacity were conducted on two occasions, separated by at least one day. The elite (n = 12) and sub-elite (n = 12) players' characteristics were, respectively: mean age 24.6 years (s = 3.7) and 20.5 years (s = 0.7); mass 73.2 kg (s = 7.6) and 62.7 kg (s = 4.2); stature 1.76 m (s = 0.07) and 1.71 m (s = 0.05); body fat 12.5% (s = 4.8) and 9.5% (s = 3.4); estimated VO(2max) 56.9 ml . kg(-1) . min(-1) (s = 3.7) and 59.5 ml . kg(-1) . min(-1) (s = 5.2). The elite players had greater maximum absolute strength in one-repetition maximum bench press (P = 0.015) compared with the sub-elite players. There were significant differences in instantaneous lower body power estimated from vertical jump height between the elite and sub-elite groups (P badminton-specific movement agility tests. Our results show that elite Malaysian male badminton players are taller, heavier, and stronger than their sub-elite counterparts. The test battery, however, did not allow us to discriminate between the elite and sub-elite players, suggesting that at the elite level tactical knowledge, technical skills, and psychological readiness could be of greater importance.

Assessment of Cardiovascular Risk in Collegiate Football Players and Nonathletes

Science.gov (United States)

Dobrosielski, Devon A.; Rosenbaum, Daryl; Wooster, Benjamin M.; Merrill, Michael; Swanson, John; Moore, J. Brian; Brubaker, Peter H.

2010-01-01

Collegiate American football players may be at risk for cardiovascular disease. Objective: To compare cardiovascular disease risk factors and cardiovascular structure and function parameters of football players, stratified by position, to a group of sedentary, nonathletes. Participants: Twenty-six collegiate football players and 13 nonathletes…

Role-player expectations regarding the education of nursing research.

Science.gov (United States)

Zeelie, S C; Bornman, J E; Botes, A C

2003-12-01

This article reports on role player expectations regarding the education of nursing research. The importance of the role player expectations are two-fold: firstly as a factor in the external environment influencing and guiding the formulation phase of the development of standards and secondly, due to the clear indications of problems regarding nursing research in the nursing profession in literature. The role player expectations were elicited using a qualitative, exploratory and contextual design. The role player population included nurse educators, nurses in managerial, clinical and research positions, students and the medical profession. The data was gathered using the naïve sketches and qualitative data analysis was done using Morse & Field's approach (1996:103-107) in combination with Tesch's data analysis approach as cited by Creswell (1994:154-156). Sixty initial categories were narrowed down to six final categories, which are the research learning programme, personnel, students, departmental policies, funding and support systems. The role player expectations were elicited as part of a research study aiming tot develop a self-evaluation system for quality assurance in nursing research and as such, the role player expectations plays a pivotal role in the development of standards for the self-evaluation system.

The players of the photovoltaic sector in France

International Nuclear Information System (INIS)

Houot, G.

2012-01-01

This document reviews 338 players in the French photovoltaic industry. Each player can be the owner of a photovoltaic power plant, or its operator, or the manufacturer of photovoltaic systems, or the manufacturer of components involved in photovoltaic systems, or the equipment wholesaler, or the designer of photovoltaic projects, or the photovoltaic system installer. For each player some pieces of information are gathered: a brief history of the enterprise, the enterprise activity, its staff, its turnover, its main achievements and its prospects. (A.C.)

Monitoring Elite Soccer Players' External Loads Using Real-Time Data.

Science.gov (United States)

Barrett, Steve

2017-11-01

To assess the validity of measuring locomotor activities and PlayerLoad using real-time (RT) data collection during soccer training. Twenty-nine English soccer players participated. Each player wore the same MEMS device (Micromechanical Electrical Systems; S5, Optimeye; CatapultSports, Melbourne, Australia) during 21 training sessions (N = 331 data sets) in the 2015-16 and 2016-17 seasons. An RT receiver (TRX; Catapultsports, Melbourne, Australia) was used to collect the locomotor activities and PlayerLoad data in RT and compared with the postevent downloaded (PED) data. PlayerLoad and locomotor activities (total distance covered; total high-speed running distance covered, >5.5#x00A0;m/s; total sprinting distance covered, >7 m/s; maximum velocity) were analyzed. Correlations were near perfect for all variables analyzed (r = .98-1.00), with a varied level of noise between RT and PED also (0.3-9.7% coefficient of variation). Locomotor activities and PlayerLoad can use both RT and PED concurrently to quantify a player's physical output during a training session. Caution should be taken with higher-velocity-based locomotor activities during RT compared to PED.

Context-dependent player's movement interpretation: application to adaptive game development

Science.gov (United States)

Picard, Francois; Estraillier, Pascal

2010-02-01

Video games are more and more controlled by the real movements of the player. However, the player is constrained by the system devices, imposing a limited vocabulary of actions associated with a set of unnatural movements. To introduce more entertaining video games to players, a component-based architecture is proposed. It has been acknowledged as the starting point for the development of adaptive applications based on the hypothesis of a high level dialogue between the system and the player. The system adaptability relies on interpretation mechanisms of the player behaviors. These behaviors are defined through the representation of the real movements of the player who freely interacts with the 3D elements composing an immersive virtual environment, following a given game scenario. The efficient interpretation of the player movements relies on the introduction in the system of the management of the scene's context. The contextual information not only helps to determine the true meaning of an observed behavior but also makes the system to adapt its processes regarding this interpretation, while managing its hardware and software resources efficiently. A commercial motion capture interface has been enhanced by the elaboration of such a system.

Residual currents in a multiple-inlet system and the conundrum of the tidal period

Science.gov (United States)

Duran-Matute, Matias; Gerkema, Theo

2015-04-01

In multiple-inlet systems, one may find that, on average, flood dominates in some inlets, while ebb dominates in others. In that case, there is a residual flow through the system, i.e. there is a net flow if one integrates over a tidal period. Conceptually, this seems straightforward. However, to measure such a residual flow presents several difficulties. First, one needs to cover the entire cross-sections of all the inlets over a year or longer to take into account the variability due to wind. Second, the residual flow is usually much smaller than the tidal prisms and hence more uncertain in view of error bars. Third, the duration of 'the' tidal period when calculating a tidally averaged flow is not well defined. Should one take the time between alternate slack tides, or between consecutive high (or low) waters, or other options? There appears to be a fundamental ambiguity in the duration of the tidal period; here we discuss its origins. The problem of defining the tidal period seems to have received little attention in the literature, or perhaps it has not been perceived as a problem at all. One reason for this neglect may be that the focus in tidal analysis is often on the (main) individual tidal constituents, whose periods are well-defined. Indeed, the harmonic method developed by Kelvin exploits this fact, making it possible to predict high and low waters precisely by adding up the different constituents after their amplitudes and phases have been determined empirically for the location in question. The period between subsequent high (or low) waters is then simply an outcome of this method. Another reason for neglecting this problem may be that the main interest was in computing a representative quantity such as the yearly average residual flow through the inlets. For such quantities, the definition of the tidal period is not as relevant since one integrates over a much longer period. Recently, however, it has been shown, for the Western Dutch Wadden Sea, that

Two-year changes in anthropometric and motor ability values as talent identification indexes in youth soccer players.

Science.gov (United States)

Hirose, Norikazu; Seki, Taigo

2016-02-01

The present study examined 2-year changes in anthropometric variables and motor abilities in elite male youth soccer players to identify potential talent identification indexes. This was a cross-sequential study examining two different age groups at two time points. Height, weight, 40-m sprint speed, muscular power (5-step bounding), and change of direction (COD) ability (10 m×5 COD) were measured in 12- and 14-year-old soccer players and repeated after 2 years (at 14 and 16 years of age). Correlations and changes in ranking between the two measurements were determined. Both groups had small ranking changes in height (12-14-year-olds: r=0.80, 14-16-year-olds: r=0.89; ptalent identification index for youth soccer players. On the other hand, muscular power and COD ability is changeable during growth period suggests that these parameters is not useful for talent identification index. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Online Game Elements, Players and the Bond Between Them

OpenAIRE

Schweizer, Sandra

2017-01-01

The results are guidelines for game developers to improve their game design. Through using the guidelines of the paper, developers know how to implement appealing online game elements which appeal to the player and draw them in. The result of the thesis are socializing, achievements and immersion are motivated the player to play online games, as well as the way online games stimulate the player's brain.

Chaotic dynamics in nonlinear duopoly Stackelberg game with heterogeneous players

Science.gov (United States)

Xiao, Yue; Peng, Yu; Lu, Qian; Wu, Xue

2018-02-01

In this paper, a nonlinear duopoly Stackelberg game of competition on output is concerned. In consideration of the effects of difference between plan products and actual products, the two heterogeneous players always adopt suitable strategies which can improve their benefits most. In general, status of each firm is unequal. As the firms take strategies sequentially and produce simultaneously, complex behaviors are brought about. Numerical simulation presents period doubling bifurcation, maximal Lyapunov exponent and chaos. Moreover, an appropriate method of chaos controlling is applied and fractal dimension is analyzed as well.

Towards Player-Driven Procedural Content Generation

DEFF Research Database (Denmark)

Shaker, Noor

Generating immersive game content is one of the ultimate goals for a game designer. This goal can be achieved taken into account that players’ perceptions of the same game differ according to a number of factors including: players’ personality, playing styles, expertise and cultural background. One...... promising avenue towards optimizing the gameplay experience for individual game players - and thereby attempt to close the affective loop in games - is to automatically tailor the game content in real-time. To realize player-driven procedural content generation one needs to specify the aspects of the game...... that have a key influence on the gameplay experience, identify the relationship between these aspects and player experience and define a mechanism for tailoring the game content to each individual needs. In this dissertation we attempt to address the following research questions towards the aim...

Motivational profile quality players handball

Directory of Open Access Journals (Sweden)

Alfonso Martínez Moreno

2017-06-01

Full Text Available In the sport context, elite category, it is necessary to know all the factors, which in one way or another, affect the athletes throughout the different competitions. The object of study is to know the motivational profile of elite handball players. The sample consisted of 495 players, of whom 47.8% were boys and 52.2% girls, their ages ranged from 12 to 16 years, with an average of 13.8 years (dt = 1.0. Descriptive statistical analyzes of the sample, absolute and relative frequencies were performed for the qualitative variables and for the quantitative values minimum, maximum, mean, standard deviation, Cronbach's alpha. Correlation between variables, with the Pearson correlation coefficient. The MANCOVA test was performed to determine if there were differences between the dimensions of the questionnaire, according to age and years of practice. The results reveal that handball players elite category of the sample object of study have mainly intrinsic motivation, achieving high scores on general motivation, motivation achievement and motivation stimulation. In addition to moderately high values in introjected regulation and very low values in demotivation.

Voluntary limit setting and player choice in most intense online gamblers: an empirical study of gambling behaviour.

Science.gov (United States)

Auer, Michael; Griffiths, Mark D

2013-12-01

Social responsibility in gambling has become a major issue for the gaming industry. The possibility for online gamblers to set voluntary time and money limits are a social responsibility practice that is now widespread among online gaming operators. The main issue concerns whether the voluntary setting of such limits has any positive impact on subsequent gambling behaviour and whether such measures are of help to problem gamblers. In this paper, this issue is examined through data collected from a representative random sample of 100,000 players who gambled on the win2day gambling website. When opening an account at the win2day site, there is a mandatory requirement for all players to set time and cash-in limits (that cannot exceed 800 per week). During a 3-month period, all voluntary time and/or money limit setting behaviour by a subsample of online gamblers (n = 5,000) within this mandatory framework was tracked and recorded for subsequent data analysis. From the 5,000 gamblers, the 10 % most intense players (as measured by theoretical loss) were further investigated. Voluntary spending limits had the highest significant effect on subsequent monetary spending among casino and lottery gamblers. Monetary spending among poker players significantly decreased after setting a voluntary time limit. The highest significant decrease in playing duration was among poker players after setting a voluntary playing duration limit. The results of the study demonstrated that voluntary limit setting had a specific and significant effect on the studied gamblers. Therefore, voluntary limits appear to show an appropriate effect in the desired target group (i.e., the most gaming intense players).

Low range of ankle dorsiflexion predisposes for patellar tendinopathy in junior elite basketball players: a 1-year prospective study.

Science.gov (United States)

Backman, Ludvig J; Danielson, Patrik

2011-12-01

Patellar tendinopathy (PT) is one of the most common reasons for sport-induced pain of the knee. Low ankle dorsiflexion range might predispose for PT because of load-bearing compensation in the patellar tendon. The purpose of this 1-year prospective study was to analyze if a low ankle dorsiflexion range increases the risk of developing PT for basketball players. Cohort study (prognosis); Level of evidence, 2. Ninety junior elite basketball players were examined for different characteristics and potential risk factors for PT, including ankle dorsiflexion range in the dominant and nondominant leg. Data were collected over a 1-year period and follow-up, including reexamination, was made at the end of the year. Seventy-five players met the inclusion criteria. At the follow-up, 12 players (16.0%) had developed unilateral PT. These players were found to have had a significantly lower mean ankle dorsiflexion range at baseline than the healthy players, with a mean difference of -4.7° (P = .038) for the dominant limb and -5.1° (P = .024) for the nondominant limb. Complementary statistical analysis showed that players with dorsiflexion range less than 36.5° had a risk of 18.5% to 29.4% of developing PT within a year, as compared with 1.8% to 2.1% for players with dorsiflexion range greater than 36.5°. Limbs with a history of 2 or more ankle sprains had a slightly less mean ankle dorsiflexion range compared to those with 0 or 1 sprain (mean difference, -1.5° to -2.5°), although this was only statistically significant for nondominant legs. This study clearly shows that low ankle dorsiflexion range is a risk factor for developing PT in basketball players. In the studied material, an ankle dorsiflexion range of 36.5° was found to be the most appropriate cutoff point for prognostic screening. This might be useful information in identifying at-risk individuals in basketball teams and enabling preventive actions. A history of ankle sprains might contribute to reduced ankle

Effect of Core Training on Male Handball Players' Throwing Velocity.

Science.gov (United States)

Manchado, Carmen; García-Ruiz, José; Cortell-Tormo, Juan Manuel; Tortosa-Martínez, Juan

2017-02-01

In handball, throwing velocity is considered to be one of the essential factors in achieving the ultimate aim of scoring a goal. The objective of the present study was to analyze the effect of a core training program on throwing velocity in 30 handball players (age 18.7 ± 3.4 years, body height 179.3 ± 7.0 cm, body mass 78.9 ± 7.7 kg), 16 of whom were in the junior category and 14 of whom were in the senior category. The 30 players were randomly divided into two groups, the control group (n = 15) and the experimental group (n = 15). For a period of ten weeks, both groups attended their regular handball training sessions (four per week), but in addition, the experimental group participated in a program specifically aimed at progressively strengthening the lumbo-pelvic region and consisting of seven exercises performed after the general warm-up in each regular session. Pre- and post-tests were carried out to analyze each player's throwing velocity from different throwing positions and thus assess the effects of this specific training program. Statistically significant differences (p ≤ 0.05) in throwing velocity were observed between the experimental group, which presented a percentage improvement of 4.5%, and the control group, which did not show any improvement. The results seem to indicate that an increase in the strength and stability of the lumbo-pelvic region can contribute to an improvement in the kinetic chain of the specific movement of throwing in handball, thus, increasing throwing velocity.

Diagnosis Aerobic Component of Operational Preparedness Skill Players

Directory of Open Access Journals (Sweden)

Vasylyuk Vasyl

2017-01-01

Full Text Available Considerable importance for the control system, selection and orientation of the players on the stage long-term preparation plays a selection of effective methods of testing the various components of functional fitness athlete for timely, objective information about the players. The use of reliable scientific methods of effective monitoring of the athlete contributes to the further improvement of skills, increase athletic achievements. The purpose of this article is to describe and summarize modern methods of diagnosis and development of aerobic component of operational preparedness players qualifications. This article describes methods that actively and effectively used in leading European football teams. Specifically Yo-Yo test, test Shuttle (beep-test, Bangsbo test, test Hoff-Helgerud, test Conconi, Wingate-test. These tests have a high level of reliability and security mechanisms for assessing aerobic power players.

Noise effects in a three-player prisoner's dilemma quantum game

International Nuclear Information System (INIS)

Ramzan, M; Khan, M K

2008-01-01

We study the three-player prisoner's dilemma game under the effect of decoherence and correlated noise. It is seen that the quantum player is always better off than the classical players. It is also seen that the game's Nash equilibrium does not change in the presence of correlated noise in contradiction to the effect of decoherence in the multiplayer case. Furthermore, it is shown that for maximum correlation the game does not behave as a noiseless game and the quantum player is still better off for all values of the decoherence parameter p which is not possible in the two-player case. In addition, the payoffs reduction due to decoherence is controlled by the correlated noise throughout the course of the game

Race differences in ventricular remodeling and function among college football players.

Science.gov (United States)

Haddad, Francois; Peter, Shanon; Hulme, Olivia; Liang, David; Schnittger, Ingela; Puryear, Josephine; Gomari, Fatemeh A; Finocchiaro, Gherardo; Myers, Jonathan; Froelicher, Victor; Garza, Daniel; Ashley, Euan A

2013-07-01

Athletic training is associated with increases in ventricular mass and volume. Recent studies have shown that left ventricular mass increases proportionally in white athletes with a mass/volume ratio approaching unity. The objective of this study was to compare the proportionality in ventricular remodeling and ventricular function in black versus white National Collegiate Athletic Association Division I football players. From 2008 to 2011, football players at Stanford University underwent cardiovascular screening with a 12-point history and physical examination, electrocardiography, and focused echocardiography. Compared with white players, black players had on average higher left ventricular mass indexes (77 ± 11 vs 71 ± 11 g/m(2), p = 0.009), higher mass/volume ratios (1.18 ± 0.16 vs 1.06 ± 0.09 g/ml, p 1.2. Mass/volume ratio was inversely related to early diastolic tissue Doppler velocity e' (r = -0.50, p football players exhibit more concentric ventricular remodeling, lower early diastolic annular velocities, and increased ventricular voltage compared with white players. Ventricular mass increases proportionally to volume in white players but not in black players. Copyright © 2013 Elsevier Inc. All rights reserved.

Dental Trauma and Mouthguard Usage among Soccer Players in Izmir, Turkey

Directory of Open Access Journals (Sweden)

Ilhan Uzel

2014-07-01

Full Text Available The aims of this study were to verify the occurrence of dental injuries in 343 amateur Turkish soccer players in İzmir and the level of knowledge of the teams’ soccer players about mouthguards. The soccer players were interviewed to determine the occurrence of dental trauma during soccer and mouthguard usage level. The data were analyzed with descriptive analysis to determine absolute and relative frequencies of answers for each one of the questions. Only 35 (10.2% soccer players reported the occurrence of some type of dental injury during soccer practice. Regarding emergency conducts, approximately 84 players (24.48% answered that replantation could be obtained after teeth avulsion, 23 players (27.38% answered that successful replantation could be obtained within 2 hours immediately after injury, and 60.71% were not able to answer this question. Regarding mouthguard use, 61.8% of soccer players did not know about mouthguards. It was possible to conclude that dental injuries are common during amateur soccer practice and that there is a lack of information in the soccer players related to the emergency conducts and prevention of dental trauma.

Ankle Sprain Injuries: A 2-Year Prospective Cohort Study in Female Greek Professional Basketball Players

Science.gov (United States)

Kofotolis, Nikolaos; Kellis, Eleftherios

2007-01-01

Context: Ankle sprains are a common basketball injury. Therefore, examination of risk factors for injury in female professional basketball players is worthwhile. Objective: To examine rates of ankle sprains, associated time missed from participation, and risk factors for injury during 2 consecutive seasons. Design: Prospective cohort study. Setting: Eighteen professional basketball facilities. Patients or Other Participants: We observed 204 players from 18 female professional basketball teams for 2 consecutive seasons during a 2-year period. Main Outcome Measure(s): Using questionnaires, we recorded the incidence of ankle sprains, participation time missed, and mechanisms of injury in games and practice sessions. Potential risk factors, such as age, body mass, height, training experience, and history of ankle sprain, were examined using multivariate logistic regression. Results: Fifty of the 204 participants sustained ankle injuries; injuries included 32 ankle sprains, which translated to an ankle sprain rate of 1.12 per 1000 hours of exposure to injury. The 32 players missed 224.4 training and game sessions and an average of 7.01 sessions per injury. Most injuries occurred in the key area of the basketball court and were the result of contact. Injury rates during games were higher than injury rates during practice sessions. Centers, followed by guards and forwards, had the highest rate of injury. Players who did not wear an external ankle support had an odds ratio of 2.481 for sustaining an ankle sprain. Conclusions: Female professional basketball athletes who did not wear an external ankle support, who played in the key area, or who functioned as centers had a higher risk for ankle sprain than did other players. PMID:18059995

Nutrition Status of Young Elite Female German Football Players.

Science.gov (United States)

Braun, Hans; von Andrian-Werburg, Judith; Schänzer, Wilhelm; Thevis, Mario

2018-02-01

To investigate energy intake, energy expenditure, and the nutritional status of young female elite football players using 7-day food and activity records and blood parameters. A total of 56 female elite football players [14.8 (0.7) y] completed the requested food and activity protocols. Misreporting was assessed by the ratio of energy intake to energy expenditure. The food records were analyzed concerning energy and macronutrient and micronutrient intakes, and energy expenditure was calculated using predictive equations. Hematological data and 25-hydroxyvitamin D serum concentrations were determined. Mean energy intake was 2262 (368) kcal/d [40.5 (7.0) kcal/kg/d] and estimated EE averaged 2403 (195) kcal/d. Fifty-three percent of the players exhibited an energy availability nutrition status of some young female football players. As a consequence, strategies have to be developed for a better information and application of sport nutrition practice among young female football players.

Nutrient intake and blood iron status of male collegiate soccer players.

Science.gov (United States)

Noda, Yuka; Iide, Kazuhide; Masuda, Reika; Kishida, Reina; Nagata, Atsumi; Hirakawa, Fumiko; Yoshimura, Yoshitaka; Imamura, Hiroyuki

2009-01-01

The purpose of this study was: 1) to collect baseline data on nutrient intake in order to advise athletes about nutrition practices that might enhance performance, and 2) to evaluate the dietary iron intake and blood iron status of Japanese collegiate soccer players. The subjects were 31 soccer players and 15 controls. Dietary information was obtained with a food frequency questionnaire. The mean carbohydrate (6.9 g.kg-1 BW) and protein (1.3 g/kg) intakes of the soccer players were marginal in comparisons with recommended targets. The mean intakes of calcium, magnesium, vitamin A, B1, B2, and C were lower than the respective Japanese recommended dietary allowances (RDAs) or adequate dietary intakes in the soccer players. The mean intakes of green and other vegetables, milk and dairy products, fruits, and eggs were lower than the recommended targets. Thus, we recommended athletes to increase the intake of these foodstuffs along with slight increase in carbohydrate and lean meat. The mean intake of iron was higher than the respective RDA in the soccer players. A high prevalence of hemolysis (71%) in the soccer players was found. None of the soccer players and controls had anemia. Two soccer players had iron depletion, while none was found in the controls. In those players who had iron deficiency, the training load need to be lowered and/or iron intake may be increased.

SPORTS SHOES PURCHASE INTENTION AMONG MALAYSIAN VOLLEYBALL PLAYERS VS. NON-VOLLEYBALL PLAYERS: A CONCEPTUAL PAPER

Directory of Open Access Journals (Sweden)

GOH PIN SIANG

2013-12-01

Full Text Available The purpose of this study is to advance the understanding of volleyball players’ purchase intention toward sport shoes by investigating the relationship between the independent variables (endorsement, advertising, pricing and electronic word-of-mouth and purchase intention. Descriptive research and causal research will be used as the research design, thus questionnaire and experimentation will be used to obtain data. Primary data in this study is attained by distributing the questionnaire to the Malaysian volleyball players throughout several volleyball tournament venues in Malaysia. The experiment will be conducted by comparing two groups of respondents, including volleyball players and non-volleyball players. This study is limited to several independent variables such as endorsement, advertising, pricing and electronic word-of-mouth. This study is significant for marketers for solving the challenges faced in the sport industry. It also helps to identify consumers’ purchase preferences for sport shoes. The marketer would understand more about their targeted customers’ intentions to purchase, thus the sport industry related with sport marketing in Malaysia might gain more profit.

Profile of weekly training load in elite male professional basketball players.

Science.gov (United States)

Manzi, Vincenzo; D'Ottavio, Stefano; Impellizzeri, Franco M; Chaouachi, Anis; Chamari, Karim; Castagna, Carlo

2010-05-01

The aim of this study was to examine the training load (TL) profile of professional elite level basketball players during the crucial parts of the competitive season (pre-play-off finals). Subjects were 8 full-time professional basketball players (age 28 +/- 3.6 years, height 199 +/-7.2 cm, body mass 102 +/- 11.5 kg, and body fat 10.4 +/- 1.5%) whose heart rate (HR) was recorded during each training session and their individual response to TL monitored using the session-rate of perceived exertion (RPE) method (200 training sessions). The association between the session-RPE method and training HR was used to assess the population validity of the session-RPE method. Significant relationships were observed between individual session-RPE and all individual HR-based TL (r values from 0.69 to 0.85; p 0.05). Elite male professional basketball imposes great physiological and psychological stress on players through training sessions and official competitions (1-2 per week). Consequently, the importance of a practical and valid method to assess individual TL is warranted. In this research, we demonstrated that session-RPE may be considered as a viable method to asses TL without the use of more sophisticated tools (i.e., HR monitors). The session-RPE method enabled the detection of periodization patterns in weekly planning in elite professional basketball during the crucial part of the competitive season (1 vs. 2 weekly fixtures model).

The importance of open- and closed-skill agility for team selection of adult male basketball players.

Science.gov (United States)

Scanlan, A T; Tucker, P S; Dalbo, V J

2015-05-01

Open-skill agility qualities have yet to be described in adult male basketball players. Further, the importance of open- and closed-skill agility for team selection remains unknown. Thus, this study aimed to: 1) describe the open- and closed-skill agility of adult male basketball players; and 2) compare these properties between starting and non-starting players. A cross-sectional between-group design was used. Six starting (playing time: 30.1 ± 8.8 min; age: 30.5 ± 4.8 years; height: 192.1 ± 7.7 cm; body mass: 100.5 ± 15.0 kg; VO(2max): 48.4 ± 6.6 mL∙kg⁻¹∙min⁻¹) and six non-starting (4.3 ± 3.6 min; 21.3 ± 5 years; 185.7 ± 7.4 cm; 94.4 ± 17.9 kg; 50.6 ± 3.9 mL∙kg⁻¹∙min⁻¹) state-level basketball players completed multiple trials for the Change of Direction Speed Test (CODST) and Reactive Agility Test (RAT). No statistically significant between-group differences were evident for CODST movement time (starters: 1.652 ± 0.047 s; non-starters: 1.626 ± 0.040 s, P=0.68), RAT response time (starters: 307.5 ± 100.5 ms; non-starters: 426.5 ± 140.7 ms, P=0.12), and RAT decision-making time (starters: 110.7 ± 11.0 ms; non-starters: 147.3 ± 14.2 ms, P=0.08). However, starters (2.001 ± 0.051 s) possessed significantly (P=0.02) faster RAT total movement times than non-starters (2.182 ± 0.040 s). These data support the utility of perceptual and cognitive components of agility performance in distinguishing starting from non-starting players in basketball. Consequently, basketball coaching and conditioning staff should incorporate sport-specific reactive training drills for all players during the annual conditioning plan.

N-Player Stochastic Differential Games. [control theory

Science.gov (United States)

Varaiya, P.

1974-01-01

Conditions are described which guarantee that the control strategies adopted by N players constitute an efficient solution, an equilibrium, or a core solution. The system dynamics are described by an Ito equation, and all players have perfect information. It was found that when the set of instantaneous joint costs and velocity vectors is convex, the conditions are necessary.

Quantum Two Player Game in Thermal Environment.

Directory of Open Access Journals (Sweden)

Jerzy Dajka

Full Text Available A two-player quantum game is considered in the presence of thermal decoherence. It is shown how the thermal environment modeled in terms of rigorous Davies approach affects payoffs of the players. The conditions for either beneficial or pernicious effect of decoherence are identified. The general considerations are exemplified by the quantum version of Prisoner Dilemma.

Dietary Intake, Body Composition, and Nutrition Knowledge of Australian Football and Soccer Players: Implications for Sports Nutrition Professionals in Practice.

Science.gov (United States)

Devlin, Brooke L; Leveritt, Michael D; Kingsley, Michael; Belski, Regina

2017-04-01

Sports nutrition professionals aim to influence nutrition knowledge, dietary intake and body composition to improve athletic performance. Understanding the interrelationships between these factors and how they vary across sports has the potential to facilitate better-informed and targeted sports nutrition practice. This observational study assessed body composition (DXA), dietary intake (multiple-pass 24-hr recall) and nutrition knowledge (two previously validated tools) of elite and subelite male players involved in two team-based sports; Australian football (AF) and soccer. Differences in, and relationships between, nutrition knowledge, dietary intake and body composition between elite AF, subelite AF and elite soccer players were assessed. A total of 66 (23 ± 4 years, 82.0 ± 9.2 kg, 184.7 ± 7.7 cm) players participated. Areas of weaknesses in nutrition knowledge are evident (57% mean score obtained) yet nutrition knowledge was not different between elite and subelite AF and soccer players (58%, 57% and 56%, respectively, p > .05). Dietary intake was not consistent with recommendations in some areas; carbohydrate intake was lower (4.6 ± 1.5 g/kg/day, 4.5 ± 1.2 g/kg/day and 2.9 ± 1.1 g/kg/day for elite and subelite AF and elite soccer players, respectively) and protein intake was higher (3.4 ± 1.1 g/kg/day, 2.1 ± 0.7 g/kg/day and 1.9 ± 0.5 g/kg/day for elite and subelite AF and elite soccer players, respectively) than recommendations. Nutrition knowledge was positively correlated with fat-free soft tissue mass (n = 66; r 2 = .051, p = .039). This insight into known modifiable factors may assist sports nutrition professionals to be more specific and targeted in their approach to supporting players to achieve enhanced performance.

Development of speed qualities of skilled water-polo players

Directory of Open Access Journals (Sweden)

Ostrovsky M.V.

2010-02-01

Full Text Available Swimming preparation of water-polo players is the basic factor of victory of command. There are a few variants of development of speed swimming preparation. The effective pedagogical mean of stimulation of speed qualities is brief exercises at the end of employments after long aerobic work. The purpose of work is an improvement of method of speed preparation of skilled water-polo players. 26 skilled water-polo players (MS -14 and KMS - 12 took part in an experiment in age from 21 to 32 years. The results of correction of structure of training employment are in-process presented in micro cycle. They are directed on the improvement of speed qualities of water-polo players.

Dynamics of tactical behaviour in association football when manipulating players' space of interaction.

Directory of Open Access Journals (Sweden)

Angel Ric

Full Text Available The analysis of positional data in association football allows the spatial distribution of players during matches to be described in order to improve the understanding of tactical-related constraints on the behavioural dynamics of players. The aim of this study was to identify how players' spatial restrictions affected the exploratory tactical behaviour and constrained the perceptual-motor workspace of players in possession of the ball, as well as inter-player passing interactions. Nineteen professional outfield male players were divided into two teams of 10 and 9 players, respectively. The game was played under three spatial constraints: a players were not allowed to move out of their allocated zones, except for the player in possession of the ball; b players were allowed to move to an adjacent zone, and; c non-specific spatial constraints. Positional data was captured using a 5 Hz interpolated GPS tracking system and used to define the configuration states of players for each second in time. The configuration state comprised 37 categories derived from tactical actions, distance from the nearest opponent, distance from the target and movement speed. Notational analysis of players in possession of the ball allowed the mean time of ball possession and the probabilities of passing the ball between players to be calculated. The results revealed that the players' long-term exploratory behaviour decreased and their short-term exploration increased when restricting their space of interaction. Relaxing players' positional constraints seemed to increase the speed of ball flow dynamics. Allowing players to move to an adjacent sub-area increased the probabilities of interaction with the full-back during play build-up. The instability of the coordinative state defined by being free from opponents when players had the ball possession was an invariant feature under all three task constraints. By allowing players to move to adjacent sub-areas, the

Towards Player Adaptivity in a Serious Game for Conflict Resolution

DEFF Research Database (Denmark)

Grappiolo, C.; Cheong, Yun-Gyung; Togelius, J.

2011-01-01

to resolve this type of conflict, the underlying system generates level content automatically which adapts to player experience and behaviour. Preliminary results demonstrate the efficiency of the procedural content generation mechanism in guiding the training of players towards targeted learning objectives.......We present a technology demonstrator for an adaptive serious game for teaching conflict resolution and discuss the research questions associated with the project. The prototype is a single-player 3D mini-game which simulates a resource management conflict scenario. In order to teach the player how...

Game Performance Evaluation in Male Goalball Players

Science.gov (United States)

Molik, Bartosz; Morgulec-Adamowicz, Natalia; Kosmol, Andrzej; Perkowski, Krzysztof; Bednarczuk, Grzegorz; Skowroński, Waldemar; Gomez, Miguel Angel; Koc, Krzysztof; Rutkowska, Izabela; Szyman, Robert J

2015-01-01

Goalball is a Paralympic sport exclusively for athletes who are visually impaired and blind. The aims of this study were twofold: to describe game performance of elite male goalball players based upon the degree of visual impairment, and to determine if game performance was related to anthropometric characteristics of elite male goalball players. The study sample consisted of 44 male goalball athletes. A total of 38 games were recorded during the Summer Paralympic Games in London 2012. Observations were reported using the Game Efficiency Sheet for Goalball. Additional anthropometric measurements included body mass (kg), body height (cm), the arm span (cm) and length of the body in the defensive position (cm). The results differentiating both groups showed that the players with total blindness obtained higher means than the players with visual impairment for game indicators such as the sum of defense (p = 0.03) and the sum of good defense (p = 0.04). The players with visual impairment obtained higher results than those with total blindness for attack efficiency (p = 0.04), the sum of penalty defenses (p = 0.01), and fouls (p = 0.01). The study showed that athletes with blindness demonstrated higher game performance in defence. However, athletes with visual impairment presented higher efficiency in offensive actions. The analyses confirmed that body mass, body height, the arm span and length of the body in the defensive position did not differentiate players’ performance at the elite level. PMID:26834872

Game Performance Evaluation in Male Goalball Players

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Molik Bartosz

2015-12-01

Full Text Available Goalball is a Paralympic sport exclusively for athletes who are visually impaired and blind. The aims of this study were twofold: to describe game performance of elite male goalball players based upon the degree of visual impairment, and to determine if game performance was related to anthropometric characteristics of elite male goalball players. The study sample consisted of 44 male goalball athletes. A total of 38 games were recorded during the Summer Paralympic Games in London 2012. Observations were reported using the Game Efficiency Sheet for Goalball. Additional anthropometric measurements included body mass (kg, body height (cm, the arm span (cm and length of the body in the defensive position (cm. The results differentiating both groups showed that the players with total blindness obtained higher means than the players with visual impairment for game indicators such as the sum of defense (p = 0.03 and the sum of good defense (p = 0.04. The players with visual impairment obtained higher results than those with total blindness for attack efficiency (p = 0.04, the sum of penalty defenses (p = 0.01, and fouls (p = 0.01. The study showed that athletes with blindness demonstrated higher game performance in defence. However, athletes with visual impairment presented higher efficiency in offensive actions. The analyses confirmed that body mass, body height, the arm span and length of the body in the defensive position did not differentiate players’ performance at the elite level.

[Eating habits of a group of professional volleyball players].

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Gacek, Maria

2011-01-01

The aim of the research was an analysis of the eating habits of professional volleyball players according to their sex and age. The research has been carried out on a group of 210 men players and women players at the age of 13-25, representatives of sports clubs in Ostrołeka, Myślenice, Bydgoszcz and Warszawa. The research has revealed a limited realisation of rational diets by both men and women players. The most common mistakes made by them include a smaller number of meals during the day than recommended (especially among men), taking up training on empty stomach and insufficient frequency of consumption of dairy products, fish, vegetables and fruit. The research has also revealed excessive consumption of sweets, sweet sparkling drinks and fast food (mainly among men). The examined players to some extent only apply regular strategies of rehydration of their organisms. A high percentage of them do not pay attention to supplementation of liquids after an effort or they drink a lot of liquids at one time. The most frequently chosen drinks were mineral water and isotonic drinks. Supplementation was applied by a small percentage of the players, mainly men, who most often chose vitamins, Izostar, creatine, L-carnitine and HMB.

The health status of retired American football players: Super Bowl III revisited.

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Nicholas, Stephen J; Nicholas, James A; Nicholas, Calvin; Diecchio, Jennifer R; McHugh, Malachy P

2007-10-01

Despite a perception that retired professional football players have poor health, there are little supporting data. Retired football players have poor health compared with age-matched population norms. Cross-sectional study; Level of evidence, 4. Thirty-six of 41 members of the 1969 Super Bowl winning team were contacted 35 years after that event (3 were deceased, and no contact information was available for 2). Players completed an SF-36 health survey and a medical history and football-specific questionnaire. Each player's football-related injury history before 1969 was documented from medical records. It was estimated that there was 80% power to detect a 10% difference in physical and mental health scores between the retired football players (age, 62 +/- 3 y) and population norms (n = 741) at an alpha level of 0.05. SF-36 scores for physical and mental health were not different from age-matched norms (physical health P = .69; mental health P = .49). The most prevalent medical conditions were arthritis (24 of 36 players), hypertension (13 of 36 players), and chronic low back pain (13 of 36 players). SF-36 physical health scores were 21% lower in players with arthritis (P football for 8.3 +/- 3.8 years, and 33 players (94%) reported having had "very fulfilling" (n = 24) or "somewhat fulfilling" (n = 9) careers. These professional football players had long and fulfilling careers with no apparent long-term detrimental effects on physical or mental health scores despite a high prevalence of arthritis.

Responses of Lower-Body Power and Match Running Demands Following Long-Haul Travel in International Rugby Sevens Players.

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Mitchell, John A; Pumpa, Kate L; Pyne, David B

2017-03-01

Mitchell, JA, Pumpa, KL, and Pyne, DB. Responses of lowerbody power and match running demands after long-haul travel in international rugby sevens players. J Strength Cond Res 31(3): 686-695, 2017-This study determined the effect of long-haul (>5 hours) travel on lower-body power and match running demands in international rugby sevens players. Lower-body power was assessed in 22 male international rugby sevens players (age 21.7 ± 2.7 years, mass 89.0 ± 6.7 kg, stature 180.5 ± 6.2 cm; mean ± SD) monitored over 17 rugby sevens tournaments. A countermovement jump was used to monitor lower-body power (peak and mean power) over repeated three week travel and competition periods (pretravel, posttravel, and posttournament). Small decreases were evident in peak power after both short and long-haul travel (-4.0%, ±3.2%; mean, ±90% confidence limits) with further reductions in peak and mean power posttournament (-4.5%, ±2.3% and -3.8%, ±1.5%) culminating in a moderate decrease in peak power overall (-7.4%, ±4.0%). A subset of 12 players (completing a minimum of 8 tournaments) had the effects of match running demands assessed with lower-body power. In this subset, long-haul travel elicited a large decrease in lower-body peak (-9.4%, ±3.5%) and mean power (-5.6%, ±2.9%) over the monitoring period, with a small decrease (-4.3%, ±3.0% and -2.2%, ±1.7%) posttravel and moderate decrease (-5.4%, ±2.5% and -3.5%, ±1.9%) posttournament, respectively. Match running demands were monitored through global positioning system. In long-haul tournaments, the 12 players covered ∼13%, ±13% greater total distance (meter) and ∼11%, ±10% higher average game meters >5 m·s when compared with short-haul (rugby sevens tournaments after long-haul travel.

Multiple periodic solutions to a class of second-order nonlinear mixed-type functional differential equations

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Xiao-Bao Shu

2005-01-01

Full Text Available By means of variational structure and Z2 group index theory, we obtain multiple periodic solutions to a class of second-order mixed-type differential equations x''(t−τ+f(t,x(t,x(t−τ,x(t−2τ=0 and x''(t−τ+λ(tf1(t,x(t,x(t−τ,x(t−2τ=x(t−τ.

The influence of physical and cognitive factors on reactive agility performance in men basketball players.

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Scanlan, Aaron; Humphries, Brendan; Tucker, Patrick S; Dalbo, Vincent

2014-01-01

This study explored the influence of physical and cognitive measures on reactive agility performance in basketball players. Twelve men basketball players performed multiple sprint, Change of Direction Speed Test, and Reactive Agility Test trials. Pearson's correlation analyses were used to determine relationships between the predictor variables (stature, mass, body composition, 5-m, 10-m and 20-m sprint times, peak speed, closed-skill agility time, response time and decision-making time) and reactive agility time (response variable). Simple and stepwise regression analyses determined the individual influence of each predictor variable and the best predictor model for reactive agility time. Morphological (r = -0.45 to 0.19), sprint (r = -0.40 to 0.41) and change-of-direction speed measures (r = 0.43) had small to moderate correlations with reactive agility time. Response time (r = 0.76, P = 0.004) and decision-making time (r = 0.58, P = 0.049) had large to very large relationships with reactive agility time. Response time was identified as the sole predictor variable for reactive agility time in the stepwise model (R(2) = 0.58, P = 0.004). In conclusion, cognitive measures had the greatest influence on reactive agility performance in men basketball players. These findings suggest reaction and decision-making drills should be incorporated in basketball training programmes.

ANTHROPOMETRIC AND PHYSIOLOGICAL CHARACTERISTICS ON INDIAN INTERUNIVERSITY BASKETBALL PLAYERS