Electromyographic analysis of repeated bouts of eccentric exercise.

Science.gov (United States)

McHugh, M P; Connolly, D A; Eston, R G; Gartman, E J; Gleim, G W

2001-03-01

The repeated bout effect refers to the protective effect provided by a single bout of eccentric exercise against muscle damage from a similar subsequent bout. The aim of this study was to determine if the repeated bout was associated with an increase in motor unit activation relative to force production, an increased recruitment of slow-twitch motor units or increased motor unit synchronization. Surface electromyographic (EMG) signals were recorded from the hamstring muscles during two bouts of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions separated by 2 weeks. The EMG per unit torque and median frequency were analysed. The initial bout of eccentric exercise resulted in strength loss, pain and muscle tenderness, while the repeated eccentric bout resulted in a slight increase in strength, no pain and no muscle tenderness (bout x time effects, P exercise. The EMG per unit torque and median frequency were not different between the initial and repeated bouts of eccentric exercise. The EMG per unit torque and median frequency increased during both bouts of eccentric exercise (P < 0.01) but did not change during either concentric bout. In conclusion, there was no evidence that the repeated bout effect was due to a neural adaptation.

Eccentric and concentric cardiac hypertrophy induced by exercise training: microRNAs and molecular determinants.

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Fernandes, T; Soci, U P R; Oliveira, E M

2011-09-01

Among the molecular, biochemical and cellular processes that orchestrate the development of the different phenotypes of cardiac hypertrophy in response to physiological stimuli or pathological insults, the specific contribution of exercise training has recently become appreciated. Physiological cardiac hypertrophy involves complex cardiac remodeling that occurs as an adaptive response to static or dynamic chronic exercise, but the stimuli and molecular mechanisms underlying transduction of the hemodynamic overload into myocardial growth are poorly understood. This review summarizes the physiological stimuli that induce concentric and eccentric physiological hypertrophy, and discusses the molecular mechanisms, sarcomeric organization, and signaling pathway involved, also showing that the cardiac markers of pathological hypertrophy (atrial natriuretic factor, β-myosin heavy chain and α-skeletal actin) are not increased. There is no fibrosis and no cardiac dysfunction in eccentric or concentric hypertrophy induced by exercise training. Therefore, the renin-angiotensin system has been implicated as one of the regulatory mechanisms for the control of cardiac function and structure. Here, we show that the angiotensin II type 1 (AT1) receptor is locally activated in pathological and physiological cardiac hypertrophy, although with exercise training it can be stimulated independently of the involvement of angiotensin II. Recently, microRNAs (miRs) have been investigated as a possible therapeutic approach since they regulate the translation of the target mRNAs involved in cardiac hypertrophy; however, miRs in relation to physiological hypertrophy have not been extensively investigated. We summarize here profiling studies that have examined miRs in pathological and physiological cardiac hypertrophy. An understanding of physiological cardiac remodeling may provide a strategy to improve ventricular function in cardiac dysfunction.

Eccentric and concentric cardiac hypertrophy induced by exercise training: microRNAs and molecular determinants

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T. Fernandes

2011-09-01

Full Text Available Among the molecular, biochemical and cellular processes that orchestrate the development of the different phenotypes of cardiac hypertrophy in response to physiological stimuli or pathological insults, the specific contribution of exercise training has recently become appreciated. Physiological cardiac hypertrophy involves complex cardiac remodeling that occurs as an adaptive response to static or dynamic chronic exercise, but the stimuli and molecular mechanisms underlying transduction of the hemodynamic overload into myocardial growth are poorly understood. This review summarizes the physiological stimuli that induce concentric and eccentric physiological hypertrophy, and discusses the molecular mechanisms, sarcomeric organization, and signaling pathway involved, also showing that the cardiac markers of pathological hypertrophy (atrial natriuretic factor, β-myosin heavy chain and α-skeletal actin are not increased. There is no fibrosis and no cardiac dysfunction in eccentric or concentric hypertrophy induced by exercise training. Therefore, the renin-angiotensin system has been implicated as one of the regulatory mechanisms for the control of cardiac function and structure. Here, we show that the angiotensin II type 1 (AT1 receptor is locally activated in pathological and physiological cardiac hypertrophy, although with exercise training it can be stimulated independently of the involvement of angiotensin II. Recently, microRNAs (miRs have been investigated as a possible therapeutic approach since they regulate the translation of the target mRNAs involved in cardiac hypertrophy; however, miRs in relation to physiological hypertrophy have not been extensively investigated. We summarize here profiling studies that have examined miRs in pathological and physiological cardiac hypertrophy. An understanding of physiological cardiac remodeling may provide a strategy to improve ventricular function in cardiac dysfunction.

Eccentric exercise training in patients with chronic obstructive pulmonary disease.

NARCIS (Netherlands)

Rooyackers, J.M.; Berkeljon, D.A.; Folgering, H.T.M.

2003-01-01

The oxygen cost of eccentric exercise is lower than that of concentric exercise at similar work-loads. In this study, the response to eccentric cycle exercise training (EET) in addition to general exercise training (GET) on exercise performance and quality of life was investigated in 24 patients

Motor unit activity after eccentric exercise and muscle damage in humans.

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Semmler, J G

2014-04-01

It is well known that unaccustomed eccentric exercise leads to muscle damage and soreness, which can produce long-lasting effects on muscle function. How this muscle damage influences muscle activation is poorly understood. The purpose of this brief review is to highlight the effect of eccentric exercise on the activation of muscle by the nervous system, by examining the change in motor unit activity obtained from surface electromyography (EMG) and intramuscular recordings. Previous research shows that eccentric exercise produces unusual changes in the EMG–force relation that influences motor performance during isometric, shortening and lengthening muscle contractions and during fatiguing tasks. When examining the effect of eccentric exercise at the single motor unit level, there are substantial changes in recruitment thresholds, discharge rates, motor unit conduction velocities and synchronization, which can last for up to 1 week after eccentric exercise. Examining the time course of these changes suggests that the increased submaximal EMG after eccentric exercise most likely occurs through a decrease in motor unit conduction velocity and an increase in motor unit activity related to antagonist muscle coactivation and low-frequency fatigue. Furthermore, there is a commonly held view that eccentric exercise produces preferential damage to high-threshold motor units, but the evidence for this in humans is limited. Further research is needed to establish whether there is preferential damage to high-threshold motor units after eccentric exercise in humans, preferably by linking changes in motor unit activity with estimates of motor unit size using selective intramuscular recording techniques.

The magnitude of muscle strain does not influence serial sarcomere number adaptations following eccentric exercise.

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Butterfield, Timothy A; Herzog, Walter

2006-02-01

It is generally accepted that eccentric exercise, when performed by a muscle that is unaccustomed to that type of contraction, results in a delayed onset of muscle soreness (DOMS). A prolonged exposure to eccentric exercise leads to the disappearance of the signs and symptoms associated with DOMS, which has been referred to as the repeated bout effect (RBE). Although the mechanisms underlying the RBE remain unclear, several mechanisms have been proposed, including the serial sarcomere number addition following exercise induced muscle damage. In the traditional DOMS and RBE protocols, muscle injury has been treated as a global parameter, with muscle force and strain assumed to be uniform throughout the muscle. To assess the effects of muscle-tendon unit strain, fiber strain, torque and injury on serial sarcomere number adaptations, three groups of New Zealand White (NZW) rabbits were subjected to chronic repetitive eccentric exercise bouts of the ankle dorsiflexors for 6 weeks. These eccentric exercise protocols consisted of identical muscle tendon unit (MTU) strain, but other mechanical factors were systematically altered. Following chronic eccentric exercise, serial sarcomere number adaptations were not identical between the three eccentric exercise protocols, and serial sarcomere number adaptations were not uniform across all regions of the muscle. Peak torque and relaxation fiber strain were the best predictors of serial sarcomere number across all three protocols. Therefore, MTU strain does not appear to be the primary cause for sarcomerogenesis, and differential adaptations within the muscle may be explained by the nonuniform architecture of the muscle, resulting in differential local fiber strains.

The Effect of Eccentric Exercise-Induced Delayed-Onset Muscle Soreness on Positioning Sense and Shooting Percentage in Wheelchair Basketball Players

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Mehmet Akif Serinken

2013-12-01

Full Text Available Background: Eccentric exercise is defined as a type of exercise in which the muscle produces power by extending. In contrast to isometric and concentric exercises, eccentric muscle activity is much more effective mechanically; however, it may expose the muscle to soreness. Delayed-Onset Muscle Soreness (DOMS emerges a couple of hours after an eccentric activity, especially in individuals who are not used to this kind of exercise, and causes a temporary decrease in muscle performance, joint movement angle and muscle power, and also a temporary increase in the blood creatine kinase (CK activity. Aims: This study investigates the effect of DOMS on the upper extremities motor performance by conducting an eccentric exercise load on the elbow flexor muscles. Study design: Cross sectional study. Methods: The study included 10 wheelchair basketball players. First, the participants underwent blood CK activity, positioning sense, muscle pain, shooting performance measurements tests at the base, and after 30 minutes and 24 and 48 hours. Then, one week later, the one-repetition-maximums of biceps curls were determined in order to define the intensity of the eccentric exercise. An eccentric exercise protocol which would cause DOMS was applied to all players. All tests were replaced with acute exhaustive eccentric exercise; the same tests were repeated in the same order after the exercise. Blood CK activity was measured by taking an earlobe capillary blood sample. The muscle pain level was measured by using a Visual Analogue Scale (VAS. Positioning sense loss was assessed via goniometer at 30º, 60º and 90º degrees horizontally. Results: The study found a statistically significant increase in blood CK activity and positioning sense loss, and a decrease in the pressure-pain threshold, as well as the shooting percentages in the exercise group when compared with the control. Conclusion: These findings suggest that DOMS negatively affects the upper extremities

Effect of eccentric exercise with reduced muscle glycogen on plasma interleukin-6 and neuromuscular responses of musculus quadriceps femoris.

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Gavin, James P; Myers, Stephen D; Willems, Mark E T

2016-07-01

Eccentric exercise can result in muscle damage and interleukin-6 (IL-6) secretion. Glycogen availability is a potent stimulator of IL-6 secretion. We examined effects of eccentric exercise in a low-glycogen state on neuromuscular function and plasma IL-6 secretion. Twelve active men (23 ± 4 yr, 179 ± 5 cm, 77 ± 10 kg, means ± SD) completed two downhill treadmill runs (gradient, -12%, 5 × 8 min; speed, 12.1 ± 1.1 km/h) with normal (NG) and reduced muscle glycogen (RG) in randomized order and at least 6 wk apart. Muscle glycogen was reduced using an established cycling protocol until exhaustion and dietary manipulation the evening before the morning run. Physiological responses were measured up to 48 h after the downhill runs. During recovery, force deficits of musculus quadriceps femoris by maximal isometric contractions were similar. Changes in low-frequency fatigue were larger with RG. Voluntary activation and plasma IL-6 levels were similar in recovery between conditions. It is concluded that unaccustomed, damaging eccentric exercise with low muscle glycogen of the m. quadriceps femoris 1) exacerbated low-frequency fatigue but 2) had no additional effect on IL-6 secretion. Neuromuscular impairment after eccentric exercise with low muscle glycogen appears to have a greater peripheral component in early recovery. Copyright © 2016 the American Physiological Society.

Achilles tendon of wistar rats treated with laser therapy and eccentric exercise

OpenAIRE

Souza, Maria Verônica de; Silva, Carlos Henrique Osório; Silva, Micheline Ozana da; Costa, Marcela Bueno Martins da; Dornas, Raul Felipe; Borges, Andréa Pacheco Batista; Natali, Antônio José

2015-01-01

ABSTRACTIntroduction:Both laser therapy and eccentric exercises are used in tendon injuries. However, the association of these physiotherapeutic modalities is yet little investigated.Objective:To evaluate the effect of low-level laser therapy associated to eccentric exercise (downhill walking) on Achilles tendinopathy of Wistar rats.Method:Eighteen Achilles tendon from 15 adult male Wistar rats were used. Tendons were distributed in six groups (laser, eccentric exercise, laser and eccentric e...

Exacerbation of Brain Injury by Post-Stroke Exercise Is Contingent Upon Exercise Initiation Timing

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Fengwu Li

2017-10-01

Full Text Available Accumulating evidence has demonstrated that post-stroke physical rehabilitation may reduce morbidity. The effectiveness of post-stroke exercise, however, appears to be contingent upon exercise initiation. This study assessed the hypothesis that very early exercise exacerbates brain injury, induces reactive oxygen species (ROS generation, and promotes energy failure. A total of 230 adult male Sprague-Dawley rats were subjected to middle cerebral artery (MCA occlusion for 2 h, and randomized into eight groups, including two sham injury control groups, three non-exercise and three exercise groups. Exercise was initiated after 6 h, 24 h and 3 days of reperfusion. Twenty-four hours after completion of exercise (and at corresponding time points in non-exercise controls, infarct volumes and apoptotic cell death were examined. Early brain oxidative metabolism was quantified by examining ROS, ATP and NADH levels 0.5 h after completion of exercise. Furthermore, protein expressions of angiogenic growth factors were measured in order to determine whether post-stroke angiogenesis played a role in rehabilitation. As expected, ischemic stroke resulted in brain infarction, apoptotic cell death and ROS generation, and diminished NADH and ATP production. Infarct volumes and apoptotic cell death were enhanced (p < 0.05 by exercise that was initiated after 6 h of reperfusion, but decreased by late exercise (24 h, 3 days. This exacerbated brain injury at 6 h was associated with increased ROS levels (p < 0.05, and decreased (p < 0.05 NADH and ATP levels. In conclusion, very early exercise aggravated brain damage, and early exercise-induced energy failure with ROS generation may underlie the exacerbation of brain injury. These results shed light on the manner in which exercise initiation timing may affect post-stroke rehabilitation.

Is eccentric exercise an effective treatment for lateral epicondylitis? A systematic review.

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Cullinane, Frances L; Boocock, Mark G; Trevelyan, Fiona C

2014-01-01

To establish the effectiveness of eccentric exercise as a treatment intervention for lateral epicondylitis. ProQuest, Medline via EBSCO, AMED, Scopus, Web of Science, CINAHL. A systematic review was undertaken to identify randomized and controlled clinical trials incorporating eccentric exercise as a treatment for patients diagnosed with lateral epicondylitis. Studies were included if: they incorporated eccentric exercise, either in isolation or as part of a multimodal treatment protocol; they assessed at least one functional or disability outcome measure; and the patients had undergone diagnostic testing. The methodological quality of each study was assessed using the Modified Cochrane Musculoskeletal Injuries Group score sheet. Twelve studies met the inclusion criteria. Three were deemed 'high' quality, seven were 'medium' quality, and two were 'low' quality. Eight of the studies were randomized trials investigating a total of 334 subjects. Following treatment, all groups inclusive of eccentric exercise reported decreased pain and improved function and grip strength from baseline. Seven studies reported improvements in pain, function, and/or grip strength for therapy treatments inclusive of eccentric exercise when compared with those excluding eccentric exercise. Only one low-quality study investigated the isolated effects of eccentric exercise for treating lateral epicondylitis and found no significant improvements in pain when compared with other treatments. The majority of consistent findings support the inclusion of eccentric exercise as part of a multimodal therapy programme for improved outcomes in patients with lateral epicondylitis.

Lengthening our perspective: morphological, cellular, and molecular responses to eccentric exercise.

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Hyldahl, Robert D; Hubal, Monica J

2014-02-01

The response of skeletal muscle to unaccustomed eccentric exercise has been studied widely, yet it is incompletely understood. This review is intended to provide an up-to-date overview of our understanding of how skeletal muscle responds to eccentric actions, with particular emphasis on the underlying molecular and cellular mechanisms of damage and recovery. This review begins by addressing the question of whether eccentric actions result in physical damage to muscle fibers and/or connective tissue. We next review the symptomatic manifestations of eccentric exercise (i.e., indirect damage markers, such as delayed onset muscle soreness), with emphasis on their relatively poorly understood molecular underpinnings. We then highlight factors that potentially modify the muscle damage response following eccentric exercise. Finally, we explore the utility of using eccentric training to improve muscle function in populations of healthy and aging individuals, as well as those living with neuromuscular disorders. Copyright © 2013 Wiley Periodicals, Inc.

Eccentric exercise decreases maximal insulin action in humans

DEFF Research Database (Denmark)

Asp, Svend; Daugaard, J R; Kristiansen, S

1996-01-01

subjects participated in two euglycaemic clamps, performed in random order. One clamp was preceded 2 days earlier by one-legged eccentric exercise (post-eccentric exercise clamp (PEC)) and one was without the prior exercise (control clamp (CC)). 2. During PEC the maximal insulin-stimulated glucose uptake...... for all three clamp steps used (P maximal activity of glycogen synthase was identical in the two thighs for all clamp steps. 3. The glucose infusion rate (GIR......) necessary to maintain euglycaemia during maximal insulin stimulation was lower during PEC compared with CC (15.7%, 81.3 +/- 3.2 vs. 96.4 +/- 8.8 mumol kg-1 min-1, P maximal...

Eccentric exercise: mechanisms and effects when used as training regime or training adjunct.

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Vogt, Michael; Hoppeler, Hans H

2014-06-01

The aim of the current review is to discuss applications and mechanism of eccentric exercise in training regimes of competitive sports. Eccentric muscle work is important in most sports. Eccentric muscle contractions enhance the performance during the concentric phase of stretch-shortening cycles, which is important in disciplines like sprinting, jumping, throwing, and running. Muscles activated during lengthening movements can also function as shock absorbers, to decelerate during landing tasks or to precisely deal with high external loading in sports like alpine skiing. The few studies available on trained subjects reveal that eccentric training can further enhance maximal muscle strength and power. It can further optimize muscle length for maximal tension development at a greater degree of extension, and has potential to improve muscle coordination during eccentric tasks. In skeletal muscles, these functional adaptations are based on increases in muscle mass, fascicle length, number of sarcomeres, and cross-sectional area of type II fibers. Identified modalities for eccentric loading in athletic populations involve classical isotonic exercises, accentuated jumping exercises, eccentric overloading exercises, and eccentric cycle ergometry. We conclude that eccentric exercise offers a promising training modality to enhance performance and to prevent injuries in athletes. However, further research is necessary to better understand how the neuromuscular system adapts to eccentric loading in athletes. Copyright © 2014 the American Physiological Society.

Local NSAID infusion inhibits satellite cell proliferation in human skeletal muscle after eccentric exercise

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Mikkelsen, U R; Langberg, H; Helmark, I C

2009-01-01

Despite the widespread consumption of nonsteroidal anti-inflammatory drugs (NSAIDs), the influence of these drugs on muscle satellite cells is not fully understood. The aim of the present study was to investigate the effect of a local NSAID infusion on satellite cells after unaccustomed eccentric...... exercise in vivo in human skeletal muscle. Eight young healthy males performed 200 maximal eccentric contractions with each leg. An NSAID was infused via a microdialysis catheter into the vastus lateralis muscle of one leg (NSAID leg) before, during, and for 4.5 h after exercise, with the other leg working...... cells (CD68(+) or CD16(+) cells) was not significantly increased in either of the legs 8 days after exercise and was unaffected by the NSAID. The main finding in the present study was that the NSAID infusion for 7.5 h during the exercise day suppressed the exercise-induced increase in the number...

Additional effects of taurine on the benefits of BCAA intake for the delayed-onset muscle soreness and muscle damage induced by high-intensity eccentric exercise.

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Ra, Song-Gyu; Miyazaki, Teruo; Ishikura, Keisuke; Nagayama, Hisashi; Suzuki, Takafumi; Maeda, Seiji; Ito, Masaharu; Matsuzaki, Yasushi; Ohmori, Hajime

2013-01-01

Taurine (TAU) has a lot of the biological, physiological, and pharmocological functions including anti-inflammatory and anti-oxidative stress. Although previous studies have appreciated the effectiveness of branched-chain amino acids (BCAA) on the delayed-onset muscle soreness (DOMS), consistent finding has not still convinced. The aim of this study was to examine the additional effect of TAU with BCAA on the DOMS and muscle damages after eccentric exercise. Thirty-six untrained male volunteers were equally divided into four groups, and ingested a combination with 2.0 g TAU (or placebo) and 3.2 g BCAA (or placebo), thrice a day, 2 weeks prior to and 4 days after elbow flexion eccentric exercise. Following the period after eccentric exercise, the physiological and blood biochemical markers for DOMS and muscle damage showed improvement in the combination of TAU and BCAA supplementation rather than in the single or placebo supplementations. In conclusion, additional supplement of TAU with BCAA would be a useful way to attenuate DOMS and muscle damages induced by high-intensity exercise.

Eccentric exercise in treatment of Achilles tendinopathy.

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Nørregaard, J; Larsen, C C; Bieler, T; Langberg, H

2007-04-01

Prognosis and treatment of Achilles tendon pain (achillodynia) has been insufficiently studied. The purpose of the present study was to examine the long-term effect of eccentric exercises compared with stretching exercises on patients with achillodynia. Patients with achillodynia for at least 3 months were randomly allocated to one of two exercise regimens. Exercise was performed daily for a 3-month period. Symptom severity was evaluated by tendon tenderness, ultrasonography, a questionnaire on pain and other symptoms, and a global assessment of improvement. Follow-up was performed at time points 3, 6, 9, 12 weeks and 1 year. Of 53 patients with achillodynia 45 patients were randomized to either eccentric exercises or stretching exercises. Symptoms gradually improved during the 1-year follow-up period and were significantly better assessed by pain and symptoms after 3 weeks and all later visits. However, no significant differences could be observed between the two groups. Women and patients with symptoms from the distal part of the tendon had significantly less improvement. Marked improvement in symptoms and findings could be gradually observed in both groups during the 1-year follow-up period. To that extent this is due to effect of both regimens or the spontaneous improvement is unsettled.

Metabolic and anti-inflammatory benefits of eccentric endurance exercise - a pilot study.

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Drexel, H; Saely, C H; Langer, P; Loruenser, G; Marte, T; Risch, L; Hoefle, G; Aczel, S

2008-04-01

Eccentric endurance exercise (e.g. hiking downwards) is less strenuous than concentric exercise (e.g. hiking upwards) but its potential to reduce cardiovascular risk is unknown. We randomly allocated 45 healthy sedentary individuals (16 men and 29 women, mean age 48 years) to one of two groups, one beginning with two months of hiking upwards, the other with two months of hiking downwards the same route, with a crossover for a further two months. For the opposite way, a cable car was used where compliance was recorded electronically. The difference in altitude was 540 metres; the distance was covered three to five times a week. Fasting and postprandial metabolic profiles were obtained at baseline and after the two month periods of eccentric and concentric exercise, respectively. Forty-two of the 45 participants completed the study; the compliance rate was therefore 93%. Compared with baseline, eccentric exercise lowered total cholesterol (by 4.1%; P = 0.026), low-density lipoprotein (LDL) cholesterol (by 8.4%, P = 0.001), Apolipoprotein B/Apolipoprotein A1 ratio (by 10.9%, P < 0.001), homeostasis model assessment of insulin resistance scores (by 26.2%, P = 0.017) and C-reactive protein (by 30.0%; P = 0.007); the magnitude of these changes was comparable to that of concentric exercise. Eccentric exercise improved glucose tolerance (by 6.2%, P = 0.023), whereas concentric exercise improved triglyceride tolerance (by 14.9%, P = 0.022). Eccentric endurance exercise is a promising new exercise modality with favourable metabolic and anti-inflammatory effects and is well applicable to sedentary individuals.

The Effect of Exercise-Induced Muscle Damage After a Bout of Accentuated Eccentric Load Drop Jumps and the Repeated Bout Effect.

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Bridgeman, Lee A; Gill, Nicholas D; Dulson, Deborah K; McGuigan, Michael R

2017-02-01

Bridgeman, LA, Gill, ND, Dulson, DK, and McGuigan, MR. The effect of exercise induced muscle damage after a bout of accentuated eccentric load drop jumps and the repeated bout effect. J Strength Cond Res 31(2): 386-394, 2017-Although previous studies have investigated exercise-induced muscle damage (EIMD) after a bout of unloaded drop jumps (DJs), none have investigated the effects of accentuated eccentric load (AEL) DJs on EIMD. The purpose of this study was to investigate the effects of 30 and 50 AEL DJs on strength, jump performance, muscle soreness, and blood markers. Eight resistance trained athletes participated in this study. In week 1, baseline countermovement jump (CMJ), squat jump (SJ), concentric and eccentric peak force (PF), creatine kinase, and muscle soreness were assessed. Subjects then completed 30 AEL DJs and baseline measures were retested immediately postintervention, 1, 24, and 48 hours later. Two weeks later, the subjects completed the same protocol with an increase in AEL DJ volume (50). Subjects' SJ height was reduced in week 1 compared with week 3, postintervention, 1, 24, and 48 hours later (ES = -0.34, -0.44, -0.38, and -0.40). Subjects' CMJ height was reduced in week 1 compared with week 3, postintervention, 1, and 24 hours later (ES = -0.37, -0.29, and -0.39). Concentric PF was reduced in week 1 compared with week 3, postintervention and 24 and 48 hours later (ES = -0.02, -0.23, and -0.32). Eccentric PF was reduced in week 1 compared with week 3, postintervention, 24, and 48 hours later (ES = -0.24, -0.16, and -0.50). In this sample, 30 AEL DJs attenuated the effects of EIMD following which 50 AEL DJs completed 2 weeks later.

The effects of a repeated bout of eccentric exercise on indices of muscle damage and delayed onset muscle soreness.

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Paddon-Jones, D; Muthalib, M; Jenkins, D

2000-03-01

This study examined markers of muscle damage following a repeated bout of maximal isokinetic eccentric exercise performed prior to full recovery from a previous bout. Twenty non-resistance trained volunteers were randomly assigned to a control (CON, n=10) or experimental (EXP, n=10) group. Both groups performed 36 maximal isokinetic eccentric contractions of the elbow flexors of the non-dominant arm (ECC1). The EXP group repeated the same eccentric exercise bout two days later (ECC2). Total work and peak eccentric torque were recorded during each set of ECC1 and ECC2. Isometric torque, delayed onset muscle soreness (DOMS), flexed elbow angle and plasma creatine kinase (CK) activity were measured prior to and immediately following ECC1 and ECC2. at 24h intervals for 7 days following ECC1 and finally on day 11. In both groups, all dependent variables changed significantly during the 2 days following ECC1. A further acute post-exercise impairment in isometric torque (30 +/- 5%) and flexed elbow angle (20 +/- 4%) was observed following ECC2 (p0.05). These findings suggest that when maximal isokinetic eccentric exercise is repeated two days after experiencing of contraction-induced muscle damage, the recovery time course is not significantly altered.

Ultrasound-Guided Percutaneous Electrolysis and Eccentric Exercises for Subacromial Pain Syndrome: A Randomized Clinical Trial

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José L. Arias-Buría

2015-01-01

Full Text Available Objective. To compare effects of ultrasound- (US- guided percutaneous electrolysis combined with an eccentric exercise program of the rotator cuff muscles in subacromial pain syndrome. Methods. Thirty-six patients were randomized and assigned into US-guided percutaneous electrolysis (n=17 group or exercise (n=19 group. Patients were asked to perform an eccentric exercise program of the rotator cuff muscles twice every day for 4 weeks. Participants assigned to US-guided percutaneous electrolysis group also received the application of galvanic current through acupuncture needle on each session once a week (total 4 sessions. Shoulder pain (NPRS and disability (DASH were assessed at baseline, after 2 sessions, and 1 week after the last session. Results. The ANOVA revealed significant Group∗Time interactions for shoulder pain and disability (all, P<0.01: individuals receiving US-guided percutaneous electrolysis combined with the eccentric exercises experienced greater improvement than those receiving eccentric exercise alone. Conclusions. US-guided percutaneous electrolysis combined with eccentric exercises resulted in small better outcomes at short term compared to when only eccentric exercises were applied in subacromial pain syndrome. The effect was statistically and clinically significant for shoulder pain but below minimal clinical difference for function. Future studies should investigate the long-term effects and potential placebo effect of this intervention.

Changes in Achilles tendon mechanical properties following eccentric heel drop exercise are specific to the free tendon.

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Obst, S J; Newsham-West, R; Barrett, R S

2016-04-01

Mechanical loading of the Achilles tendon during isolated eccentric contractions could induce immediate and region-dependent changes in mechanical properties. Three-dimensional ultrasound was used to examine the immediate effect of isolated eccentric exercise on the mechanical properties of the distal (free tendon) and proximal (gastrocnemii) regions of the Achilles tendon. Participants (n = 14) underwent two testing sessions in which tendon measurements were made at rest and during a 30% and 70% isometric plantar flexion contractions immediately before and after either: (a) 3 × 15 eccentric heel drops or (b) 10-min rest. There was a significant time-by-session interaction for free tendon length and strain for all loading conditions (P tendon length and strain at all contraction intensities after eccentric exercise (P tendon for any of the measured parameters. Immediate changes in Achilles tendon mechanical properties were specific to the free tendon and consistent with changes due to mechanical creep. These findings suggest that the mechanical properties of the free tendon may be more vulnerable to change with exercise compared with the gastrocnemii aponeurosis or tendon. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Modulation of mitochondrial biomarkers by intermittent hypobaric hypoxia and aerobic exercise after eccentric exercise in trained rats.

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Rizo-Roca, David; Ríos-Kristjánsson, Juan Gabriel; Núñez-Espinosa, Cristian; Santos-Alves, Estela; Magalhães, José; Ascensão, António; Pagès, Teresa; Viscor, Ginés; Torrella, Joan Ramon

2017-07-01

Unaccustomed eccentric contractions induce muscle damage, calcium homeostasis disruption, and mitochondrial alterations. Since exercise and hypoxia are known to modulate mitochondrial function, we aimed to analyze the effects on eccentric exercise-induced muscle damage (EEIMD) in trained rats using 2 recovery protocols based on: (i) intermittent hypobaric hypoxia (IHH) and (ii) IHH followed by exercise. The expression of biomarkers related to mitochondrial biogenesis, dynamics, oxidative stress, and bioenergetics was evaluated. Soleus muscles were excised before (CTRL) and 1, 3, 7, and 14 days after an EEIMD protocol. The following treatments were applied 1 day after the EEIMD: passive normobaric recovery (PNR), 4 h daily exposure to passive IHH at 4000 m (PHR) or IHH exposure followed by aerobic exercise (AHR). Citrate synthase activity was reduced at 7 and 14 days after application of the EEIMD protocol. However, this reduction was attenuated in AHR rats at day 14. PGC-1α and Sirt3 and TOM20 levels had decreased after 1 and 3 days, but the AHR group exhibited increased expression of these proteins, as well as of Tfam, by the end of the protocol. Mfn2 greatly reduced during the first 72 h, but returned to basal levels passively. At day 14, AHR rats had higher levels of Mfn2, OPA1, and Drp1 than PNR animals. Both groups exposed to IHH showed a lower p66shc(ser 36 )/p66shc ratio than PNR animals, as well as higher complex IV subunit I and ANT levels. These results suggest that IHH positively modulates key mitochondrial aspects after EEIMD, especially when combined with aerobic exercise.

Eccentric exercise training as a countermeasure to non-weight-bearing soleus muscle atrophy

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Kirby, Christopher R.; Ryan, Mirelle J.; Booth, Frank W.

1992-01-01

This investigation tested whether eccentric resistance training could prevent soleus muscle atrophy during non-weight bearing. Adult female rats were randomly assigned to either weight bearing +/- intramuscular electrodes or non-weight bearing +/- intramuscular electrodes groups. Electrically stimulated maximal eccentric contractions were performed on anesthetized animals at 48-h intervals during the 10-day experiment. Non-weight bearing significantly reduced soleus muscle wet weight (28-31 percent) and noncollagenous protein content (30-31 percent) compared with controls. Eccentric exercise training during non-weight bearing attenuated but did not prevent the loss of soleus muscle wet weight and noncollagenous protein by 77 and 44 percent, respectively. The potential of eccentric exercise training as an effective and highly efficient counter-measure to non-weight-bearing atrophy is demonstrated in the 44 percent attenuation of soleus muscle noncollagenous protein loss by eccentric exercise during only 0.035 percent of the total non-weight-bearing time period.

Therapeutic potential of eccentric exercises for age-related muscle atrophy

Directory of Open Access Journals (Sweden)

Jae-Young Lim

2016-09-01

Full Text Available Recent studies have focused on evidence-based interventions to prevent mobility decline and enhance physical performance in older adults. Several modalities, in addition to traditional strengthening programs, have been designed to manage age-related functional decline more effectively. In this study, we reviewed the current relevant literatures to assess the therapeutic potential of eccentric exercises for age-related muscle atrophy (sarcopenia. Age-related changes in human skeletal muscle, and their relationship with physical performance, are discussed with reference to in vitro physiologic and human biomechanics studies. An overview of issues relevant to sarcopenia is provided in the context of the recent consensus on the diagnosis and management of the condition. A decline in mobility among the aging population is closely linked with changes in the muscle force–velocity relationship. Interventions based specifically on increasing velocity and eccentric strength can improve function more effectively compared with traditional strengthening programs. Eccentric strengthening programs are introduced as a specific method for improving both muscle force and velocity. To be more effective, exercise interventions for older adults should focus on enhancing the muscle force–velocity relationship. Exercises that can be performed easily, and that utilize eccentric strength (which is relatively spared during the aging process, are needed to improve both muscle force and velocity.

Eccentric Contraction-Induced Muscle Fibre Adaptation

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Arabadzhiev T. I.

2009-12-01

Full Text Available Hard-strength training induces strength increasing and muscle damage, especially after eccentric contractions. Eccentric contractions also lead to muscle adaptation. Symptoms of damage after repeated bout of the same or similar eccentrically biased exercises are markedly reduced. The mechanism of this repeated bout effect is unknown. Since electromyographic (EMG power spectra scale to lower frequencies, the adaptation is related to neural adaptation of the central nervous system (CNS presuming activation of slow-non-fatigable motor units or synchronization of motor unit firing. However, the repeated bout effect is also observed under repeated stimulation, i.e. without participation of the CNS. The aim of this study was to compare the possible effects of changes in intracellular action potential shape and in synchronization of motor units firing on EMG power spectra. To estimate possible degree of the effects of central and peripheral changes, interferent EMG was simulated under different intracellular action potential shapes and different degrees of synchronization of motor unit firing. It was shown that the effect of changes in intracellular action potential shape and muscle fibre propagation velocity (i.e. peripheral factors on spectral characteristics of EMG signals could be stronger than the effect of synchronization of firing of different motor units (i.e. central factors.

Comparing the effects of eccentric training with eccentric training and static stretching exercises in the treatment of patellar tendinopathy. A controlled clinical trial.

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Dimitrios, Stasinopoulos; Pantelis, Manias; Kalliopi, Stasinopoulou

2012-05-01

The aim of the present study was to investigate the effectiveness of eccentric training and eccentric training with static stretching exercises in the management of patellar tendinopathy. Controlled clinical trial. Rheumatology and rehabilitation centre. Forty-three patients who had patellar tendinopathy for at least three months. They were allocated to two groups by alternative allocation. Group A (n = 22) was treated with eccentric training of patellar tendon and static stretching exercises of quadriceps and hamstrings and Group B (n = 21) received eccentric training of patellar tendon. All patients received five treatments per week for four weeks. Pain and function were evaluated using the VISA-P score at baseline, at the end of treatment (week 4), and six months (week 24) after the end of treatment. At the end of treatment, there was a rise in VISA-P score in both groups compared with baseline (Peccentric training and static stretching exercises produced the largest effect (PEccentric training and static stretching exercises is superior to eccentric training alone to reduce pain and improve function in patients with patellar tendinopathy at the end of the treatment and at follow-up.

Assessment of eccentric exercise-induced muscle damage of the elbow flexors by tensiomyography.

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Hunter, Angus M; Galloway, Stuart D R; Smith, Iain J; Tallent, Jamie; Ditroilo, Massimiliano; Fairweather, Malcolm M; Howatson, Glyn

2012-06-01

Exercise induced muscle damage (EIMD) impairs maximal torque production which can cause a decline in athletic performance and/or mobility. EIMD is commonly assessed by using maximal voluntary contraction (MVC), creatine kinase (CK) and muscle soreness. We propose as an additional technique, tensiomyography (TMG), recently introduced to measure mechanical and muscle contractile characteristics. The purpose of this study was to determine the validity of TMG in detecting changes in maximal torque following EIMD. Nineteen participants performed eccentric elbow flexions to achieve EIMD on the non- dominant arm and used the dominant elbow flexor as a control. TMG parameters, MVC and rate of torque development (RTD) were measured prior to EIMD and repeated for another six consecutive days. Creatine kinase, muscle soreness and limb girth were also measured during this period. Twenty four hours after inducing EIMD, MVC torque, RTD and TMG maximal displacement had significantly (pTMG recovered to 12%, 24% and 17% of respective pre-EIMD values. In conclusion, as hypothesised TMG maximal displacement significantly followed other standard EIMD responses. This could therefore be useful in detecting muscle damage from impaired muscle function and its recovery following EIMD. Copyright © 2012 Elsevier Ltd. All rights reserved.

ISOMETRIC EXERCISE VERSUS COMBINED CONCENTRIC-ECCENTRIC EXERCISE TRAINING IN PATIENTS WITH OSTEOARTHRITIS KNEE

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Nigombam Amit Kumar

2015-12-01

Full Text Available Background: Osteoarthritis is a slowly evolving articular disease, which appears to originate in the cartilage and affects the underlying bone and soft tissues. OA results in pain and functional disability. The purpose of this study was to determine the effect of isometric exercises and combined concentric-eccentric exercises in reducing pain and functional disability in patients with osteoarthritis of knee. Methods: Forty individuals who were diagnosed as osteoarthritis by qualified orthopaedics and orthopaedic surgeons were chosen and were randomly divided into 2 groups Group A (N=20 and Group B (N=20. Group A was treated with isometric exercises and Group B was treated with combined concentric-eccentric exercises. The intervention lasted eight weeks and the physical activity was carried out for 3 days a week. Both the groups were assessed for pain and functional disability of knee joint by using WOMAC osteoarthritis index and VAS. Results: Between group analysis of pre and post study data reveals that VAS and WOMAC osteoarthritis index revealed significant findings (P=0.00. Group B performs significantly better on both the scales after the treatment. Conclusion: Both the groups showed significant improvement in decreasing pain and functional disability. But mean scores of Group B showed greater improvement in reducing pain and functional disability as compared to Group A in patients with knee osteoarthritis. Thus the results suggest that a combined concentric-eccentric e

Eccentric or Concentric Exercises for the Treatment of Tendinopathies?

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Couppé, Christian; Svensson, René B; Silbernagel, Karin Grävare

2015-01-01

with respect to parameters like load magnitude, speed of movement, and recovery period between exercise sessions. Future studies should control for these loading parameters, evaluate various exercise dosages, and also think beyond isolated eccentric exercises to arrive at firm recommendations regarding...... exercise has been promoted. In this review we cover the relevant evidence for different exercise regimes in tendinopathy rehabilitation with particular focus on the applied loads that are experienced by the tendon and how the exercise regime may affect these applied loads. There is no convincing clinical...

Xanthine oxidase in human skeletal muscle following eccentric exercise

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Hellsten, Ylva; Frandsen, Ulrik; Orthenblad, N.

1997-01-01

the increase in xanthine oxidase in the muscle there were no detectable changes in the levels of muscle malondialdehyde or in plasma antioxidant capacity up to 4 days post-exercise. 5. It is concluded that eccentric exercise leads to an increased level of xanthine oxidase in human muscle and that the increase...

Does intermittent pneumatic leg compression enhance muscle recovery after strenuous eccentric exercise?

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Cochrane, D J; Booker, H R; Mundel, T; Barnes, M J

2013-11-01

Intermittent pneumatic compression (IPC) has gained rapid popularity as a post-exercise recovery modality. Despite its widespread use and anecdotal claims for enhancing muscle recovery there is no scientific evidence to support its use. 10 healthy, active males performed a strenuous bout of eccentric exercise (3 sets of 100 repetitions) followed by IPC treatment or control performed immediately after exercise and at 24 and 48 h post-exercise. Muscular performance measurements were taken prior to exercise and 24, 48 and 72 h post-exercise and included single-leg vertical jump (VJ) and peak and average isometric [knee angle 75º] (ISO), concentric (CON) and eccentric (ECC) contractions performed at slow (30° · s⁻¹) and fast (180° · s⁻¹) velocities. Plasma creatine kinase (CK) samples were taken at pre- and post-exercise 24, 48 and 72 h. Strenuous eccentric exercise resulted in a significant decrease in peak ISO, peak and average CON (30° · s⁻¹) at 24 h compared to pre-exercise for both IPC and control, however VJ performance remained unchanged. There were no significant differences between conditions (IPC and control) or condition-time interactions for any of the contraction types (ISO, CON, ECC) or velocities (CON, ECC 30° · s⁻¹ and 180° · s⁻¹). However, CK was significantly elevated at 24 h compared to pre-exercise in both conditions (IPC and control). IPC did not attenuate muscle force loss following a bout of strenuous eccentric exercise in comparison to a control. While IPC has been used in the clinical setting to treat pathologic conditions, the parameters used to treat muscle damage following strenuous exercise in healthy participants are likely to be very different than those used to treat pathologic conditions. © Georg Thieme Verlag KG Stuttgart · New York.

Eccentric Exercises Reduce Hamstring Strains in Elite Adult Male Soccer Players: A Critically Appraised Topic.

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Shadle, Ian B; Cacolice, Paul A

2017-11-01

Clinical Scenario: Hamstring strains are a common sport-related injury, which may limit athletic performance for an extended period of time. These injuries are common in the soccer setting. As such, it is important to determine an appropriate prevention program to minimize the risk of such an injury for these athletes. Eccentric hamstring training may be an effective and practical hamstring strain prevention strategy. What is the effect of eccentric exercises on hamstring strain prevention in adult male soccer players? Summary of Key Findings: Current literature was searched for studies of level 2 evidence or higher that investigated the effect of eccentric exercises in preventing hamstring strains in adult male soccer players. Three articles returned from the literature search met the inclusion criteria. A fourth article looked at differences in strength gains between eccentric and concentric hamstring strengthening exercises, but did not record hamstring strain incidence. A fifth article, a systematic review, met all the criteria except for the correct population. Of the 3 studies, 2 were randomized control trails and 1 was a cohort study. Clinical Bottom Line: There is robust supportive evidence that eccentric hamstring exercises can prevent a hamstring injury to an elite adult male soccer player. Therefore, it is recommended that athletic trainers and other sports medicine providers evaluate current practices relating to reducing hamstring strains and consider implementing eccentric exercise based prevention programs. Strength of Recommendation: All evidence was attained from articles with a level of evidence 2b or higher, based on the Center for Evidence-Based Medicine (CEBM) criteria, stating that eccentric exercises can decrease hamstring strains.

Blood flow after contraction and cuff occlusion is reduced in subjects with muscle soreness after eccentric exercise

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Souza-Silva, Eduardo; Wittrup Christensen, Steffan; Hirata, Rogerio Pessoto

2018-01-01

Purpose: Delayed onset muscle soreness (DOMS) occur within 1-2 days after eccentric exercise but the mechanism mediating hypersensitivity is unclear. This study hypothesized that eccentric exercise reduces the blood flow response following muscle contractions and cuff occlusion, which may result...... anterior muscle. All measures were done bilaterally at day-0 (pre-exercise), day-2 and day-6 (post-exercise). Subjects scored the muscle soreness on a Likert scale for 6 days. Results: Eccentric exercise increased Likert scores at day-1 and day-2 compared with day-0 (P... in accumulated algesic substances being a part of the sensitization in DOMS. Methods: Twelve healthy subjects (5 women) performed dorsiflexion exercise (5 sets of 10 repeated eccentric contractions) in one leg, while the contralateral leg was the control. The maximal voluntary contraction (MVC) of the tibialis...

Prolonged submaximal eccentric exercise is associated with increased levels of plasma IL-6

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Rohde, Thomas; MacLean, D A; Richter, Erik

1997-01-01

To study the relationship between exercise-related muscle proteolysis and the cytokine response, a prolonged eccentric exercise model of one leg was used. Subjects performed two trials [a branched-chain amino acid (BCAA) supplementation and a control trial]. The release of amino acids from muscle...... during and after the eccentric exercise was decreased in the BCAA trial, suggesting a suppression of net muscle protein degradation. The plasma concentrations of interleukin (IL)-6 increased from 0.75 +/- 0.19 (preexercise) to 5.02 +/- 0.96 pg/ml (2 h postexercise) in the control trial and in the BCAA...... supplementation trial from 1.07 +/- 0.41 to 4.15 +/- 1.21 pg/ml. Eccentric exercise had no effect on the concentrations of neutrophils, lymphocytes, CD16+/CD56+, CD4+, CD8+, CD14+/CD38+, lymphocyte proliferative response, or cytotoxic activities. BCAA supplementation reduced the concentration of CD14+/CD38+ cells...

Effects of combined β-hydroxy-β-methylbutyrate (HMB) and whey protein ingestion on symptoms of eccentric exercise-induced muscle damage.

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Shirato, Minayuki; Tsuchiya, Yosuke; Sato, Teruyuki; Hamano, Saki; Gushiken, Takeshi; Kimura, Naoto; Ochi, Eisuke

2016-01-01

The purpose of this study was to examine the effects of combined β-hydroxy-β-methylbutyrate (HMB) and whey protein ingestion on muscle strength and damage following a single bout of eccentric exercise. Eighteen untrained male subjects were assigned to HMB and Whey protein (HMB + Whey; 3 g/day HMB and 36.6 g/day whey protein, n = 6), HMB (3 g/day, n = 6), or whey protein (36.6 g/day, n = 6) groups. Ingestion commenced 7 days before non-dominant elbow flexor eccentric exercise (30 deg/sec, 6 reps × 7 sets) and continued until 4 days post-exercise. The maximal isometric strength, muscle soreness, plasma creatine kinase (CK), lactate dehydrogenase (LDH) were assessed pre-exercise, and at 1, 2, 3, and 5 days after exercise. The change scores of maximal isometric strength significantly decreased at day 1, 2, and 5 in the whey protein group compared to pre value and that in HMB + Whey protein and HMB groups decreased at day 1 and 5. The muscle soreness significantly increased in the whey and HMB + Whey protein groups at day 3 compared to pre value (p HMB and whey protein does not have a role to inhibit muscle strength loss and soreness, and decrease in muscle damage markers after eccentric exercise in comparison with HMB and whey protein alone.

Effects of Short-Term Docosahexaenoic Acid Supplementation on Markers of Inflammation after Eccentric Strength Exercise in Women

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Katherine E. Corder, Katherine R. Newsham, Jennifer L. McDaniel, Uthayashanker R. Ezekiel, Edward P. Weiss

2016-03-01

Full Text Available The omega-3 fatty acid docosahexaenoic acid (DHA has anti-inflammatory and anti-nociceptive (pain inhibiting effects. Because strenuous exercise often results in local inflammation and pain, we hypothesized that DHA supplementation attenuates the rise in markers of local muscle inflammation and delayed onset muscle soreness (DOMS that occur after eccentric strength exercise. Twenty-seven, healthy women (33 ± 2 y, BMI 23.1±1.0 kg·m-2 were randomized to receive 9d of 3000 mg/d DHA or placebo in a double-blind fashion. On day 7 of the supplementation period, the participants performed 4 sets of maximal-effort eccentric biceps curl exercise. Before and 48h after the eccentric exercise, markers of inflammation were measured including measures of muscle soreness (10-point visual analog pain scale, VAS, swelling (arm circumference, muscle stiffness (active and passive elbow extension, skin temperature, and salivary C-reactive protein (CRP concentrations. As expected, muscle soreness and arm circumference increased while active and passive elbow extension decreased. The increase in soreness was 23% less in the DHA group (48h increase in VAS soreness ratings: 4.380.4 vs. 5.600.5, p=0.02. Furthermore, the number of subjects who were able to achieve full active elbow extension 48h after eccentric exercise was greater in the DHA group (71% vs. 15%, p = 0.006, indicating significantly less muscle stiffness. No between-group differences were observed for passive elbow extension (p = 0.78 or arm swelling (p = 0.75. Skin temperature and salivary CRP concentrations did not change from baseline to 48h after exercise in either group. These findings indicate that short-term DHA supplementation reduces exercise-induced muscle soreness and stiffness. Therefore, in addition to other health benefits that n-3 fatty acids have been associated with, DHA supplementation could be beneficial for improving tolerance to new and/or strenuous exercise programs and thereby

Response of Coagulation Indices to Two Types of Exercise of Eccentric and Isometric in Male Bodybuilding Athletes

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Maryam Azimpour

2016-05-01

Full Text Available Abstract Background and Objectives: Although activation of blood coagulation system in response to physical activity has been identified to some extent, but the contribution of eccentric activity in comparison with isometric activity as resistance exercise, is not clear yet. Therefore, this research was carried out with the purpose of investigating the effect of one session of eccentric and isometric resistance exercise on some coagulation factors in male bodybuilders. Methods: In this semi-experimental study, 28 volunteers were randomly selected from male bodybuilders and divided into two experimental groups and one control group. One of the experimental groups performed eccentric exercise [controlled return (extension of the elbow flexion movement involving an eccentric contraction] and another group performed isometric exercises (holding barbell while flexing elbows at 45 degrees. In order to assess coagulation indices, blood sampling was performed 15 minutes before and immediately after the exercise. Results: Thromboplastin and prothrombin times did not significantly change immediately after the exercise, but the number of platelets significantly increased in both isometric and eccentric types of exercise immediately after the exercise. Conclusion: The results of isometric and eccentric acute resistance exercise showed that the exercise had no negative impact on blood coagulation factors, and increased coagulation system activity reflects the increased number of platelets. The difference between the results of researches carried out in this direction can be resulted from the difference between the exercise protocols, methods and measurement time, and level of preparedness of the participants in the research.

Does Eccentric Exercise Reduce Pain and Improve Strength in Physically Active Adults With Symptomatic Lower Extremity Tendinosis? A Systematic Review

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Wasielewski, Noah J; Kotsko, Kevin M

2007-01-01

Objective: To critically review evidence for the effectiveness of eccentric exercise to treat lower extremity tendinoses. Data Sources: Databases used to locate randomized controlled trials (RCTs) included PubMed (1980–2006), CINAHL (1982–2006), Web of Science (1995–2006), SPORT Discus (1980–2006), Physiotherapy Evidence Database (PEDro), and the Cochrane Collaboration Database. Key words included tendon, tendonitis, tendinosis, tendinopathy, exercise, eccentric, rehabilitation, and therapy. Study Selection: The criteria for trial selection were (1) the literature was written in English, (2) the research design was an RCT, (3) the study participants were adults with a clinical diagnosis of tendinosis, (4) the outcome measures included pain or strength, and (5) eccentric exercise was used to treat lower extremity tendinosis. Data Extraction: Specific data were abstracted from the RCTs, including eccentric exercise protocol, adjunctive treatments, concurrent physical activity, and treatment outcome. Data Synthesis: The calculated post hoc statistical power of the selected studies (n = 11) was low, and the average methodologic score was 5.3/10 based on PEDro criteria. Eccentric exercise was compared with no treatment (n = 1), concentric exercise (n = 5), an alternative eccentric exercise protocol (n = 1), stretching (n = 2), night splinting (n = 1), and physical agents (n = 1). In most trials, tendinosis-related pain was reduced with eccentric exercise over time, but only in 3 studies did eccentric exercise decrease pain relative to the control treatment. Similarly, the RCTs demonstrated that strength-related measures improved over time, but none revealed significant differences relative to the control treatment. Based on the best evidence available, it appears that eccentric exercise may reduce pain and improve strength in lower extremity tendinoses, but whether eccentric exercise is more effective than other forms of therapeutic exercise for the resolution

Response of macrophages in rat skeletal muscle after eccentric exercise.

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Zuo, Qun; Wang, Shu-Chen; Yu, Xin-Kai; Chao, Wei-Wei

2018-04-01

Macrophages are known to be important for healing numerous injured tissues depending on their functional phenotypes in response to different stimuli. The objective of this study was to reveal macrophage phenotypic changes involved in exercise-induced skeletal muscle injury and regeneration. Adult male Sprague-Dawley rats experienced one session of downhill running (16° decline, 16 m/min) for 90 min. After exercise the blood and soleus muscles were collected at 0 h, 6 h, 12 h, 1 d, 2 d, 3 d, 1 w and 2 w after exercise, separately. It was showed that CD68 + M1 macrophages mainly infiltrated into muscle necrotic sites at 1-3 d, while CD163 + M2 macrophages were present in muscles from 0 h to 2 weeks after exercise. Using transmission electron microscopy, we observed activated satellite cells 1 d after exercise. Th1-associated transcripts of iNOS and Ccl2 were inhibited post exercise, while COX-2 mRNA was dramatically increased 12 h after running (p < 0.01). M2 phenotype marker Arg-1 increased 12 h and 3 d (p < 0.05, p < 0.01) after exercise, and Clec10a and Mrc2 were up-regulated in muscles 12 h following exercise (p < 0.05, p < 0.05). The data demonstrate the dynamic patterns of macrophage phenotype in skeletal muscle upon eccentric exercise stimuli, and M1 and M2 phenotypes perform different functions during exercise-induced skeletal muscle injury and recovery. Copyright © 2018 Daping Hospital and the Research Institute of Surgery of the Third Military Medical University. Production and hosting by Elsevier B.V. All rights reserved.

Eccentric exercise: acute and chronic effects on healthy and diseased tendons.

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Kjaer, Michael; Heinemeier, Katja M

2014-06-01

Eccentric exercise can influence tendon mechanical properties and matrix protein synthesis. mRNA for collagen and regulatory factors thereof are upregulated in animal tendons, independent of muscular contraction type, supporting the view that tendon, compared with skeletal muscle, is less sensitive to differences in type and/or amount of mechanical stimulus with regard to expression of collagen, regulatory factors for collagen, and cross-link regulators. In overused (tendinopathic) human tendon, eccentric exercise training has a beneficial effect, but the mechanism by which this is elicited is unknown, and slow concentric loading appears to have similar beneficial effects. It may be that tendinopathic regions, as long as they are subjected to a certain magnitude of load at a slow speed, independent of whether this is eccentric or concentric in nature, can reestablish their normal tendon fibril alignment and cell morphology. Copyright © 2014 the American Physiological Society.

Sonographic evaluation of the immediate effects of eccentric heel drop exercise on Achilles tendon and gastrocnemius muscle stiffness using shear wave elastography

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Leung, Wilson K.C.; Chu, KL

2017-01-01

Background Mechanical loading is crucial for muscle and tendon tissue remodeling. Eccentric heel drop exercise has been proven to be effective in the management of Achilles tendinopathy, yet its induced change in the mechanical property (i.e., stiffness) of the Achilles tendon (AT), medial and lateral gastrocnemius muscles (MG and LG) was unknown. Given that shear wave elastography has emerged as a powerful tool in assessing soft tissue stiffness with promising intra- and inter-operator reliability, the objective of this study was hence to characterize the stiffness of the AT, MG and LG in response to an acute bout of eccentric heel drop exercise. Methods Forty-five healthy young adults (36 males and nine females) performed 10 sets of 15-repetition heel drop exercise on their dominant leg with fully-extended knee, during which the AT and gastrocnemius muscles, but not soleus, were highly stretched. Before and immediately after the heel drop exercise, elastic moduli of the AT, MG and LG were measured by shear wave elastography. Results After the heel drop exercise, the stiffness of AT increased significantly by 41.8 + 33.5% (P eccentric heel drop exercise. The findings from this pilot study shed some light on how and to what extent the AT and gastrocnemius muscles mechanically responds to an isolated set of heel drop exercise. Taken together, appropriate eccentric load might potentially benefit mechanical adaptations of the AT and gastrocnemius muscles in the rehabilitation of patients with Achilles tendinopathy. PMID:28740756

Taurine supplementation attenuates delayed increase in exercise-induced arterial stiffness.

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Ra, Song-Gyu; Choi, Youngju; Akazawa, Nobuhiko; Ohmori, Hajime; Maeda, Seiji

2016-06-01

There is a delayed increase in arterial stiffness after eccentric exercise that is possibly mediated by the concurrent delayed increase in circulating oxidative stress. Taurine has anti-oxidant action, and taurine supplementation may be able to attenuate the increase in oxidative stress after exercise. The purpose of the present study was to investigate whether taurine supplementation attenuates the delayed increase in arterial stiffness after eccentric exercise. In the present double-blind, randomized, and placebo-controlled trial, we divided 29 young, healthy men into 2 groups. Subjects received either 2.0 g of placebo (n = 14) or taurine (n = 15) 3 times per day for 14 days prior to the exercise, on the day of exercise, and the following 3 days. The exercise consisted of 2 sets of 20 maximal-effort eccentric repetitions with the nondominant arm only. On the morning of exercise and for 4 days thereafter, we measured serum malondialdehyde (MDA) and carotid-femoral pulse wave velocity (cfPWV) as indices of oxidative stress and arterial stiffness, respectively. On the third and fourth days after exercise, both MDA and cfPWV significantly increased in the placebo group. However, these elevations were significantly attenuated in the taurine group. The increase in MDA was associated with an increase in cfPWV from before exercise to 4 days after exercise (r = 0.597, p taurine group. Our results suggest that delayed increase in arterial stiffness after eccentric exercise was probably affected by the exercise-induced oxidative stress and was attenuated by the taurine supplementation.

Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises

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Gerold R. Ebenbichler

2017-05-01

Full Text Available Purpose: To investigate the differences in neural control of back muscles activated during the eccentric vs. the concentric portions of a cyclic, submaximal, fatiguing trunk extension exercise via the analysis of amplitude and time-frequency parameters derived from surface electromyographic (SEMG data.Methods: Using back dynamometers, 87 healthy volunteers performed three maximum voluntary isometric trunk extensions (MVC's, an isometric trunk extension at 80% MVC, and 25 cyclic, dynamic trunk extensions at 50% MVC. Dynamic testing was performed with the trunk angular displacement ranging from 0° to 40° and the trunk angular velocity set at 20°/s. SEMG data was recorded bilaterally from the iliocostalis lumborum at L1, the longissimus dorsi at L2, and the multifidus muscles at L5. The initial value and slope of the root mean square (RMS-SEMG and the instantaneous median frequency (IMDF-SEMG estimates derived from the SEMG recorded during each exercise cycle were used to investigate the differences in MU control marking the eccentric vs. the concentric portions of the exercise.Results: During the concentric portions of the exercise, the initial RMS-SEMG values were almost twice those observed during the eccentric portions of the exercise. The RMS-SEMG values generally increased during the concentric portions of the exercise while they mostly remained unchanged during the eccentric portions of the exercise with significant differences between contraction types. Neither the initial IMDF-SEMG values nor the time-course of the IMDF-SEMG values significantly differed between the eccentric and the concentric portions of the exercise.Conclusions: The comparison of the investigated SEMG parameters revealed distinct neural control strategies during the eccentric vs. the concentric portions of the cyclic exercise. We explain these differences by relying upon the principles of orderly recruitment and common drive governing motor unit behavior.

Diclofenac pretreatment effects on the toll-like receptor 4/nuclear factor kappa B-mediated inflammatory response to eccentric exercise in rat liver.

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Barcelos, Rômulo Pillon; Bresciani, Guilherme; Rodriguez-Miguelez, Paula; Cuevas, Maria José; Soares, Félix Alexandre Antunes; Barbosa, Nilda Vargas; González-Gallego, Javier

2016-03-01

Acute exercise is a stress stimulus that may cause cell damage through the activation of the toll-like receptor (TLR)4 pathway, resulting in the translocation of nuclear factor kappa B (NF-κB) into the cell nucleus and the upregulation of inflammatory genes. Nonsteroidal anti-inflammatory drugs, such as diclofenac, are often prescribed to counteract exercise-induced inflammation. This study analyzed effects of diclofenac pretreatment on the TLR4/NF-κB pathway in rat liver after an acute eccentric exercise. Twenty male Wistar rats were divided in four groups: control-saline, control-diclofenac, exercise-saline and exercise-diclofenac. The rats received saline or diclofenac (10mg/kg) for 7days prior to an eccentric exercise bout. After exercise there was an increase in TLR4, myeloid differentiation primary response gene 88 (MyD88), TIR domain-containing adaptor inducing interferon (TRIF) and p65 NF-κB subunit protein levels. Exercise also resulted in increased mRNA and protein expression of interleukin (IL)-6, inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF)-α. Proinflammatory effects of exercise were prevented by the administration of diclofenac, which blunted the activation of the TLR4/NF-κB pathway and the inflammatory response in the liver of exercised rats. Results from the present study highlight the role of TLR4 as a target for anti-inflammatory interventions. Copyright © 2016 Elsevier Inc. All rights reserved.

Attenuation of muscle damage by preconditioning with muscle hyperthermia 1-day prior to eccentric exercise.

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Nosaka, K; Muthalib, M; Lavender, A; Laursen, P B

2007-01-01

This study investigated the hypothesis that muscle damage would be attenuated in muscles subjected to passive hyperthermia 1 day prior to exercise. Fifteen male students performed 24 maximal eccentric actions of the elbow flexors with one arm; the opposite arm performed the same exercise 2-4 weeks later. The elbow flexors of one arm received a microwave diathermy treatment that increased muscle temperature to over 40 degrees C, 16-20 h prior to the exercise. The contralateral arm acted as an untreated control. Maximal voluntary isometric contraction strength (MVC), range of motion (ROM), upper arm circumference, muscle soreness, plasma creatine kinase activity and myoglobin concentration were measured 1 day prior to exercise, immediately before and after exercise, and daily for 4 days following exercise. Changes in the criterion measures were compared between conditions (treatment vs. control) using a two-way repeated measures ANOVA with a significance level of P < 0.05. All measures changed significantly following exercise, but the treatment arm showed a significantly faster recovery of MVC, a smaller change in ROM, and less muscle soreness compared with the control arm. However, the protective effect conferred by the diathermy treatment was significantly less effective compared with that seen in the second bout performed 4-6 weeks after the initial bout by a subgroup of the subjects (n = 11) using the control arm. These results suggest that passive hyperthermia treatment 1 day prior to eccentric exercise-induced muscle damage has a prophylactic effect, but the effect is not as strong as the repeated bout effect.

Blood flow after contraction and cuff occlusion is reduced in subjects with muscle soreness after eccentric exercise

DEFF Research Database (Denmark)

Souza-Silva, Eduardo; Wittrup Christensen, Steffan; Hirata, Rogerio Pessoto

2018-01-01

Purpose: Delayed onset muscle soreness (DOMS) occur within 1-2 days after eccentric exercise but the mechanism mediating hypersensitivity is unclear. This study hypothesized that eccentric exercise reduces the blood flow response following muscle contractions and cuff occlusion, which may result ...

Electromyographic analysis of an eccentric calf muscle exercise in persons with and without Achilles tendinopathy.

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Reid, Duncan; McNair, Peter J; Johnson, Shelley; Potts, Geoff; Witvrouw, Erik; Mahieu, Nele

2012-08-01

To compare surface electromyographic (EMG) activity of the gastrocnemius and soleus muscles between persons with and without Achilles tendinopathy (AT) during an eccentric muscle exercise in different knee joint positions. Repeated measures design. Research laboratory. Participants (n = 18) diagnosed with AT and 18 control subjects were recruited. Gastrocnemius and soleus muscle activity was examined by surface (EMG) during extended and flexed knee joint conditions while performing the eccentric training technique. The EMG data were expressed as a percentage of a maximum voluntary contraction (MVC). EMG activity was notably higher (mean difference: 10%, effect size: 0.59) in those subjects with AT. Irrespective of the presence of AT, there was a significant interaction effect between muscle and joint position. The gastrocnemius muscle was significantly more active in the extended knee condition and soleus muscle activity was unchanged across joint positions. The results indicated that the presence of AT influenced calf muscle activity levels during performance of the eccentric exercise. There were differences in muscle activity during the extended and flexed knee conditions. This result does support performing Alfredson, Pietila, Jonsson, and Lorentzon (1998) eccentric exercise in an extended knee position but the specific effects of the knee flexed position on the Achilles tendon during eccentric exercise have yet to be determined, particularly in those with AT. Copyright © 2011 Elsevier Ltd. All rights reserved.

EFFECT OF ECCENTRIC EXERCISE PROGRAMME ON PAIN AND GRIP STRENGTH FOR SUBJECTS WITH MEDIAL EPICONDYLITIS

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Mishra Prashant Akhilesh

2014-04-01

Full Text Available Background and Objective: Therapeutic eccentric exercise may provide both a structural and functional benefit during tendinopathy rehabilitation. The objective is to find the effect of eccentric exercises on improvement of pain and grip strength for subjects with Medial Epicondylitis. Method: Pre to post test experimental study design randomized thirty subjects with medial epicondylitis, 15 each into Group A and Group B. Group B subjects were treated with conventional therapy and Eccentric exercises. Group A subjects were treated with conventional therapy. Results: When means of post intervention were compared using Independent ‘t’ between groups there was no statistically significant difference in improvements obtained in VAS scores and grip strength. There was a statistically significant change in means of VAS score and Grip strength when means were analyzed by using Paired‘t’ test and Wilcoxon signed rank test within the groups with positive percentage of change. Conclusion: It is concluded that four weeks of Eccentric Exercise Programme combined with conventional therapy shown significant effect on improving pain and Grip strength, however the improvement obtained has no difference when compared with control conventional treatment for Subjects with Medial Epicondylitis.

THE COMBINATION OF α-LIPOIC ACID INTAKE WITH ECCENTRIC EXERCISE MODULATES ERYTHROPOIETIN RELEASE.

Science.gov (United States)

Morawin, B; Turowski, D; Naczk, M; Siatkowski, I; Zembron-Lacny, A

2014-08-01

The generation of reactive nitrogen/oxygen species (RN/OS) represents an important mechanism in erythropoietin (EPO) expression and skeletal muscle adaptation to physical and metabolic stress. RN/OS generation can be modulated by intense exercise and nutrition supplements such as α-lipoic acid, which demonstrates both anti- and pro-oxidative action. The study was designed to show the changes in the haematological response through the combination of α-lipoic acid intake with running eccentric exercise. Sixteen healthy young males participated in the randomised and placebo-controlled study. The exercise trial involved a 90-min run followed by a 15-min eccentric phase at 65% VO2max (-10% gradient). It significantly increased serum concentrations of nitric oxide (NO), hydrogen peroxide (H2O2) and pro-oxidative products such as 8-isoprostanes (8-iso), lipid peroxides (LPO) and protein carbonyls (PC). α-Lipoic acid intake (Thiogamma: 1200 mg daily for 10 days prior to exercise) resulted in a 2-fold elevation of serum H2O2 concentration before exercise, but it prevented the generation of NO, 8-iso, LPO and PC at 20 min, 24 h, and 48 h after exercise. α-Lipoic acid also elevated serum EPO level, which highly correlated with NO/H2O2 ratio (r = 0.718, P exercise (placebo 732 ± 207 IU · L(-1), α-lipoic acid 481 ± 103 IU · L(-1)), and correlated with EPO (r = 0.478, P release and reduces muscle damage after running eccentric exercise.

Effects of concentric and repeated eccentric exercise on muscle damage and calpain-calpastatin gene expression in human skeletal muscle

DEFF Research Database (Denmark)

Vissing, K.; Overgaard, K.; Nedergaard, A.

2008-01-01

, and was compared to a control-group (n = 6). Muscle strength and soreness and plasma creatine kinase and myoglobin were measured before and during 7 days following exercise bouts. Muscle biopsies were collected from m. vastus lateralis of both legs prior to and at 3, 24 h and 7 days after exercise and quantified...... for muscle Ca2+-content and mRNA levels for calpain isoforms and calpastatin. Exercise reduced muscle strength and increased muscle soreness predominantly in the eccentric leg (P ... eccentric exercise bout (P muscle Ca2+-content did not differ between interventions. mRNA levels for calpain 2 and calpastatin were upregulated exclusively by eccentric exercise 24 h post-exercise (P

Influence of Arm-cranking on Changes in Plasma CK Activity after High Force Eccentric Exercise of the Elbow Flexors

OpenAIRE

Kazunori, NOSAKA; Kei, SAKAMOTO; Mike, NEWTON; Exercise and Sports Science, Graduate School of Integrated Science, Yokohama City University:School of Biomedical and Sports Science, Edith Cowan University; Exercise and Sports Science, Graduate School of Integrated Science, Yokohama City University; School of Biomedical and Sports Science, Edith Cowan University

2002-01-01

It was hypothesized that the time course of changes in plasma creatine kinase (CK) activity following eccentric exercise was influenced by rhythmical muscle contractions performed after eccentric exercise. This study examined whether arm-cranking (AC) alters the time course of changes in plasma creatine kinase (CK) activity after eccentric exercise of the elbow flexors (ECC). Six male students performed two bouts of ECC separated by 3 weeks, and AC (25watts, 2-hours) was performed immediately...

Forward lunge: a training study of eccentric exercises of the lower limbs.

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Jönhagen, Sven; Ackermann, Paul; Saartok, Tönu

2009-05-01

A few studies have shown that eccentric exercise is effective for prevention and treatment of muscle injuries. Most earlier studies on eccentric exercises have used training with advanced equipment. Forward lunges are considered eccentric exercises, and they may be performed without any equipment. These exercises are commonly used by sprint runners. We performed a prospective, randomized, 6-week training study comparing the effects of walking or jumping forward lunges on hamstring and quadriceps strength and function. Thirty-two soccer players were included in the study. The forward lunge training was done as an addition to ordinary soccer training twice a week for 6 weeks. The outcome was measured by the maximal hamstring and quadriceps strength tests and by functional tests with 1-leg hop tests and 30-m sprint runs. Overall muscle pain was evaluated using a visual analogue scale score, and local pain was estimated with an algometer. Whereas the walking lunge improved hamstring strength, the jumping lunge resulted in sprint running improvements. Algometer testing showed a general increase in the pain detection thresholds of all subjects, including the controls. Thus, precautions should be taken when algometers are used for temporal studies of pain. Walking and jumping forward lunges can be used for improving hamstring strength and running speed in young soccer player. The findings may have relevance when designing protocols for prevention and rehabilitation of muscle injuries.

Eccentric Exercise, Kinesiology Tape, and Balance in Healthy Men.

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Hosp, Simona; Folie, Ramona; Csapo, Robert; Hasler, Michael; Nachbauer, Werner

2017-07-01

  Deficits in balance have been identified as a possible risk factor for knee injuries in athletes. Despite a lack of evidence for its effectiveness, kinesiology tape (KT) is widely used to prevent knee injuries.   To investigate the influence of KT at the knee joint on balance ability in healthy men after eccentric exercise.   Crossover study.   University laboratory.   Twelve young men with no history of lower limb injury volunteered for the study (age = 23.3 ± 2.6 years). All participants were students enrolled in a sports science program.   Participants performed the balance test with and without KT at the knee joint on 2 separate days.   The ability to maintain balance was assessed during a single-legged-stance test using a computerized balance-stability test system. The test was performed before and after 30 minutes of downhill walking on a treadmill.   Eccentric exercise resulted in a deterioration of balance ability, which was attenuated by the use of KT. Further analyses revealed that the effectiveness of KT depended on the participant's balance status, with the preventive effect being greater in participants presenting with poorer baseline balance ability.   Applied to the knee joint, KT counteracted the exercise-related deterioration of balance ability observed when no tape was used. Participants presenting with below-average balance ability received more benefit from KT. By preventing exercise-related impairment of balance ability, KT might help to reduce the risk of sport-associated knee injuries.

Histomorphometric analysis of the Achilles tendon of Wistar rats treated with laser therapy and eccentric exercise

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Maria V. de Souza

2015-12-01

Full Text Available Abstract: Low-level laser therapy is recommended for the treatment of tendinopathies despite the contradictory results related to the ideal dose of energy, wavelength and time of application. This study aimed to assess the effects of laser therapy and eccentric exercise on tendinopathy of the Achilles tendon of Wistar rats. Forty-eight adult male rats were randomly distributed into four groups (L= laser; E= eccentric exercise; LE = laser and eccentric exercise; and R= rest. Laser therapy (904nm/3J/cm2 and/or eccentric exercise (downhill walking; 15o incline treadmill; 12m/min; 50min/day was started 24h after induction of unilateral tendinopathy and remained for 20 days. At 3, 7, 14 and 21 days after lesion induction, three rats from each group were euthanized and the tendons were collected for histological and morphometric analyses. There was no difference among groups or among times for the characteristics hemorrhage (p=0.4154, fibrinous adhesion formation (p=0.0712, and organization of collagen fibers (p=0.2583 and of the connective tissue (p=0.1046. For these groups, regardless of the time, eccentric exercise led to epitenon thickening (p=0.0204, which was lower in the group treated with laser therapy. Histological analysis revealed differences (p=0.0032 in the number of inflammatory cells over time. They were more numerous in the group that only exercised. This result was confirmed by morphometric analysis, which showed a significant interaction (groups x time for this characteristic. Eccentric exercise increased (p=0.0014 the inflammatory infiltrate over time (3 and 21 days. However, association with laser therapy reduced inflammatory reaction. On the other hand, the combination of the treatments increased angiogenesis in morphometric (p=0.0000 and histological (p=0.0006 analyses compared with the other groups, while the isolated application of low-level laser reduced this characteristic over time. Animals maintained at rest presented the

Effects of eccentric exercise on trapezius electromyography during computer work with active and passive pauses

DEFF Research Database (Denmark)

Samani, Afshin; Holtermann, Andreas; Søgaard, Karen

2009-01-01

) and active (30% maximum voluntary contraction of shoulder elevation) pauses given every 40s over 2 days, before, immediately and 24h after eccentric exercise. Surface EMG signals were recorded from four parts of the trapezius during computer work. FINDINGS: EMG amplitude during computer work decreased......BACKGROUND: The aim of this laboratory study was to investigate the effects of eccentric exercises on the trapezius muscle spatial electromyographic (EMG) activity during computer work with active and passive pauses. METHODS: Twelve healthy male subjects performed computer work with passive (relax...... immediately after exercise (Pwork with active pauses compared with passive ones (P

Eccentric Exercise in Treatment of Patellar Tendinopathy in High Level Basketball Players. A Randomized Clinical Trial.

OpenAIRE

Sosa, Carlos; Lorenzo Calvo, Alberto; Jiménez, Sergio L.; Bonfanti, Noelia

2014-01-01

Chronic patellar tendinopathy is a common pathology in sporting population. To date, there is no agreed upon protocol as election treatment. Eccentric exercises have been used with satisfactory outcomes. The purpose of this trial is compare the effects of two eccentric exercise protocols. 0.146 SJR (2014) Q4, 199/231 Health (social science), 131/169 Physical therapy, sports therapy and rehabilitation, 119/128 Sports sciences UEM

Changes on Tendon Stiffness and Clinical Outcomes in Athletes Are Associated With Patellar Tendinopathy After Eccentric Exercise.

Science.gov (United States)

Lee, Wai-Chun; Ng, Gabriel Yin-Fat; Zhang, Zhi-Jie; Malliaras, Peter; Masci, Lorenzo; Fu, Siu-Ngor

2017-12-19

Eccentric exercise is commonly used as a form of loading exercise for individuals with patellar tendinopathy. This study investigated the change of mechanical properties and clinical outcomes and their interrelationships after a 12-week single-legged decline-board exercise with and without extracorporeal shockwave therapy (ESWT). Randomized controlled trial. Outpatient clinic of a university. Thirty-four male in-season athletes with patellar tendinopathy for more than 3 months were randomized into exercise and combined groups. The exercise group received a 12-week single-legged decline-squat exercise, and the combined group performed an identical exercise program in addition to a weekly session of ESWT in the initial 6 weeks. Tendon stiffness and strain were examined using ultrasonography and dynamometry. Visual analog scale and Victoria Institute of Sports Assessment-patella (VISA-p) score were used to assess pain and dysfunction. These parameters were measured at preintervention and postintervention. Significant time effect but no significant group effect on the outcome measures; significant reduction in tendon stiffness (P = 0.02) and increase in tendon strain (P = 0.00); and reduction of intensity of pain (P = 0.00) and dysfunction (P = 0.00) were observed. Significant correlations between changes in tendon stiffness and VISA-p score (ρ = -0.58, P = 0.05); alteration in tendon strain, pain intensity (ρ = -0.63, P = 0.03); and VISA-p score (ρ = 0.60, P = 0.04) were detected after the exercise program. Eccentric exercise-induced modulation on tendon mechanical properties and clinical symptoms are associated in athletes with patellar tendinopathy.

THE COMBINATION OF α-LIPOIC ACID INTAKE WITH ECCENTRIC EXERCISE MODULATES ERYTHROPOIETIN RELEASE

Directory of Open Access Journals (Sweden)

B. Morawin

2014-08-01

Full Text Available The generation of reactive nitrogen/oxygen species (RN/OS represents an important mechanism in erythropoietin (EPO expression and skeletal muscle adaptation to physical and metabolic stress. RN/OS generation can be modulated by intense exercise and nutrition supplements such as α-lipoic acid, which demonstrates both anti- and pro-oxidative action. The study was designed to show the changes in the haematological response through the combination of α-lipoic acid intake with running eccentric exercise. Sixteen healthy young males participated in the randomised and placebo-controlled study. The exercise trial involved a 90-min run followed by a 15-min eccentric phase at 65% VO2max (-10% gradient. It significantly increased serum concentrations of nitric oxide (NO, hydrogen peroxide (H2O2 and pro-oxidative products such as 8-isoprostanes (8-iso, lipid peroxides (LPO and protein carbonyls (PC. α-Lipoic acid intake (Thiogamma: 1200 mg daily for 10 days prior to exercise resulted in a 2-fold elevation of serum H2O2 concentration before exercise, but it prevented the generation of NO, 8-iso, LPO and PC at 20 min, 24 h, and 48 h after exercise. α-Lipoic acid also elevated serum EPO level, which highly correlated with NO/H2O2 ratio (r=0.718, P<0.01. Serum total creatine kinase (CK activity, as a marker of muscle damage, reached a peak at 24 h after exercise (placebo 732 ± 207 IU · L-1, α-lipoic acid 481 ± 103 IU · L-1, and correlated with EPO (r = 0.478, P<0.01 in the α-lipoic acid group. In conclusion, the intake of high α-lipoic acid modulates RN/OS generation, enhances EPO release and reduces muscle damage after running eccentric exercise.

Effects of Short-Term Docosahexaenoic Acid Supplementation on Markers of Inflammation after Eccentric Strength Exercise in Women.

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Corder, Katherine E; Newsham, Katherine R; McDaniel, Jennifer L; Ezekiel, Uthayashanker R; Weiss, Edward P

2016-03-01

The omega-3 fatty acid docosahexaenoic acid (DHA) has anti-inflammatory and anti-nociceptive (pain inhibiting) effects. Because strenuous exercise often results in local inflammation and pain, we hypothesized that DHA supplementation attenuates the rise in markers of local muscle inflammation and delayed onset muscle soreness (DOMS) that occur after eccentric strength exercise. Twenty-seven, healthy women (33 ± 2 y, BMI 23.1±1.0 kg·m(-2)) were randomized to receive 9d of 3000 mg/d DHA or placebo in a double-blind fashion. On day 7 of the supplementation period, the participants performed 4 sets of maximal-effort eccentric biceps curl exercise. Before and 48h after the eccentric exercise, markers of inflammation were measured including measures of muscle soreness (10-point visual analog pain scale, VAS), swelling (arm circumference), muscle stiffness (active and passive elbow extension), skin temperature, and salivary C-reactive protein (CRP) concentrations. As expected, muscle soreness and arm circumference increased while active and passive elbow extension decreased. The increase in soreness was 23% less in the DHA group (48h increase in VAS soreness ratings: 4.380.4 vs. 5.600.5, p=0.02). Furthermore, the number of subjects who were able to achieve full active elbow extension 48h after eccentric exercise was greater in the DHA group (71% vs. 15%, p = 0.006), indicating significantly less muscle stiffness. No between-group differences were observed for passive elbow extension (p = 0.78) or arm swelling (p = 0.75). Skin temperature and salivary CRP concentrations did not change from baseline to 48h after exercise in either group. These findings indicate that short-term DHA supplementation reduces exercise-induced muscle soreness and stiffness. Therefore, in addition to other health benefits that n-3 fatty acids have been associated with, DHA supplementation could be beneficial for improving tolerance to new and/or strenuous exercise programs and thereby might

Concentric and eccentric time-under-tension during strengthening exercises: Validity and reliability of stretch-sensor recordings from an elastic exercise-band

DEFF Research Database (Denmark)

Rathleff, Michael Skovdal; Thorborg, Kristian; Bandholm, Thomas Quaade

2013-01-01

Total, single repetition and contraction-phase specific (concentric and eccentric) time-under-tension (TUT) are important exercise-descriptors, as they are linked to the physiological and clinical response in exercise and rehabilitation....

Eccentric versus conventional exercise therapy in patients with rotator cuff tendinopathy: a randomized, single blinded, clinical trial.

Science.gov (United States)

Dejaco, Beate; Habets, Bas; van Loon, Corné; van Grinsven, Susan; van Cingel, Robert

2017-07-01

To investigate the effectiveness of isolated eccentric versus conventional exercise therapy in patients with rotator cuff tendinopathy. Thirty-six patients with rotator cuff tendinopathy, diagnosed by an orthopaedic surgeon, were included and randomly allocated to an isolated eccentric exercise (EE) group (n = 20, mean age = 50.2 ± 10.8 years) or a conventional exercise (CG) group (n = 16, mean age = 48.6 ± 12.3 years). Both groups fulfilled a 12-week daily home-based exercise programme and received a total amount of nine treatment sessions. The Constant Murley score was used to evaluate both objective (e.g. range of motion and strength) and subjective measures (e.g. pain and activities of daily living). A visual analogue scale (VAS) was used to evaluate pain during daily activities. As secondary outcomes, shoulder range of motion and isometric abduction strength in 45° in the scapular plane were evaluated. All measurements were taken at baseline, at 6, 12 and 26 weeks. After 26 weeks, both groups showed a significant increase in the Constant Murley score and a significant decrease in VAS scores. No difference was found between the groups, for any of the evaluated outcome measures. A 12-week-isolated eccentric training programme of the rotator cuff is beneficial for shoulder function and pain after 26 weeks in patients with rotator cuff tendinopathy. However, it is no more beneficial than a conventional exercise programme for the rotator cuff and scapular muscles. Based on the results, clinicians should take into account that performing two eccentric exercises twice a day is as effective as performing six concentric/eccentric exercises once a day in patients with rotator cuff tendinopathy.

Is there really an eccentric action of the hamstrings during the swing phase of high-speed running? Part II: Implications for exercise.

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Van Hooren, Bas; Bosch, Frans

2017-12-01

We have previously argued that there may actually be no significant eccentric, but rather predominantly an isometric action of the hamstring muscle fibres during the swing phase of high-speed running when the attachment points of the hamstrings are moving apart. Based on this we suggested that isometric rather than eccentric exercises are a more specific way of conditioning the hamstrings for high-speed running. In this review we argue that some of the presumed beneficial adaptations following eccentric training may actually not be related to the eccentric muscle fibre action, but to other factors such as exercise intensity. Furthermore, we discuss several disadvantages associated with commonly used eccentric hamstring exercises. Subsequently, we argue that high-intensity isometric exercises in which the series elastic element stretches and recoils may be equally or even more effective at conditioning the hamstrings for high-speed running, since they also avoid some of the negative side effects associated with eccentric training. We provide several criteria that exercises should fulfil to effectively condition the hamstrings for high-speed running. Adherence to these criteria will guarantee specificity with regards to hamstrings functioning during running. Practical examples of isometric exercises that likely meet several criteria are provided.

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.

Science.gov (United States)

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.

Acute effects of movement velocity on blood lactate and growth hormone responses after eccentric bench press exercise in resistance-trained men.

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Calixto, Rd; Verlengia, R; Crisp, Ah; Carvalho, Tb; Crepaldi, Md; Pereira, Aa; Yamada, Ak; da Mota, Gr; Lopes, Cr

2014-12-01

This study aimed to compare the effects of different velocities of eccentric muscle actions on acute blood lactate and serum growth hormone (GH) concentrations following free weight bench press exercises performed by resistance-trained men. Sixteen healthy men were divided into two groups: slow eccentric velocity (SEV; n = 8) and fast eccentric velocity (FEV; n = 8). Both groups performed four sets of eight eccentric repetitions at an intensity of 70% of their one repetition maximum eccentric (1RMecc) test, with 2-minute rest intervals between sets. The eccentric velocity was controlled to 3 seconds per range of motion for SEV and 0.5 seconds for the FEV group. There was a significant difference (P bench press exercise in the SEV group (1.7 ± 0.6 ng · mL(-1)) relative to the FEV group (0.1 ± 0.0 ng · mL(-1)). In conclusion, the velocity of eccentric muscle action influences acute responses following bench press exercises performed by resistance-trained men using a slow velocity resulting in a greater metabolic stress and hormone response.

Exercise-induced muscle damage and the repeated bout effect: evidence for cross transfer.

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Starbuck, Chelsea; Eston, Roger G

2012-03-01

We examined whether a prior bout of eccentric exercise in the elbow flexors provided protection against exercise-induced muscle damage in the contralateral arm. Fifteen males (age 22.7 ± 2.1 years; height 178.6 ± 6.8 cm, mass 75.8 ± 9.3 kg) were randomly assigned to two groups who performed two bouts of 60 eccentric contractions (30°/s) separated by 2 weeks: ipsilateral (n = 7, both bouts performed in the same arm), contralateral (n = 8, one bout performed in each arm). Strength, muscle soreness and resting arm angle (RAA) were measured at baseline and at 1, 24 and 48 h post exercise. Surface electromyography was recorded during both bouts of exercise. The degree of strength loss was attenuated (p < 0.05) in the ipsilateral group after the second bout of eccentric exercise (-22 cf. -3% for bout 1 and 2 at 24 h, respectively). Strength loss following eccentric exercise was also attenuated (p < 0.05) at 24 h in the contralateral group (-30 cf. 13% for bout 1 and 2, respectively). Muscle soreness (≈34 cf 19 mm) and change in RAA (≈5 cf. 3%) were also lower following the second bout of eccentric exercise (p < 0.05), although there was no difference in the overall change in these values between groups. Median frequency (MF) was decreased by 31% between bouts, with no difference between groups. Data support observations that the repeated bout effect transfers to the opposite (untrained) limb. The similar reduction in MF between bouts for the two groups provides evidence for a centrally mediated, neural adaptation.

The Effect of Single Portion Glutamine Supplement Consumption on Injury Indices of Muscle After Eccentric Resistance Exercise

OpenAIRE

Azadeh Najarzadeh; Hadi Atarod; Hasan Mozaffari-Khosravi; Ali Dehghani; Foad Asjodi

2015-01-01

Abstract Background: Delayed muscular soreness after resistance exercises or eccentric trainings is probably because of muscle damage and injury. Nutrition by playing a crucial role in both protein synthesize and catabolism can influence the extent of muscle injury. The objective of this study was to assess the effect of single portion of Glutamine supplement consumption on injury indices of muscle after a session eccentric resistance exercise. Materials and Methods: this study used a ...

Local NSAID infusion does not affect protein synthesis and gene expression in human muscle after eccentric exercise

DEFF Research Database (Denmark)

Mikkelsen, U R; Schjerling, P; Helmark, Ida Carøe

2010-01-01

models, and inhibit the exercise-induced satellite cell proliferation and protein synthesis in humans. However, the cellular mechanisms eliciting these responses remain unknown. Eight healthy male volunteers performed 200 maximal eccentric contractions with each leg. To block prostaglandin synthesis...... locally in the skeletal muscle, indomethacin (NSAID) was infused for 7.5 h via microdialysis catheters into m. vastus lateralis of one leg. Protein synthesis was determined by the incorporation of 1,2-(13)C(2) leucine into muscle protein from 24 to 28 h post-exercise. Furthermore, mRNA expression...... of selected genes was measured in muscle biopsies (5 h and 8 days post-exercise) by real-time reverse transcriptase PCR. Myofibrillar and collagen protein synthesis were unaffected by the local NSAID infusion. Five hours post-exercise, the mRNA expression of cyclooxygenase-2 (COX2) was sixfold higher...

Loss of nNOS inhibits compensatory muscle hypertrophy and exacerbates inflammation and eccentric contraction-induced damage in mdx mice

Science.gov (United States)

Froehner, Stanley C.; Reed, Sarah M.; Anderson, Kendra N.; Huang, Paul L.; Percival, Justin M.

2015-01-01

Approaches targeting nitric oxide (NO) signaling show promise as therapies for Duchenne and Becker muscular dystrophies. However, the mechanisms by which NO benefits dystrophin-deficient muscle remain unclear, but may involve nNOSβ, a newly discovered enzymatic source of NO in skeletal muscle. Here we investigate the impact of dystrophin deficiency on nNOSβ and use mdx mice engineered to lack nNOSμ and nNOSβ to discern how the loss of nNOS impacts dystrophic skeletal muscle pathology. In mdx muscle, nNOSβ was mislocalized and its association with the Golgi complex was reduced. nNOS depletion from mdx mice prevented compensatory skeletal muscle cell hypertrophy, decreased myofiber central nucleation and increased focal macrophage cell infiltration, indicating exacerbated dystrophic muscle damage. Reductions in muscle integrity in nNOS-null mdx mice were accompanied by decreases in specific force and increased susceptibility to eccentric contraction-induced muscle damage compared with mdx controls. Unexpectedly, muscle fatigue was unaffected by nNOS depletion, revealing a novel latent compensatory mechanism for the loss of nNOS in mdx mice. Together with previous studies, these data suggest that localization of both nNOSμ and nNOSβ is disrupted by dystrophin deficiency. They also indicate that nNOS has a more complex role as a modifier of dystrophic pathology and broader therapeutic potential than previously recognized. Importantly, these findings also suggest nNOSβ as a new drug target and provide a new conceptual framework for understanding nNOS signaling and the benefits of NO therapies in dystrophinopathies. PMID:25214536

Detection of titin fragments in urine in response to exercise-induced muscle damage.

Directory of Open Access Journals (Sweden)

Kazue Kanda

Full Text Available Many studies have attempted to determine the associations between blood biomarkers and exercise-induced muscle damage. However, poor correlations between the changes in biomarker levels and the magnitude of muscle symptoms have been reported. Recent advances in proteomic tools offer a strategy for the comprehensive analysis of protein expression, which can be used to identify biomarkers. Here, we used a proteomic analysis to identify urinary proteins that appear in response to a calf-raise exercise, including repetitive eccentric muscle contractions, and found that a titin (also known as connectin N-terminal fragment molecule appears in the urine after eccentric exercise. We measured the titin fragment in urine samples from nine individuals before and after eccentric exercise using a newly-established enzyme-linked immunosorbent assay and found that the titin fragment excretion rate increased 96 h after the exercise (5.1 to 77.6 pg/min, p <0.01. The changes in the titin fragment excretion rate were correlated strongly with blood markers of muscle damage and with muscle symptoms. These findings suggest that the urinary titin fragment is potentially a noninvasive biomarker of muscle damage.

Supplementation with a Polyphenol-Rich Extract, TensLess® , Attenuates Delayed Onset Muscle Soreness and Improves Muscle Recovery from Damages After Eccentric Exercise.

Science.gov (United States)

Romain, Cindy; Freitas, Tomás T; Martínez-Noguera, Francisco J; Laurent, Caroline; Gaillet, Sylvie; Chung, Linda H; Alcaraz, Pedro E; Cases, Julien

2017-11-01

High-intensity exercises are known to provoke delayed onset muscle soreness (DOMS). Delayed onset muscle soreness typically occurs within the first 24 h, peaks between 24 and 72 h, and can last as long as 5-7 days post-exercise. Delayed onset muscle soreness is a multifactorial process involving both mechanical and biochemical components, associated with clinical features that may limit range of motion, and athletes seek for effective recovery strategies to optimize future training sessions. TensLess ® is a food supplement developed to help manage post-exercise recovery. The supplement has been investigated on 13 recreationally active athletes of both sex, during a randomized, double-blind, and crossover clinical investigation, including a 3-week washout period. The clinical investigation was based on the study of TensLess ® effects for DOMS management and on the reduction of associated muscle damages following an eccentric exercise protocol. Supplementation with TensLess ® induced significant decrease in DOMS perception (-33%; p = 0.008) as of the first 24 h; this was significantly correlated with a lowered release of muscle damage-associated biomarkers, namely myoglobin, creatinine, and creatine kinase, for the whole length of the recovery period. Taken together, these positive results clearly indicate that post-exercise supplementation with TensLess ® may preserve myocytes and reduce soreness following eccentric exercise-induced damages, and, accordingly, significantly shorten muscle recovery. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

A COX-2 inhibitor reduces muscle soreness, but does not influence recovery and adaptation after eccentric exercise

DEFF Research Database (Denmark)

Paulsen, G; Egner, I M; Drange, M

2010-01-01

The aim of this study was to investigate the effect of a cyclooxygenase (COX)-2 inhibitor on the recovery of muscle function, inflammation, regeneration after, and adaptation to, unaccustomed eccentric exercise. Thirty-three young males and females participated in a double-blind, placebo-controll......The aim of this study was to investigate the effect of a cyclooxygenase (COX)-2 inhibitor on the recovery of muscle function, inflammation, regeneration after, and adaptation to, unaccustomed eccentric exercise. Thirty-three young males and females participated in a double-blind, placebo...

BounceBack™ capsules for reduction of DOMS after eccentric exercise: a randomized, double-blind, placebo-controlled, crossover pilot study

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Singh Betsy B

2009-06-01

Full Text Available Abstract Background Delayed onset muscle soreness (DOMS is muscle pain and discomfort experienced approximately one to three days after exercise. DOMS is thought to be a result of microscopic muscle fiber tears that occur more commonly after eccentric exercise rather than concentric exercise. This study sought to test the efficacy of a proprietary dietary supplement, BounceBack™, to alleviate the severity of DOMS after standardized eccentric exercise. Methods The study was a randomized, double-blind, placebo-controlled, crossover study. Ten healthy community-dwelling untrained subjects, ranging in age from 18–45 years, were enrolled. Mean differences within and between groups were assessed inferentially at each data collection time-point using t-tests for all outcome measures. Results In this controlled pilot study, intake of BounceBack™ capsules for 30 days resulted in a significant reduction in standardized measures of pain and tenderness post-eccentric exercise compared to the placebo group. There were trends towards reductions in plasma indicators of inflammation (high sensitivity C-reactive protein and muscle damage (creatine phosphokinase and myoglobin. Conclusion BounceBack™ capsules were able to significantly reduce standardized measures of pain and tenderness at several post-eccentric exercise time points in comparison to placebo. The differences in the serological markers of DOMS, while not statistically significant, appear to support the clinical findings. The product appears to have a good safety profile and further study with a larger sample size is warranted based on the current results.

BounceBack capsules for reduction of DOMS after eccentric exercise: a randomized, double-blind, placebo-controlled, crossover pilot study.

Science.gov (United States)

Udani, Jay K; Singh, Betsy B; Singh, Vijay J; Sandoval, Elizabeth

2009-06-05

Delayed onset muscle soreness (DOMS) is muscle pain and discomfort experienced approximately one to three days after exercise. DOMS is thought to be a result of microscopic muscle fiber tears that occur more commonly after eccentric exercise rather than concentric exercise. This study sought to test the efficacy of a proprietary dietary supplement, BounceBack, to alleviate the severity of DOMS after standardized eccentric exercise. The study was a randomized, double-blind, placebo-controlled, crossover study. Ten healthy community-dwelling untrained subjects, ranging in age from 18-45 years, were enrolled. Mean differences within and between groups were assessed inferentially at each data collection time-point using t-tests for all outcome measures. In this controlled pilot study, intake of BounceBack capsules for 30 days resulted in a significant reduction in standardized measures of pain and tenderness post-eccentric exercise compared to the placebo group. There were trends towards reductions in plasma indicators of inflammation (high sensitivity C-reactive protein) and muscle damage (creatine phosphokinase and myoglobin). BounceBack capsules were able to significantly reduce standardized measures of pain and tenderness at several post-eccentric exercise time points in comparison to placebo. The differences in the serological markers of DOMS, while not statistically significant, appear to support the clinical findings. The product appears to have a good safety profile and further study with a larger sample size is warranted based on the current results.

BounceBack™ capsules for reduction of DOMS after eccentric exercise: a randomized, double-blind, placebo-controlled, crossover pilot study

Science.gov (United States)

Udani, Jay K; Singh, Betsy B; Singh, Vijay J; Sandoval, Elizabeth

2009-01-01

Background Delayed onset muscle soreness (DOMS) is muscle pain and discomfort experienced approximately one to three days after exercise. DOMS is thought to be a result of microscopic muscle fiber tears that occur more commonly after eccentric exercise rather than concentric exercise. This study sought to test the efficacy of a proprietary dietary supplement, BounceBack™, to alleviate the severity of DOMS after standardized eccentric exercise. Methods The study was a randomized, double-blind, placebo-controlled, crossover study. Ten healthy community-dwelling untrained subjects, ranging in age from 18–45 years, were enrolled. Mean differences within and between groups were assessed inferentially at each data collection time-point using t-tests for all outcome measures. Results In this controlled pilot study, intake of BounceBack™ capsules for 30 days resulted in a significant reduction in standardized measures of pain and tenderness post-eccentric exercise compared to the placebo group. There were trends towards reductions in plasma indicators of inflammation (high sensitivity C-reactive protein) and muscle damage (creatine phosphokinase and myoglobin). Conclusion BounceBack™ capsules were able to significantly reduce standardized measures of pain and tenderness at several post-eccentric exercise time points in comparison to placebo. The differences in the serological markers of DOMS, while not statistically significant, appear to support the clinical findings. The product appears to have a good safety profile and further study with a larger sample size is warranted based on the current results. PMID:19500355

Effects of eccentric cycling exercise on IGF-I splice variant expression in the muscles of young and elderly people

DEFF Research Database (Denmark)

Hameed, M.; Toft, A.D.; Harridge, S.D.

2008-01-01

growth factor (MGF) were studied in response to 1 h of eccentric cycling exercise in young and old individuals. Subjects (nine young, aged 20-27 years and eight elderly, aged 67-75 years) completed an eccentric exercise protocol that consisted of 60 min of reverse pedal cycling. Workloads were chosen......Recovery from micro damage resulting from intensive exercise has been shown to take longer in older muscles. To investigate the factors that may contribute to muscle repair, we have studied the expression of two splice variants of the insulin-like growth factor-I (IGF-I) gene. IGF-IEa and mechano....... No difference was observed between the baseline levels of the two splice variants between the two subject groups. Eccentric cycling exercise resulted in a significant increase in the mean MGF mRNA in both young and old subjects but did not alter IGF-IEa mRNA levels in either age group. As reported previously...

Diclofenac pretreatment modulates exercise-induced inflammation in skeletal muscle of rats through the TLR4/NF-κB pathway.

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Barcelos, Rômulo Pillon; Bresciani, Guilherme; Cuevas, Maria José; Martínez-Flórez, Susana; Soares, Félix Alexandre Antunes; González-Gallego, Javier

2017-07-01

Nonsteroidal anti-inflammatory drugs, such as diclofenac, are widely used to treat inflammation and pain in several conditions, including sports injuries. This study analyzes the influence of diclofenac on the toll-like receptor-nuclear factor kappa B (TLR-NF-κB) pathway in skeletal muscle of rats submitted to acute eccentric exercise. Twenty male Wistar rats were divided into 4 groups: control-saline, control-diclofenac, exercise-saline, and exercise-diclofenac. Diclofenac or saline were administered for 7 days prior to an acute eccentric exercise bout. The inflammatory status was evaluated through mRNA levels of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), IL-1β, and tumor necrosis factor alpha (TNF-α), and protein content of COX-2, IL-6, and TNF-α in vastus lateralis muscle. Data obtained showed that a single bout of eccentric exercise significantly increased COX-2 gene expression. Similarly, mRNA expression and protein content of other inflammation-related genes also increased after the acute exercise. However, these effects were attenuated in the exercise + diclofenac group. TLR4, myeloid differentiation primary response gene 88 (MyD88), and p65 were also upregulated after the acute eccentric bout and the effect was blunted by the anti-inflammatory drug. These findings suggest that pretreatment with diclofenac may represent an effective tool to ameliorate the pro-inflammatory status induced by acute exercise in rat skeletal muscle possibly through an attenuation of the TLR4-NF-κB signaling pathway.

Vitamins C and E for asthma and exercise-induced bronchoconstriction.

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Wilkinson, Mark; Hart, Anna; Milan, Stephen J; Sugumar, Karnam

2014-06-17

The association between dietary antioxidants and asthma or exercise-induced bronchoconstriction (EIB) is not fully understood. Vitamin C and vitamin E are natural antioxidants that are predominantly present in fruits and vegetables; inadequate vitamin E intake is associated with airway inflammation. It has been postulated that the combination may be more beneficial than either single antioxidant for people with asthma and exercise-induced bronchoconstriction. To assess the effects of supplementation of vitamins C and E versus placebo (or no vitamin C and E supplementation) on exacerbations and health-related quality of life (HRQL) in adults and children with chronic asthma. To also examine the potential effects of vitamins C and E on exercise-induced bronchoconstriction in people with asthma and in people without a diagnosis of asthma who experience symptoms only on exercise. Trials were identified from the Cochrane Airways Review Group Specialised Register and from trial registry websites. Searches were conducted in September 2013. We included randomised controlled trials of adults and children with a diagnosis of asthma. We separately considered trials in which participants had received a diagnosis of exercise-induced bronchoconstriction (or exercise-induced asthma). Trials comparing vitamin C and E supplementation versus placebo were included. We included trials in which asthma management for treatment and control groups included similar background therapy. Short-term use of vitamins C and E at the time of exacerbation or for cold symptoms in people with asthma is outside the scope of this review. Two review authors independently screened the titles and abstracts of potential studies and subsequently screened full-text study reports for inclusion. We used standard methods as expected by The Cochrane Collaboration. It was not possible to aggregate the five included studies (214 participants). Four studies (206 participants) addressed the question of whether

ACUTE EFFECTS OF MOVEMENT VELOCITY ON BLOOD LACTATE AND GROWTH HORMONE RESPONSES AFTER ECCENTRIC BENCH PRESS EXERCISE IN RESISTANCE-TRAINED MEN

OpenAIRE

Calixto, RD; Verlengia, R; Crisp, AH; Carvalho, TB; Crepaldi, MD; Pereira, AA; Yamada, AK; da Mota, GR; Lopes, CR

2014-01-01

This study aimed to compare the effects of different velocities of eccentric muscle actions on acute blood lactate and serum growth hormone (GH) concentrations following free weight bench press exercises performed by resistance-trained men. Sixteen healthy men were divided into two groups: slow eccentric velocity (SEV; n = 8) and fast eccentric velocity (FEV; n = 8). Both groups performed four sets of eight eccentric repetitions at an intensity of 70% of their one repetition maximum eccentric...

The Effect of Two Acute Eccentric and Concentric Exercises on Serum Irisin Level and Insulin Resistance Index in Inactive Obese Women

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Faranak Balaghi Inaloo

2016-12-01

Full Text Available Abstract Background: Recently a myokine named irisin has been discovered that effects on obesity, metabolism and glucose homeostasis through browning white adipose tissue and thermogenesis. However, the effects of type and intensity of exercises on it have remained unclear. The purpose of this study was to evaluate the effects of two acute eccentric and concentric exercises on serum irisin level and insulin resistance in obese sedentary women. Materials and Methods: The study was quasi-experimental. 15 female students with a body mass index above 30 kg/m2 and mean age 24.86±2.87 years participated in the study. After measuring the maximal uptake oxygen of participants, they did two acute eccentric and concentric exercises using treadmill in a cross-over design within 10 days. After at least 8 hours- fasting, blood samples were collected before and immediately after each activity, to measure the levels of irisin, glucose and insulin. Data were analyzed using paired t-test and repeated measures ANOVA. In addition, Pearson correlation was used to examine the relationship between variables. Results: the irisin levels increased significantly after both types of exercises (p<0.05, that this increase in concentric activity was more than eccentric activity. Insulin resistance increased immediately after both exercises as well, that this increase in concentric exercise was statistically significant (p<0.05. Conclusion: However, both eccentric and concentric exercises had no effect on improving insulin resistance in obese women, but they can be considered as a good stimulus for the secretion of Irisin.

Influence of Arm-cranking on Changes in Plasma CK Activity after High Force Eccentric Exercise of the Elbow Flexors

OpenAIRE

Kosaka, Kazunori; Sakamoto, Kei; Newton, Mike

2002-01-01

NOSAKA, K., SAKAMOTO, K. and NEWTON, M., Influence of Armcranking on Changes in Plasma CK Activlty after High Force Eccentric Exerclse of the Elbow Flexours. Abv. Exerc. Sports Physiol., Vol.8, No.2 pp.45-50, 2002. It was hypothesized that the time course of changes in plasma creatine kinase(CK) activity following eccentrie exercise was influenced by rhythmical muscle contractions performned after eccentric exercise. This study examined whether arm-cranking (AC) alters the time course of chan...

Manual therapy and eccentric exercise in the management of Achilles tendinopathy.

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Jayaseelan, Dhinu J; Kecman, Michael; Alcorn, Daniel; Sault, Josiah D

2017-05-01

Chronic Achilles tendinopathy (AT) is an overuse condition seen among runners. Eccentric exercise can decrease pain and improve function for those with chronic degenerative tendon changes; however, some individuals have continued pain requiring additional intervention. While joint mobilization and manipulation has not been studied in the management in Achilles tendinopathy, other chronic tendon dysfunction, such as lateral epicondylalgia, has responded well to manual therapy (MT). Three runners were seen in physical therapy (PT) for chronic AT. They were prescribed eccentric loading exercises and calf stretching. Joint mobilization and manipulation was implemented to improve foot and ankle mobility, decrease pain, and improve function. Immediate within-session changes in pain, heel raise repetitions, and pressure pain thresholds (PPT) were noted following joint-directed MT in each patient. Each patient improved in self-reported function on the Achilles tendon specific Victorian Institute for Sport Assessment questionnaire (VISA-A), pain levels, PPT, joint mobility, ankle motion, and single-leg heel raises at discharge and 9-month follow-up. The addition of MT directed at local and remote sites may enhance the rehabilitation of patients with AT. Further research is necessary to determine the efficacy of adding joint mobilization to standard care for AT. Case series. Therapy, Level 4.

Different training responses to eccentric endurance exercise at low and moderate altitudes in pre-diabetic men: a pilot study.

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Klarod, Kultida; Philippe, Marc; Gatterer, Hannes; Burtscher, Martin

2017-01-01

This pilot study aimed (a) to evaluate the effects of eccentric exercise training at low and moderate altitudes on physical fitness in pre-diabetic men and (b) to establish whether or not oxidative stress levels and antioxidant status were associated with performance improvements. In this crossover trial, five pre-diabetic men conducted nine downhill walking sessions (3 days/week, 3 consecutive weeks) at low altitude (from 1360 to 850 m) and one year later at moderate altitude (from 2447 to 2000 m). Exercise testing and the determination of parameters of oxidative stress and antioxidant capacity were performed pre- and post-training. The biological antioxidant activity of plasma (BAP) increased after eccentric training at moderate altitude ( p  training at moderate-altitude training ( p  = 0.009). Maximum power output improved after training at low altitude and the changes were significantly related to baseline BAP/dROMs ratio ( r  = 0.90). No decrease was seen for fasting plasma glucose. Eccentric exercise training in pre-diabetic men improved performance only when performed at low altitude and this improvement was positively related to the baseline BAP/dROMs ratio. In contrast, 3 weeks of eccentric exercise training increased BAP levels and the BAP/dROMs ratio only at moderate altitude without improving the performance. Thus, one might speculate that the BAP/dROMs ratio has to increase before performance improvements occur at moderate altitude.

The influence of resistance exercise with emphasis on specific contractions (concentric vs. eccentric on muscle strength and post-exercise autonomic modulation: a randomized clinical trial

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Mariana O. Gois

2014-01-01

Full Text Available Background: Compared to eccentric contractions, concentric contractions result in higher cardiovascular stress. However, we do not know how these two types of contractions influence cardiac autonomic modulation during the post-exercise recovery period. Objective: to compare the effect of resistance training that is performed with concentric vs. eccentric emphasis on muscle strength and on post-exercise recovery which was assessed by examining heart rate variability (HRV, for the knee extensor muscle group in young healthy adults. Methods: For this study, 105 men between 18 and 30 years of age were randomized into 4 groups: concentric control (CONCC, eccentric control (ECCC, concentric training (CONCT and eccentric training (ECCT. The CONCC and ECCC groups underwent one session of resistance exercise (RE using the knee extensor muscle group (3 sets of 1 repetition at 100% of the maximal repetition [1MR] and the CONCT and ECCT groups performed 10 training sessions. The HRV was analyzed at baseline and across four recovery periods (T1, T2, T3 and T4. Results: The ECCT group exhibited increased muscle strength at the end of the study. Regarding cardiac autonomic modulation, the CONCC and ECCC groups exhibited increases in overall variability (SDNN and SD2 at T1 compared to baseline, and the ECCT group demonstrated increases in variables reflecting vagal modulation and the recovery process (RMSSD, SD1 and HF [ms2] at T1, T2 and T4 compared to baseline. Conclusions: Resistance training with emphasis on eccentric contractions promoted strength gain and an increase in cardiac vagal modulation during recovery compared to baseline.

Protein hydrolysates and recovery of muscle damage following eccentric exercise

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Dale M.J.

2015-01-01

Full Text Available Background: A whey protein hydrolysate (NatraBoost XR; WPHNB has been shown to speed repair muscle damage. We sought to determine whether this benefit is specific to this hydrolysate to evaluate a marker for quality control. Methods: Three hydrolysates of the same whey protein isolate (WPI were prepared (WPHNB, WPH1 and WPH2. Isometric knee extensor strength was measured in 39 sedentary male participants before and after 100 maximal eccentric contractions of the knee extensors to induce muscle damage. Participants were then randomised to consume 250 ml of flavoured water (FW, n=9, or 250 ml of FW containing 25 g of either NatraBoost XR (n=3, WPH1 (n=9, WPH2 (n=9 or WPI (n=9. Strength was reassessed over the next seven days while the supplements were consumed daily. Fibroblasts were cultured for 48 hr in the presence of the different hydrolysates, WPI, saline or fetal bovine serum to ascertain effects on cell proliferation. Results: Strength was reduced in all treatment groups after eccentric exercise (P<0.001. Strength recovered steadily over 7 days in the FW, WPI, WPH1 and WPH2 treatment groups (P<0.001, with no difference between treatments (P=0.87. WPHNB promoted faster strength recovery compared with the other treatments (P<0.001. Fibroblast proliferation was greater with WPHNB compared with saline, WPI or the other hydrolysates (P<0.001. Conclusions: Promoting recovery from muscle damage seems unique to WPHNB. In vitro fibroblast proliferation may be a useful marker for quality control. It is not clear whether effects on fibroblast proliferation contribute to the in vivo effect of WPHNB on muscle damage.

Effects of air-pulsed cryotherapy on neuromuscular recovery subsequent to exercise-induced muscle damage.

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Guilhem, Gaël; Hug, François; Couturier, Antoine; Regnault, Stéphanie; Bournat, Laure; Filliard, Jean-Robert; Dorel, Sylvain

2013-08-01

Localized cooling has been proposed as an effective strategy to limit the deleterious effects of exercise-induced muscle damage on neuromuscular function. However, the literature reports conflicting results. This randomized controlled trial aimed to determine the effects of a new treatment, localized air-pulsed cryotherapy (-30°C), on the recovery time-course of neuromuscular function following a strenuous eccentric exercise. Controlled laboratory study. A total of 24 participants were included in either a control group (CONT) or a cryotherapy group (CRYO). Immediately after 3 sets of 20 maximal isokinetic eccentric contractions of elbow flexors, and then 1, 2, and 3 days after exercise, the CRYO group received a cryotherapy treatment (3 × 4 minutes at -30°C separated by 1 minute). The day before and 1, 2, 3, 7, and 14 days after exercise, several parameters were quantified: maximal isometric torque and its associated maximal electromyographic activity recorded by a 64-channel electrode, delayed-onset muscle soreness (DOMS), biceps brachii transverse relaxation time (T2) measured using magnetic resonance imaging, creatine kinase activity, interleukin-6, and C-reactive protein. Maximal isometric torque decreased similarly for the CONT (-33% ± 4%) and CRYO groups (-31% ± 6%). No intergroup differences were found for DOMS, electromyographic activity, creatine kinase activity, and T2 level averaged across the whole biceps brachii. C-reactive protein significantly increased for CONT (+93% at 72 hours, P cryotherapy delayed the significant increase of T2 and the decrease of electromyographic activity level for CRYO compared with CONT (between day 1 and day 3) in the medio-distal part of the biceps brachii. Although some indicators of muscle damage after severe eccentric exercise were delayed (ie, local formation of edema and decrease of muscle activity) by repeated air-pulsed cryotherapy, we provide evidence that this cooling procedure failed to improve long

High-threshold motor unit firing reflects force recovery following a bout of damaging eccentric exercise.

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Macgregor, Lewis J; Hunter, Angus M

2018-01-01

Exercise-induced muscle damage (EIMD) is associated with impaired muscle function and reduced neuromuscular recruitment. However, motor unit firing behaviour throughout the recovery period is unclear. EIMD impairment of maximal voluntary force (MVC) will, in part, be caused by reduced high-threshold motor unit firing, which will subsequently increase to recover MVC. Fourteen healthy active males completed a bout of eccentric exercise on the knee extensors, with measurements of MVC, rate of torque development and surface electromyography performed pre-exercise and 2, 3, 7 and 14 days post-exercise, on both damaged and control limb. EIMD was associated with decreased MVC (235.2 ± 49.3 Nm vs. 161.3 ± 52.5 Nm; p exercise. Mean motor unit firing rate was reduced (16.4 ± 2.2 Hz vs. 12.6 ± 1.7 Hz; p motor units only, 48h post-exercise, and common drive was elevated (0.36 ± 0.027 vs. 0.56 ± 0.032; pexercise. The firing rate of high-threshold motor units was reduced in parallel with impaired muscle function, whilst early recruited motor units remained unaltered. Common drive of motor units increased in offset to the firing rate impairment. These alterations correlated with the recovery of force decrement, but not of pain elevation. This study provides fresh insight into the central mechanisms associated with EIMD recovery, relative to muscle function. These findings may in turn lead to development of novel management and preventative procedures.

Eccentric exercises; why do they work, what are the problems and how can we improve them?

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Rees, J D; Wolman, R L; Wilson, A

2009-04-01

Eccentric exercises (EE) have proved successful in the management of chronic tendinopathy, particularly of the Achilles and patellar tendons, where they have been shown to be effective in controlled trials. However, numerous questions regarding EE remain. The standard protocols are time-consuming and require very motivated patients. EE are effective in some tendinopathies but not others. Furthermore, the location of the lesion can have a profound effect on efficacy; for example, standard EE in insertional lesions of the Achilles are ineffective. Until recently little was known of the effect of EE on tendinopathic tendons, although a greater understanding of this process is emerging. Additionally, recent in vivo evidence directly comparing eccentric and concentric exercises provides a possible explanation for the therapeutic benefit of EE. The challenge now is to make EE more effective. Suggestions on areas of future research are made.

Including the Copenhagen Adduction Exercise in the FIFA 11+ Provides Missing Eccentric Hip Adduction Strength Effect in Male Soccer Players: A Randomized Controlled Trial.

Science.gov (United States)

Harøy, Joar; Thorborg, Kristian; Serner, Andreas; Bjørkheim, André; Rolstad, Linn E; Hölmich, Per; Bahr, Roald; Andersen, Thor Einar

2017-11-01

The FIFA 11+ was developed as a complete warm-up program to prevent injuries in soccer players. Although reduced hip adduction strength is associated with groin injuries, none of the exercises included in the FIFA 11+ seem to specifically target hip adduction strength. To investigate the effect on eccentric hip adduction strength of the FIFA 11+ warm-up program with or without the Copenhagen adduction exercise. Randomized controlled trial; Level of evidence, 1. We recruited 45 eligible players from 2 U19 elite male soccer teams. Players were randomized into 2 groups; 1 group carried out the standard FIFA 11+ program, while the other carried out the FIFA 11+ but replaced the Nordic hamstring exercise with the Copenhagen adduction exercise. Both groups performed the intervention 3 times weekly for 8 weeks. Players completed eccentric strength and sprint testing before and after the intervention. Per-protocol analyses were performed, and 12 players were excluded due to low compliance (<67% of sessions completed). The main outcome was eccentric hip adduction strength (N·m/kg). Between-group analyses revealed a significantly greater increase in eccentric hip adduction strength of 0.29 Nm/kg (8.9%; P = .01) in favor of the group performing the Copenhagen adduction exercise, whereas no within-group change was noted in the group that used the standard FIFA 11+ program (-0.02 N·m/kg [-0.7%]; P = .69). Including the Copenhagen adduction exercise in the FIFA 11+ program increases eccentric hip adduction strength, while the standard FIFA 11+ program does not. Registration: Registration: ISRCTN13731446 (International Standard Randomised Controlled Trial Number registry).

Recent advances in the understanding of the repeated bout effect: the protective effect against muscle damage from a single bout of eccentric exercise.

Science.gov (United States)

McHugh, Malachy P

2003-04-01

The repeated bout effect refers to the adaptation whereby a single bout of eccentric exercise protects against muscle damage from subsequent eccentric bouts. While the mechanism for this adaptation is poorly understood there have been significant recent advances in the understanding of this phenomenon. The purpose of this review is to provide an update on previously proposed theories and address new theories that have been advanced. The potential adaptations have been categorized as neural, mechanical and cellular. There is some evidence to suggest that the repeated bout effect is associated with a shift toward greater recruitment of slow twitch motor units. However, the repeated bout effect has been demonstrated with electrically stimulated contractions, indicating that a peripheral, non-neural adaptation predominates. With respect to mechanical adaptations there is evidence that both dynamic and passive muscle stiffness increase with eccentric training but there are no studies on passive or dynamic stiffness adaptations to a single eccentric bout. The role of the cytoskeleton in regulating dynamic stiffness is a possible area for future research. With respect to cellular adaptations there is evidence of longitudinal addition of sarcomeres and adaptations in the inflammatory response following an initial bout of eccentric exercise. Addition of sarcomeres is thought to reduce sarcomere strain during eccentric contractions thereby avoiding sarcomere disruption. Inflammatory adaptations are thought to limit the proliferation of damage that typically occurs in the days following eccentric exercise. In conclusion, there have been significant advances in the understanding of the repeated bout effect, however, a unified theory explaining the mechanism or mechanisms for this protective adaptation remains elusive.

High-threshold motor unit firing reflects force recovery following a bout of damaging eccentric exercise

Science.gov (United States)

Macgregor, Lewis J.

2018-01-01

Exercise-induced muscle damage (EIMD) is associated with impaired muscle function and reduced neuromuscular recruitment. However, motor unit firing behaviour throughout the recovery period is unclear. EIMD impairment of maximal voluntary force (MVC) will, in part, be caused by reduced high-threshold motor unit firing, which will subsequently increase to recover MVC. Fourteen healthy active males completed a bout of eccentric exercise on the knee extensors, with measurements of MVC, rate of torque development and surface electromyography performed pre-exercise and 2, 3, 7 and 14 days post-exercise, on both damaged and control limb. EIMD was associated with decreased MVC (235.2 ± 49.3 Nm vs. 161.3 ± 52.5 Nm; p motor unit firing rate was reduced (16.4 ± 2.2 Hz vs. 12.6 ± 1.7 Hz; p motor units only, 48h post-exercise, and common drive was elevated (0.36 ± 0.027 vs. 0.56 ± 0.032; pmotor units was reduced in parallel with impaired muscle function, whilst early recruited motor units remained unaltered. Common drive of motor units increased in offset to the firing rate impairment. These alterations correlated with the recovery of force decrement, but not of pain elevation. This study provides fresh insight into the central mechanisms associated with EIMD recovery, relative to muscle function. These findings may in turn lead to development of novel management and preventative procedures. PMID:29630622

The Acute Effect of Local Vibration As a Recovery Modality from Exercise-Induced Increased Muscle Stiffness

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Hervé Pournot, Jérémy Tindel, Rodolphe Testa, Laure Mathevon, Thomas Lapole

2016-03-01

Full Text Available Exercise involving eccentric muscle contractions is known to decrease range of motion and increase passive muscle stiffness. This study aimed at using ultrasound shear wave elastography to investigate acute changes in biceps brachii passive stiffness following intense barbell curl exercise involving both concentric and eccentric contractions. The effect of local vibration (LV as a recovery modality from exercise-induced increased stiffness was further investigated. Eleven subjects performed 4 bouts of 10 bilateral barbell curl movements at 70% of the one-rep maximal flexion force. An arm-to-arm comparison model was then used with one arm randomly assigned to the passive recovery condition and the other arm assigned to the LV recovery condition (10 min of 55-Hz vibration frequency and 0.9-mm amplitude. Biceps brachii shear elastic modulus measurements were performed prior to exercise (PRE, immediately after exercise (POST-EX and 5 min after the recovery period (POST-REC. Biceps brachii shear elastic modulus was significantly increased at POST-EX (+53 ± 48%; p < 0.001 and POST-REC (+31 ± 46%; p = 0.025 when compared to PRE. No differences were found between passive and LV recovery (p = 0.210. LV as a recovery strategy from exercise-induced increased muscle stiffness was not beneficial, probably due to an insufficient mechanical action of vibrations.

Impact of statin use on exercise-induced cardiac troponin elevations.

NARCIS (Netherlands)

Eijsvogels, T.M.H.; Januzzi, J.L., Jr.; Taylor, B.A.; Isaacs, S.K.; D'Hemecourt, P.; Zaleski, A.; Dyer, S.; Troyanos, C.; Weiner, R.B.; Thompson, P.D.; Baggish, A.L.

2014-01-01

Marathon running commonly causes a transient elevation of creatine kinase and cardiac troponin I (cTnI). The use of statins before marathon running exacerbates the release of creatine kinase from skeletal muscle, but the effect of statin use on exercise-induced cTnI release is unknown. We therefore

Supplementation with beta-hydroxy-beta-methylbutyrate (HMB) and alpha-ketoisocaproic acid (KIC) reduces signs and symptoms of exercise-induced muscle damage in man.

Science.gov (United States)

van Someren, Ken A; Edwards, Adam J; Howatson, Glyn

2005-08-01

This study examined the effects of beta-hydroxyl-beta-methylbutyrate (HMB) and alpha-ketoisocaproic acid (KIC) supplementation on signs and symptoms of exercise-induced muscle damage following a single bout of eccentrically biased resistance exercise. Six non-resistance trained male subjects performed an exercise protocol designed to induce muscle damage on two separate occasions, performed on the dominant or non-dominant arm in a counter-balanced crossover design. Subjects were assigned to an HMB/KIC (3 g HMB and 0.3 g alpha-ketoisocaproic acid, daily) or placebo treatment for 14 d prior to exercise in the counter-balanced crossover design. One repetition maximum (1RM), plasma creatine kinase activity (CK), delayed onset muscle soreness (DOMS), limb girth, and range of motion (ROM) were determined pre-exercise, at 1h, 24 h, 48 h, and 72 h post-exercise. DOMS and the percentage changes in 1RM, limb girth, and ROM all changed over the 72 h period (P HMB//IC supplementation attenuated the CK response, the percentage decrement in 1RM, and the percentage increase in limb girth (P HMB/KIC treatment. In conclusion, 14 d of HMB and KIC supplementation reduced signs and symptoms of exercise-induced muscle damage in non-resistance trained males following a single bout of eccentrically biased resistance exercise.

EFFICACY OF CYRIAX PHYSIOTHERAPY VERSUS ECCENTRIC STRENGTHENING AND STRETCHING EXERCISES IN CHRONIC LATERAL EPICONDYLITIS PATIENTS

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Madhusmita Koch

2015-10-01

Full Text Available Background: Lateral Epicondylitis is the most common lesion of the elbow, affecting the tendinous origin of the wrist extensors. Although conservative treatment of this condition has been the subject of numerous studies, there is no agreement as to the most effective management strategy. Therefore, this study was designed to compare the efficacy of Cyriax physiotherapy Versus Eccentric Strengthening and Stretching exercises in reducing the pain and improving the grip strength and functional status of the affected extremity in chronic lateral epicondylitis. Method: An experimental study design, 60 subjects meeting the inclusion criteria were selected for the study and were randomly assigned into two groups: Group A (N=30 received Cyriax Physiotherapy and Group B(N=30 received Eccentric strengthening and static stretching of Extensor Carpi Radialis Brevis. Low Level Laser Therapy was a common treatment for both the groups. After 4 weeks of treatment, assessment was performed using Visual Analogue Scale (VAS, Hand Held Dynamometer (HHD and Patient Rated Tennis Elbow Evaluation Questionnaire (PRTEE at 0 week and at the end of 4 weeks. Results: Data analysis revealed that there is no statistically significant difference between the groups in VAS, HHD and PRTEE scores i.e. average improvement post treatment in both the groups are equal, but within group comparisons showed significant improvements in both the groups. Conclusion: The efficacy of Cyriax Physiotherapy is equal to Eccentric Strengthening and Stretching Exercises in chronic lateral epicondylitis.

Effect of BCAA supplement timing on exercise-induced muscle soreness and damage: a pilot placebo-controlled double-blind study.

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Ra, Song-Gyu; Miyazaki, Teruo; Kojima, Ryo; Komine, Shoichi; Ishikura, Keisuke; Kawanaka, Kentaro; Honda, Akira; Matsuzaki, Yasushi; Ohmori, Hajime

2017-09-22

The aim of present study was to compare the effects of branched-chain amino acid (BCAA) supplementation taken before or after exercise on delayed onset muscle soreness (DOMS) and exercise-induced muscle damage (EIMD). Fifteen young men (aged 21.5 ± 0.4 years) were given either BCAA (9.6 g·day-1) or placebo before and after exercise (and for 3 days prior to and following the exercise day) in three independent groups: the Control group (placebo before and after exercise), the PRE group (BCAA before exercise and placebo after exercise), and the POST group (placebo before exercise and BCAA after exercise). Participants performed 30 repetitions of eccentric exercise with the non-dominant arm. DOMS, upper arm circumference (CIR), elbow range of motion (ROM), serum creatine kinase (CK), lactate dehydrogenase (LDH), and aldolase, BCAA, and Beta-hydroxy-Beta-methylbutyrate (3HMB) were measured immediately before and after the exercise and on the following 4 days. Serum BCAA and 3HMB concentrations increased significantly in the PRE group immediately after the exercise, recovering to baseline over the following days. In the days following the exercise day, DOMS, CIR, and ROM were significantly improved in the PRE group compared to the Control group, with weaker effects in the POST group. Serum activities of CK, LDH, and aldolase in the days following the exercise day were significantly suppressed in the PRE group compared to Control group. Present study confirmed that repeated BCAA supplementation before exercise had a more beneficial effect in attenuating DOMS and EIMD induced by eccentric exercise than repeated supplementation after exercise.

Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise.

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Drescher, U; Mookerjee, S; Steegmanns, A; Knicker, A; Hoffmann, U

2017-06-01

To evaluate the effects of exercise velocity (60, 150, 240deg∙s -1 ) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO 2 ) following high-intensity concentric-eccentric isokinetic exercise. Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t 1/2 ) for oxygen uptake (V˙O 2 pulm), carbon dioxide output (V˙CO 2 pulm), and ventilation (V˙ E ). Significant differences of the t 1/2 values were identified between 60 and 150deg∙s -1 . Significant differences in the t 1/2 values were observed between V˙O 2 pulm and V˙CO 2 pulm and between V˙CO 2 pulm and V˙ E . The time to attain the first avDO 2 -peak showed significant differences between arm and leg exercise. The present study illustrates, that V˙O 2 pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O 2 pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases. Copyright © 2017 Elsevier B.V. All rights reserved.

[Early exercise training after exacerbation in patients with chronic respiratory failure].

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Takahashi, Hiromitsu; Molleyres, Sandrine; Dousse, Nicolas; Contal, Olivier; Janssens, Jean-Paul

2011-11-23

Patients who suffered from an exacerbation of a chronic respiratory disorder are often very limited in terms of their exercise capacity because of severe dyspnea and amyotrophy of peripheral muscles. Early implementation of pulmonary rehabilitation may help these patients to avoid the complications of a prolonged bedridden period, and increase more rapidly their mobility. Early rehabilitation has become more frequent, but requires special skills from the care givers (chest therapists). Techniques which enhance muscular performance and motility of patients who are recovering from an exacerbation such as electromoystimulation or mobilisation under non-invasive ventilation, give encouraging results; their impact on length of hospital stay requires further studies.

Early rehabilitation exercise program for inpatients during an acute exacerbation of chronic obstructive pulmonary disease: a randomized controlled trial.

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Tang, Clarice Y; Blackstock, Felicity C; Clarence, Michael; Taylor, Nicholas F

2012-01-01

To determine whether an early rehabilitation program was safe and feasible for patients during an acute exacerbation of chronic obstructive pulmonary disease (COPD). In this phase 1 randomized controlled trial, patients with an acute exacerbation of COPD admitted to the hospital were randomly allocated to a low-intensity exercise group, a moderate- to high-intensity exercise group, or a control group, who received routine physical therapy. In addition to routine physical therapy, patients in the exercise group had to participate in an exercise program. The program consisted of twice-daily aerobic and resistance exercise sessions. Primary outcomes were the number and classification of adverse events and program adherence. In 174 exercise sessions, there was 1 serious adverse event of arrhythmia in the low-intensity exercise group that resolved within 1 hour. There were 12 other minor adverse events involving 5 patients with no significant differences between groups. Patients completed an average of 80% of their scheduled sessions with no significant between-group differences. The exercise groups improved significantly in walking distance; however, no significant between-group differences were observed. There was preliminary evidence that it was safe and feasible to implement an exercise program for patients during an acute exacerbation of COPD. Additional studies with larger sample sizes are required to accurately evaluate program effectiveness.

Eccentric versus traditional resistance exercise for older adult fallers in the community: a randomized trial within a multi-component fall reduction program.

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LaStayo, Paul; Marcus, Robin; Dibble, Leland; Wong, Bob; Pepper, Ginette

2017-07-17

Addressing muscle deficits within a multi-component exercise fall reduction program is a priority, especially for the highest risk older adults, i.e., those who have fallen previously. Eccentric resistance exercise with its high-force producing potential, at a low energetic cost, may be ideally-suited to address muscle impairments in this population. The purpose of this study was to compare the effects of resistance exercise via negative, eccentrically-induced, work (RENEW) versus traditional (TRAD) resistance exercise on mobility, balance confidence, muscle power and cross sectional area, as well as the number of days high fall risk older adults survived without a fall event over a 1 year period. Randomized, two group, four time point (over 1 year) clinical trial testing RENEW versus TRAD as part of a 3 month multi-component exercise fall reduction program (MCEFRP). Primary outcomes of mobility, balance confidence, muscle power output and cross sectional area were analyzed using mixed effects modeling. The secondary outcomes of days to fall and days to near-fall were analyzed using survival analysis. The MCEFRP did have an effect on fall risk factors considered reversible with exercise interventions though there was no differential effect of RENEW versus TRAD (p = 0.896) on mobility, balance confidence, muscle power and cross sectional area. There were also no group differences in the number of days survived without a fall (p = 0.565) or near-fall (p = 0.678). Despite 100% of participants having at least one fall in the year prior to the MCEFRP, however, after 3 months of exercise and 9 months of follow-up fall or near fall. There were no differential effects of RENEW or TRAD as components of a MCEFRP on the primary or secondary outcomes. The two modes of resistance exercise had identical effects on fall risk and fall-free survival. NCT01080196 ; March 2, 2010 (retrospectively registered).

Skeletal Muscle Estrogen Receptor Activation in Response to Eccentric Exercise Up-Regulates Myogenic-Related Gene Expression Independent of Differing Serum Estradiol Levels Occurring during the Human Menstrual Cycle.

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Haines, Mackenzie; McKinley-Barnard, Sarah K; Andre, Thomas L; Gann, Josh J; Hwang, Paul S; Willoughby, Darryn S

2018-03-01

This study sought to determine if the differences in serum estradiol we have previously observed to occur during the mid-follicular (MF) and mid-luteal (ML) phases of the female menstrual cycle could be attributed to estrogen-induced receptor activation and subsequent effects on myogenic-related genes which may otherwise impact muscle regeneration in response to eccentric exercise. Twenty-two physically-active females (20.9 ± 1.4 years, 63.5 ± 9.0 kg, 1.65 ± 0.08 m) underwent an eccentric exercise bout of the knee extensors during the MF and ML phases of their 28-day menstrual cycle. Prior to (PRE), at 6 (6HRPOST), and 24 (24HRPOST) hours post-exercise for each session, participants had muscle biopsies obtained. Skeletal muscle estradiol and estrogen receptor-α (ER-α) content and ER-DNA binding were determined with ELISA. Real-time PCR was used to assess ER-α, Myo-D, and cyclin D1 mRNA expression. Data were analyzed utilizing a 2 x 3 repeated measures univariate analyses of variance (ANOVA) for each criterion variable (p ≤ .05). Skeletal muscle estradiol levels were not significantly impacted by either menstrual phase (p > 0.05); however, both ER-α mRNA and protein were significantly increased during MF (p < 0.05). ER-DNA binding and Myo-D mRNA expression increased significantly in both menstrual phases in response to exercise but were not different from one another; however, cyclin D1 mRNA expression was significantly greater during MF. This study demonstrates that skeletal muscle ER-α activation in response to eccentric exercise up-regulates myogenic-related gene expression independent of serum estradiol levels occurring during the human menstrual cycle.

Dual AAV therapy ameliorates exercise-induced muscle injury and functional ischemia in murine models of Duchenne muscular dystrophy.

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Zhang, Yadong; Yue, Yongping; Li, Liang; Hakim, Chady H; Zhang, Keqing; Thomas, Gail D; Duan, Dongsheng

2013-09-15

Neuronal nitric oxide synthase (nNOS) membrane delocalization contributes to the pathogenesis of Duchenne muscular dystrophy (DMD) by promoting functional muscle ischemia and exacerbating muscle injury during exercise. We have previously shown that supra-physiological expression of nNOS-binding mini-dystrophin restores normal blood flow regulation and prevents functional ischemia in transgenic mdx mice, a DMD model. A critical next issue is whether systemic dual adeno-associated virus (AAV) gene therapy can restore nNOS-binding mini-dystrophin expression and mitigate muscle activity-related functional ischemia and injury. Here, we performed systemic gene transfer in mdx and mdx4cv mice using a pair of dual AAV vectors that expressed a 6 kb nNOS-binding mini-dystrophin gene. Vectors were packaged in tyrosine mutant AAV-9 and co-injected (5 × 10(12) viral genome particles/vector/mouse) via the tail vein to 1-month-old dystrophin-null mice. Four months later, we observed 30-50% mini-dystrophin positive myofibers in limb muscles. Treatment ameliorated histopathology, increased muscle force and protected against eccentric contraction-induced injury. Importantly, dual AAV therapy successfully prevented chronic exercise-induced muscle force drop. Doppler hemodynamic assay further showed that therapy attenuated adrenergic vasoconstriction in contracting muscle. Our results suggest that partial transduction can still ameliorate nNOS delocalization-associated functional deficiency. Further evaluation of nNOS binding mini-dystrophin dual AAV vectors is warranted in dystrophic dogs and eventually in human patients.

Electromyographic comparison of concentric and eccentric ...

African Journals Online (AJOL)

The study was conducted to compare the Electromyographic (EMG) activity variation of contractions (concentric and eccentric) during three different abdominal exercises (sit-up) exercises on rectus abdominal (upper and lower rectus). The sit-up exercises were: straight leg sit-up, bent leg sit-up and crunches. The EMG ...

Evidence of a Redox-Dependent Regulation of Immune Responses to Exercise-Induced Inflammation

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Alexandra Sakelliou

2016-01-01

Full Text Available We used thiol-based antioxidant supplementation (n-acetylcysteine, NAC to determine whether immune mobilisation following skeletal muscle microtrauma induced by exercise is redox-sensitive in healthy humans. According to a two-trial, double-blind, crossover, repeated measures design, 10 young men received either placebo or NAC (20 mg/kg/day immediately after a muscle-damaging exercise protocol (300 eccentric contractions and for eight consecutive days. Blood sampling and performance assessments were performed before exercise, after exercise, and daily throughout recovery. NAC reduced the decline of reduced glutathione in erythrocytes and the increase of plasma protein carbonyls, serum TAC and erythrocyte oxidized glutathione, and TBARS and catalase activity during recovery thereby altering postexercise redox status. The rise of muscle damage and inflammatory markers (muscle strength, creatine kinase activity, CRP, proinflammatory cytokines, and adhesion molecules was less pronounced in NAC during the first phase of recovery. The rise of leukocyte and neutrophil count was decreased by NAC after exercise. Results on immune cell subpopulations obtained by flow cytometry indicated that NAC ingestion reduced the exercise-induced rise of total macrophages, HLA+ macrophages, and 11B+ macrophages and abolished the exercise-induced upregulation of B lymphocytes. Natural killer cells declined only in PLA immediately after exercise. These results indicate that thiol-based antioxidant supplementation blunts immune cell mobilisation in response to exercise-induced inflammation suggesting that leukocyte mobilization may be under redox-dependent regulation.

Recovery From Exercise-Induced Muscle Damage: Cold-Water Immersion Versus Whole-Body Cryotherapy.

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Abaïdia, Abd-Elbasset; Lamblin, Julien; Delecroix, Barthélémy; Leduc, Cédric; McCall, Alan; Nédélec, Mathieu; Dawson, Brian; Baquet, Georges; Dupont, Grégory

2017-03-01

To compare the effects of cold-water immersion (CWI) and whole-body cryotherapy (WBC) on recovery kinetics after exercise-induced muscle damage. Ten physically active men performed single-leg hamstring eccentric exercise comprising 5 sets of 15 repetitions. Immediately postexercise, subjects were exposed in a randomized crossover design to CWI (10 min at 10°C) or WBC (3 min at -110°C) recovery. Creatine kinase concentrations, knee-flexor eccentric (60°/s) and posterior lower-limb isometric (60°) strength, single-leg and 2-leg countermovement jumps, muscle soreness, and perception of recovery were measured. The tests were performed before and immediately, 24, 48, and 72 h after exercise. Results showed a very likely moderate effect in favor of CWI for single-leg (effect size [ES] = 0.63; 90% confidence interval [CI] = -0.13 to 1.38) and 2-leg countermovement jump (ES = 0.68; 90% CI = -0.08 to 1.43) 72 h after exercise. Soreness was moderately lower 48 h after exercise after CWI (ES = -0.68; 90% CI = -1.44 to 0.07). Perception of recovery was moderately enhanced 24 h after exercise for CWI (ES = -0.62; 90% CI = -1.38 to 0.13). Trivial and small effects of condition were found for the other outcomes. CWI was more effective than WBC in accelerating recovery kinetics for countermovement-jump performance at 72 h postexercise. CWI also demonstrated lower soreness and higher perceived recovery levels across 24-48 h postexercise.

Leucine-Enriched Essential Amino Acids Augment Muscle Glycogen Content in Rats Seven Days after Eccentric Contraction

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Hiroyuki Kato

2017-10-01

Full Text Available Eccentric contractions induce muscle damage, which impairs recovery of glycogen and adenosine tri-phosphate (ATP content over several days. Leucine-enriched essential amino acids (LEAAs enhance the recovery in muscles that are damaged after eccentric contractions. However, the role of LEAAs in this process remains unclear. We evaluated the content in glycogen and high energy phosphates molecules (phosphocreatine (PCr, adenosine di-phosphate (ADP and ATP in rats that were following electrically stimulated eccentric contractions. Muscle glycogen content decreased immediately after the contraction and remained low for the first three days after the stimulation, but increased seven days after the eccentric contraction. LEAAs administration did not change muscle glycogen content during the first three days after the contraction. Interestingly, however, it induced a further increase in muscle glycogen seven days after the stimulation. Contrarily, ATP content decreased immediately after the eccentric contraction, and remained lower for up to seven days after. Additionally, LEAAs administration did not affect the ATP content over the experimental period. Finally, ADP and PCr levels did not significantly change after the contractions or LEAA administration. LEAAs modulate the recovery of glycogen content in muscle after damage-inducing exercise.

Whey protein supplementation accelerates satellite cell proliferation during recovery from eccentric exercise

DEFF Research Database (Denmark)

Farup, Jean; Rahbek, Stine Klejs; Knudsen, Inge Skovgaard

2014-01-01

well investigated. In a comparative human study, we investigated the effect of hydrolyzed whey protein supplementation following eccentric exercise on fiber type-specific SC accumulation. Twenty-four young healthy subjects received either hydrolyzed whey protein + carbohydrate (whey, n = 12) or iso...... creatine kinase (CK) were evaluated as indices of recovery from muscle damage. In type II fiber-associated SCs, the whey group increased SCs/fiber from 0.05 [0.02; 0.07] to 0.09 [0.06; 0.12] (p ... the placebo group (p whey group increased SCs/myonuclei from 4 % [2; 5] to 10 % [4; 16] (p 

Comparative study of two protocols of eccentric exercise on knee pain and function in athletes with patellar tendinopathy: randomized controlled study

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Cunha, Ronaldo Alves da; Dias, Andreia Natacha; Santos, Marcelo Bannwart; Lopes, Alexandre Dias

2012-01-01

INTRODUCTION: The eccentric squat on a slope has been proved effective in conservative treatment of patellar tendinopathy, especially in the athletic population. However, several aspects such as intensity and pain during therapy still differ among authors. OBJECTIVES: To compare the effectiveness of two protocols of eccentric exercise (performed with and without pain), in the improvement of knee function and pain intensity in athletes with patellar tendinopathy. METHODS: 7 athletes of both ge...

Physiological comparison of concentric and eccentric arm cycling in males and females.

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C Martyn Beaven

Full Text Available Lower body eccentric exercise is well known to elicit high levels of muscular force with relatively low cardiovascular and metabolic strain. As a result, eccentric exercise has been successfully utilised as an adaptive stressor to improve lower body muscle function in populations ranging from the frail and debilitated, to highly-trained individuals. Here we investigate the metabolic, cardiorespiratory, and energy costs of upper body eccentric exercise in a healthy population. Seven men and seven women performed 4-min efforts of eccentric (ECC or concentric (CON arm cycling on a novel arm ergometer at workloads corresponding to 40, 60, and 80% of their peak workload as assessed in an incremental concentric trial. The heart rate, ventilation, cardiac output, respiratory exchange ratio, and blood lactate concentrations were all clearly greater in CON condition at all of the relative workloads (all p0.05. In contrast, delta efficiency (ηΔ, as previously defined by Coyle and colleagues in 1992, demonstrated a sex difference (men>women; p<0.05. Sex differences were also apparent in arteriovenous oxygen difference and heart rate during CON. Here, we reinforce the high-force, low cost attributes of eccentric exercise which can be generalised to the muscles of the upper body. Upper body eccentric exercise is likely to form a useful adjunct in debilitative, rehabilitative, and adaptive clinical exercise programs; however, reports of a shift towards an oxidative phenotype should be taken into consideration by power athletes. We suggest delta efficiency as a sensitive measure of efficiency that allowed the identification of sex differences.

The mechanism for efficacy of eccentric loading in Achilles tendon injury; an in vivo study in humans.

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Rees, J D; Lichtwark, G A; Wolman, R L; Wilson, A M

2008-10-01

Degenerative disorders of tendons present an enormous clinical challenge. They are extremely common, prone to recur and existing medical and surgical treatments are generally unsatisfactory. Recently eccentric, but not concentric, exercises have been shown to be highly effective in managing tendinopathy of the Achilles (and other) tendons. The mechanism for the efficacy of these exercises is unknown although it has been speculated that forces generated during eccentric loading are of a greater magnitude. Our objective was to determine the mechanism for the beneficial effect of eccentric exercise in Achilles tendinopathy. Seven healthy volunteers performed eccentric and concentric loading exercises for the Achilles tendon. Tendon force and length changes were determined using a combination of motion analysis, force plate data and real-time ultrasound. There was no significant difference in peak tendon force or tendon length change when comparing eccentric with concentric exercises. However, high-frequency oscillations in tendon force occurred in all subjects during eccentric exercises but were rare in concentric exercises (P < 0.0001). These oscillations provide a mechanism to explain the therapeutic benefit of eccentric loading in Achilles tendinopathy and parallels recent evidence from bone remodelling, where the frequency of the loading cycles is of more significance than the absolute magnitude of the force.

Exercise-Induced Asthma

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... Videos for Educators Search English Español Exercise-Induced Asthma KidsHealth / For Parents / Exercise-Induced Asthma What's in ... Exercise-Induced Asthma Print What Is Exercise-Induced Asthma? Most kids and teens with asthma have symptoms ...

Virus-induced exacerbations in asthma and COPD

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Daisuke eKurai

2013-10-01

Full Text Available Chronic obstructive pulmonary disease (COPD is characterized by chronic airway inflammation and/or airflow limitation due to pulmonary emphysema. Chronic bronchitis, pulmonary emphysema, and bronchial asthma may all be associated with airflow limitation; therefore, exacerbation of asthma may be associated with the pathophysiology of COPD. Furthermore, recent studies have suggested that the exacerbation of asthma, namely virus-induced asthma, may be associated with a wide variety of respiratory viruses.COPD and asthma have different underlying pathophysiological processes and thus require individual therapies. Exacerbation of both COPD and asthma, which are basically defined and diagnosed by clinical symptoms, is associated with a rapid decline in lung function and increased mortality. Similar pathogens, including human rhinovirus, respiratory syncytial virus, influenza virus, parainfluenza virus and coronavirus, are also frequently detected during exacerbation of asthma and/or COPD. Immune response to respiratory viral infections, which may be related to the severity of exacerbation in each disease, varies in patients with both COPD and asthma. In this regard, it is crucial to recognize and understand both the similarities and differences of clinical features in patients with COPD and/or asthma associated with respiratory viral infections, especially in the exacerbative stage.In relation to definition, epidemiology, and pathophysiology, this review aims to summarize current knowledge concerning exacerbation of both COPD and asthma by focusing on the clinical significance of associated respiratory virus infections.

Acute neuromuscular and performance responses to Nordic hamstring exercises completed before or after football training.

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Lovell, Ric; Siegler, Jason C; Knox, Michael; Brennan, Scott; Marshall, Paul W M

2016-12-01

The optimal scheduling of Nordic Hamstring exercises (NHEs) relative to football training sessions is unknown. We examined the acute neuromuscular and performance responses to NHE undertaken either before (BT) or after (AT) simulated football training. Twelve amateur players performed six sets of five repetitions of the NHE either before or after 60 min of standardised football-specific exercise (SAFT 60 ). Surface electromyography signals (EMG) of the hamstring muscles were recorded during both the NHE, and maximum eccentric actions of the knee flexors (0.52 rad · s -1 ) performed before and after the NHE programme, and at 15 min intervals during SAFT 60 . Ten-metre sprint times were recorded on three occasions during each 15 min SAFT 60 segment. Greater eccentric hamstring fatigue following the NHE programme was observed in BT versus AT (19.8 %; very likely small effect), which was particularly apparent in the latter range of knee flexion (0-15°; 39.6%; likely moderate effect), and synonymous with hamstring EMG declines (likely small-likely moderate effects). Performing NHE BT attenuated sprint performance declines (2.0-3.2%; likely small effects), but decreased eccentric hamstring peak torque (-14.1 to -18.9%; likely small effects) during football-specific exercise. Performing NHE prior to football training reduces eccentric hamstring strength and may exacerbate hamstring injury risk.

HAMSTRING ARCHITECTURAL AND FUNCTIONAL ADAPTATIONS FOLLOWING LONG VS. SHORT MUSCLE LENGTH ECCENTRIC TRAINING

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Kenny Guex

2016-08-01

Full Text Available Most common preventive eccentric-based exercises, such as Nordic hamstring do not include any hip flexion. So, the elongation stress reached is lower than during the late swing phase of sprinting. The aim of this study was to assess the evolution of hamstring architectural (fascicle length and pennation angle and functional (concentric and eccentric optimum angles and concentric and eccentric peak torques parameters following a 3-week eccentric resistance program performed at long (LML versus short muscle length (SML. Both groups performed eight sessions of 3-5x8 slow maximal eccentric knee extensions on an isokinetic dynamometer: the SML group at 0° and the LML group at 80° of hip flexion. Architectural parameters were measured using ultrasound imaging and functional parameters using the isokinetic dynamometer. The fascicle length increased by 4.9% (p<0.01, medium effect size in the SML and by 9.3% (p<0.001, large effect size in the LML group. The pennation angle did not change (p=0.83 in the SML and tended to decrease by 0.7° (p=0.09, small effect size in the LML group. The concentric optimum angle tended to decrease by 8.8° (p=0.09, medium effect size in the SML and by 17.3° (p<0.01, large effect size in the LML group. The eccentric optimum angle did not change (p=0.19, small effect size in the SML and tended to decrease by 10.7° (p=0.06, medium effect size in the LML group. The concentric peak torque did not change in the SML (p=0.37 and the LML (p=0.23 groups, whereas eccentric peak torque increased by 12.9% (p<0.01, small effect size and 17.9% (p<0.001, small effect size in the SML and the LML group, respectively. No group-by-time interaction was found for any parameters. A correlation was found between the training-induced change in fascicle length and the change in concentric optimum angle (r=-0.57, p<0.01. These results suggest that performing eccentric exercises lead to several architectural and functional adaptations. However

Exercise-induced rhabdomyolysis mechanisms and prevention: A literature review

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Jooyoung Kim

2016-09-01

Full Text Available Exercise-induced rhabdomyolysis (exRML, a pathophysiological condition of skeletal muscle cell damage that may cause acute renal failure and in some cases death. Increased Ca2+ level in cells along with functional degradation of cell signaling system and cell matrix have been suggested as the major pathological mechanisms associated with exRML. The onset of exRML may be exhibited in athletes as well as in general population. Previous studies have reported that possible causes of exRML were associated with excessive eccentric contractions in high temperature, abnormal electrolytes balance, and nutritional deficiencies possible genetic defects. However, the underlying mechanisms of exRML have not been clearly established among health professionals or sports medicine personnel. Therefore, we reviewed the possible mechanisms and correlated prevention of exRML, while providing useful and practical information for the athlete and general exercising population.

Mechanical, hormonal, and hypertrophic adaptations to 10 weeks of eccentric and stretch-shortening cycle exercise training in old males

NARCIS (Netherlands)

Vaczi, Mark; Nagy, Szilvia A.; Koszegi, Tamas; Ambrus, Mira; Bogner, Peter; Perlaki, Gabor; Orsi, Gergely; Toth, Katalin; Hortobagyi, Tibor

2014-01-01

The growth promoting effects of eccentric (ECC) contractions are well documented but it is unknown if the rate of stretch per se plays a role in such muscular responses in healthy aging human skeletal muscle. We tested the hypothesis that exercise training of the quadriceps muscle with low rate ECC

The development of a repetition-load scheme for the eccentric-only bench press exercise.

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Moir, Gavin L; Erny, Kyle F; Davis, Shala E; Guers, John J; Witmer, Chad A

2013-01-01

The purpose of the present study was to develop a repetition-load scheme for the eccentric-only bench press exercise. Nine resistance trained men (age: 21.6 ± 1.0 years; 1-repetition maximum [RM] bench press: 137.7 ± 30.4 kg) attended four testing sessions during a four week period. During the first session each subject's 1-RM bench press load utilizing the stretch-shortening cycle was determined. During the remaining sessions they performed eccentric-only repetitions to failure using supra-maximal loads equivalent to 110%, 120% and 130% of their 1-RM value with a constant cadence (30 reps·min(-1)). Force plates and a three dimensional motion analysis system were used during these final three sessions in order to evaluate kinematic and kinetic variables. More repetitions were completed during the 110% 1-RM condition compared to the 130% 1-RM condition (p=0.01). Mean total work (p=0.046) as well as vertical force (p=0.049), vertical work (p=0.017), and vertical power output (p=0.05) were significantly greater during the 130% 1-RM condition compared to the 110% 1-RM condition. A linear function was fitted to the number of repetitions completed under each load condition that allowed the determination of the maximum number of repetitions that could be completed under other supra-maximal loads. This linear function predicted an eccentric-only 1-RM in the bench press with a load equivalent to 164.8% 1-RM, producing a load of 227.0 ± 50.0 kg. The repetition-load scheme presented here should provide a starting point for researchers to investigate the kinematic, kinetic and metabolic responses to eccentric-only bench press workouts.

Exercise-Induced Bronchoconstriction (EIB)

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... Conditions & Treatments ▸ Conditions Dictionary ▸ Exercise-Induced Bronchoconstriction Share | Exercise-Induced Bronchoconstriction (EIB) « Back to A to Z Listing Exercise-Induced Bronchoconstriction, (EIB), often known as exercise-induced ...

Eccentric Contraction-Induced Muscle Injury: Reproducible, Quantitative, Physiological Models to Impair Skeletal Muscle's Capacity to Generate Force.

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Call, Jarrod A; Lowe, Dawn A

2016-01-01

In order to investigate the molecular and cellular mechanisms of muscle regeneration an experimental injury model is required. Advantages of eccentric contraction-induced injury are that it is a controllable, reproducible, and physiologically relevant model to cause muscle injury, with injury being defined as a loss of force generating capacity. While eccentric contractions can be incorporated into conscious animal study designs such as downhill treadmill running, electrophysiological approaches to elicit eccentric contractions and examine muscle contractility, for example before and after the injurious eccentric contractions, allows researchers to circumvent common issues in determining muscle function in a conscious animal (e.g., unwillingness to participate). Herein, we describe in vitro and in vivo methods that are reliable, repeatable, and truly maximal because the muscle contractions are evoked in a controlled, quantifiable manner independent of subject motivation. Both methods can be used to initiate eccentric contraction-induced injury and are suitable for monitoring functional muscle regeneration hours to days to weeks post-injury.

Electromyographic analysis of exercise resulting in symptoms of muscle damage.

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McHugh, M P; Connolly, D A; Eston, R G; Gleim, G W

2000-03-01

Surface electromyographic (EMG) signals were recorded from the hamstring muscles during six sets of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions. The EMG per unit torque increased during eccentric (P exercise. Similarly, the median frequency increased during eccentric (P exercise. The EMG per unit torque was lower for submaximal eccentric than maximum isometric contractions (P unit torque was lower for eccentric than concentric contractions (P exercise resulted in significant isometric strength loss (P exercise, while the most severe pain and muscle tenderness occurred 2 days after eccentric exercise. A lower EMG per unit torque is consistent with the selective recruitment of a small number of motor units during eccentric exercise. A higher median frequency during eccentric contractions may be explained by selective recruitment of fast-twitch motor units. The present results are consistent with the theory that muscle damage results from excessive stress on a small number of active fibres during eccentric contractions.

The Use of Session RPE to Monitor the Intensity of Weight Training in Older Women: Acute Responses to Eccentric, Concentric, and Dynamic Exercises

Directory of Open Access Journals (Sweden)

Sandro S. Ferreira

2014-01-01

Full Text Available The rating of perceived exertion (RPE is ability to detect and interpret organic sensations while performing exercises. This method has been used to measure the level of effort that is felt during weight-training at a given intensity. The purpose of this investigation was to compare session RPE values with those of traditional RPE measurements for different weight-training muscle actions, performed together or separately. Fourteen women with no former weight-training experience were recruited for the investigation. All participants completed five sessions of exercise: familiarization, maximum force, concentric-only (CONC-only, eccentric-only (ECC-only, and dynamic (DYN = CONC + ECC. The traditional RPE method was measured after each series of exercises, and the session RPE was measured 30 min after the end of the training session. The statistical analyses used were the paired t-test, one-way analysis of variance, and repeated measures analysis of variance. Significant differences between traditional RPE and session RPE for DYN, CONC, and ECC exercises were not found. This investigation demonstrated that session RPE is similar to traditional RPE in terms of weight-training involving concentric, eccentric, or dynamic muscle exercises, and that it can be used to prescribe and monitor weight-training sessions in older subjects.

Astym treatment vs. eccentric exercise for lateral elbow tendinopathy: a randomized controlled clinical trial

Science.gov (United States)

Stegink-Jansen, Caroline W.

2015-01-01

Introduction. Patients with chronic lateral elbow (LE) tendinopathy, commonly known as tennis elbow, often experience prolonged symptoms and frequent relapses. Astym treatment, evidenced in animal studies to promote the healing and regeneration of soft tissues, is hypothesized to improve outcomes in LE tendinopathy patients. This study had two objectives: (1) to compare the efficacy of Astym treatment to an evidence-based eccentric exercise program (EE) for patients with chronic LE tendinopathy, and (2) to quantify outcomes of subjects non-responsive to EE who were subsequently treated with Astym treatment. Study Design. Prospective, two group, parallel, randomized controlled trial completed at a large orthopedic center in Indiana. Inclusion criteria: age range of 18–65 years old, with clinical indications of LE tendinopathy greater than 12 weeks, with no recent corticosteriod injection or disease altering comorbidities. Methods. Subjects with chronic LE tendinopathy (107 subjects with 113 affected elbows) were randomly assigned using computer-generated random number tables to 4 weeks of Astym treatment (57 elbows) or EE treatment (56 elbows). Data collected at baseline, 4, 8, 12 weeks, 6 and 12 months. Primary outcome measure: DASH; secondary outcome measures: pain with activity, maximum grip strength and function. The treating physicians and the rater were blinded; subjects and treating clinicians could not be blinded due to the nature of the treatments. Results. Resolution response rates were 78.3% for the Astym group and 40.9% for the EE group. Astym subjects showed greater gains in DASH scores (p = 0.047) and in maximum grip strength (p = 0.008) than EE subjects. Astym therapy also resolved 20/21 (95.7%) of the EE non-responders, who showed improvements in DASH scores (p effects were reported. Conclusion. This study suggests Astym therapy is an effective treatment option for patients with LE tendinopathy, as an initial treatment, and after an eccentric

Acute effects of dynamic exercises on the relationship between the motor unit firing rate and the recruitment threshold.

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Ye, Xin; Beck, Travis W; DeFreitas, Jason M; Wages, Nathan P

2015-04-01

The aim of this study was to compare the acute effects of concentric versus eccentric exercise on motor control strategies. Fifteen men performed six sets of 10 repetitions of maximal concentric exercises or eccentric isokinetic exercises with their dominant elbow flexors on separate experimental visits. Before and after the exercise, maximal strength testing and submaximal trapezoid isometric contractions (40% of the maximal force) were performed. Both exercise conditions caused significant strength loss in the elbow flexors, but the loss was greater following the eccentric exercise (t=2.401, P=.031). The surface electromyographic signals obtained from the submaximal trapezoid isometric contractions were decomposed into individual motor unit action potential trains. For each submaximal trapezoid isometric contraction, the relationship between the average motor unit firing rate and the recruitment threshold was examined using linear regression analysis. In contrast to the concentric exercise, which did not cause significant changes in the mean linear slope coefficient and y-intercept of the linear regression line, the eccentric exercise resulted in a lower mean linear slope and an increased mean y-intercept, thereby indicating that increasing the firing rates of low-threshold motor units may be more important than recruiting high-threshold motor units to compensate for eccentric exercise-induced strength loss. Copyright © 2014 Elsevier B.V. All rights reserved.

Treatment of dyslipidemia with statins and physical exercises: recent findings of skeletal muscle responses.

Science.gov (United States)

Bonfim, Mariana Rotta; Oliveira, Acary Souza Bulle; do Amaral, Sandra Lia; Monteiro, Henrique Luiz

2015-04-01

Statin treatment in association with physical exercise practice can substantially reduce cardiovascular mortality risk of dyslipidemic individuals, but this practice is associated with myopathic event exacerbation. This study aimed to present the most recent results of specific literature about the effects of statins and its association with physical exercise on skeletal musculature. Thus, a literature review was performed using PubMed and SciELO databases, through the combination of the keywords "statin" AND "exercise" AND "muscle", restricting the selection to original studies published between January 1990 and November 2013. Sixteen studies evaluating the effects of statins in association with acute or chronic exercises on skeletal muscle were analyzed. Study results indicate that athletes using statins can experience deleterious effects on skeletal muscle, as the exacerbation of skeletal muscle injuries are more frequent with intense training or acute eccentric and strenuous exercises. Moderate physical training, in turn, when associated to statins does not increase creatine kinase levels or pain reports, but improves muscle and metabolic functions as a consequence of training. Therefore, it is suggested that dyslipidemic patients undergoing statin treatment should be exposed to moderate aerobic training in combination to resistance exercises three times a week, and the provision of physical training prior to drug administration is desirable, whenever possible.

Muscle fascicle behavior during eccentric cycling and its relation to muscle soreness.

Science.gov (United States)

Peñailillo, Luis; Blazevich, Anthony J; Nosaka, Kazunori

2015-04-01

A single bout of eccentric exercise confers a protective effect against muscle damage and soreness in subsequent eccentric exercise bouts, but the mechanisms underpinning this effect are unclear. This study compared vastus lateralis (VL) muscle-tendon behavior between two eccentric cycling bouts to test the hypothesis that muscle-tendon behavior would be different between bouts and would be associated with the protective effect. Eleven untrained men (27.1 ± 7.0 yr) performed two bouts of eccentric cycling (ECC1 and ECC2) separated by 2 wk for 10 min at 65% of maximal concentric workload (191.9 ± 44.2 W) each. Muscle soreness (by visual analog scale) and maximal voluntary isometric contraction (MVC) torque of the knee extensors were assessed before and 1-2 d after exercise. Using ultrasonography, VL fascicle length and angle changes during cycling were assessed, and tendinous tissue (TT) length changes were estimated. VL EMG amplitude, crank torque, and knee joint angles were measured during cycling. Soreness was greater (P tendon behavior may be an important mechanism underpinning the protective effect.

Passive smoking reduces and vitamin C increases exercise-induced oxidative stress: does this make passive smoking an anti-oxidant and vitamin C a pro-oxidant stimulus?

Science.gov (United States)

Theodorou, Anastasios A; Paschalis, Vassilis; Kyparos, Antonios; Panayiotou, George; Nikolaidis, Michalis G

2014-11-07

The current interpretative framework states that, for a certain experimental treatment (usually a chemical substance) to be classified as "anti-oxidant", it must possess the property of reducing (or even nullifying) exercise-induced oxidative stress. The aim of the study was to compare side by side, in the same experimental setup, redox biomarkers responses to an identical acute eccentric exercise session, before and after chronic passive smoking (considered a pro-oxidant stimulus) or vitamin C supplementation (considered an anti-oxidant stimulus). Twenty men were randomly assigned into either passive smoking or vitamin C group. All participants performed two acute eccentric exercise sessions, one before and one after either exposure to passive smoking or vitamin C supplementation for 12 days. Vitamin C, oxidant biomarkers (F2-isoprostanes and protein carbonyls) and the non-enzymatic antioxidant (glutathione) were measured, before and after passive smoking, vitamin C supplementation or exercise. It was found that chronic exposure to passive smoking increased the level of F2-isoprostanes and decreased the level of glutathione at rest, resulting in minimal increase or absence of oxidative stress after exercise. Conversely, chronic supplementation with vitamin C decreased the level of F2-isoprostanes and increased the level of glutathione at rest, resulting in marked exercise-induced oxidative stress. Contrary to the current scientific consensus, our results show that, when a pro-oxidant stimulus is chronically delivered, it is more likely that oxidative stress induced by subsequent exercise is decreased and not increased. Reversely, it is more likely to find greater exercise-induced oxidative stress after previous exposure to an anti-oxidant stimulus. We believe that the proposed framework will be a useful tool to reach more pragmatic explanations of redox biology phenomena. Copyright © 2014 Elsevier Inc. All rights reserved.

Resistance exercise prevents plantar flexor deconditioning during bed rest

Science.gov (United States)

Bamman, M. M.; Hunter, G. R.; Stevens, B. R.; Guilliams, M. E.; Greenisen, M. C.

1997-01-01

Because resistance exercise (REX) and unloading induce opposing neuromuscular adaptations, we tested the efficacy of REX against the effects of 14 d of bed rest unloading (BRU) on the plantar flexor muscle group. Sixteen men were randomly assigned to no exercise (NOE, N = 8) or REX (N = 8). REX performed 5 sets x 6-10 repetitions to failure of constant resistance concentric/eccentric plantar flexion every other day during BRU. One-repetition maximum (1RM) strength was tested on the training device. The angle-specific torque-velocity relationship across 5 velocities (0, 0.52, 1.05, 1.75, and 2.97 rad.s-1) and the full range-of-motion power-velocity relationship were assessed on a dynamometer. Torque-position analyses identified strength changes at shortened, neutral, and stretched muscle lengths. Concentric and eccentric contractile work were measured across ten repetitions at 1.05 rad.s-1. Maximal neural activation was measured by surface electromyography (EMG). 1RM decreased 9% in NOE and improved 11% in REX (P joint positions. Concentric (15%) and eccentric (11%) contractile work fell in NOE (P < 0.05) but not in REX. Maximal plantar flexor EMG did not change in either group. In summary, constant resistance concentric/eccentric REX completely prevented plantar flexor performance deconditioning induced by BRU. The reported benefits of REX should prove useful in prescribing exercise for astronauts in microgravity and for patients susceptible to functional decline during bed- or chair-bound hospital stays.

Force and power characteristics of a resistive exercise device for use in space

Science.gov (United States)

Berg, Hans E.; Tesch, Per A.

We have developed a non-gravity dependent mechanical device, which provides resistance during coupled concentric and eccentric muscle actions, through the inertia of a spinning fly-wheel (Fly-Wheel Ergometry; FWE). Our research shows that lower-limb FWE exercise can produce forces and thus muscular stress comparable to what is typical of advanced resistance training using free weights. FWE also offers greater training stimuli during eccentric relative to concentric muscle actions, as evidenced by force and electromyographic (EMG) measurements. Muscle use of specific muscle groups, as assessed by the exercise-induced contrast shift of magnetic resonance images, is similar during lower-limb FWE and the barbell squat. Unlike free-weight exercise, FWE allows for maximal voluntary effort in each repetition of an exercise bout. Likewise, FWE exercise, not unassisted free-weight exercise, produces eccentric "overload". Collectively, the inherent features of this resistive exercise device and the results of the physiological evaluations we have performed, suggest that resistance exercise using FWE could be used as an effective exercise counter-measure in space. The flywheel principle can be employed to any exercise configuration and designed into a compact device allowing for exercises stressing those muscles and bone structures, which are thought to be most affected by long-duration spaceflight.

Astym treatment vs. eccentric exercise for lateral elbow tendinopathy: a randomized controlled clinical trial

Directory of Open Access Journals (Sweden)

Thomas L. Sevier

2015-05-01

Full Text Available Introduction. Patients with chronic lateral elbow (LE tendinopathy, commonly known as tennis elbow, often experience prolonged symptoms and frequent relapses. Astym treatment, evidenced in animal studies to promote the healing and regeneration of soft tissues, is hypothesized to improve outcomes in LE tendinopathy patients. This study had two objectives: (1 to compare the efficacy of Astym treatment to an evidence-based eccentric exercise program (EE for patients with chronic LE tendinopathy, and (2 to quantify outcomes of subjects non-responsive to EE who were subsequently treated with Astym treatment.Study Design. Prospective, two group, parallel, randomized controlled trial completed at a large orthopedic center in Indiana. Inclusion criteria: age range of 18–65 years old, with clinical indications of LE tendinopathy greater than 12 weeks, with no recent corticosteriod injection or disease altering comorbidities.Methods. Subjects with chronic LE tendinopathy (107 subjects with 113 affected elbows were randomly assigned using computer-generated random number tables to 4 weeks of Astym treatment (57 elbows or EE treatment (56 elbows. Data collected at baseline, 4, 8, 12 weeks, 6 and 12 months. Primary outcome measure: DASH; secondary outcome measures: pain with activity, maximum grip strength and function. The treating physicians and the rater were blinded; subjects and treating clinicians could not be blinded due to the nature of the treatments.Results. Resolution response rates were 78.3% for the Astym group and 40.9% for the EE group. Astym subjects showed greater gains in DASH scores (p = 0.047 and in maximum grip strength (p = 0.008 than EE subjects. Astym therapy also resolved 20/21 (95.7% of the EE non-responders, who showed improvements in DASH scores (p < 0.005, pain with activity (p = 0.002, and function (p = 0.004 following Astym treatment. Gains continued at 6 and 12 months. No adverse effects were reported.Conclusion. This study

Treatment of Dyslipidemia with Statins and Physical Exercises: Recent Findings of Skeletal Muscle Responses

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Bonfim, Mariana Rotta, E-mail: mrb-unesp@yahoo.com.br [Programa de Pós-Graduação em Ciências da Motricidade, Instituto de Biociências, Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Rio Claro, SP (Brazil); Oliveira, Acary Souza Bulle [Setor de Doenças Neuromusculares, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, SP (Brazil); Amaral, Sandra Lia do; Monteiro, Henrique Luiz [Departamento de Educação Física, Faculdade de Ciências, UNESP, Bauru, SP (Brazil)

2015-04-15

Statin treatment in association with physical exercise practice can substantially reduce cardiovascular mortality risk of dyslipidemic individuals, but this practice is associated with myopathic event exacerbation. This study aimed to present the most recent results of specific literature about the effects of statins and its association with physical exercise on skeletal musculature. Thus, a literature review was performed using PubMed and SciELO databases, through the combination of the keywords “statin” AND “exercise” AND “muscle”, restricting the selection to original studies published between January 1990 and November 2013. Sixteen studies evaluating the effects of statins in association with acute or chronic exercises on skeletal muscle were analyzed. Study results indicate that athletes using statins can experience deleterious effects on skeletal muscle, as the exacerbation of skeletal muscle injuries are more frequent with intense training or acute eccentric and strenuous exercises. Moderate physical training, in turn, when associated to statins does not increase creatine kinase levels or pain reports, but improves muscle and metabolic functions as a consequence of training. Therefore, it is suggested that dyslipidemic patients undergoing statin treatment should be exposed to moderate aerobic training in combination to resistance exercises three times a week, and the provision of physical training prior to drug administration is desirable, whenever possible.

Treatment of Dyslipidemia with Statins and Physical Exercises: Recent Findings of Skeletal Muscle Responses

International Nuclear Information System (INIS)

Bonfim, Mariana Rotta; Oliveira, Acary Souza Bulle; Amaral, Sandra Lia do; Monteiro, Henrique Luiz

2015-01-01

Statin treatment in association with physical exercise practice can substantially reduce cardiovascular mortality risk of dyslipidemic individuals, but this practice is associated with myopathic event exacerbation. This study aimed to present the most recent results of specific literature about the effects of statins and its association with physical exercise on skeletal musculature. Thus, a literature review was performed using PubMed and SciELO databases, through the combination of the keywords “statin” AND “exercise” AND “muscle”, restricting the selection to original studies published between January 1990 and November 2013. Sixteen studies evaluating the effects of statins in association with acute or chronic exercises on skeletal muscle were analyzed. Study results indicate that athletes using statins can experience deleterious effects on skeletal muscle, as the exacerbation of skeletal muscle injuries are more frequent with intense training or acute eccentric and strenuous exercises. Moderate physical training, in turn, when associated to statins does not increase creatine kinase levels or pain reports, but improves muscle and metabolic functions as a consequence of training. Therefore, it is suggested that dyslipidemic patients undergoing statin treatment should be exposed to moderate aerobic training in combination to resistance exercises three times a week, and the provision of physical training prior to drug administration is desirable, whenever possible

Flexibility training and the repeated-bout effect: priming interventions prior to eccentric training of the knee flexors.

Science.gov (United States)

Leslie, Andrew W; Lanovaz, Joel L; Andrushko, Justin W; Farthing, Jonathan P

2017-10-01

Both the repeated-bout effect and increased flexibility have been linked to reduced muscle damage, fatigue, and strength loss after intense eccentric exercise. Our purpose was to compare the eccentric-training (ECC) response after first priming the muscles with either static flexibility training or a single intense bout of eccentric exercise. Twenty-five participants were randomly assigned to flexibility training (n = 8; 3×/week; 30 min/day), a single bout of intense eccentric exercise (n = 9), or no intervention (control; n = 8) during a 4-week priming phase, prior to completing a subsequent 4-week period of eccentric training of the knee flexors. Testing was completed prior to the priming phase, before ECC, during acute ECC (0 h, 24 h, and 48 h after bouts 1 and 4), and after ECC. Measures included muscle thickness (MT; via ultrasound); isometric, concentric, and eccentric strength; muscle power (dynamometer); electromyography; range of motion; optimal angle of peak torque; and soreness (visual analog scale). Flexibility training and single-bout groups had 47% less soreness at 48 h after the first bout of ECC compared with control (p training group had 10% less soreness at 48 h after the fourth ECC bout compared with both the single-bout and control groups (p training group (-9%) after the fourth ECC bout compared with control (-19%; p training may be more effective than a single session of eccentric exercise in reducing adverse symptoms during the acute stages of eccentric training; however, these benefits did not translate into greater performance after training.

Right ventricular function during acute exacerbation of severe equine asthma.

Science.gov (United States)

Decloedt, A; Borowicz, H; Slowikowska, M; Chiers, K; van Loon, G; Niedzwiedz, A

2017-09-01

Pulmonary hypertension has been described in horses with severe equine asthma, but its effect on the right ventricle has not been fully elucidated. To evaluate right ventricular structure and function after a 1-week period of pulmonary hypertension secondary to acute exacerbation of severe equine asthma. Prospective study. A clinical episode of severe equine asthma was induced experimentally in six susceptible horses. Examinations in remission and on day 7 of the clinical episode included a physical examination with clinical scoring, echocardiography, arterial blood gas measurements, venous blood sampling for cardiac biomarkers, intracardiac pressure measurements, right ventricular and right atrial myocardial biopsies, airway endoscopy and bronchoalveolar lavage. After 1 month of recovery, physical examination, echocardiography and cardiac biomarker analysis were repeated. Echocardiographic and pressure measurements were compared with those in 10 healthy control horses. All horses developed clinical signs of acute pulmonary obstruction. Right heart pressures increased significantly. Altered right ventricular function could be detected by tissue Doppler and speckle tracking echocardiography. Cardiac troponin concentrations did not increase significantly, but were highly elevated in one horse which exercised in the paddock prior to sampling. Focal neutrophil infiltration was present in two myocardial samples. Even in remission, asthmatic horses showed a thicker right ventricular wall, an increased left ventricular end-systolic eccentricity index at chordal level and decreased right ventricular longitudinal strain compared with controls. The induced clinical episode was rather mild and the number of horses was limited because of the invasive nature of the study. Pulmonary obstruction in asthmatic horses induces pulmonary hypertension with right ventricular structural and functional changes. © 2017 EVJ Ltd.

Connective tissue regeneration in skeletal muscle after eccentric contraction-induced injury.

Science.gov (United States)

Mackey, Abigail L; Kjaer, Michael

2017-03-01

Human skeletal muscle has the potential to regenerate completely after injury induced under controlled experimental conditions. The events inside the myofibers as they undergo necrosis, followed closely by satellite cell-mediated myogenesis, have been mapped in detail. Much less is known about the adaptation throughout this process of both the connective tissue structures surrounding the myofibers and the fibroblasts, the cells responsible for synthesizing this connective tissue. However, the few studies investigating muscle connective tissue remodeling demonstrate a strong response that appears to be sustained for a long time after the major myofiber responses have subsided. While the use of electrical stimulation to induce eccentric contractions vs. voluntary eccentric contractions appears to lead to a greater extent of myofiber necrosis and regenerative response, this difference is not apparent when the muscle connective tissue responses are compared, although further work is required to confirm this. Pharmacological agents (growth hormone and angiotensin II type I receptor blockers) are considered in the context of accelerating the muscle connective tissue adaptation to loading. Cautioning against this, however, is the association between muscle matrix protein remodeling and protection against reinjury, which suggests that a (so far undefined) period of vulnerability to reinjury may exist during the remodeling phases. The role of individual muscle matrix components and their spatial interaction during adaptation to eccentric contractions is an unexplored field in human skeletal muscle and may provide insight into the optimal timing of rest vs. return to activity after muscle injury. Copyright © 2017 the American Physiological Society.

Impact of exacerbations on COPD

Directory of Open Access Journals (Sweden)

A. Anzueto

2010-06-01

Full Text Available Exacerbations of chronic obstructive pulmonary disease (COPD determine disease-associated morbidity, mortality, resource burden and healthcare costs. Acute exacerbation care requirements range from unscheduled primary care visits to emergency room, inpatient or intensive care, generating significant costs in COPD. Even after an exacerbation resolves, respiratory, physical, social and emotional impairment may persist for prolonged time. Frequent exacerbations, mainly in patients with severe COPD, accelerate disease progression and mortality. Thus, patients with frequent exacerbations have a more rapid decline in lung function, worse quality of life and decreased exercise performance. Management of COPD directed to reduce incidence and severity of exacerbations improves long-term health status and conserves health care resources and costs.

Characteristics associated with clinical severity and inflammatory phenotype of naturally occurring virus-induced exacerbations of asthma in adults

DEFF Research Database (Denmark)

Bjerregaard, Asger; Laing, Ingrid A; Poulsen, Nadia

2017-01-01

BACKGROUND: In experimental studies viral infections have been shown to induce type 2 inflammation in asthmatics, but whether this is a feature of naturally occurring virus-induced asthma exacerbations is unknown. Thymic stromal lymphopoietin (TSLP) released from the airway epithelium in response...... occurring virus-induced exacerbations of asthma and whether TSLP is associated with this type 2 inflammation. METHODS: Patients presenting to hospital with acute asthma were examined during the exacerbation, and after 4 weeks recovery. The assessments included spirometry, FeNO and induced sputum...... in patients during virus-induced asthma exacerbations, to the same degree as non-viral exacerbations, and correlate negatively with FEV1. However, in virus-positive patients, high TSLP expression during exacerbation was associated with low sputum eosinophils, suggesting that the effect of TSLP in vivo...

Patellar tendon load in different types of eccentric squats.

Science.gov (United States)

Frohm, A; Halvorsen, K; Thorstensson, A

2007-07-01

Differences in mechanical loading of the patellar tendon have been suggested as a reason for varying effects in rehabilitation of patellar tendinopathy using different eccentric squat exercises and devices. The aim was to characterize the magnitude and pattern of mechanical load at the knee and on the patellar tendon during four types of eccentric squat. Subjects performed squats with a submaximal free weight and with maximal effort in a device for eccentric overloading (Bromsman), on a decline board and horizontal surface. Kinematics was recorded with a motion-capture system, reaction forces with force plates, and electromyography from three leg muscles with surface electrodes. Inverse dynamics was used to calculate knee joint kinetics. Eccentric work, mean and peak patellar tendon force, and angle at peak force were greater (25-30%) for squats on decline board compared to horizontal surface with free weight, but not in Bromsman. Higher knee load forces (60-80%), but not work, were observed with Bromsman than free weight. Angular excursions at the knee and ankle were larger with decline board, particularly with free weight, and smaller in Bromsman than with free weight. Mean electromyography was greater on a decline board for gastrocnemius (13%) and vastus medialis (6%) with free weight, but in Bromsman only for gastrocnemius (7%). The results demonstrated clear differences in the biomechanical loading on the knee during different squat exercises. Quantification of such differences provides information that could be used to explain differences in rehabilitation effects as well as in designing more optimal rehabilitation exercises for patellar tendinopathy.

Age-related functional changes and susceptibility to eccentric contraction-induced damage in skeletal muscle cell.

Science.gov (United States)

Choi, Seung-Jun

2016-09-01

Depending upon external loading conditions, skeletal muscles can either shorten, lengthen, or remain at a fixed length as they produce force. Fixed-end or isometric contractions stabilize joints and allow muscles to act as active struts during locomotion. Active muscles dissipate energy when they are lengthened by an external force that exceeds their current force producing capacity. These unaccustomed eccentric activities often lead to muscle weakness, soreness, and inflammation. During aging, the ability to produce force under these conditions is reduced and appears to be due to not only reductions in muscle mass but also to alterations in the basic mechanisms of contraction. These alterations include impairments in the excitation-contraction process, and the action of the cross-bridges. Also, it is well known that age-related skeletal muscle atrophy is characterized by a preferential atrophy of fast fibers, and increased susceptibility to fast muscle fiber when aged muscles are exposed to eccentric contraction followed by the impaired recovery process has been reported. Taken together, the selective loss of fast muscle fiber in aged muscle could be affected by eccentric-induced muscle damage, which has significant implication to identify the etiology of the age-related functional changes. Therefore, in this review the alteration of age-related muscle function and its impact to/of eccentric induced muscle damage and recovery will be addressed in detail.

Age-related functional changes and susceptibility to eccentric contraction-induced damage in skeletal muscle cell

Directory of Open Access Journals (Sweden)

Seung-Jun Choi

2016-09-01

Full Text Available Depending upon external loading conditions, skeletal muscles can either shorten, lengthen, or remain at a fixed length as they produce force. Fixed-end or isometric contractions stabilize joints and allow muscles to act as active struts during locomotion. Active muscles dissipate energy when they are lengthened by an external force that exceeds their current force producing capacity. These unaccustomed eccentric activities often lead to muscle weakness, soreness, and inflammation. During aging, the ability to produce force under these conditions is reduced and appears to be due to not only reductions in muscle mass but also to alterations in the basic mechanisms of contraction. These alterations include impairments in the excitation–contraction process, and the action of the cross-bridges. Also, it is well known that age-related skeletal muscle atrophy is characterized by a preferential atrophy of fast fibers, and increased susceptibility to fast muscle fiber when aged muscles are exposed to eccentric contraction followed by the impaired recovery process has been reported. Taken together, the selective loss of fast muscle fiber in aged muscle could be affected by eccentric-induced muscle damage, which has significant implication to identify the etiology of the age-related functional changes. Therefore, in this review the alteration of age-related muscle function and its impact to/of eccentric induced muscle damage and recovery will be addressed in detail.

Exertional muscle injury: evaluation of concentric versus eccentric actions with serial MR imaging.

Science.gov (United States)

Shellock, F G; Fukunaga, T; Mink, J H; Edgerton, V R

1991-06-01

Eccentric muscular actions involve the forced lengthening or stretching of muscles and tend to produce exertional injuries. This study used magnetic resonance (MR) imaging to serially evaluate muscles in five healthy, untrained subjects who performed exhaustive biceps exercise by doing isolated eccentric and concentric actions with a dumbbell. Symptoms were assessed, and T2-weighted images of the arms were obtained before exercise and 1, 3, 5, 10, 25, 40, 50, 60, and 80 days after exercise. Statistically significant increases in T2 relaxation times indicative of muscle injury occurred on each day of MR imaging evaluation in muscles performing eccentric actions, peaking on day 3 in two subjects; day 5, two subjects; and day 10, one subject. The pattern and extent of the abnormalities on MR images were variable. Pain, soreness, and joint stiffness were present on days 1, 3, and 5 in muscles that performed eccentric actions. MR imaging showed subclinical abnormalities that lasted as long as 75 days after the disappearance of symptoms (two subjects). Muscles that performed concentric actions had no changes in T2 relaxation times and were asymptomatic throughout the study.

The influence of capillarization on satellite cell pool expansion and activation following exercise-induced muscle damage in healthy young men.

Science.gov (United States)

Nederveen, Joshua P; Joanisse, Sophie; Snijders, Tim; Thomas, Aaron C Q; Kumbhare, Dinesh; Parise, Gianni

2018-03-15

Skeletal muscle stem cells (satellite cells) play a crucial role in repair and remodelling of muscle in response to exercise. Satellite cells are in close spatial proximity to muscle capillaries and therefore may be influenced by them. In this study, we describe the activation and expansion of the satellite cell pool in response to eccentric contraction-induced muscle damage in individuals with significantly different levels of muscle capillarization. Individuals with greater capillarization and capacity for muscle perfusion demonstrated enhanced activation and/or expansion of the satellite cell pool allowing for an accelerated recovery of muscle function. These results provide insight into the critical relationship between muscle capillarization and satellite cells during skeletal muscle repair. Factors that determine the skeletal muscle satellite cell (SC) response remain incompletely understood. It is known, however, that SC activation status is closely related to the anatomical relationship between SCs and muscle capillaries. We investigated the impact of muscle fibre capillarization on the expansion and activation status of SCs following a muscle-damaging exercise protocol in healthy young men. Twenty-nine young men (21 ± 0.5 years) performed 300 unilateral eccentric contractions (180 deg s -1 ) of the knee extensors. Percutaneous muscle biopsies from the vastus lateralis and blood samples from the antecubital vein were taken prior to (Pre) exercise and at 6, 24, 72 and 96 h of post-exercise recovery. A comparison was made between subjects who had a relative low mixed muscle capillary-to-fibre perimeter exchange index (CFPE; Low group) and high mixed muscle CFPE index (High group) at baseline. Type I and type II muscle fibre size, myonuclear content, capillarization, and SC response were determined via immunohistochemistry. Overall, there was a significant correlation (r = 0.39; P < 0.05) between the expansion of SC content (change in total Pax7

Exercise during Short-Term and Long-Term Continuous Exposure to Hypoxia Exacerbates Sleep-Related Periodic Breathing

Science.gov (United States)

Tellez, Helio Fernandez; Morrison, Shawnda A.; Neyt, Xavier; Mairesse, Olivier; Piacentini, Maria Francesca; Macdonald-Nethercott, Eoin; Pangerc, Andrej; Dolenc-Groselj, Leja; Eiken, Ola; Pattyn, Nathalie; Mekjavic, Igor B.; Meeusen, Romain

2016-01-01

Study Objectives: Exposure to hypoxia elevates chemosensitivity, which can lead to periodic breathing. Exercise impacts gas exchange, altering chemosensitivity; however, interactions between sleep, exercise and chronic hypoxic exposure have not been examined. This study investigated whether exercise exacerbates sleep-related periodic breathing in hypoxia. Methods: Two experimental phases. Short-Term Phase: a laboratory controlled, group-design study in which 16 active, healthy men (age: 25 ± 3 y, height: 1.79 ± 0.06 m, mass: 74 ± 8 kg) were confined to a normobaric hypoxic environment (FIO2 = 0.139 ± 0.003, 4,000 m) for 10 days, after random assignment to a sedentary (control, CON) or cycle-exercise group (EX). Long-Term Phase: conducted at the Concordia Antarctic Research Station (3,800 m equivalent at the Equator) where 14 men (age: 36 ± 9 y, height: 1.77 ± 0.09 m, mass: 75 ± 10 kg) lived for 12–14 months, continuously confined. Participants were stratified post hoc based on self-reported physical activity levels. We quantified apnea-hypopnea index (AHI) and physical activity variables. Results: Short-Term Phase: mean AHI scores were significantly elevated in the EX group compared to CON (Night1 = CON: 39 ± 51, EX: 91 ± 59; Night10 = CON: 32 ± 32, EX: 92 ± 48; P = 0.046). Long-Term Phase: AHI was correlated to mean exercise time (R2 = 0.4857; P = 0.008) and the coefficient of variation in night oxyhemoglobin saturation (SpO2; R2 = 0.3062; P = 0.049). Conclusions: Data indicate that exercise (physical activity) per se affects night SpO2 concentrations and AHI after a minimum of two bouts of moderate-intensity hypoxic exercise, while habitual physical activity in hypobaric hypoxic confinement affects breathing during sleep, up to 13+ months' duration Citation: Tellez HF, Morrison SA, Neyt X, Mairesse O, Piacentini MF, Macdonald-Nethercott E, Pangerc A, Dolenc-Groselj L, Eiken O, Pattyn N, Mekjavic IB, Meeusen R. Exercise during short-term and long

Enhanced Glycogen Storage of a Subcellular Hot Spot in Human Skeletal Muscle during Early Recovery from Eccentric Contractions

Science.gov (United States)

Nielsen, Joachim; Farup, Jean; Rahbek, Stine Klejs; de Paoli, Frank Vincenzo; Vissing, Kristian

2015-01-01

Unaccustomed eccentric exercise is accompanied by muscle damage and impaired glucose uptake and glycogen synthesis during subsequent recovery. Recently, it was shown that the role and regulation of glycogen in skeletal muscle are dependent on its subcellular localization, and that glycogen synthesis, as described by the product of glycogen particle size and number, is dependent on the time course of recovery after exercise and carbohydrate availability. In the present study, we investigated the subcellular distribution of glycogen in fibers with high (type I) and low (type II) mitochondrial content during post-exercise recovery from eccentric contractions. Analysis was completed on five male subjects performing an exercise bout consisting of 15 x 10 maximal eccentric contractions. Carbohydrate-rich drinks were subsequently ingested throughout a 48 h recovery period and muscle biopsies for analysis included time points 3, 24 and 48 h post exercise from the exercising leg, whereas biopsies corresponding to prior to and at 48 h after the exercise bout were collected from the non-exercising, control leg. Quantitative imaging by transmission electron microscopy revealed an early (post 3 and 24 h) enhanced storage of intramyofibrillar glycogen (defined as glycogen particles located within the myofibrils) of type I fibers, which was associated with an increase in the number of particles. In contrast, late in recovery (post 48 h), intermyofibrillar, intramyofibrillar and subsarcolemmal glycogen in both type I and II fibers were lower in the exercise leg compared with the control leg, and this was associated with a smaller size of the glycogen particles. We conclude that in the carbohydrate-supplemented state, the effect of eccentric contractions on glycogen metabolism depends on the subcellular localization, muscle fiber’s oxidative capacity, and the time course of recovery. The early enhanced storage of intramyofibrillar glycogen after the eccentric contractions may

Treatment of Dyslipidemia with Statins and Physical Exercises: Recent Findings of Skeletal Muscle Responses

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Mariana Rotta Bonfim

2015-04-01

Full Text Available Statin treatment in association with physical exercise practice can substantially reduce cardiovascular mortality risk of dyslipidemic individuals, but this practice is associated with myopathic event exacerbation. This study aimed to present the most recent results of specific literature about the effects of statins and its association with physical exercise on skeletal musculature. Thus, a literature review was performed using PubMed and SciELO databases, through the combination of the keywords “statin” AND “exercise” AND “muscle”, restricting the selection to original studies published between January 1990 and November 2013. Sixteen studies evaluating the effects of statins in association with acute or chronic exercises on skeletal muscle were analyzed. Study results indicate that athletes using statins can experience deleterious effects on skeletal muscle, as the exacerbation of skeletal muscle injuries are more frequent with intense training or acute eccentric and strenuous exercises. Moderate physical training, in turn, when associated to statins does not increase creatine kinase levels or pain reports, but improves muscle and metabolic functions as a consequence of training. Therefore, it is suggested that dyslipidemic patients undergoing statin treatment should be exposed to moderate aerobic training in combination to resistance exercises three times a week, and the provision of physical training prior to drug administration is desirable, whenever possible.

The effectiveness of the treatment of severe exercise-induced asthma in schoolchildren

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M.N. Garas

2017-03-01

Full Text Available Background. Bronchial asthma is one of the most common chronic multifactorial diseases of the lungs. At least 10–12 % of patients with bronchial asthma are suffering from a severe form of the disease. One aspect of inadequate severe asthma control is its phenotypic heterogeneity, interest of experts increases to the problem of exercise-induced asthma. The purpose of the study was to increase efficiency of treatment for severe exercise-induced asthma in schoolchildren based on the analysis of the attack dynamics and to achieve disease control according to main inflammatometric and spirometric indices. Materials and methods. We examined 46 children with severe persistent bronchial asthma, in particular, 15 schoolchildren suffering from severe exercise-induced asthma, the second clinical group (comparison one consisted of 31 children suffering from severe type of the disease, with no signs of exercise-induced bronchoconstriction. Basic therapy effectiveness was determined prospectively by assessing the disease control using AST-test with an interval of 3 months. The severity of bronchial obstruction syndrome in patients on admission to hospital during exacerbation was assessed by score scale. Airway hyperresponsiveness was evaluated according to the results of bronchoprovocation with histamine. Results. Children of I clinical group had more significant manifestations of bronchial obstruction during the week of inpatient treatment than the comparison group of patients, including significantly more severe manifestations of bronchial obstruction were verified on 1st and 7th day of hospitalization. Due to the analysis of basic therapy effectiveness, only a quarter of I clinical group patients and a larger part of schoolchildren in comparison group achieved the partial control after a 3-month course of anti-inflammatory treatment. Eosinophilic inflammation was observed in most children with severe exercise-induced asthma (60.1 % and in 47.2 % of

[Systematic review about eccentric training in chronic patella tendinopathy].

Science.gov (United States)

Lorenzen, J; Krämer, R; Vogt, P M; Knobloch, K

2010-12-01

Eccentric training has become a popular treatment for patellar tendinopathy. Aim of this review is to display different exercise prescriptions for patellar tendinopathy, to help clinicians make appropriate choices and identify areas needing further research. Is eccentric training as a conservative treatment in chronic patellar tendinopathy of beneficial effect versus other conservative treatments? According to the current scientific data, is it possible to recommend dosages and duration of training time of eccentric training? Systematic review of the current scientific literature on eccentric training as a conservative treatment in chronic Achilles tendinopathy according to the PRISMA-guidelines [Preferred Reporting Items for Systematic Reviews and Meta-Analyses]. National library of Medicine [NLM] between the years 1950 and 2010. Prospective randomised controlled trials (RCT). 7 articles with a total of 165 patients and in which eccentric training was one of the interventions, all published after 2000, were included. The median cohort study size was 20 subjects with a range from 15 to 35 subjects. Median follow-up duration was 12 weeks with a range from 4 to 12 weeks. Encouraging results, but variable study quality, with small numbers or short follow-up periods. The content of the different training programmes varied, but most were home-based programmes with twice daily training for 12 weeks. A number of potentially significant differences were identified in the eccentric programmes used: drop squats or slow eccentric movement, squatting on a 25° decline board or level ground, exercising into tendon pain or short of pain, loading the eccentric phase only or both phases, and progressing with speed then loading or simply loading. A pooled statistical evaluation of the included trials could not be performed due to different study designs as well as limited documentation of subjects' compliance. Most studies suggest that eccentric training may have a positive effect

Exercise-induced rhabdomyolysis.

Science.gov (United States)

Lee, George

2014-11-03

Exercise-induced rhabdomyolysis, or exertional rhabdomyolysis (ER), is a clinical entity typically considered when someone presents with muscle stiffness, swelling, and pain out of proportion to the expected fatigue post exercise. The diagnosis is confirmed by myoglobinuria, and an elevated serum Creatinine Phosphokinase (CPK) level, usually 10 times the normal range. However, an elevation in CPK is seen in most forms of strenuous exercise, up to 20 times the upper normal range. Therefore, there is no definitive pathologic CPK cut-off. Fortunately the dreaded complication of acute renal failure is rare compared to other forms rhabdomyolysis. We review the risks, diagnosis, clinical course and treatment for exercise- induced rhabdomyolysis.

The heat shock protein response following eccentric exercise in human skeletal muscle is unaffected by local NSAID infusion

DEFF Research Database (Denmark)

Mikkelsen, U R; Paulsen, G; Schjerling, P

2013-01-01

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely consumed in relation to pain and injuries in skeletal muscle, but may adversely affect muscle adaptation probably via inhibition of prostaglandin synthesis. Induction of heat shock proteins (HSP) represents an important adaptive response...... in muscle subjected to stress, and in several cell types including cardiac myocytes prostaglandins are important in induction of the HSP response. This study aimed to determine the influence of NSAIDs on the HSP response to eccentric exercise in human skeletal muscle. Healthy males performed 200 maximal...

Prevalence of exercise-induced bronchoconstriction and exercise-induced laryngeal obstruction in a general adolescent population.

Science.gov (United States)

Johansson, Henrik; Norlander, Katarina; Berglund, Lars; Janson, Christer; Malinovschi, Andrei; Nordvall, Lennart; Nordang, Leif; Emtner, Margareta

2015-01-01

Exercise-induced respiratory symptoms are common among adolescents. Exercise is a known stimulus for transient narrowing of the airways, such as exercise-induced bronchoconstriction (EIB) and exercise-induced laryngeal obstruction (EILO). Our aim was to investigate the prevalence of EIB and EILO in a general population of adolescents. In this cross-sectional study, a questionnaire on exercise-induced dyspnoea was sent to all adolescents born in 1997 and 1998 in Uppsala, Sweden (n=3838). A random subsample of 146 adolescents (99 with self-reported exercise-induced dyspnoea and 47 without this condition) underwent standardised treadmill exercise tests for EIB and EILO. The exercise test for EIB was performed while breathing dry air; a positive test was defined as a decrease of ≥10% in FEV1 from baseline. EILO was investigated using continuous laryngoscopy during exercise. The estimated prevalence of EIB and EILO in the total population was 19.2% and 5.7%, respectively. No gender differences were found. In adolescents with exercise-induced dyspnoea, 39.8% had EIB, 6% had EILO and 4.8% had both conditions. In this group, significantly more boys than girls had neither EIB nor EILO (64.7% vs 38.8%; p=0.026). There were no significant differences in body mass index, lung function, diagnosed asthma or medication between the participants with exercise-induced dyspnoea who had or did not have a positive EIB or EILO test result. Both EIB and EILO are common causes of exercise-induced dyspnoea in adolescents. EILO is equally common among girls and boys and can coexist with EIB. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Chaotic micromixer utilizing electro-osmosis and induced charge electro-osmosis in eccentric annulus

International Nuclear Information System (INIS)

Feng, Huicheng; Wong, Teck Neng; Marcos; Che, Zhizhao

2016-01-01

Efficient mixing is of significant importance in numerous chemical and biomedical applications but difficult to realize rapidly in microgeometries due to the lack of turbulence. We propose to enhance mixing by introducing Lagrangian chaos through electro-osmosis (EO) or induced charge electro-osmosis (ICEO) in an eccentric annulus. The analysis reveals that the created Lagrangian chaos can achieve a homogeneous mixing much more rapidly than either the pure EO or the pure ICEO. Our systematic investigations on the key parameters, ranging from the eccentricity, the alternating time period, the number of flow patterns in one time period, to the specific flow patterns utilized for the Lagrangian chaos creation, present that the Lagrangian chaos is considerably robust. The system can obtain a good mixing effect with wide ranges of eccentricity, alternating time period, and specific flow patterns utilized for the Lagrangian chaos creation as long as the number of flow patterns in one time period is two. As the electric field increases, the time consumption for homogenous mixing is reduced more remarkably for the Lagrangian chaos of the ICEO than that of the EO.

Chaotic micromixer utilizing electro-osmosis and induced charge electro-osmosis in eccentric annulus

Energy Technology Data Exchange (ETDEWEB)

Feng, Huicheng; Wong, Teck Neng, E-mail: mtnwong@ntu.edu.sg; Marcos [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Che, Zhizhao [State Key Laboratory of Engines, Tianjin University, Tianjin 300072 (China)

2016-06-15

Efficient mixing is of significant importance in numerous chemical and biomedical applications but difficult to realize rapidly in microgeometries due to the lack of turbulence. We propose to enhance mixing by introducing Lagrangian chaos through electro-osmosis (EO) or induced charge electro-osmosis (ICEO) in an eccentric annulus. The analysis reveals that the created Lagrangian chaos can achieve a homogeneous mixing much more rapidly than either the pure EO or the pure ICEO. Our systematic investigations on the key parameters, ranging from the eccentricity, the alternating time period, the number of flow patterns in one time period, to the specific flow patterns utilized for the Lagrangian chaos creation, present that the Lagrangian chaos is considerably robust. The system can obtain a good mixing effect with wide ranges of eccentricity, alternating time period, and specific flow patterns utilized for the Lagrangian chaos creation as long as the number of flow patterns in one time period is two. As the electric field increases, the time consumption for homogenous mixing is reduced more remarkably for the Lagrangian chaos of the ICEO than that of the EO.

Human Skeletal Muscle Stem Cells in Adaptations to Exercise; Effects of Resistance Exercise Contraction Mode and Protein Supplementation

DEFF Research Database (Denmark)

Farup, Jean

2014-01-01

the effect of contraction mode specific resistance training and protein supplementation on whole muscle and tendon hypertrophy. Quadriceps muscle and patellar tendon cross-sectional area (CSA) was quantified using magnetic resonance imaging pre and post 12 weeks of eccentric (Ecc) or concentric (Conc...... concentric resistance training and ingestion of protein influence myocellular adaptations, with special emphasis on muscle stem cell adaptations, during both acute and prolonged resistance exercise in human skeletal muscle. Paper I. Whey protein supplementation accelerates satellite cell proliferation during...... recovery from eccentric exercise In paper I, we evaluated the effect of a single bout of unaccustomed eccentric exercise on fiber type specific SC content by immunohistochemistry. Subjects received either hydrolysed whey protein (Whey) or iso-caloric carbohydrate (Placebo) in the days post eccentric...

EFFECTS OF CONCENTRIC AND ECCENTRIC MUSCLE ACTIONS ON SERUM MYOSTATIN AND FOLLISTATIN-LIKE RELATED GENE LEVELS

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Lemuel Taylor

2004-12-01

Full Text Available The present study determined the effects of concentric and eccentric muscle actions on the contents of serum myostatin and follistatin-like related gene (FLRG. Eight untrained males performed one exercise bout with each leg, separated by three weeks. One bout consisted of 7 sets of 10 repetitions of eccentric muscle actions of the knee extensors at 150% of the concentric 1-RM while the other bout consisted of 7 sets of 10 repetitions of concentric muscle actions at 75% 1-RM. The legs used and the bouts performed were randomized. Five days prior to each exercise bout, baseline measurements were taken for muscle strength. For both bouts, a venous blood sample was obtained immediately prior to exercise and again at 6, 24, and 48 hr post-exercise. Data were analyzed with 2 X 4 (bout x test ANOVA (p < 0.05. Increases in serum myostatin and FLRG occurred with each exercise bout and, excluding 48 hr post-exercise, were significantly correlated to one another (p < 0.05. After eccentric exercise, peak increases of 68% and 50% (p < 0.05 were observed for myostatin and FLRG, respectively. Similar increases of 54% and 44% (p < 0.05 were observed after concentric muscle actions. There was no significant difference in expression of myostatin or FLRG as a function of muscle action type. Our results suggest that a single bout of exercise with either eccentric or concentric muscle actions appear to elicit a similar increase in serum myostatin and FLRG. Therefore, the type of muscle action may not be as much a mitigating factor for increasing serum myostatin and FLRG rather than the muscle action per se.

Eccentric Training for Tendon Healing After Acute Lesion: A Rat Model.

Science.gov (United States)

Kaux, Jean-François; Libertiaux, Vincent; Leprince, Pierre; Fillet, Marianne; Denoel, Vincent; Wyss, Clémence; Lecut, Christelle; Gothot, André; Le Goff, Caroline; Croisier, Jean-Louis; Crielaard, Jean-Michel; Drion, Pierre

2017-05-01

The tendon is a dynamic entity that remodels permanently. Platelet-rich plasma (PRP) injection has been shown to have a beneficial effect on tendon healing after lesion in rats. Furthermore, eccentric exercise seems to improve the mechanical quality of the tendon. A combination of PRP injection and eccentric training might be more effective than either treatment alone. Controlled laboratory study. Adult male rats were anesthetized, an incision was performed in the middle of their left patellar tendon and an injection of physiological fluid (PF) or homologous PRP was randomly made at the lesion level. The rats were then divided into 2 groups: the eccentric group, undergoing eccentric training 3 times a week, and the untrained group, without any training. Thus, 4 groups were compared. After 5 weeks, the tendons were removed and their ultimate tensile strength and energy were measured. Tendons were frozen for proteomic analyses when all biomechanical tests were completed. Statistical analysis was performed with linear mixed effect models. No significant difference was found between the treatments using PF injection or PRP injection alone. However, the value of the ultimate tensile force at rupture was increased by 4.5 N (108% of control, P = .006) when eccentric training was performed. An intragroup analysis revealed that eccentric training significantly improved the ultimate force values for the PRP group. Proteomic analysis revealed that eccentric training led to an increase in abundance of several cytoskeletal proteins in the PF group, while a decrease in abundance of enzymes of the glycolytic pathway occurred in the PRP-treated groups, indicating that this treatment might redirect the exercise-driven metabolic plasticity of the tendon. Eccentric training altered the metabolic plasticity of tendon and led to an improvement of injured tendon resistance regardless of the treatment injected (PF or PRP). This study demonstrates the necessity of eccentric rehabilitation

Use of post-exercise laryngoscopy to evaluate exercise induced dyspnea.

LENUS (Irish Health Repository)

McNally, P

2010-10-01

We present the case of a child with asthma who continued to have marked exercise induced dyspnea despite appropriate treatment, and in the face of adequate control of all other asthma symptoms. Spirometry showed a marked truncation of inspiratory flow, and laryngoscopy performed immediately after exercise showed laryngomalacia with dynamic, partial inspiratory obstruction. Exercise induced laryngomalacia (EIL) is a rare cause of exercise induced dyspnea which is diagnosed by post exercise flexible laryngoscopy and may require supraglottoplasty.

Unaccustomed eccentric contractions impair plasma K+ regulation in the absence of changes in muscle Na+,K+-ATPase content.

Directory of Open Access Journals (Sweden)

Craig A Goodman

Full Text Available The Na+,K+-ATPase (NKA plays a fundamental role in the regulation of skeletal muscle membrane Na+ and K+ gradients, excitability and fatigue during repeated intense contractions. Many studies have investigated the effects of acute concentric exercise on K+ regulation and skeletal muscle NKA, but almost nothing is known about the effects of repeated eccentric contractions. We therefore investigated the effects of unaccustomed maximal eccentric knee extensor contractions on K+ regulation during exercise, peak knee extensor muscle torque, and vastus lateralis muscle NKA content and 3-O-MFPase activity. Torque measurements, muscle biopsies, and venous blood samples were taken before, during and up to 7 days following the contractions in six healthy adults. Eccentric contractions reduced peak isometric muscle torque immediately post-exercise by 26±11% and serum creatine kinase concentration peaked 24 h post-exercise at 339±90 IU/L. During eccentric contractions, plasma [K+] rose during Set 1 and remained elevated at ∼4.9 mM during sets 4-10; this was despite a decline in work output by Set 4, which fell by 18.9% at set 10. The rise in plasma [K+] x work(-1 ratio was elevated over Set 2 from Set 4- Set 10. Eccentric contractions had no effect on muscle NKA content or maximal in-vitro 3-O-MFPase activity immediately post- or up to 7 d post-exercise. The sustained elevation in plasma [K+] despite a decrease in work performed by the knee extensor muscles suggests an impairment in K+ regulation during maximal eccentric contractions, possibly due to increased plasma membrane permeability or to excitation-contraction uncoupling.

Eccentric rehabilitation exercise increases peritendinous type I collagen synthesis in humans with Achilles tendinosis

DEFF Research Database (Denmark)

Langberg, Henning; Ellingsgaard, Helga; Madsen, Thomas

2007-01-01

It has been shown that 12 weeks of eccentric heavy resistance training can reduce pain in runners suffering from chronic Achilles tendinosis, but the mechanism behind the effectiveness of this treatment is unknown. The present study investigates the local effect of an eccentric training regime on...... in the healthy tendons. The clinical effect of the 12 weeks of eccentric training was determined by using a standardized loading procedure of the Achilles tendons showing a decrease in pain in all the chronic injured tendons (VAS before 44+/-9, after 13+/-9; P......It has been shown that 12 weeks of eccentric heavy resistance training can reduce pain in runners suffering from chronic Achilles tendinosis, but the mechanism behind the effectiveness of this treatment is unknown. The present study investigates the local effect of an eccentric training regime...... of heavy-resistance eccentric training apart from their regular training and soccer activity. Before and after the training period the tissue concentration of indicators of collagen turnover was measured by the use of the microdialysis technique. After training, collagen synthesis was increased...

Fish oil prevents sucrose-induced fatty liver but exacerbates high-safflower oil-induced fatty liver in ddy mice.

Science.gov (United States)

Yamazaki, Tomomi; Nakamori, Akiko; Sasaki, Eriko; Wada, Satoshi; Ezaki, Osamu

2007-12-01

Diets high in sucrose/fructose or fat can result in hepatic steatosis (fatty liver). We analyzed the effects of dietary fish oil on fatty liver induced by sucrose, safflower oil, and butter in ddY mice. In experiment I, mice were fed a high-starch diet [70 energy% (en%) starch] plus 20% (wt/wt) sucrose in the drinking water or fed a high-safflower oil diet (60 en%) for 11 weeks. As a control, mice were fed a high-starch diet with drinking water. Fish oil (10 en%) was either supplemented or not. Mice supplemented with sucrose or fed safflower oil showed a 1.7-fold or 2.2-fold increased liver triglyceride content, respectively, compared with that of control mice. Fish oil completely prevented sucrose-induced fatty liver, whereas it exacerbated safflower oil-induced fatty liver. Sucrose increased SREBP-1c and target gene messenger RNAs (mRNAs), and fish oil completely inhibited these increases. In experiment II, mice were fed a high-safflower oil or a high-butter diet, with or without fish oil supplementation. Fish oil exacerbated safflower oil-induced fatty liver but did not affect butter-induced fatty liver. Fish oil increased expression of peroxisome proliferator-activated receptor gamma (PPARgamma) and target CD36 mRNA in safflower oil-fed mice. These increases were not observed in sucrose-supplemented or butter-fed mice. The effects of dietary fish oil on fatty liver differ according to the cause of fatty liver; fish oil prevents sucrose-induced fatty liver but exacerbates safflower oil-induced fatty liver. The exacerbation of fatty liver may be due, at least in part, to increased expression of liver PPARgamma.

The Effect of Single Portion Glutamine Supplement Consumption on Injury Indices of Muscle After Eccentric Resistance Exercise

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Azadeh Najarzadeh

2015-07-01

Full Text Available Abstract Background: Delayed muscular soreness after resistance exercises or eccentric trainings is probably because of muscle damage and injury. Nutrition by playing a crucial role in both protein synthesize and catabolism can influence the extent of muscle injury. The objective of this study was to assess the effect of single portion of Glutamine supplement consumption on injury indices of muscle after a session eccentric resistance exercise. Materials and Methods: this study used a randomized, double blind design that consisted of 80 volvnteer non-athletic males (aged 22.2±2.2years, height 175±5 cm, weight 71/64±9 kg, body mass index 23/2±2/2 kg/m2, and body fat 17/5±2/4%. A total of 40 participants were divided randomly into 2 groups, supplement group (receiving 0/1 g/kg Body weight/ day Glutamine and placebo group (receiving 0/1 g/kg Body weight/ day Maltodextrin. Serum keratine kinase (CK was determined by photometric method, muscle pain and knee joint range of motion were measured using, respectively, a standard scale of PAS and goniometer before, 24 and 48 hours after a resistance test involving knee flexion. Results: Glutamine supplement consumption caused no significant differences in CK levels reduction in none of the measured times, but it reduced the muscle pain at the times of 24 and 48 hours in comparison with the placebo group. In addition, the knee joint range of motion was significantly improved at 24 hours after the test. Conclusion: It seems that this dose of Glutamine supplementation can reduce the apparent signs apart from muscle injury indices reduction.

Research progress of exercise-induced fatigue

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Peng-yi DAI

2016-12-01

Full Text Available Exercise-induced fatigue is a comprehensive response to a variety of physiological and biochemical changes in the body, and can affect people's quality of life to different extents. If no timely recovery after occurrence of fatigue, accumulated gradually, it can lead to "burnout", a "overtraining syndrome", "chronic fatigue syndrome", etc., which will cause endocrine disturbance, immune suppression, even physical illness. Exercise-induced fatigue becomes an important factor endangering human health. In recent years, many experts and scholars at home and abroad are committed to the research of exercise-induced fatigue, and have put forward a variety of hypothesis to explain the cause of exercise-induced fatigue. They expect to find out the methods for preventing and eliminating exercise-induced fatigue. This article discusses mainly the pathogenesis, model building, elimination/ relief, etc. of exercise-induced fatigue to point out the research achievements of exercise-induced fatigue and its existing problems. DOI: 10.11855/j.issn.0577-7402.2016.11.14

EXERCISE IN RESISTANCE-TRAINED MEN

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RD Calixto

2015-01-01

Full Text Available This study aimed to compare the effects of different velocities of eccentric muscle actions on acute blood lactate and serum growth hormone (GH concentrations following free weight bench press exercises performed by resistance-trained men. Sixteen healthy men were divided into two groups: slow eccentric velocity (SEV; n = 8 and fast eccentric velocity (FEV; n = 8. Both groups performed four sets of eight eccentric repetitions at an intensity of 70% of their one repetition maximum eccentric (1RMecc test, with 2-minute rest intervals between sets. The eccentric velocity was controlled to 3 seconds per range of motion for SEV and 0.5 seconds for the FEV group. There was a significant difference (P < 0.001 in the kinetics of blood lactate removal (at 3, 6, 9, 15, and 20 min and higher mean values for peak blood lactate (P = 0.001 for the SEV group (9.1 ± 0.5 mM compared to the FEV group (6.1 ± 0.4 mM. Additionally, serum GH concentrations were significantly higher (P < 0.001 at 15 minutes after bench press exercise in the SEV group (1.7 ± 0.6 ng · mL-1 relative to the FEV group (0.1 ± 0.0 ng · mL-1. In conclusion, the velocity of eccentric muscle action influences acute responses following bench press exercises performed by resistance-trained men using a slow velocity resulting in a greater metabolic stress and hormone response.

Mitochondrial Ferritin Deletion Exacerbates β-Amyloid-Induced Neurotoxicity in Mice

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Peina Wang

2017-01-01

Full Text Available Mitochondrial ferritin (FtMt is a mitochondrial iron storage protein which protects mitochondria from iron-induced oxidative damage. Our previous studies indicate that FtMt attenuates β-amyloid- and 6-hydroxydopamine-induced neurotoxicity in SH-SY5Y cells. To explore the protective effects of FtMt on β-amyloid-induced memory impairment and neuronal apoptosis and the mechanisms involved, 10-month-old wild-type and Ftmt knockout mice were infused intracerebroventricularly (ICV with Aβ25–35 to establish an Alzheimer’s disease model. Knockout of Ftmt significantly exacerbated Aβ25–35-induced learning and memory impairment. The Bcl-2/Bax ratio in mouse hippocampi was decreased and the levels of cleaved caspase-3 and PARP were increased. The number of neuronal cells undergoing apoptosis in the hippocampus was also increased in Ftmt knockout mice. In addition, the levels of L-ferritin and FPN1 in the hippocampus were raised, and the expression of TfR1 was decreased. Increased MDA levels were also detected in Ftmt knockout mice treated with Aβ25–35. In conclusion, this study demonstrated that the neurological impairment induced by Aβ25–35 was exacerbated in Ftmt knockout mice and that this may relate to increased levels of oxidative stress.

The effect of different accentuated eccentric load levels in eccentric-concentric loading contractions on acute neuromuscular, growth hormone and blood lactate responses during a hypertrophic protocol

OpenAIRE

Ojasto, Timo

2007-01-01

When accentuated load is applied during the eccentric (ECC) phase of eccentric-concentric (ECC-CON) contractions, it is defined as dynamic accentuated external resistance (DAER) exercise. This study monitored acute neuromuscular responses, growth hormone (GH) and blood lactate (La) concentrations to find out the most efficient ECC-CON loading strategy for muscle hypertrophy by employing various DAER resistances in the bench-press. Male subjects (age=32.4±4.3years, n=11) were assigned as subje...

Bevacizumab Exacerbates Paclitaxel-Induced Neuropathy: A Retrospective Cohort Study.

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Ayumu Matsuoka

Full Text Available Bevacizumab (BEV, a humanized anti-vascular endothelial growth factor (VEGF monoclonal antibody, enhances the antitumor effectiveness of paclitaxel (PTX-based chemotherapy in many metastatic cancers. A recent study in mice showed that VEGF receptor inhibitors can interfere with the neuroprotective effects of endogenous VEGF, potentially triggering the exacerbation of PTX-induced neuropathy. In clinical trials, exacerbation of neuropathy in patients who received PTX combined with BEV (PTX+BEV has generally been explained by increased exposure to PTX owing to the extended duration of chemotherapy. We investigated whether the concurrent use of BEV is associated with the exacerbation of PTX-induced neuropathy.Female patients with breast cancer who had received weekly PTX or PTX+BEV from September 2011 through May 2016 were studied retrospectively. PTX-induced neuropathy was evaluated at the same time points (at the 6th and 12th courses of chemotherapy in both cohorts. A multivariate Cox proportional-hazards model was used to assess the independent effect of BEV on the time to the onset of neuropathy.A total of 107 patients (median age, 55 years; range, 32-83 were studied. Sixty-one patients received PTX as adjuvant chemotherapy, 23 received PTX for metastatic disease, and 23 received PTX+BEV for metastatic disease. Peripheral sensory neuropathy was worse in patients who received PTX+BEV than in those who received PTX alone: at the 6th course, Grade 0/1/2/3 = 4/13/4/0 vs. 25/42/6/0 (P = 0.095; at the 12th course, 2/3/11/3 vs. 7/30/23/2 (P = 0.016. At the 12th course, the incidence of Grade 2 or higher neuropathy was significantly higher in patients treated with PTX+BEV than in those treated with PTX alone (74% vs. 40%; P = 0.017. In multivariate analysis, BEV was significantly associated with an increased risk of neuropathy (HR 2.32, 95% CI 1.21-4.44, P = 0.012.The concurrent use of BEV could worsen PTX-induced neuropathy in patients with breast

TIME COURSE CHANGE OF IGF1/AKT/MTOR/P70S6K PATHWAY ACTIVATION IN RAT GASTROCNEMIUS MUSCLE DURING REPEATED BOUTS OF ECCENTRIC EXERCISE

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Eisuke Ochi

2010-06-01

Full Text Available The purpose of this study was to examine whether insulin-like growth factor (IGF-1 and Akt/mTOR/p70S6K pathway activity is altered by chronic eccentric exercise in rat medial gastrocnemius muscle. Male Wistar rats (n = 24 were randomly assigned to 1 of the 2 groups: eccentric exercise (ECC group or sham-operated control (CON group. Rats in the ECC group were trained every second day for 10 days (5 sessions in total or 20 days (10 sessions in total. After either 5 or 10 exercise sessions, muscle specimens were dissected and weighed. The mRNA expression of IGF-1 and its variant, mechano growth factor (MGF, was evaluated using real time reverse transcriptase-polymerase chain reaction (RT-PCR. Tissue concentrations of Akt (P, mTOR (P, and p70S6K (P were measured by using western blot analysis. The medial gastrocnemius muscle mass of the ECC group did not show any significant difference after 5 exercise sessions, whereas the muscle mass increased significantly after 10 exercise sessions with a concomitant increase in the cross-sectional area of muscle fibers (p < 0.05. The expression of IGF-1 mRNA and the tissue concentrations of Akt (P and p70S6K (P after 10 exercise sessions was significantly higher than those of the age-matched controls and the rats that received 5 exercise sessions. The expression of MGF mRNA in both ECC5S and ECC10S were significantly higher than that in each period-matched control (p < 0.01. The tissue concentration of mTOR (P after 10 sessions showed a significant increase when compared with period-matched controls (p < 0.01. These results suggest that activation of the IGF-1/Akt/mTOR/p70S6K signaling pathway becomes dominant in the later phase of chronic exercise, when significant muscular hypertrophy is observed

Exercise induced asthma and endogenous opioids.

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Gaillard, R C; Bachman, M; Rochat, T; Egger, D; de Haller, R; Junod, A F

1986-01-01

Concentrations of endogenous opioid peptides in the plasma are increased during exercise and these substances have been implicated in the pathogenesis of asthma induced by chloropropramide and alcohol in diabetic patients. This work was undertaken to determine whether exercise induced asthma might be mediated by endogenous opioids. Plasma beta endorphin, met-enkephalin, and adrenocorticotrophic hormone (ACTH) concentrations were measured in five asthmatic patients and five normal volunteers breathing cold air during exercise. In four of the patients the effect of an infusion of naloxone on FEV1 was also measured during exercise induced asthma. Exercise produced acute bronchoconstriction in all asthmatics, characterised by a fall in FEV1; whereas no change occurred in normal subjects. There was no difference in plasma met-enkephalin, beta endorphin, and ACTH concentration between the two groups. Infusion of naloxone neither prevented nor worsened exercise induced asthma. These data suggest that endogenous opioids probably do not play a part in the development of exercise induced asthma. PMID:2944240

Eccentric muscle damage has variable effects on motor unit recruitment thresholds and discharge patterns in elbow flexor muscles.

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Dartnall, Tamara J; Rogasch, Nigel C; Nordstrom, Michael A; Semmler, John G

2009-07-01

The purpose of this study was to determine the effect of eccentric muscle damage on recruitment threshold force and repetitive discharge properties of low-threshold motor units. Ten subjects performed four tasks involving isometric contraction of elbow flexors while electromyographic (EMG) data were recorded from human biceps brachii and brachialis muscles. Tasks were 1) maximum voluntary contraction (MVC); 2) constant-force contraction at various submaximal targets; 3) motor unit recruitment threshold task; and 4) minimum motor unit discharge rate task. These tasks were performed on three separate days before, immediately after, and 24 h after eccentric exercise of elbow flexor muscles. MVC force declined (42%) immediately after exercise and remained depressed (29%) 24 h later, indicative of muscle damage. Mean motor unit recruitment threshold for biceps brachii was 8.4+/-4.2% MVC, (n=34) before eccentric exercise, and was reduced by 41% (5.0+/-3.0% MVC, n=34) immediately after and by 39% (5.2+/-2.5% MVC, n=34) 24 h after exercise. No significant changes in motor unit recruitment threshold were observed in the brachialis muscle. However, for the minimum tonic discharge rate task, motor units in both muscles discharged 11% faster (10.8+/-2.0 vs. 9.7+/-1.7 Hz) immediately after (n=29) exercise compared with that before (n=32). The minimum discharge rate variability was greater in brachialis muscle immediately after exercise (13.8+/-3.1%) compared with that before (11.9+/-3.1%) and 24 h after exercise (11.7+/-2.4%). No significant changes in minimum discharge rate variability were observed in the biceps brachii motor units after exercise. These results indicate that muscle damage from eccentric exercise alters motor unit recruitment thresholds for >or=24 h, but the effect is not the same in the different elbow flexor muscles.

Plyometric training improves voluntary activation and strength during isometric, concentric and eccentric contractions.

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Behrens, Martin; Mau-Moeller, Anett; Mueller, Karoline; Heise, Sandra; Gube, Martin; Beuster, Nico; Herlyn, Philipp K E; Fischer, Dagmar-C; Bruhn, Sven

2016-02-01

This study investigated effects of plyometric training (6 weeks, 3 sessions/week) on maximum voluntary contraction (MVC) strength and neural activation of the knee extensors during isometric, concentric and eccentric contractions. Twenty-seven participants were randomly assigned to the intervention or control group. Maximum voluntary torques (MVT) during the different types of contraction were measured at 110° knee flexion (180°=full extension). The interpolated twitch technique was applied at the same knee joint angle during isometric, concentric and eccentric contractions to measure voluntary activation. In addition, normalized root mean square of the EMG signal at MVT was calculated. The twitch torque signal induced by electrical nerve stimulation at rest was used to evaluate training-related changes at the muscle level. In addition, jump height in countermovement jump was measured. After training, MVT increased by 20Nm (95% CI: 5-36Nm, P=0.012), 24Nm (95% CI: 9-40Nm, P=0.004) and 27Nm (95% CI: 7-48Nm, P=0.013) for isometric, concentric and eccentric MVCs compared to controls, respectively. The strength enhancements were associated with increases in voluntary activation during isometric, concentric and eccentric MVCs by 7.8% (95% CI: 1.8-13.9%, P=0.013), 7.0% (95% CI: 0.4-13.5%, P=0.039) and 8.6% (95% CI: 3.0-14.2%, P=0.005), respectively. Changes in the twitch torque signal of the resting muscle, induced by supramaximal electrical stimulation of the femoral nerve, were not observed, indicating no alterations at the muscle level, whereas jump height was increased. Given the fact that the training exercises consisted of eccentric muscle actions followed by concentric contractions, it is in particular relevant that the plyometric training increased MVC strength and neural activation of the quadriceps muscle regardless of the contraction mode. Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

The interplay between neuroendocrine activity and psychological stress-induced exacerbation of allergic asthma

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Tomomitsu Miyasaka

2018-01-01

Full Text Available Psychological stress is recognized as a key factor in the exacerbation of allergic asthma, whereby brain responses to stress act as immunomodulators for asthma. In particular, stress-induced enhanced type 2 T-helper (Th2-type lung inflammation is strongly associated with asthma pathogenesis. Psychological stress leads to eosinophilic airway inflammation through activation of the hypothalamic-pituitary-adrenal pathway and autonomic nervous system. This is followed by the secretion of stress hormones into the blood, including glucocorticoids, epinephrine, and norepinephrine, which enhance Th2 and type 17 T-helper (Th17-type asthma profiles in humans and rodents. Recent evidence has shown that a defect of the μ-opioid receptor in the brain along with a defect of the peripheral glucocorticoid receptor signaling completely disrupted stress-induced airway inflammation in mice. This suggests that the stress response facilitates events in the central nervous and endocrine systems, thus exacerbating asthma. In this review, we outline the recent findings on the interplay between stress and neuroendocrine activities followed by stress-induced enhanced Th2 and Th17 immune responses and attenuated regulatory T (Treg cell responses that are closely linked with asthma exacerbation. We will place a special focus on our own data that has emphasized the continuity from central sensing of psychological stress to enhanced eosinophilic airway inflammation. The mechanism that modulates psychological stress-induced exacerbation of allergic asthma through neuroendocrine activities is thought to involve a series of consecutive pathological events from the brain to the lung, which implies there to be a “neuropsychiatry phenotype” in asthma.

Muscle plasticity related to changes in tubulin and αB-crystallin levels induced by eccentric contraction in rat skeletal muscles.

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Jee, H; Ochi, E; Sakurai, T; Lim, J-Y; Nakazato, K; Hatta, H

2016-09-01

We used the model of eccentric contraction of the hindlimb muscle by Ochi et al. to examine the role of eccentric contraction in muscle plasticity. This model aims to focus on stimulated skeletal muscle responses by measuring tissue weights and tracing the quantities of αB-crystallin and tubulin. The medial gastrocnemius muscle (GCM) responded to electrically induced eccentric contraction (EIEC) with significant increases in tissue weight (p muscle weight after EIEC. EIEC in the GCM caused contractile-induced sustenance of the traced proteins, but the soleus muscle exhibited a remarkable decrease in α-tubulin and a 19% decrease in αB-crystallin. EIEC caused fast-to-slow myosin heavy chain (MHC) isoform type-oriented shift within both the GCM and soleus muscle. These results have shown that different MHC isoform type-expressing slow and fast muscles commonly undergo fast-to-slow type MHC isoform transformation. This suggests that different levels of EIEC affected each of the slow and fast muscles to induce different quantitative changes in the expression of αB-crystallin and α-tubulin.

Skeletal Muscle Remodeling in Response to Eccentric vs. Concentric Loading: Morphological, Molecular, and Metabolic Adaptations

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Martino V. Franchi

2017-07-01

Full Text Available Skeletal muscle contracts either by shortening or lengthening (concentrically or eccentrically, respectively; however, the two contractions substantially differ from one another in terms of mechanisms of force generation, maximum force production and energy cost. It is generally known that eccentric actions generate greater force than isometric and concentric contractions and at a lower metabolic cost. Hence, by virtue of the greater mechanical loading involved in active lengthening, eccentric resistance training (ECC RT is assumed to produce greater hypertrophy than concentric resistance training (CON RT. Nonetheless, prevalence of either ECC RT or CON RT in inducing gains in muscle mass is still an open issue, with some studies reporting greater hypertrophy with eccentric, some with concentric and some with similar hypertrophy within both training modes. Recent observations suggest that such hypertrophic responses to lengthening vs. shortening contractions are achieved by different adaptations in muscle architecture. Whilst the changes in muscle protein synthesis in response to acute and chronic concentric and eccentric exercise bouts seem very similar, the molecular mechanisms regulating the myogenic adaptations to the two distinct loading stimuli are still incompletely understood.Thus, the present review aims to, (a critically discuss the literature on the contribution of eccentric vs. concentric loading to muscular hypertrophy and structural remodeling, and, (b clarify the molecular mechanisms that may regulate such adaptations.We conclude that, when matched for either maximum load or work, similar increase in muscle size is found between ECC and CON RT. However, such hypertrophic changes appear to be achieved through distinct structural adaptations, which may be regulated by different myogenic and molecular responses observed between lengthening and shortening contractions.

Exercise Based- Pain Relief Program

DEFF Research Database (Denmark)

Zadeh, Mahdi Hossein

in the current study was to use exercise induced- muscle damage followed by ECC as an acute pain model and observe its effects on the sensitivity of the nociceptive system and blood supply in healthy subjects. Then, the effect of a repeated bout of the same exercise as a healthy pain relief strategy......Exercise-based pain management programs are suggested for relieving from musculoskeletal pain; however the pain experienced after unaccustomed, especially eccentric exercise (ECC) alters people´s ability to participate in therapeutic exercises. Subsequent muscle pain after ECC has been shown...... to cause localized pressure pain and hyperalgesia. A prior bout of ECC has been repeatedly reported to produce a protective adaptation known as repeated bout effect (RBE). One of the main scopes of the current project was to investigate the adaptations by which the RBE can be resulted from. The approach...

Heat sensitive persons with multiple sclerosis are more tolerant to resistance exercise than to endurance exercise

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Skjerbæk, Anders G; Møller, Andreas Buch; Jensen, Ellen

2012-01-01

BACKGROUND: Heat sensitivity (HS) is reported by 58% of all persons with multiple sclerosis (MS), causing symptom exacerbation possibly limiting exercise participation. OBJECTIVE: The purpose of this study was to test the hypotheses that (a) a relationship between exercise-induced changes in core...... randomly completed a session of RE and EE, or EE and RE, respectively. Testing was conducted pre, post and one hour after exercise and consisted of Visual Analogue Scale (VAS) scoring (fatigue, spasticity, pain, strength, walking and balance), the 5-time sit-to-stand (5STS), the Multiple Sclerosis......-temperature (C(temp)) and changes in symptom intensity exists, and (b) that resistance exercise (RE), as a consequence of a minor increase in core temperature, will induce a lesser worsening of symptoms than endurance exercise (EE) in HS persons with MS. METHODS: On two separate days, 16 HS persons with MS...

Acute Alcohol Intoxication Exacerbates Rhabdomyolysis-Induced Acute Renal Failure in Rats.

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Tsai, Jen-Pi; Lee, Chung-Jen; Subeq, Yi-Maun; Lee, Ru-Ping; Hsu, Bang-Gee

2017-01-01

Traumatic and nontraumatic rhabdomyolysis can lead to acute renal failure (ARF), and acute alcohol intoxication can lead to multiple abnormalities of the renal tubules. We examined the effect of acute alcohol intoxication in a rat model of rhabdomyolysis and ARF. Intravenous injections of 5 g/kg ethanol were given to rats over 3 h, followed by glycerol-induced rhabdomyolysis. Biochemical parameters, including blood urea nitrogen (BUN), creatinine (Cre), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and creatine phosphokinase (CPK), were measured before and after induction of rhabdomyolysis. Renal tissue injury score, renal tubular cell expression of E-cadherin, nuclear factor-κB (NF-κB), and inducible nitric oxide synthase (iNOS) were determined. Relative to rats in the vehicle group, rats in the glycerol-induced rhabdomyolysis group had significantly increased serum levels of BUN, Cre, GOT, GPT, and CPK, elevated renal tissue injury scores, increased expression of NF-κB and iNOS, and decreased expression of E-cadherin. Ethanol exacerbated all of these pathological responses. Our results suggest that acute alcohol intoxication exacerbates rhabdomyolysis-induced ARF through its pro-oxidant and inflammatory effects.

Haemophilus influenzae from Patients with Chronic Obstructive Pulmonary Disease Exacerbation Induce More Inflammation than Colonizers

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Chin, Cecilia L.; Manzel, Lori J.; Lehman, Erin E.; Humlicek, Alicia L.; Shi, Lei; Starner, Timothy D.; Denning, Gerene M.; Murphy, Timothy F.; Sethi, Sanjay; Look, Dwight C.

2005-01-01

Rationale: Airway infection with Haemophilus influenzae causes airway inflammation, and isolation of new strains of this bacteria is associated with increased risk of exacerbations in patients with chronic obstructive pulmonary disease (COPD). Objective: To determine whether strains of H. influenzae associated with exacerbations cause more inflammation than strains that colonize the airways of patients with COPD. Methods: Exacerbation strains of H. influenzae were isolated from patients during exacerbation of clinical symptoms with subsequent development of a homologous serum antibody response and were compared with colonization strains that were not associated with symptom worsening or an antibody response. Bacterial strains were compared using an in vivo mouse model of airway infection and in vitro cell culture model of bacterial adherence and defense gene and signaling pathway activation in primary human airway epithelial cells. Results: H. influenzae associated with exacerbations caused more airway neutrophil recruitment compared with colonization strains in the mouse model of airway bacterial infection. Furthermore, exacerbation strains adhered to epithelial cells in significantly higher numbers and induced more interleukin-8 release after interaction with airway epithelial cells. This effect was likely mediated by increased activation of the nuclear factor-κB and p38 mitogen-activated protein kinase signaling pathways. Conclusions: The results indicate that H. influenzae strains isolated from patients during COPD exacerbations often induce more airway inflammation and likely have differences in virulence compared with colonizing strains. These findings support the concept that bacteria infecting the airway during COPD exacerbations mediate increased airway inflammation and contribute to decreased airway function. PMID:15805181

Brain activation associated with eccentric movement: A narrative review of the literature.

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Perrey, Stéphane

2018-02-01

The movement occurring when a muscle exerts tension while lengthening is known as eccentric muscle action. Literature contains limited evidence on how our brain controls eccentric movement. However, how the cortical regions in the motor network are activated during eccentric muscle actions may be critical for understanding the underlying control mechanism of eccentric movements encountered in daily tasks. This is a novel topic that has only recently begun to be investigated through advancements in neuroimaging methods (electroencephalography, EEG; functional magnetic resonance imaging, fMRI). This review summarizes a selection of seven studies indicating mainly: longer time and higher cortical signal amplitude (EEG) for eccentric movement preparation and execution, greater magnitude of cortical signals with wider activated brain area (EEG, fMRI), and weaker brain functional connectivity (fMRI) between primary motor cortex (M1) and other cortical areas involved in the motor network during eccentric muscle actions. Only some differences among studies due to the forms of movement with overload were observed in the contralateral (to the active hand) M1 activity during eccentric movement. Altogether, the findings indicate an important challenge to the brain for controlling the eccentric movement. However, our understanding remains limited regarding the acute effects of eccentric exercise on cortical regions and their cooperation as functional networks that support motor functions. Further analysis and standardized protocols will provide deeper insights into how different cortical regions of the underlying motor network interplay with each other in increasingly demanding muscle exertions in eccentric mode.

Exercise Promotes Healthy Aging of Skeletal Muscle

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Cartee, Gregory D; Hepple, Russell T; Bamman, Marcas M

2016-01-01

caused by diseases and lifestyle factors. Secondary aging can exacerbate deficits in mitochondrial function and muscle mass, concomitant with the development of skeletal muscle insulin resistance. Exercise opposes deleterious effects of secondary aging by preventing the decline in mitochondrial...... respiration, mitigating aging-related loss of muscle mass and enhancing insulin sensitivity. This review focuses on mechanisms by which exercise promotes "healthy aging" by inducing modifications in skeletal muscle....

ESTRADIOL IN FEMALES MAY NEGATE SKELETAL MUSCLE MYOSTATIN MRNA EXPRESSION AND SERUM MYOSTATIN PROPEPTIDE LEVELS AFTER ECCENTRIC MUSCLE CONTRACTIONS

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Darryn S. Willoughby

2006-12-01

Full Text Available Eccentric contractions produce a significant degree of inflammation and muscle injury that may increase the expression of myostatin. Due to its anti- oxidant and anti-flammatory effects, circulating 17-β estradiol (E2 may attenuate myostatin expression. Eight males and eight females performed 7 sets of 10 reps of eccentric contractions of the knee extensors at 150% 1-RM. Each female performed the eccentric exercise bout on a day that fell within her mid-luteal phase (d 21-23 of her 28-d cycle. Blood and muscle samples were obtained before and 6 and 24 h after exercise, while additional blood samples were obtained at 48 and 72 h after exercise. Serum E2 and myostatin LAP/propeptide (LAP/pro levels were determined with ELISA, and myostatin mRNA expression determined using RT-PCR. Data were analyzed with two-way ANOVA and bivariate correlations (p 0.05. Compared to pre-exercise, males had significant increases (p < 0.05 in LAP/propetide and mRNA of 78% and 28%, respectively, at 24 h post-exercise, whereas females underwent respective decreases of 10% and 21%. E2 and LAP/propeptide were correlated at 6 h (r = -0.804, p = 0.016 and 24 h post- exercise (r = -0.841, p = 0.009 in males, whereas in females E2 levels were correlated to myostatin mRNA at 6 h (r =0.739, p = 0.036 and 24 h (r = 0.813, p = 0.014 post-exercise and LAP/propeptide at 6 h (r = 0.713, p = 0.047 and 24 h (r = 0.735, p = 0.038. In females, myostatin mRNA expression and serum LAP/propeptide levels do not appear to be significantly up-regulated following eccentric exercise, and may be due to higher levels of circulating E2

Trauma-induced systemic inflammatory response versus exercise-induced immunomodulatory effects.

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Fehrenbach, Elvira; Schneider, Marion E

2006-01-01

Accidental trauma and heavy endurance exercise, both induce a kind of systemic inflammatory response, also called systemic inflammatory response syndrome (SIRS). Exercise-related SIRS is conditioned by hyperthermia and concomitant heat shock responses, whereas trauma-induced SIRS manifests concomitantly with tissue necrosis and immune activation, secondarily followed by fever. Inflammatory cytokines are common denominators in both trauma and exercise, although there are marked quantitative differences. Different anti-inflammatory cytokines may be involved in the control of inflammation in trauma- and exercise-induced stress. Exercise leads to a balanced equilibrium between inflammatory and anti-inflammatory responses. Intermittent states of rest, as well as anti-oxidant capacity, are lacking or minor in trauma but are high in exercising individuals. Regular training may enhance immune competence, whereas trauma-induced SIRS often paves the way for infectious complications, such as sepsis.

An Eccentrically Biased Rehabilitation Program Early after TKA Surgery

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Robin L. Marcus

2011-01-01

Full Text Available Rehabilitation services are less-studied aspects of the management following total knee arthroplasty (TKA despite long-term suboptimal physical functioning and chronic deficits in muscle function. This paper describes the preliminary findings of a six-week (12 session eccentrically-biased rehabilitation program targeted at deficits in physical function and muscle function, initiated one month following surgery. A quasiexperimental, one group, pretest-posttest study with thirteen individuals (6 female, 7 male; mean age 57±7 years examined the effectiveness of an eccentrically-biased rehabilitation program. The program resulted in improvements in the primary physical function endpoints (SF-36 physical component summary and the six-minute walk test with increases of 59% and 47%, respectively. Muscle function endpoints (knee extension strength and power also increased 107% and 93%, respectively. Eccentrically-biased exercise used as an addition to rehabilitation may help amplify and accelerate physical function following TKA surgery.

Expression of developmental myosin and morphological characteristics in adult rat skeletal muscle following exercise-induced injury.

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Smith, H K; Plyley, M J; Rodgers, C D; McKee, N H

1999-07-01

The extent and stability of the expression of developmental isoforms of myosin heavy chain (MHCd), and their association with cellular morphology, were determined in adult rat skeletal muscle fibres following injury induced by eccentrically-biased exercise. Adult female Wistar rats [274 (10) g] were either assigned as non-exercised controls or subjected to 30 min of treadmill exercise (grade, -16 degrees; speed, 15 m x min(-1)), and then sacrificed following 1, 2, 4, 7, or 12 days of recovery (n = 5-6 per group). Histologically and immunohistologically stained serial, transverse cryosections of the soleus (S), vastus intermedius (VI), and tibialis anterior (TA) muscles were examined using light microscopy and digital imaging. Fibres staining positively for MHCd (MHCd+) were seldom detected in the TA. In the VI and S, higher proportions of MHCd+ fibres (0.8% and 2.5%, respectively) were observed in rats at 4 and 7 days post-exercise, in comparison to all other groups combined (0.2%, 1.2%; P < or = 0.01). In S, MHCd+ fibres were observed less frequently by 12 days (0.7%) than at 7 days (2.6%) following exercise. The majority (85.1%) of the MHCd+ fibres had morphological characteristics indicative of either damage, degeneration, repair or regeneration. Most of the MHCd+ fibres also expressed adult slow, and/or fast myosin heavy chain. Quantitatively, the MHCd+ fibres were smaller (< 2500 microm2) and more angular than fibres not expressing MHCd. Thus, there was a transient increase in a small, but distinct population of MHCd+ fibres following unaccustomed, functional exercise in adult rat S and VI muscles. The observed close coupling of MHCd expression with morphological changes within muscle fibres suggests that these characteristics have a common, initial exercise-induced injury-related stimulus.

Test-retest reliabilty of exercise-induced hypoalgesia after aerobic exercise

DEFF Research Database (Denmark)

Vaegter, Henrik Bjarke; Dørge, Daniel Bandholtz; Schmidt, Kristian Sonne

2018-01-01

Objective: Exercise increases pressure pain thresholds (PPTs) in exercising and nonexercising muscles, known as exercise-induced hypoalgesia (EIH). No studies have investigated the test-retest reliability of change in PPTs after aerobic exercise. Primary objectives were to compare the effect...

The Effects of Eccentric Contraction Duration on Muscle Strength, Power Production, Vertical Jump, and Soreness.

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Mike, Jonathan N; Cole, Nathan; Herrera, Chris; VanDusseldorp, Trisha; Kravitz, Len; Kerksick, Chad M

2017-03-01

Mike, JN, Cole, N, Herrera, C, VanDusseldorp, T, Kravitz, L, and Kerksick, CM. The effects of eccentric contraction duration on muscle strength, power production, vertical jump, and soreness. J Strength Cond Res 31(3): 773-786, 2017-Previous research has investigated the effects of either eccentric-only training or comparing eccentric and concentric exercise on changes related to strength and power expression, but no research to date has investigated the impact of altering the duration of either the concentric or the eccentric component on these parameters. Therefore, the purpose of this study was to assess the duration of eccentric (i.e., 2-second, 4-second vs. 6-second) muscle contractions and their effect on muscle strength, power production, vertical jump, and soreness using a plate-loaded barbell Smith squat exercise. Thirty college-aged men (23 ± 3.5 years, 178 ± 6.8 cm, 82 ± 12 kg, and 11.6 ± 5.1% fat) with 3.0 ± 1.0 years of resistance training experience and training frequency of 4.3 ± 0.9 days per week were randomized and assigned to 1 of 3 eccentric training groups that incorporated different patterns of contraction. For every repetition, all 3 groups used 2-second concentric contractions and paused for 1 second between the concentric and eccentric phases. The control group (2S) used 2-second eccentric contractions, whereas the 4S group performed 4-second eccentric contractions and the 6S group performed 6-second eccentric contractions. All repetitions were completed using the barbell Smith squat exercise. All participants completed a 4-week training protocol that required them to complete 2 workouts per week using their prescribed contraction routine for 4 sets of 6 repetitions at an intensity of 80-85% one repetition maximum (1RM). For all performance data, significant group × time (G × T) interaction effects were found for average power production across all 3 sets of a squat jump protocol (p = 0.04) while vertical jump did not reach

A pilot study of the eccentric decline squat in the management of painful chronic patellar tendinopathy.

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Purdam, C R; Jonsson, P; Alfredson, H; Lorentzon, R; Cook, J L; Khan, K M

2004-08-01

This non-randomised pilot study investigated the effect of eccentric quadriceps training on 17 patients (22 tendons) with painful chronic patellar tendinopathy. Two different eccentric exercise regimens were used by subjects with a long duration of pain with activity (more than six months). (a) Nine consecutive patients (10 tendons; eight men, one woman; mean age 22 years) performed eccentric exercise with the ankle joint in a standard (foot flat) position. (b) Eight patients (12 tendons; five men, three women; mean age 28 years) performed eccentric training standing on a 25 degrees decline board, designed to increase load on the knee extensor mechanism. The eccentric training was performed twice daily, with three sets of 15 repetitions, for 12 weeks. Primary outcome measures were (a) 100 mm visual analogue scale (VAS), where the subject recorded the amount of pain during activity, and (b) return to previous activity. Follow up was at 12 weeks, with a further limited follow up at 15 months. Good clinical results were obtained in the group who trained on the decline board, with six patients (nine tendons) returning to sport and showing a significantly reduced amount of pain over the 12 week period. Mean VAS scores fell from 74.2 to 28.5 (p = 0.004). At 15 months, four patients (five tendons) reported satisfactory results (mean VAS 26.2). In the standard squat group the results were poor, with only one athlete returning to previous activity. Mean VAS scores in this group were 79.0 at baseline and 72.3 at 12 weeks (p = 0.144). In a small group of patients with patellar tendinopathy, eccentric squats on a decline board produced encouraging results in terms of pain reduction and return to function in the short term. Eccentric exercise using standard single leg squats in a similar sized group appeared to be a less effective form of rehabilitation in reducing pain and returning subjects to previous levels of activity.

Statin therapy exacerbates alcohol-induced constriction of cerebral arteries via modulation of ethanol-induced BK channel inhibition in vascular smooth muscle.

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Simakova, Maria N; Bisen, Shivantika; Dopico, Alex M; Bukiya, Anna N

2017-12-01

Statins constitute the most commonly prescribed drugs to decrease cholesterol (CLR). CLR is an important modulator of alcohol-induced cerebral artery constriction (AICAC). Using rats on a high CLR diet (2% CLR) we set to determine whether atorvastatin administration (10mg/kg daily for 18-23weeks) modified AICAC. Middle cerebral arteries were pressurized in vitro at 60mmHg and AICAC was evoked by 50mM ethanol, that is within the range of blood alcohol detected in humans following moderate-to-heavy drinking. AICAC was evident in high CLR+atorvastatin group but not in high CLR diet+placebo. Statin exacerbation of AICAC persisted in de-endothelialized arteries, and was blunted by CLR enrichment in vitro. Fluorescence imaging of filipin-stained arteries showed that atorvastatin decreased vascular smooth muscle (VSM) CLR when compared to placebo, this difference being reduced by CLR enrichment in vitro. Voltage- and calcium-gated potassium channels of large conductance (BK) are known VSM targets of ethanol, with their beta1 subunit being necessary for ethanol-induced channel inhibition and resulting AICAC. Ethanol-induced BK inhibition in excised membrane patches from freshly isolated myocytes was exacerbated in the high CLR diet+atorvastatin group when compared to high CLR diet+placebo. Unexpectedly, atorvastatin decreased the amount and function of BK beta1 subunit as documented by immunofluorescence imaging and functional patch-clamp studies. Atorvastatin exacerbation of ethanol-induced BK inhibition disappeared upon artery CLR enrichment in vitro. Our study demonstrates for the first time statin's ability to exacerbate the vascular effect of a widely consumed drug of abuse, this exacerbation being driven by statin modulation of ethanol-induced BK channel inhibition in the VSM via CLR-mediated mechanism. Copyright © 2017 Elsevier Inc. All rights reserved.

The Impact of Exercise on Statin-Associated Skeletal Muscle Myopathy

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Chung, Hae R.; Vakil, Mayand; Munroe, Michael; Parikh, Alay; Meador, Benjamin M.; Wu, Pei T.; Jeong, Jin H.; Woods, Jeffrey A.; Wilund, Kenneth R.; Boppart, Marni D.

2016-01-01

HMG-CoA reductase inhibitors (statins) are the most effective pharmacological means of reducing cardiovascular disease risk. The most common side effect of statin use is skeletal muscle myopathy, which may be exacerbated by exercise. Hypercholesterolemia and training status are factors that are rarely considered in the progression of myopathy. The purpose of this study was to determine the extent to which acute and chronic exercise can influence statin-induced myopathy in hypercholesterolemic (ApoE-/-) mice. Mice either received daily injections of saline or simvastatin (20 mg/kg) while: 1) remaining sedentary (Sed), 2) engaging in daily exercise for two weeks (novel, Nov), or 3) engaging in daily exercise for two weeks after a brief period of training (accustomed, Acct) (2x3 design, n = 60). Cholesterol, activity, strength, and indices of myofiber damage and atrophy were assessed. Running wheel activity declined in both exercise groups receiving statins (statin x time interaction, pstatin treatment (statin main effect, pstatin x exercise interaction, pstatin treatment. Exercise (Acct and Nov) increased atrogin-1 mRNA in combination with statin treatment, yet enhanced fiber damage or atrophy was not observed. The results from this study suggest that exercise (Nov, Acct) does not exacerbate statin-induced myopathy in ApoE-/- mice, yet statin treatment reduces activity in a manner that prevents muscle from mounting a beneficial adaptive response to training. PMID:27936249

Eccentric rehabilitation exercise increases peritendinous type I collagen synthesis in humans with Achilles tendinosis.

Science.gov (United States)

Langberg, H; Ellingsgaard, H; Madsen, T; Jansson, J; Magnusson, S P; Aagaard, P; Kjaer, M

2007-02-01

It has been shown that 12 weeks of eccentric heavy resistance training can reduce pain in runners suffering from chronic Achilles tendinosis, but the mechanism behind the effectiveness of this treatment is unknown. The present study investigates the local effect of an eccentric training regime on elite soccer players suffering from chronic Achilles tendinosis on the turnover of the peritendinous connective tissue. Twelve elite male soccer players, of whom six suffered from unilateral tendinosis and six were healthy controls, participated in this study. All participants performed 12 weeks of heavy-resistance eccentric training apart from their regular training and soccer activity. Before and after the training period the tissue concentration of indicators of collagen turnover was measured by the use of the microdialysis technique. After training, collagen synthesis was increased in the initially injured tendon (n=6; carboxyterminal propeptide of type I collagen (PICP): pre 3.9+/-2.5 microg/L to post 19.7+/-5.4 microg/L, Ptendons in response to training (n=6; PICP: pre 8.3+/-5.2 microg/L to post 11.5+/-5.0 microg/L, P>0.05). Collagen degradation, measured as carboxyterminal telopeptide region of type I collagen (ICTP), was not affected by training neither in the injured nor in the healthy tendons. The clinical effect of the 12 weeks of eccentric training was determined by using a standardized loading procedure of the Achilles tendons showing a decrease in pain in all the chronic injured tendons (VAS before 44+/-9, after 13+/-9; Peccentric training regime. The present study demonstrates that chronically injured Achilles tendons respond to 12 weeks of eccentric training by increasing collagen synthesis rate. In contrast, the collagen metabolism in healthy control tendons seems not to be affected by eccentric training. These findings could indicate a relation between collagen metabolism and recovery from injury in human tendons.

Leakage flow-induced vibration of an eccentric tube-in-tube slip joint

International Nuclear Information System (INIS)

Mulcahy, T.M.

1985-08-01

Eccentricity of a specific slip-joint design separating two cantilevered, telescoping tubes did not create any self-excited lateral vibrations that had not been observed previously for a concentric slip joint. In fact, the eccentricity made instabilities less likely to occur, but only marginally. Most important, design rules previously established to avoid instabilities for the concentric slip joint remain valid for the eccentric slip joint. 6 refs., 9 figs., 2 tabs

Greater Strength Gains after Training with Accentuated Eccentric than Traditional Isoinertial Loads in Already Strength-Trained Men

Science.gov (United States)

Walker, Simon; Blazevich, Anthony J.; Haff, G. Gregory; Tufano, James J.; Newton, Robert U.; Häkkinen, Keijo

2016-01-01

As training experience increases it becomes more challenging to induce further neuromuscular adaptation. Consequently, strength trainers seek alternative training methods in order to further increase strength and muscle mass. One method is to utilize accentuated eccentric loading, which applies a greater external load during the eccentric phase of the lift as compared to the concentric phase. Based upon this practice, the purpose of this study was to determine the effects of 10 weeks of accentuated eccentric loading vs. traditional isoinertial resistance training in strength-trained men. Young (22 ± 3 years, 177 ± 6 cm, 76 ± 10 kg, n = 28) strength-trained men (2.6 ± 2.2 years experience) were allocated to concentric-eccentric resistance training in the form of accentuated eccentric load (eccentric load = concentric load + 40%) or traditional resistance training, while the control group continued their normal unsupervised training program. Both intervention groups performed three sets of 6-RM (session 1) and three sets of 10-RM (session 2) bilateral leg press and unilateral knee extension exercises per week. Maximum force production was measured by unilateral isometric (110° knee angle) and isokinetic (concentric and eccentric 30°.s−1) knee extension tests, and work capacity was measured by a knee extension repetition-to-failure test. Muscle mass was assessed using panoramic ultrasonography and dual-energy x-ray absorptiometry. Surface electromyogram amplitude normalized to maximum M-wave and the twitch interpolation technique were used to examine maximal muscle activation. After training, maximum isometric torque increased significantly more in the accentuated eccentric load group than control (18 ± 10 vs. 1 ± 5%, p < 0.01), which was accompanied by an increase in voluntary activation (3.5 ± 5%, p < 0.05). Isokinetic eccentric torque increased significantly after accentuated eccentric load training only (10 ± 9%, p < 0.05), whereas concentric torque

Interseason variability in isokinetic strength and poor correlation with Nordic hamstring eccentric strength in football players.

Science.gov (United States)

van Dyk, N; Witvrouw, E; Bahr, R

2018-04-25

In elite sport, the use of strength testing to establish muscle function and performance is common. Traditionally, isokinetic strength tests have been used, measuring torque during concentric and eccentric muscle action. A device that measures eccentric hamstring muscle strength while performing the Nordic hamstring exercise is now also frequently used. The study aimed to investigate the variability of isokinetic muscle strength over time, for example, between seasons, and the relationship between isokinetic testing and the new Nordic hamstring exercise device. All teams (n = 18) eligible to compete in the premier football league in Qatar underwent a comprehensive strength assessment during their periodic health evaluation at Aspetar Orthopaedic and Sports Medicine Hospital in Qatar. Isokinetic strength was investigated for measurement error, and correlated to Nordic hamstring exercise strength. Of the 529 players included, 288 players had repeated tests with 1/2 seasons between test occasions. Variability (measurement error) between test occasions was substantial, as demonstrated by the measurement error (approximately 25 Nm, 15%), whether separated by 1 or 2 seasons. Considering hamstring injuries, the same pattern was observed among injured (n = 60) and uninjured (n = 228) players. A poor correlation (r = .35) was observed between peak isokinetic hamstring eccentric torque and Nordic hamstring exercise peak force. The strength imbalance between limbs calculated for both test modes was not correlated (r = .037). There is substantial intraindividual variability in all isokinetic test measures, whether separated by 1 or 2 seasons, irrespective of injury. Also, eccentric hamstring strength and limb-to-limb imbalance were poorly correlated between the isokinetic and Nordic hamstring exercise tests. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Exercise-induced quadriceps muscle fatigue in men and women: effects of arterial oxygen content and respiratory muscle work.

Science.gov (United States)

Dominelli, Paolo B; Molgat-Seon, Yannick; Griesdale, Donald E G; Peters, Carli M; Blouin, Jean-Sébastien; Sekhon, Mypinder; Dominelli, Giulio S; Henderson, William R; Foster, Glen E; Romer, Lee M; Koehle, Michael S; Sheel, A William

2017-08-01

High work of breathing and exercise-induced arterial hypoxaemia (EIAH) can decrease O 2 delivery and exacerbate exercise-induced quadriceps fatigue in healthy men. Women have a higher work of breathing during exercise, dedicate a greater fraction of whole-body V̇O2 towards their respiratory muscles and develop EIAH. Despite a greater reduction in men's work of breathing, the attenuation of quadriceps fatigue was similar between the sexes. The degree of EIAH was similar between sexes, and regardless of sex, those who developed the greatest hypoxaemia during exercise demonstrated the most attenuation of quadriceps fatigue. Based on our previous finding that women have a greater relative oxygen cost of breathing, women appear to be especially susceptible to work of breathing-related changes in quadriceps muscle fatigue. Reducing the work of breathing or eliminating exercise-induced arterial hypoxaemia (EIAH) during exercise decreases the severity of quadriceps fatigue in men. Women have a greater work of breathing during exercise, dedicate a greater fraction of whole-body V̇O2 towards their respiratory muscles, and demonstrate EIAH, suggesting women may be especially susceptible to quadriceps fatigue. Healthy subjects (8 male, 8 female) completed three constant load exercise tests over 4 days. During the first (control) test, subjects exercised at ∼85% of maximum while arterial blood gases and work of breathing were assessed. Subsequent constant load exercise tests were iso-time and iso-work rate, but with EIAH prevented by inspiring hyperoxic gas or work of breathing reduced via a proportional assist ventilator (PAV). Quadriceps fatigue was assessed by measuring force in response to femoral nerve stimulation. For both sexes, quadriceps force was equally reduced after the control trial (-27 ± 2% baseline) and was attenuated with hyperoxia and PAV (-18 ± 1 and -17 ± 2% baseline, P Physiology © 2017 The Physiological Society.

PERSONALITY DOES NOT INFLUENCE EXERCISE-INDUCED MOOD ENHANCEMENT AMONG FEMALE EXERCISERS

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Andrew M. Lane

2005-09-01

Full Text Available The present study investigated the influence of personality on exercise-induced mood changes. It was hypothesised that (a exercise would be associated with significant mood enhancement across all personality types, (b extroversion would be associated with positive mood and neuroticism with negative mood both pre- and post-exercise, and (c personality measures would interact with exercise-induced mood changes. Participants were 90 female exercisers (M = 25.8 yr, SD = 9.0 yr who completed the Eysenck Personality Inventory (EPI once and the Brunel Mood Scale (BRUMS before and after a 60-minute exercise session. Median splits were used to group participants into four personality types: stable introverts (n = 25, stable extroverts (n = 20, neurotic introverts (n = 26, and neurotic extroverts (n = 19. Repeated measures MANOVA showed significant mood enhancement following exercise across all personality types. Neuroticism was associated with negative mood scores pre- and post-exercise but the effect of extroversion on reported mood was relatively weak. There was no significant interaction effect between exercise-induced mood enhancement and personality. In conclusion, findings lend support to the notion that exercise is associated with improved mood. However, findings show that personality did not influence this effect, although neuroticism was associated with negative mood

Nordic hamstring exercise training alters knee joint kinematics and hamstring activation patterns in young men.

Science.gov (United States)

Delahunt, Eamonn; McGroarty, Mark; De Vito, Giuseppe; Ditroilo, Massimiliano

2016-04-01

To investigate the kinematic and muscle activation adaptations during performance of the Nordic hamstring exercise (NHE) to a 6-week eccentric hamstring training programme using the NHE as the sole mode of exercise. Twenty-nine healthy males were randomly allocated to a control (CG) or intervention (IG) group. The IG participated in a 6-week eccentric hamstring exercise programme using the NHE. The findings of the present study were that a 6-week eccentric hamstring training programme improved eccentric hamstring muscle strength (202.4 vs. 177.4 nm, p = 0.0002, Cohen's d = 0.97) and optimized kinematic (longer control of the forward fall component of the NHE, 68.1° vs. 73.7°, p = 0.022, Cohen's d = 0.90) and neuromuscular parameters (increased electromyographic activity of the hamstrings, 83.2 vs. 56.6 % and 92.0 vs. 54.2 %, p 1.25) associated with NHE performance. This study provides some insight into potential mechanisms by which an eccentric hamstring exercise programme utilizing the NHE as the mode of exercise may result in an improvement in hamstring muscle control during eccentric contractions.

Bronchial or Laryngeal Obstruction Induced by Exercise?

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Ayoub Bey

2017-06-01

Full Text Available A child suspected of exercise-induced laryngeal obstruction and asthma is examined by laryngoscopy and respiratory resistance (Rrs after exercise challenge. Immediately at exercise cessation, the visualized adduction of the larynx in inspiration is reflected in a paroxystic increase in Rrs. While normal breathing has apparently resumed later on during recovery from exercise, the pattern of Rrs in inspiration is observed to reoccur following a deep breath or swallowing. The procedure may thus help diagnosing the site of exercise-induced obstruction when laryngoscopy is not available and identify re-inducers of laryngeal dysfunction.

[Exercise-induced inspiratory stridor. An important differential diagnosis of exercise-induced asthma].

Science.gov (United States)

Christensen, Pernille; Thomsen, Simon Francis; Rasmussen, Niels; Backer, Vibeke

2007-11-19

Recent studies suggest that exercise-induced inspiratory stridor (EIIS) is an important and often overlooked differential diagnosis of exercise-induced asthma. EIIS is characterised by astma-like symptoms, but differs by inspiratory limitation, fast recovery, and a lack of effect of inhaled bronchodilators. The prevalence of EIIS is reported to be 5-27%, and affects both children and adults. The pathophysiology, the pathogenesis, and the treatment of the condition are not yet clarified. At present, a population-based study is being conducted in order to address these points.

Eccentric training as a new approach for rotator cuff tendinopathy: Review and perspectives

Science.gov (United States)

Camargo, Paula R; Alburquerque-Sendín, Francisco; Salvini, Tania F

2014-01-01

Excessive mechanical loading is considered the major cause of rotator cuff tendinopathy. Although tendon problems are very common, they are not always easy to treat. Eccentric training has been proposed as an effective conservative treatment for the Achilles and patellar tendinopathies, but less evidence exists about its effectiveness for the rotator cuff tendinopathy. The mechanotransduction process associated with an adequate dose of mechanical load might explain the beneficial results of applying the eccentric training to the tendons. An adequate load increases healing and an inadequate (over or underuse) load can deteriorate the tendon structure. Different eccentric training protocols have been used in the few studies conducted for people with rotator cuff tendinopathy. Further, the effects of the eccentric training for rotator cuff tendinopathy were only evaluated on pain, function and strength. Future studies should assess the effects of the eccentric training also on shoulder kinematics and muscle activity. Individualization of the exercise prescription, comprehension and motivation of the patients, and the establishment of specific goals, practice and efforts should all be considered when prescribing the eccentric training. In conclusion, eccentric training should be used aiming improvement of the tendon degeneration, but more evidence is necessary to establish the adequate dose-response and to determine long-term follow-up effects. PMID:25405092

Effects of Plyometric Versus Concentric and Eccentric Conditioning Contractions on Upper-Body Postactivation Potentiation.

Science.gov (United States)

Ulrich, Gert; Parstorfer, Mario

2017-07-01

There are limited data on postactivation potentiation's (PAP) effects after plyometric conditioning contractions (CCs), especially in the upper body. This study compared plyometric CCs with concentric-eccentric and eccentric CCs aiming to improve upper-body power performance due to a PAP effect. Sixteen resistance-trained males completed 3 experimental trials in a randomized order that comprised either a plyometric (PLY), a concentric-eccentric (CON), or an eccentric-only (ECC) CC. Maximal muscle performance, as determined by a ballistic bench-press throw, was measured before (baseline) and 1, 4, 8, 12, and 16 min after each CC. Compared with baseline, bench-press power was significantly enhanced only in CON (P = .046, ES = 0.21) after 8 min of recovery. However, the results obtained from the comparisons between baseline power performance and the individual best power performance for each subject after each CC stimulus showed significant increases in PLY (P < .001, ES = 0.31) and CON (P < .001, ES = 0.38). There was no significant improvement in ECC (P = .106, ES = 0.11). The results indicate that only CON CCs generated increases in bench-press power after 8 min of rest. However, considering an individual rest interval, PLY CCs led to an enhanced power performance in the bench-press exercise, and this increase was comparable to that induced by CON CCs. Due to the easy practical application before a competition, PLY CCs might be an interesting part of warm-up strategies aiming to improve upper-body power performance by reason of PAP.

Prior exercise and antioxidant supplementation: effect on oxidative stress and muscle injury

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Schilling Brian K

2007-10-01

Full Text Available Abstract Background Both acute bouts of prior exercise (preconditioning and antioxidant nutrients have been used in an attempt to attenuate muscle injury or oxidative stress in response to resistance exercise. However, most studies have focused on untrained participants rather than on athletes. The purpose of this work was to determine the independent and combined effects of antioxidant supplementation (vitamin C + mixed tocopherols/tocotrienols and prior eccentric exercise in attenuating markers of skeletal muscle injury and oxidative stress in resistance trained men. Methods Thirty-six men were randomly assigned to: no prior exercise + placebo; no prior exercise + antioxidant; prior exercise + placebo; prior exercise + antioxidant. Markers of muscle/cell injury (muscle performance, muscle soreness, C-reactive protein, and creatine kinase activity, as well as oxidative stress (blood protein carbonyls and peroxides, were measured before and through 48 hours of exercise recovery. Results No group by time interactions were noted for any variable (P > 0.05. Time main effects were noted for creatine kinase activity, muscle soreness, maximal isometric force and peak velocity (P Conclusion There appears to be no independent or combined effect of a prior bout of eccentric exercise or antioxidant supplementation as used here on markers of muscle injury in resistance trained men. Moreover, eccentric exercise as used in the present study results in minimal blood oxidative stress in resistance trained men. Hence, antioxidant supplementation for the purpose of minimizing blood oxidative stress in relation to eccentric exercise appears unnecessary in this population.

High fractional exhaled nitric oxide and sputum eosinophils are associated with an increased risk of future virus-induced exacerbations: A prospective cohort study.

Science.gov (United States)

Bjerregaard, A; Laing, I A; Backer, V; Sverrild, A; Khoo, S-K; Chidlow, G; Sikazwe, C; Smith, D W; Le Souëf, P; Porsbjerg, C

2017-08-01

The major trigger of asthma exacerbations is infection with a respiratory virus, most commonly rhinovirus. Type 2 inflammation is known to be associated with an increased risk of exacerbations in general. Whether type 2 inflammation at baseline increases the risk of future virus-induced exacerbations is unknown. To assess whether type 2 inflammation is associated with an increased risk of virus-induced exacerbations of asthma. Stable asthmatics had spirometry, skin prick test, measurement of FeNO and sputum induced for differential cell counts. Patients were followed up for 18 months, during which they were assessed at the research unit when they had symptoms of an exacerbation. Nasal swabs collected at these assessments underwent viral detection by PCR. A total of 81 asthma patients were recruited, of which 22 (27%) experienced an exacerbation during the follow-up period. Of these, 15 (68%) had a respiratory virus detected at exacerbation. Sputum eosinophils >1% at baseline increased the risk of having a subsequent virus-induced exacerbation (HR 7.6 95% CI: 1.6-35.2, P=.010) as did having FeNO >25 ppb (HR 3.4 95% CI: 1.1-10.4, P=.033). Established type 2 inflammation during stable disease is a risk factor for virus-induced exacerbations in a real-life setting. Measures of type 2 inflammation, such as sputum eosinophils and FeNO, could be included in the risk assessment of patients with asthma in future studies. © 2017 John Wiley & Sons Ltd.

[Exercise-induced rhabdomyolysis - a new trend?

Science.gov (United States)

Fardal, Hilde; Gøransson, Lasse G

2016-10-01

The purpose of this study was to investigate whether or not there has been an increase in the number of admissions for exercise-induced rhabdomyolysis at Stavanger University Hospital (SUS) in recent years. The study is a retrospective review of patients discharged over the period January 2010 to March 2015 with a diagnosis of exercise-induced rhabdomyolysis and with maximum creatine kinase (CK) levels more than ten times the upper reference limit. A total of 33 patients, 21 women and 12 men, with a median age of 28 years (18 - 68), were included in the study. Of the 33 patients, three quarters (25) were admitted in 2014 - 15, compared with eight over the period 2010 - 13. One patient developed kidney failure that required dialysis. The treatment depended more on the attending physician and department than on the patient's clinical condition and CK-level, but this did not seem to affect the rate of complications. The incidence of exercise-induced rhabdomyolysis at SUS increased from autumn 2014, and this coincided with increased media attention and a new exercise trend. We recommend standardising the treatment of exercise-induced rhabdomyolysis, as current treatment recommendations are based on rhabdomyolysis triggered by causes other than exercise.

Large eccentric strength increase using the Copenhagen Adduction exercise in football

DEFF Research Database (Denmark)

Ishøi, L; Sørensen, C N; Kaae, N M

2016-01-01

(control). EHAD, eccentric hip abduction strength (EHAB), and side-bridge endurance were measured using reliable test procedures at baseline and follow-up by a blinded tester. There was a significant interaction between group and time on EHAD, EHAB, and EHAD/EHAB ratio (P 

Pulmonary rehabilitation and severe exacerbations of COPD: solution or white elephant?

Directory of Open Access Journals (Sweden)

William D-C. Man

2015-10-01

Full Text Available Hospitalisations for severe exacerbations of chronic obstructive pulmonary disease are associated with significant physical and psychological consequences including an increase in symptom severity, severe reductions in physical activity, a deleterious effect on skeletal muscle, impaired exercise tolerance/ability to self-care, decline in quality of life, and increased anxiety and depression. As these consequences are potentially amenable to exercise training, there is a clear rationale for pulmonary rehabilitation in the peri/post-exacerbation setting. Although a 2011 Cochrane review was overwhelmingly positive, subsequent trials have shown less benefit and real-life observational studies have revealed poor acceptability. Qualitative studies have demonstrated that the patient experience is a determining factor while the presence of comorbidities may influence referral, adherence and response to pulmonary rehabilitation. Systematic reviews of less supervised interventions, such as self-management, have shown limited benefits in the post-exacerbation setting. The recent update of the Cochrane review of peri-exacerbation pulmonary rehabilitation showed that benefits were associated with the “comprehensive” nature of the intervention (the number of sessions received, the intensity of exercise training and education delivered, and the degree of supervision but implementation is demanding. The challenge is to develop interventions that are deliverable and acceptable around the time of an acute exacerbation but also deliver the desired clinical impact.

Changes in water content in response to an acute bout of eccentric loading in a patellar tendon with a history of tendinopathy: A case report.

Science.gov (United States)

Ho, Kai-Yu; Kulig, Kornelia

2016-10-01

This case-based report assessed resting water content and exercise-driven water exchange within a tendon with a history of tendinopathy and compared the response to that of a healthy uninvolved tendon. Case Report. University imaging center. The participant was a 27-year-old female basketball player 39 months following knee trauma. Patellar tendinopathy developed 12 months after the injury episode and was treated with eccentric exercises. Eighteen months from the beginning of the first eccentric training bout, the participant reported full resolution of symptoms and returned to her pre-injury sport participation without symptoms. Eccentric decline squat exercise. Tendon water content obtained from magnetic resonance imaging (MRI). MRI acquired 39 months post-injury demonstrated increased resting water content of the involved tendon (involved: 91.1% vs. uninvolved: 84.6%). Immediately after the eccentric squat maneuver, water content decreased on both involved and uninvolved tendons (involved: 89.5% vs. uninvolved: 83.3%). Elevated resting water content of the involved tendon found in this report may be indicative of reduced tendon stiffness. A similar amount of water content reduction was observed on both sides following mechanical loading, suggesting that the involved tendon may respond to the eccentric exercise similarly to the uninvolved tendon. Future investigations are needed to study the relationships among tendon water exchanges, mechanical properties, patient symptoms, and tissue injuries.

Isokinetic eccentric resistance training prevents loss in mechanical muscle function after running

DEFF Research Database (Denmark)

Oliveira, Anderson S. C.; Caputo, Fabrizio; Aagaard, Per

2013-01-01

session, subjects performed treadmill running (~35 min) and the previously mentioned measurements were repeated immediately after running. Subsequently, subjects were randomized to training (n = 12) consisting of 24 sessions of maximal IERT knee extensors actions at 180° s(-1), or served as controls (n...... damages. However, IERT may not avoid reductions in explosive muscle actions. In turn, this may allow more intense training sessions to be performed, facilitating the adaptive response to running training.......The aim of the study was to verify whether 8 weeks of resistance training employing maximal isokinetic eccentric (IERT) knee extensor actions would reduce the acute force loss observed after high-intensity treadmill running exercise. It was hypothesized that specific IERT would induce protective...

Benefits of whole body vibration training in patients hospitalised for COPD exacerbations - a randomized clinical trial.

Science.gov (United States)

Greulich, Timm; Nell, Christoph; Koepke, Janine; Fechtel, Juliane; Franke, Maja; Schmeck, Bernd; Haid, Daniel; Apelt, Sandra; Filipovic, Silke; Kenn, Klaus; Janciauskiene, Sabina; Vogelmeier, Claus; Koczulla, Andreas Rembert

2014-04-11

Patients with stable COPD show improvements in exercise capacity and muscular function after the application of whole body vibration. We aimed to evaluate whether this modality added to conventional physiotherapy in exacerbated hospitalised COPD patients would be safe and would improve exercise capacity and quality of life. 49 hospitalised exacerbated COPD patients were randomized (1:1) to undergo physiotherapy alone or physiotherapy with the addition of whole body vibration. The primary endpoint was the between-group difference of the 6-minute walking test (day of discharge - day of admission). Secondary assessments included chair rising test, quality of life, and serum marker analysis. Whole body vibration did not cause procedure-related adverse events. Compared to physiotherapy alone, it led to significantly stronger improvements in 6-minute walking test (95.55 ± 76.29 m vs. 6.13 ± 81.65 m; p = 0.007) and St. Georges Respiratory Questionnaire (-6.43 ± 14.25 vs. 5.59 ± 19.15, p = 0.049). Whole body vibration increased the expression of the transcription factor peroxisome proliferator receptor gamma coactivator-1-α and serum levels of irisin, while it decreased serum interleukin-8. Whole body vibration during hospitalised exacerbations did not cause procedure-related adverse events and induced clinically significant benefits regarding exercise capacity and health-related quality of life that were associated with increased serum levels of irisin, a marker of muscle activity. German Clinical Trials Register DRKS00005979. Registered 17 March 2014.

Obesity promotes oxidative stress and exacerbates blood-brain barrier disruption after high-intensity exercise

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Hee-Tae Roh

2017-06-01

Conclusion: Our study suggests that episodic vigorous exercise can increase oxidative stress and blood neurotrophic factor levels and induce disruption of the BBB. Moreover, high levels of neurotrophic factor in the blood after exercise in the obese group may be due to BBB disruption, and it is assumed that oxidative stress was the main cause of this BBB disruption.

Velocity-specific strength recovery after a second bout of eccentric exercise.

Science.gov (United States)

Barss, Trevor S; Magnus, Charlene R A; Clarke, Nick; Lanovaz, Joel L; Chilibeck, Philip D; Kontulainen, Saija A; Arnold, Bart E; Farthing, Jonathan P

2014-02-01

A bout of eccentric exercise (ECC) has the protective effect of reducing muscle damage during a subsequent bout of ECC known as the "repeated bout effect" (RBE). The purpose of this study was to determine if the RBE is greater when both bouts of ECC are performed using the same vs. different velocity of contraction. Thirty-one right-handed participants were randomly assigned to perform an initial bout of either fast (3.14 rad·s [180°·s]) or slow (0.52 rad·s [30°·s]) maximal isokinetic ECCs of the elbow flexors. Three weeks later, the participants completed another bout of ECC at the same velocity (n = 16), or at a different velocity (n = 15). Indirect muscle damage markers were measured before, immediately after, and at 24, 48, and 72 hours postexercise. Measures included maximal voluntary isometric contraction (MVC) strength (dynamometer), muscle thickness (MT; ultrasound), delayed onset muscle soreness (DOMS; visual analog scale), biceps and triceps muscle activation amplitude (electromyography), voluntary activation (interpolated twitch), and twitch torque. After the repeated bout, MVC strength recovered faster compared with the same time points after the initial bout for only the same velocity group (p = 0.017), with no differences for all the other variables. Irrespective of velocity, MT and DOMS were reduced after the repeated bout compared with that of the initial bout at 24, 48, and 72 hours with a corresponding increase in TT at 72 hours (p effects contribute to the RBE. The current findings support the idea of multiple mechanisms contributing to the RBE.

PREFERRED MODALITY INFLUENCES ON EXERCISE-INDUCED MOOD CHANGES

Directory of Open Access Journals (Sweden)

Andrew M. Lane

2005-06-01

Full Text Available The present study tested, both retrospectively and prospectively, exercise-induced mood changes among regular exercisers. Specifically, it examined the extent to which preferred exercise modality promoted greater mood benefits. A group of 25 exercise participants (M = 35.5 yr., SD = 10.5 yr. took part in the study. All participants had exercised at least three times a week (M = 3.5, SD = 2.3 during the previous year. Participants completed a 14-item Exercise Preference Questionnaire to provide retrospective evaluations of their most- and least-preferred type of exercise. For the prospective investigation, participants completed the Brunel Mood Scale (BRUMS 15 minutes before and immediately after their most- and least-preferred exercise sessions. One week separated completion of each exercise session. Retrospective assessment of exercise-induced mood changes showed strong support for enhanced mood following the preferred mode of exercise. Also, as hypothesized, prospective results showed that mood enhancement was greater following the preferred exercise modality, but significant mood enhancement also occurred following the least-preferred modality among experienced exercisers. In conclusions, findings support the principle that exercise can provide psychological benefits to its participants, in the form of positive affective outcomes, something that appears to be enhanced by preferred exercise modality. Given the important public health implications of exercise adherence, future research should seek to further investigate the mechanisms of exercise-induced mood enhancement

High fractional exhaled nitric oxide and sputum eosinophils are associated with an increased risk of future virus-induced exacerbations

DEFF Research Database (Denmark)

Bjerregaard, A; Laing, I A; Backer, V

2017-01-01

the follow-up period. Of these, 15 (68%) had a respiratory virus detected at exacerbation. Sputum eosinophils >1% at baseline increased the risk of having a subsequent virus-induced exacerbation (HR 7.6 95% CI: 1.6-35.2, P=.010) as did having FeNO >25 ppb (HR 3.4 95% CI: 1.1-10.4, P=.033). CONCLUSION...... AND CLINICAL RELEVANCE: Established type 2 inflammation during stable disease is a risk factor for virus-induced exacerbations in a real-life setting. Measures of type 2 inflammation, such as sputum eosinophils and FeNO, could be included in the risk assessment of patients with asthma in future studies....

Intense resistance exercise induces early and transient increases in ryanodine receptor 1 phosphorylation in human skeletal muscle.

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Sebastian Gehlert

Full Text Available BACKGROUND: While ryanodine receptor 1 (RyR1 critically contributes to skeletal muscle contraction abilities by mediating Ca²⁺ion oscillation between sarcoplasmatic and myofibrillar compartments, AMP-activated protein kinase (AMPK senses contraction-induced energetic stress by phosphorylation at Thr¹⁷². Phosphorylation of RyR1 at serine²⁸⁴³ (pRyR1Ser²⁸⁴³ results in leaky RyR1 channels and impaired Ca²⁺homeostasis. Because acute resistance exercise exerts decreased contraction performance in skeletal muscle, preceded by high rates of Ca²⁺-oscillation and energetic stress, intense myofiber contractions may induce increased RyR1 and AMPK phosphorylation. However, no data are available regarding the time-course and magnitude of early RyR1 and AMPK phosphorylation in human myofibers in response to acute resistance exercise. PURPOSE: Determine the effects and early time-course of resistance exercise on pRyR1Ser²⁸⁴³ and pAMPKThr¹⁷² in type I and II myofibers. METHODS: 7 male subjects (age 23±2 years, height: 185±7 cm, weight: 82±5 kg performed 3 sets of 8 repetitions of maximum eccentric knee extensions. Muscle biopsies were taken at rest, 15, 30 and 60 min post exercise. pRyR1Ser²⁸⁴³ and pAMPKThr¹⁷² levels were determined by western blot and semi-quantitative immunohistochemistry techniques. RESULTS: While total RyR1 and total AMPK levels remained unchanged, RyR1 was significantly more abundant in type II than type I myofibers. pRyR1Ser²⁸⁴³ increased 15 min and peaked 30 min (p<0.01 post exercise in both myofiber types. Type I fibers showed relatively higher increases in pRyR1Ser²⁸⁴³ levels than type II myofibers and remained elevated up to 60 min post resistance exercise (p<0.05. pAMPKThr¹⁷² also increased 15 to 30 min post exercise (p<0.01 in type I and II myofibers and in whole skeletal muscle. CONCLUSION: Resistance exercise induces acutely increased pRyR1Ser²⁸⁴³ and

AMPKα in Exercise-Induced Substrate Metabolism and Exercise Training-Induced Metabolic and Mitochondrial Adaptations

DEFF Research Database (Denmark)

Fentz, Joachim

in response to 4 weeks of voluntary running wheel exercise training. However, the acute exercise-induced increase in mRNA expression of several metabolic and mitochondrial marker genes is impaired in the mice lacking AMPKα1 and α2. In addition to the two studies and some currently unpublished data this thesis...

Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

International Nuclear Information System (INIS)

Wit, Julien de; Lewis, Nikole K.; Knutson, Heather A.; Batygin, Konstantin; Fuller, Jim; Antoci, Victoria; Fulton, Benjamin J.; Laughlin, Gregory; Deming, Drake; Shporer, Avi; Cowan, Nicolas B.; Agol, Eric; Burrows, Adam S.; Fortney, Jonathan J.; Langton, Jonathan; Showman, Adam P.

2017-01-01

Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet’s atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet–star interactions in HAT-P-2's eccentric planetary system gained from the analysis of ∼350 hr of 4.5 μ m observations with the Spitzer Space Telescope . The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b’s 4.5 μ m photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet’s orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2's pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

The Effects of Pre-Exercise Ginger Supplementation on Muscle Damage and Delayed Onset Muscle Soreness.

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Matsumura, Melissa D; Zavorsky, Gerald S; Smoliga, James M

2015-06-01

Ginger possesses analgesic and pharmacological properties mimicking non-steroidal antiinflammatory drugs. We aimed to determine if ginger supplementation is efficacious for attenuating muscle damage and delayed onset muscle soreness (DOMS) following high-intensity resistance exercise. Following a 5-day supplementation period of placebo or 4 g ginger (randomized groups), 20 non-weight trained participants performed a high-intensity elbow flexor eccentric exercise protocol to induce muscle damage. Markers associated with muscle damage and DOMS were repeatedly measured before supplementation and for 4 days following the exercise protocol. Repeated measures analysis of variance revealed one repetition maximum lift decreased significantly 24 h post-exercise in both groups (p ginger group (p = 0.002), and improved at 72 (p = 0.021) and 96 h (p = 0.044) only in the placebo group. Blood creatine kinase significantly increased for both groups (p = 0.015) but continued to increase only in the ginger group 72 (p = 0.006) and 96 h (p = 0.027) post-exercise. Visual analog scale of pain was significantly elevated following eccentric exercise (p ginger. In conclusion, 4 g of ginger supplementation may be used to accelerate recovery of muscle strength following intense exercise but does not influence indicators of muscle damage or DOMS. Copyright © 2015 John Wiley & Sons, Ltd.

Nicotinamide exacerbates hypoxemia in ventilator-induced lung injury independent of neutrophil infiltration.

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Heather D Jones

Full Text Available Ventilator-induced lung injury is a form of acute lung injury that develops in critically ill patients on mechanical ventilation and has a high degree of mortality. Nicotinamide phosphoribosyltransferase is an enzyme that is highly upregulated in ventilator-induced lung injury and exacerbates the injury when given exogenously. Nicotinamide (vitamin B3 directly inhibits downstream pathways activated by Nicotinamide phosphoribosyltransferase and is protective in other models of acute lung injury.We administered nicotinamide i.p. to mice undergoing mechanical ventilation with high tidal volumes to study the effects of nicotinamide on ventilator-induced lung injury. Measures of injury included oxygen saturations and bronchoalveolar lavage neutrophil counts, protein, and cytokine levels. We also measured expression of nicotinamide phosophoribosyltransferase, and its downstream effectors Sirt1 and Cebpa, Cebpb, Cebpe. We assessed the effect of nicotinamide on the production of nitric oxide during ventilator-induced lung injury. We also studied the effects of ventilator-induced lung injury in mice deficient in C/EBPε.Nicotinamide treatment significantly inhibited neutrophil infiltration into the lungs during ventilator-induced lung injury, but did not affect protein leakage or cytokine production. Surprisingly, mice treated with nicotinamide developed significantly worse hypoxemia during mechanical ventilation. This effect was not linked to increases in nitric oxide production or alterations in expression of Nicotinamide phosphoribosyl transferase, Sirt1, or Cebpa and Cebpb. Cebpe mRNA levels were decreased with either nicotinamide treatment or mechanical ventilation, but mice lacking C/EBPε developed the same degree of hypoxemia and ventilator-induced lung injury as wild-type mice.Nicotinamide treatment during VILI inhibits neutrophil infiltration of the lungs consistent with a strong anti-inflammatory effect, but paradoxically also leads to the

The Influence of CO2 and Exercise on Hypobaric Hypoxia Induced Pulmonary Edema in Rats

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Ryan L. Sheppard

2018-02-01

Full Text Available Introduction: Individuals with a known susceptibility to high altitude pulmonary edema (HAPE demonstrate a reduced ventilation response and increased pulmonary vasoconstriction when exposed to hypoxia. It is unknown whether reduced sensitivity to hypercapnia is correlated with increased incidence and/or severity of HAPE, and while acute exercise at altitude is known to exacerbate symptoms the effect of exercise training on HAPE susceptibility is unclear.Purpose: To determine if chronic intermittent hypercapnia and exercise increases the incidence of HAPE in rats.Methods: Male Wistar rats were randomized to sedentary (sed-air, CO2 (sed-CO2, exercise (ex-air, or exercise + CO2 (ex-CO2 groups. CO2 (3.5% and treadmill exercise (15 m/min, 10% grade were conducted on a metabolic treadmill, 1 h/day for 4 weeks. Vascular reactivity to CO2 was assessed after the training period by rheoencephalography (REG. Following the training period, animals were exposed to hypobaric hypoxia (HH equivalent to 25,000 ft for 24 h. Pulmonary injury was assessed by wet/dry weight ratio, lung vascular permeability, bronchoalveolar lavage (BAL, and histology.Results: HH increased lung wet/dry ratio (HH 5.51 ± 0.29 vs. sham 4.80 ± 0.11, P < 0.05, lung permeability (556 ± 84 u/L vs. 192 ± 29 u/L, P < 0.001, and BAL protein (221 ± 33 μg/ml vs. 114 ± 13 μg/ml, P < 0.001, white blood cell (1.16 ± 0.26 vs. 0.66 ± 0.06, P < 0.05, and platelet (16.4 ± 2.3, vs. 6.0 ± 0.5, P < 0.001 counts in comparison to normobaric normoxia. Vascular reactivity was suppressed by exercise (−53% vs. sham, P < 0.05 and exercise+CO2 (−71% vs. sham, P < 0.05. However, neither exercise nor intermittent hypercapnia altered HH-induced changes in lung wet/dry weight, BAL protein and cellular infiltration, or pulmonary histology.Conclusion: Exercise training attenuates vascular reactivity to CO2 in rats but neither exercise training nor chronic intermittent hypercapnia affect HH- induced

Food-dependent exercise-induced anaphylaxis to flaxseed

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Helmut Gall

2000-01-01

Full Text Available The present paper reports on a 26-year-old atopic patient suffering from seasonal rhinoconjunctivitis and flexural eczemas. On two occasions, he experienced nausea, generalized urticaria and dyspnea within 2 h after consumption of a wholemeal roll and subsequent exercise (football training or walking. In each case, the episode necessitated intravenous emergency therapy with an antihistamine and a corticosteroid. In order to elucidate the two exercise-induced anaphylactic events we performed prick tests and the radioallergosorbent test (RAST with the ingredients of the wholemeal roll. Only flaxseed gave positive results. In addition, we performed an exercise test on a bicycle ergometer (15 min at 150 W and an oral challenge test with foods, using a double-blind and placebo-controlled study. Only oral challenge with a teaspoon of flaxseed with additional exercise on the bicycle ergometer elicited itching, urticaria, nausea, coughing and dyspnea. The oral challenge with flaxseed followed by exercise induced immediate-type reactions and, thus, led to the diagnosis of food-dependent exercise- induced anaphylaxis to flaxseed.

Exercise-induced inspiratory symptoms in school children

DEFF Research Database (Denmark)

Buchvald, Frederik; Phillipsen, Lue Drasbaek; Hjuler, Thomas

2016-01-01

BACKGROUND AND AIMS: Exercise-induced inspiratory symptoms (EIIS) have multiple causes, one of which is exercise-induced laryngeal obstruction (EILO). There is limited knowledge regarding EIIS in children, both in primary care practices and in pediatric asthma clinics. The aim of this study was t...

Effectiveness of Shockwave Treatment Combined With Eccentric Training for Patellar Tendinopathy: A Double-Blinded Randomized Study.

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Thijs, Karin M; Zwerver, Johannes; Backx, Frank J G; Steeneken, Victor; Rayer, Stephan; Groenenboom, Petra; Moen, Maarten H

2017-03-01

To evaluate the effectiveness of a combined treatment of focused shockwave therapy (ESWT) and eccentric training compared with sham-shockwave therapy (placebo) and eccentric training in participants with patellar tendinopathy (PT) after 24 weeks. Randomized controlled trial. Sports medicine departments of a university hospital and a general hospital in the Netherlands. Fifty-two physically active male and female participants with a clinical diagnosis of PT (mean age: 28.6 years; range, 18-45) were randomly allocated to the ESWT (n = 22) or sham shockwave (n = 30). Extracorporeal shockwave therapy and sham shockwave were applied in 3 sessions at 1-week intervals with a piezoelectric device. All participants were instructed to perform eccentric exercises (3 sets of 15 repetitions twice a day) for 3 months on a decline board at home. The Victorian Institute of Sport Assessment-Patella (VISA-P) scores (primary), pain scores during functional knee loading tests, and Likert score (secondary) were registered at baseline and at 6, 12, and 24 weeks after the start with the ESWT or sham-shockwave treatment. No significant differences for the primary and secondary outcome measures were found between the groups. In the ESWT/eccentric group, the VISA-P increased from 54.5 ± 15.4 to 70.9 ± 17.8, whereas the VISA-P in the sham-shockwave/eccentric group increased from 58.9 ± 14.6 to 78.2 ± 15.8 (between-group change in VISA-P at 24 weeks -4.8; 95% confidence interval, -12.7 to 3.0, P = 0.150). This study showed no additional effect of 3 sessions ESWT in participants with PT treated with eccentric exercises. The results should be interpreted with caution because of small sample size and considerable loss to follow-up, particularly in the ESWT group.

Change of Direction Speed: Toward a Strength Training Approach with Accentuated Eccentric Muscle Actions.

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Chaabene, Helmi; Prieske, Olaf; Negra, Yassine; Granacher, Urs

2018-03-28

There is growing evidence that eccentric strength training appears to have benefits over traditional strength training (i.e., strength training with combined concentric and eccentric muscle actions) from muscular, neuromuscular, tendinous, and metabolic perspectives. Eccentric muscle strength is particularly needed to decelerate and stabilize the body during the braking phase of a jump exercise or during rapid changes of direction (CoD) tasks. However, surprisingly little research has been conducted to elucidate the effects of eccentric strength training or strength training with accentuated eccentric muscle actions on CoD speed performance. In this current opinion article, we present findings from cross-sectional studies on the relationship between measures of eccentric muscle strength and CoD speed performance. In addition, we summarize the few available studies on the effects of strength training with accentuated eccentric muscle actions on CoD speed performance in athletic populations. Finally, we propose strength training with accentuated eccentric muscle actions as a promising element in strength and conditioning programs of sports with high CoD speed demands. Our findings from five cross-sectional studies revealed statistically significant moderate- to large-sized correlations (r = 0.45-0.89) between measures of eccentric muscle strength and CoD speed performance in athletic populations. The identified three intervention studies were of limited methodological quality and reported small- to large-sized effects (d = 0.46-1.31) of strength training with accentuated eccentric muscle actions on CoD speed performance in athletes. With reference to the available but preliminary literature and from a performance-related point of view, we recommend strength and conditioning coaches to include strength training with accentuated eccentric muscle actions in training routines of sports with high CoD speed demands (e.g., soccer, handball, basketball, hockey) to

Effect of eccentric exercise program for early tibialis posterior tendinopathy.

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Kulig, Kornelia; Lederhaus, Eric S; Reischl, Steve; Arya, Shruti; Bashford, Greg

2009-09-01

Morphology and vascularization of painful tibialis posterior (TP) tendons before and after an intervention targeting the degenerated tendon were examined. Functional status and pain level were also assessed. A10-week twice daily, progressive eccentric tendon loading, calf stretching program with orthoses was implemented with ten, early stage TP tendinopathy subjects. TP tendons were imaged by grayscale and Doppler ultrasound at INITIAL and POST evaluations to assess the tendon's morphology and signs of neovascularization. The Foot Functional Index (FFI), Physical Activity Scale (PAS), 5-Minute Walk Test, and single heel raise (SHR) test were completed at INITIAL and POST evaluations. The Global Rating Scale (GRS) was completed at 6 months followup. One-way ANOVA was used to compare the FFI at INITIAL, POST, and 6-MONTH time points. Paired t-tests were used to compare means between the remaining variables. The level of significance was p = 0.05. There was a significant difference in FFI total, pain, and disability at the three time-points. Post-hoc paired t-tests revealed that the FFI scores were lower for the total score and pain and disability subcategories when comparing from INITIAL to POST and INITIAL to 6-MONTH evaluations (p Tendon morphology and vascularization remained abnormal following the intervention. A 10-week tendon specific eccentric program resulted in improvements in symptoms and function without changes in tendon morphology or neovascularization.

Decline eccentric squats increases patellar tendon loading compared to standard eccentric squats.

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Kongsgaard, M; Aagaard, P; Roikjaer, S; Olsen, D; Jensen, M; Langberg, H; Magnusson, S P

2006-08-01

Recent studies have shown excellent clinical results using eccentric squat training on a 25 degrees decline board to treat patellar tendinopathy. It remains unknown why therapeutic management of patellar tendinopathy using decline eccentric squats offer superior clinical efficacy compared to standard horizontal eccentric squats. This study aimed to compare electromyography activity, patellar tendon strain and joint angle kinematics during standard and decline eccentric squats. Thirteen subjects performed unilateral eccentric squats on flat-and a 25 degrees decline surface. During the squats, electromyography activity was obtained in eight representative muscles. Also, ankle, knee and hip joint goniometry was obtained. Additionally, patellar tendon strain was measured in vivo using ultrasonography as subjects maintained a unilateral isometric 90 degrees knee angle squat position on either flat or 25 degrees decline surface. Patellar tendon strain was significantly greater (Psquat position on the decline surface compared to the standard surface. The stop angles of the ankle and hip joints were significantly smaller during the decline compared to the standard squats (Psquats (Psquats. The use of a 25 degrees decline board increases the load and the strain of the patellar tendon during unilateral eccentric squats. This finding likely explains previous reports of superior clinical efficacy of decline eccentric squats in the rehabilitative management of patellar tendinopathy.

Protective action of a hexane crude extract of Pterodon emarginatus fruits against oxidative and nitrosative stress induced by acute exercise in rats

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Alfredo Patrícia P

2005-08-01

Full Text Available Abstract Background The aim of the present work was to evaluate the effect of a hexane crude extract (HCE of Pterodon emarginatus on the oxidative and nitrosative stress induced in skeletal muscle, liver and brain of acutely exercised rats. Methods Adult male rats were subjected to acute exercise by standardized contractions of the tibialis anterior (TA muscle (100 Hz, 15 min and treated orally with the HCE (once or three times with a fixed dose of 498 mg/kg, before and after acute exercise. Serum creatine kinase activity was determined by a kinetic method and macrophage infiltration by histological analyses of TA muscle. Lipid peroxidation was measured as malondialdehyde (MDA levels. Nitric oxide production was evaluated by measuring nitrite formation, using Griess reagent, and nitrotyrosine was assessed by western blotting. Results Serum creatine kinase activities in the controls (111 U/L increased 1 h after acute exercise (443 U/L. Acute exercise also increased the infiltration of macrophages into TA muscle; lipid peroxidation levels in TA muscle (967%, liver (55.5% and brain (108.9%, as well as the nitrite levels by 90.5%, 30.7% and 60%, respectively. The pattern of nitrotyrosine formation was also affected by acute exercise. Treatment with HCE decreased macrophage infiltration, lipid peroxidation, nitrite production and nitrotyrosine levels to control values. Conclusion Acute exercise induced by functional electrical stimulation in rats resulted in increase in lipid peroxidation, nitrite and nitrotyrosine levels in brain, liver and skeletal muscle. The exercise protocol, that involved eccentric muscle contraction, also caused some muscle trauma, associated with over-exertion, leading to inflammation. The extract of P. emarginatus abolished most of these oxidative processes, thus confirming the high antioxidant activity of this oil which infusions are used in folk medicine against inflammatory processes.

Virtual Proprioception for eccentric training.

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LeMoyne, Robert; Mastroianni, Timothy

2017-07-01

Wireless inertial sensors enable quantified feedback, which can be applied to evaluate the efficacy of therapy and rehabilitation. In particular eccentric training promotes a beneficial rehabilitation and strength training strategy. Virtual Proprioception for eccentric training applies real-time feedback from a wireless gyroscope platform enabled through a software application for a smartphone. Virtual Proprioception for eccentric training is applied to the eccentric phase of a biceps brachii strength training and contrasted to a biceps brachii strength training scenario without feedback. During the operation of Virtual Proprioception for eccentric training the intent is to not exceed a prescribed gyroscope signal threshold based on the real-time presentation of the gyroscope signal, in order to promote the eccentric aspect of the strength training endeavor. The experimental trial data is transmitted wireless through connectivity to the Internet as an email attachment for remote post-processing. A feature set is derived from the gyroscope signal for machine learning classification of the two scenarios of Virtual Proprioception real-time feedback for eccentric training and eccentric training without feedback. Considerable classification accuracy is achieved through the application of a multilayer perceptron neural network for distinguishing between the Virtual Proprioception real-time feedback for eccentric training and eccentric training without feedback.

Effects of In-Season Inertial Resistance Training With Eccentric Overload in a Sports Population at Risk for Patellar Tendinopathy.

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Gual, Gabriel; Fort-Vanmeerhaeghe, Azahara; Romero-Rodríguez, Daniel; Tesch, Per A

2016-07-01

Gual, G, Fort-Vanmeerhaeghe, A, Romero-Rodríguez, D, and Tesch, PA. Effects of in-season inertial resistance training with eccentric overload in a sports population at risk for patellar tendinopathy. J Strength Cond Res 30(7): 1834-1842, 2016-Volleyball and basketball players can be considered as a population at risk for patellar tendinopathy. Given the paradox that eccentric training elicits therapeutic benefits yet might provoke such injury, we investigated the influence of a weekly bout of inertial squat resistance exercise offering eccentric overload on lower limb muscle power and patellar tendon complaints. Players of 8 (4 basketball and 4 volleyball) teams (38 women and 43 men) were randomly assigned to either the intervention (IG) or control (CG) group. Although IG and CG maintained scheduled in-season training routines over 24 weeks, IG, in addition, performed 1 weekly session of eccentric overload by 4 sets of 8 repetitions of the squat using flywheel inertial resistance. Victorian Institute of Sports Assessment patellar tendinopathy questionnaire (VISA-p), vertical countermovement jump, and squat power, both concentric (Squat-Con) and eccentric (Squat-Ecc), tests were performed before (T1), during (T2), and after (T3) the 24 weeks of intervention. Neither group suffered from patellar tendinopathy during the study period. VISA-p displayed no differences across groups at any measurement period. Countermovement jump scores significantly (p ≤ 0.05) differed between groups in favor of the IG. Both Squat-Con and Squat-Ecc mean scores from the IG were significantly (p training bout to a regular basketball and volleyball exercise routine enhances lower limb muscle power without triggering patellar tendon complaints. Future studies, using the current exercise paradigm, aim to explore its efficacy to prevent or combat patellar tendinopathy in sports calling for frequent explosive jumps.

The Effects of Adding Whey Protein and Branched-chain Amino Acid to Carbohydrate Beverages on Indices of Muscle Damage after Eccentric Resistance Exercise in Untrained Young Males

OpenAIRE

Foad Asjodi; Hamid Mohebi; Ebrahim Mirzajani; Azimeh Izadi

2017-01-01

Abstract Background: The aim of this study was to evaluate the effects of supplementation of Branched-Chain Amino Acids (BCAAs) plus carbohydrate (CHO) and whey protein plus CHO on muscle damage indices after eccentric resistant exercise. Materials and Methods: Twenty four untrained healthy males participated in this study. They were randomly divided into three groups, BCAA +glucose (0.1+0.1g/kg) supplement group (n=8), Whey+glucose (0.1+0.1g/kg) supplement group (n=8), and placebo (ma...

Skeletal Adaptations to Different Levels of Eccentric Resistance Following Eight Weeks of Training

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English, Kirk L.; Loehr, James A.; Lee, Stuart M. C.; Maddocks, Mary J.; Laughlin, Mitzi S.; Hagan, R. Donald

2007-01-01

Coupled concentric-eccentric resistive exercise maintains bone mineral density (BMD) during bed rest and aging. PURPOSE: We hypothesized that 8 wks of lower body resistive exercise training with higher ratios of eccentric to concentric loading would enhance hip and lumbar BMD. METHODS: Forty untrained male volunteers (34.9+/-7.0 yrs, 80.9+/-9.8 kg, 178.2+/-7.1 cm; mean+/-SD) were matched for leg press (LP) 1-Repetition Maximum (1-RM) strength and randomly assigned to one of 5 training groups. Concentric load (% 1-RM) was constant across groups, but each group trained with different levels of eccentric load (0, 33, 66, 100, or 138% of concentric) for all training sessions. Subjects performed a periodized supine LP and heel raise (HR) training program 3 d wk-1 for 8 wks using a modified Agaton Fitness System (Agaton Fitness AB, Boden, Sweden). Hip and lumbar BMD (g/sq cm) was measured in triplicate pre- and post-training using DXA (Hologic Discovery ). Pre- and post-training means were compared using the appropriate ANOVA and Tukey's post hoc tests. Within group pre- to post-training BMD was compared using paired t-tests with a Bonferroni adjustment. RESULTS: There was a main effect of training on L1, L2, L3, L4, total lumbar, and greater trochanter BMD, but there were no differences between groups. CONCLUSION: Eights wks of lower body resistive exercise increased greater trochanter and lumbar BMD. Inability to detect group differences may have been influenced by a potentially osteogenic vibration associated with device operation in the 0, 33, and 66% groups.

Exercise excess pressure and exercise-induced albuminuria in patients with type 2 diabetes mellitus.

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Climie, Rachel E D; Srikanth, Velandai; Keith, Laura J; Davies, Justin E; Sharman, James E

2015-05-01

Exercise-induced albuminuria is common in patients with type 2 diabetes mellitus (T2DM) in response to maximal exercise, but the response to light-moderate exercise is unclear. Patients with T2DM have abnormal central hemodynamics and greater propensity for exercise hypertension. This study sought to determine the relationship between light-moderate exercise central hemodynamics (including aortic reservoir and excess pressure) and exercise-induced albuminuria. Thirty-nine T2DM (62 ± 9 yr; 49% male) and 39 nondiabetic controls (53 ± 9 yr; 51% male) were examined at rest and during 20 min of light-moderate cycle exercise (30 W; 50 revolutions/min). Albuminuria was assessed by the albumin-creatinine ratio (ACR) at rest and 30 min postexercise. Hemodynamics recorded included brachial and central blood pressure (BP), aortic stiffness, augmented pressure (AP), aortic reservoir pressure, and excess pressure integral (Pexcess). There was no difference in ACR between groups before exercise (P > 0.05). Exercise induced a significant rise in ACR in T2DM but not controls (1.73 ± 1.43 vs. 0.53 ± 1.0 mg/mol, P = 0.002). All central hemodynamic variables were significantly higher during exercise in T2DM (i.e., Pexcess, systolic BP and AP; P exercise Pexcess was associated with postexercise ACR (r = 0.51, P = 0.002), and this relationship was independent of age, sex, body mass index, heart rate, aortic stiffness, antihypertensive medication, and ambulatory daytime systolic BP (β = 0.003, P = 0.003). Light-moderate exercise induced a significant rise in ACR in T2DM, and this was independently associated with Pexcess, a potential marker of vascular dysfunction. These novel findings suggest that Pexcess could be important for appropriate renal function in T2DM. Copyright © 2015 the American Physiological Society.

Nox4 Is Dispensable for Exercise Induced Muscle Fibre Switch.

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Juri Vogel

Full Text Available By producing H2O2, the NADPH oxidase Nox4 is involved in differentiation of mesenchymal cells. Exercise alters the composition of slow and fast twitch fibres in skeletal. Here we hypothesized that Nox4 contributes to exercise-induced adaptation such as changes in muscle metabolism or muscle fibre specification and studied this in wildtype and Nox4-/- mice.Exercise, as induced by voluntary running in a running wheel or forced running on a treadmill induced a switch from fast twitch to intermediate fibres. However the induced muscle fibre switch was similar between Nox4-/- and wildtype mice. The same held true for exercise-induced expression of PGC1α or AMPK activation. Both are increased in response to exercise, but with no difference was observed between wildtype and Nox4-/- mice.Thus, exercise-induced muscle fibre switch is Nox4-independent.

Heat stress exacerbates the reduction in middle cerebral artery blood velocity during prolonged self-paced exercise.

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Périard, J D; Racinais, S

2015-06-01

This study examined the influence of hyperthermia on middle cerebral artery mean blood velocity (MCA Vmean). Eleven cyclists undertook a 750 kJ self-paced time trial in HOT (35 °C) and COOL (20 °C) conditions. Exercise time was longer in HOT (56 min) compared with COOL (49 min; P blood flow, and heart rate were higher throughout HOT compared with COOL (P blood pressure and oxygen uptake were lower from 50% of work completed onward in HOT compared with COOL (P heat appears to have exacerbated the reduction in MCA Vmean, in part via increases in peripheral blood flow and a decrease in arterial blood pressure. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

PGC-1alpha in exercise- and exercise training-induced metabolic adaptations

DEFF Research Database (Denmark)

Jørgensen, Stine Ringholm

and interferes with the exercise-induced adaptive response in human skeletal muscle. Study II demonstrates that mouse liver glucose-6-phosphatase (G6Pase) mRNA content increased in recovery from acute exercise in both wildtype (WT) and PGC-1α knockout (KO) mice, while phosphoenolpyruvate carboxykinase (PEPCK......) and pyruvate carboxylase mRNA content did not change in either genotype. Exercise training increased PEPCK protein content in both WT and PGC-1α KO mice. In addition, the mRNA and protein content of cytochrome (Cyt) c and cytochrome c oxidase (COX) subunit I increased in response to acute exercise and exercise...

Profile of isokinetic eccentric-to-concentric strength ratios of shoulder rotator muscles in elite female team handball players.

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Andrade, Marilia Dos Santos; Fleury, Anna Maria; de Lira, Claudio Andre Barbosia; Dubas, Joao Paulo; da Silva, Antonio Carlos

2010-05-01

The purpose of this study was to establish the isokinetic profile of shoulder rotator muscles strength in female handball players. Twenty-seven handball players performed concentric and eccentric strength tests of both dominant and non-dominant upper limbs on an isokinetic dynamometer. Internal and external rotator muscles peak torque was assessed at 1.05, 3.14, and 5.23 rad . s(-1) in concentric mode and at 3.14 and 5.23 rad . s(-1) in eccentric mode. Concentric balance ratio and functional ratio were obtained. Bi-lateral deficiency was compared. Concentric strength for internal and external rotation was significantly greater for the dominant than for the non-dominant limb for all speeds (P muscles were stronger in the dominant than the non-dominant limb (P stronger than the non-dominant side, balance concentric ratios remained the same, with only the functional strength ratio different at 5.23 rad . s(-1). Our results suggest that concentric strength exercises be used for internal and external rotators on the non-dominant side, and functional exercise that improves eccentric rotation strength for prevention programmes.

ECCENTRIC JUPITERS VIA DISK–PLANET INTERACTIONS

International Nuclear Information System (INIS)

Duffell, Paul C.; Chiang, Eugene

2015-01-01

Numerical hydrodynamics calculations are performed to determine the conditions under which giant planet eccentricities can be excited by parent gas disks. Unlike in other studies, Jupiter-mass planets are found to have their eccentricities amplified—provided their orbits start off as eccentric. We disentangle the web of co-rotation, co-orbital, and external resonances to show that this finite-amplitude instability is consistent with that predicted analytically. Ellipticities can grow until they reach of order of the disk's aspect ratio, beyond which the external Lindblad resonances that excite eccentricity are weakened by the planet's increasingly supersonic epicyclic motion. Forcing the planet to still larger eccentricities causes catastrophic eccentricity damping as the planet collides into gap walls. For standard parameters, the range of eccentricities for instability is modest; the threshold eccentricity for growth (∼0.04) is not much smaller than the final eccentricity to which orbits grow (∼0.07). If this threshold eccentricity can be lowered (perhaps by non-barotropic effects), and if the eccentricity driving documented here survives in 3D, it may robustly explain the low-to-moderate eccentricities ≲0.1 exhibited by many giant planets (including Jupiter and Saturn), especially those without planetary or stellar companions

Exercise-induced rhabdomyolysis - a patient series.

Science.gov (United States)

Tazmini, Kiarash; Schreiner, Christoffer; Bruserud, Sidsel; Raastad, Truls; Solberg, Erik Ekker

2017-11-14

No guidelines are available for the treatment and follow up of exercise-induced rhabdomyolysis. The purpose of this study was to describe the treatment, complications and follow-up of patients with exercise-induced rhabdomyolysis at Diakonhjemmet Hospital. A retrospective observational study from 2011 up to and including 2015 of patients with exercise-induced rhabdomyolysis ≥ 18 years and with creatine kinase > 5 000 IU/l. We registered a total of 42 patients and obtained informed consent from 31. Twenty were treated as inpatients with a median hospitalisation time of 2.5 (1–6) days. Median creatine kinase was 36 797 (17 172–53 548) IU/l upon admission and 16 051 (11 845–26 505) IU/l at discharge. Median intravenous fluid volume was 6 000 (1 000–27 700) ml. Eleven patients underwent urinary alkalinisation. None developed severe kidney injury or other serious complications such as electrolyte imbalance, compartment syndrome or disseminated intravascular coagulation, either during hospitalisation or in the course of the study period. Healthy persons with exercise-induced rhabdomyolysis have a very low risk of complications. Our patients are treated as outpatients or considered for discharge with creatine kinase < 40 000 IU/l measured at least three days after their workout, and if they have no risk factors or other complications.

Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

Energy Technology Data Exchange (ETDEWEB)

Wit, Julien de [Department of Earth, Atmospheric and Planetary Sciences, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Lewis, Nikole K. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Knutson, Heather A.; Batygin, Konstantin [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Fuller, Jim [TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125 (United States); Antoci, Victoria [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Fulton, Benjamin J. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Laughlin, Gregory [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Deming, Drake [Department of Astronomy, University of Maryland at College Park, College Park, MD 20742 (United States); Shporer, Avi [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91009 (United States); Cowan, Nicolas B. [Department of Physics, Department of Earth and Planetary Sciences, McGill University, 3550 rue University, Montreal, QC H3A 2A7 (Canada); Agol, Eric [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Burrows, Adam S. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Langton, Jonathan [Department of Physics, Principia College, Elsah, IL 62028 (United States); Showman, Adam P. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

2017-02-20

Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet’s atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet–star interactions in HAT-P-2's eccentric planetary system gained from the analysis of ∼350 hr of 4.5 μ m observations with the Spitzer Space Telescope . The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b’s 4.5 μ m photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet’s orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2's pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

HIV - implications for exercise in treatment and rehabilitation

Directory of Open Access Journals (Sweden)

M. Mars

2004-01-01

following muscle injury or surgery. It is usual to advise patients with a viral infection to avoid exercise because of the risk of developing myocarditis. Should HIV+ patients should be encouraged to undertake exercise as part of rehabilitation and should they further be advised to participate in regular exercise? There is sufficient evidence to support the benefits of regular exercise in the HIV+ patient. They will experience a training effect dependent on the normal parameters of frequency, intensity, duration, and mode of exercise.  The disease does place potential limitations to exercise, as the HI virus directly affects pulmonary, cardiac, skeletal muscle and endocrine function.  The effects of these changes may be  exacerbated by secondary infection and other pathological changes may be induced by treatment.  The advent of highly active antiretroviral therapy has brought with it a range of metabolic changes that may also influence exercise  participation. The limitations to exercise imposed by HIV infection and its treatment are reviewed.

Molecular Mechanisms in Exercise-Induced Cardioprotection

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Saeid Golbidi

2011-01-01

Full Text Available Physical inactivity is increasingly recognized as modifiable behavioral risk factor for cardiovascular diseases. A partial list of proposed mechanisms for exercise-induced cardioprotection include induction of heat shock proteins, increase in cardiac antioxidant capacity, expression of endoplasmic reticulum stress proteins, anatomical and physiological changes in the coronary arteries, changes in nitric oxide production, adaptational changes in cardiac mitochondria, increased autophagy, and improved function of sarcolemmal and/or mitochondrial ATP-sensitive potassium channels. It is currently unclear which of these protective mechanisms are essential for exercise-induced cardioprotection. However, most investigations focus on sarcolemmal KATP channels, NO production, and mitochondrial changes although it is very likely that other mechanisms may also exist. This paper discusses current information about these aforementioned topics and does not consider potentially important adaptations within blood or the autonomic nervous system. A better understanding of the molecular basis of exercise-induced cardioprotection will help to develop better therapeutic strategies.

Exercise-induced phospho-proteins in skeletal muscle

DEFF Research Database (Denmark)

Deshmukh, A S; Hawley, J A; Zierath, J R

2008-01-01

Efforts to identify exercise-induced signaling events in skeletal muscle have been influenced by ground-breaking discoveries in the insulin action field. Initial discoveries demonstrating that exercise enhances insulin sensitivity raised the possibility that contraction directly modulates insulin...... receptor signaling events. Although the acute effects of exercise on glucose metabolism are clearly insulin-independent, the canonical insulin signaling cascade has been used as a framework by investigators in an attempt to resolve the mechanisms by which muscle contraction governs glucose metabolism....... This review focuses on recent advances in our understanding of exercise-induced signaling pathways governing glucose metabolism in skeletal muscle. Particular emphasis will be placed on the characterization of AS160, a novel Akt substrate that plays a role in the regulation of glucose transport....

Skeletal muscle collagen content in humans after high-force eccentric contractions

DEFF Research Database (Denmark)

Mackey, Abigail; Donnelly, Alan E; Turpeenniemi-Hujanen, Taina

2004-01-01

The purpose of this study was to investigate the effects of high-force eccentric muscle contractions on collagen remodeling and on circulating levels of matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) in humans. Nine volunteers [5 men and 4 women, mean age 23 (SD...... 4) yr] each performed a bout of 100 maximum voluntary eccentric contractions of the knee extensors. Muscle biopsies were taken before exercise and on days 4 and 22 afterward. Image analysis of stained tissue sections was used to quantify endomysial collagen staining intensity. Maximum voluntary...... contractile force declined by 39 +/- 23% (mean +/- SD) on day 2 postexercise and recovered thereafter. Serum creatine kinase activity peaked on day 4 postexercise (P Collagen type IV staining intensity increased significantly on day 22 postexercise to 126 +/- 29% (mean +/- SD) of preexercise values...

Isometric pre-conditioning blunts exercise-induced muscle damage but does not attenuate changes in running economy following downhill running.

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Lima, Leonardo C R; Bassan, Natália M; Cardozo, Adalgiso C; Gonçalves, Mauro; Greco, Camila C; Denadai, Benedito S

2018-05-08

Running economy (RE) is impaired following unaccustomed eccentric-biased exercises that induce muscle damage. It is also known that muscle damage is reduced when maximal voluntary isometric contractions (MVIC) are performed at a long muscle length 2-4 days prior to maximal eccentric exercise with the same muscle, a phenomenon that can be described as isometric pre-conditioning (IPC). We tested the hypothesis that IPC could attenuate muscle damage and changes in RE following downhill running. Thirty untrained men were randomly assigned into experimental or control groups and ran downhill on a treadmill (-15%) for 30 min. Participants in the experimental group completed 10 MVIC in a leg press machine two days prior to downhill running, while participants in the control group did not perform IPC. The magnitude of changes in muscle soreness determined 48 h after downhill running was greater for the control group (122 ± 28 mm) than for the experimental group (92 ± 38 mm). Isometric peak torque recovered faster in the experimental group compared with the control group (3 days vs. no full recovery, respectively). No significant effect of IPC was found for countermovement jump height, serum creatine kinase activity or any parameters associated with RE. These results supported the hypothesis that IPC attenuates changes in markers of muscle damage. The hypothesis that IPC attenuates changes in RE was not supported by our data. It appears that the mechanisms involved in changes in markers of muscle damage and parameters associated with RE following downhill running are not completely shared. Copyright © 2018 Elsevier B.V. All rights reserved.

Eccentric Torque-Producing Capacity is Influenced by Muscle Length in Older Healthy Adults.

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Melo, Ruth C; Takahashi, Anielle C M; Quitério, Robison J; Salvini, Tânia F; Catai, Aparecida M

2016-01-01

Considering the importance of muscle strength to functional capacity in the elderly, the study investigated the effects of age on isokinetic performance and torque production as a function of muscle length. Eleven younger (24.2 ± 2.9 years) and 16 older men (62.7 ± 2.5 years) were subjected to concentric and eccentric isokinetic knee extension/flexion at 60 and 120° · s(-1) through a functional range of motion. The older group presented lower peak torque (in newton-meters) than the young group for both isokinetic contraction types (age effect, p torque deficits in the older group were near 30 and 29% for concentric and eccentric contraction, respectively. Concentric peak torque was lower at 120° · s(-1) than at 60° · s(-1) for both groups (angular velocity effect, p torque was the only exercise tested that showed an interaction effect between age and muscle length (p torque responses to the muscle length between groups. Compared with the young group, the eccentric knee extension torque was 22-56% lower in the older group, with the deficits being lower in the shortened muscle length (22-27%) and higher (33-56%) in the stretched muscle length. In older men, the production of eccentric knee strength seems to be dependent on the muscle length. At more stretched positions, older subjects lose the capacity to generate eccentric knee extension torque. More studies are needed to assess the mechanisms involved in eccentric strength preservation with aging and its relationship with muscle length.

The effect of eccentric and concentric calf muscle training on Achilles tendon stiffness.

Science.gov (United States)

Morrissey, Dylan; Roskilly, Anna; Twycross-Lewis, Richard; Isinkaye, Tomide; Screen, Hazel; Woledge, Roger; Bader, Dan

2011-03-01

To compare in vivo effects of eccentric and concentric calf muscle training on Achilles tendon stiffness, in subjects without tendinopathy. Thirty-eight recreational athletes completed 6 weeks eccentric (6 males, 13 females, 21.6  ±  2.2 years) or concentric training (8 males, 11 females, 21.1  ±  2.0 years). Achilles tendon stiffness, tendon modulus and single-leg jump height were measured before and after intervention. Exercise adherence was recorded using a diary. All data are reported as mean  ±  SD. Groups were matched for height and weight but the eccentric training group were more active at baseline (P Tendon stiffness was higher in the eccentrically trained group at baseline compared to the concentrically trained group (20.9  ±  7.3 N/mm v 13.38  ±  4.66 N/mm; P = 0.001) and decreased significantly after eccentric training (to 17.2 ( ±  5.9) N/mm (P = 0.035)). There was no stiffness change in the concentric group (P = 0.405). Stiffness modulus showed similar changes to stiffness. An inverse correlation was found between initial, and subsequent, reduction in stiffness (r = -0.66). Jump height did not change and no correlation between stiffness change and adherence was observed in either group (r = 0.01). Six weeks of eccentric training can alter Achilles tendon stiffness while a matched concentric programme shows no similar effects. Studies in patients with Achilles tendinopathy are warranted.

AMPKα is essential for acute exercise-induced gene responses but not for exercise training-induced adaptations in mouse skeletal muscle

DEFF Research Database (Denmark)

Fentz, Joachim; Kjøbsted, Rasmus; Maag Kristensen, Caroline

2015-01-01

-induced increases in exercise capacity and expression of metabolic proteins as well as acute exercise-induced gene regulation would be compromised in AMPKα1 and -α2 muscle-specific double knockout (mdKO) mice. An acute bout of exercise increased skeletal muscle mRNA content of cytochrome C oxidase subunit I......, glucose transporter 4 and VEGF in an AMPK-dependent manner, while cluster of differentiation 36 and fatty acid transport protein 1 mRNA content increased similarly in AMPKα wild type (WT) and mdKO mice. During four weeks of voluntary running wheel exercise training, the AMPKα mdKO mice ran less than WT...

Differential response of heat shock proteins to uphill and downhill exercise in heart, skeletal muscle, lung and kidney tissues.

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Lollo, Pablo C B; Moura, Carolina S; Morato, Priscila N; Amaya-Farfan, Jaime

2013-01-01

Running on a horizontal plane is known to increase the concentration of the stress biomarker heat-shock protein (HSP), but no comparison of the expression of HSP70 has yet been established between the uphill (predominantly concentric) and downhill (predominantly eccentric) muscle contractions exercise. The objective of the study was to investigate the relationships between eccentric and concentric contractions on the HSP70 response of the lung, kidney, gastrocnemius, soleus and heart. Twenty-four male Wistar weanling rats were divided into four groups: non-exercised and three different grades of treadmill exercise groups: horizontal, uphill (+7%) and downhill (-7% of inclination). At the optimal time-point of six hours after the exercise, serum uric acid, creatine kinase (CK) and lactate dehydrogenase (LDH) were determined by standard methods and HSP70 by the Western blot analysis. HSP70 responds differently to different types of running. For kidney, heart, soleus and gastrocnemius, the HSP70 expression increased, 230, 180, 150 and 120% respectively of the reference (horizontal). When the contraction was concentric (uphill) and compared to downhill the increase in response of HSP70 was greater in 80% for kidney, 75% for gastrocnemius, 60% for soleus and 280% for the heart. Uric acid was about 50% higher (0.64 ± 0.03 mg·dL(-1)) in the uphill group as compared to the horizontal or downhill groups. Similarly, the activities of serum CK and LDH were both 100% greater for both the uphill and downhill groups as compared to the horizontal group (2383 ± 253 and 647.00 ± 73 U/L, respectively). The responsiveness of HSP70 appeared to be quite different depending on the type of tissue, suggesting that the impact of exercise was not restricted to the muscles, but extended to the kidney tissue. The uphill exercise increases HSP70 beyond the eccentric type and the horizontal running was a lower HSP70 responsive stimulus. Key PointsExercise can induce increases in HSP70 in

Geometrical theory to predict eccentric photorefraction intensity profiles in the human eye

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Roorda, Austin; Campbell, Melanie C. W.; Bobier, W. R.

1995-08-01

In eccentric photorefraction, light returning from the retina of the eye is photographed by a camera focused on the eye's pupil. We use a geometrical model of eccentric photorefraction to generate intensity profiles across the pupil image. The intensity profiles for three different monochromatic aberration functions induced in a single eye are predicted and show good agreement with the measured eccentric photorefraction intensity profiles. A directional reflection from the retina is incorporated into the calculation. Intensity profiles for symmetric and asymmetric aberrations are generated and measured. The latter profile shows a dependency on the source position and the meridian. The magnitude of the effect of thresholding on measured pattern extents is predicted. Monochromatic aberrations in human eyes will cause deviations in the eccentric photorefraction measurements from traditional crescents caused by defocus and may cause misdiagnoses of ametropia or anisometropia. Our results suggest that measuring refraction along the vertical meridian is preferred for screening studies with the eccentric photorefractor.

COMPARISON OF CONCENTRIC AND ECCENTRIC HAMSTRING STRENGTH TRAINING IN IMPROVING MUSCLE STRENGTH AND POWER AMONG FUTSAL PLAYERS A RANDOMIZED CONTROLLED TRIAL

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Arunkumar Nedunchezhiyan

2016-12-01

Full Text Available Background: Hamstring injury is a common problem in many sports, especially those involving acceleration and maximal sprints. Hamstring strains are both common and painful. During sprinting the hip flexor and knee extensor torques are frequently produced and is opposed by the hamstring muscles, hence there are numerous studies done on the muscle strength training to prevent the hamstring strain injury as it is statistically stated as the highest rate involved injury in the contact sport. This study has been focused to evaluate the effectiveness of concentric and eccentric exercises in improving hamstring muscle strength and power among futsal players. Method: Thirty recreational futsal players were recruited for the study and were randomly divided into two groups. Each group received either hamstring curl exercise (concentric or Nordic hamstring exercise (eccentric twice a week for 4 weeks. The manual muscle test (MMT and 40-yard dash test was used to evaluate the muscle strength and power respectively by comparing the pretest and posttest values for both groups. Results: Wilcoxon signed rank test showed that there is no statistically significant difference between pre and post test values of MMT (Concentric (right side, z=.317; left side, z=.157, Eccentric (right side, z=.157; left side, z=.317 in both groups. Based on paired 't' test there is a significant difference between the pre and post test on improving muscle power [Concentric group, P=.020; Eccentric Group, P=.000]. Mann–Whitney U test and unpaired 't' test showed that there is no significant difference between both groups of MMT (z=.775 and 40-yard dash test (P=.707 respectively. Conclusion: The concentric strength training and eccentric strength training have a similar effect in improving hamstring muscle power in futsal players.

Full Range of Motion Induces Greater Muscle Damage Than Partial Range of Motion in Elbow Flexion Exercise With Free Weights.

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Baroni, Bruno M; Pompermayer, Marcelo G; Cini, Anelize; Peruzzolo, Amanda S; Radaelli, Régis; Brusco, Clarissa M; Pinto, Ronei S

2017-08-01

Baroni, BM, Pompermayer, MG, Cini, A, Peruzzolo, AS, Radaelli, R, Brusco, CM, and Pinto, RS. Full range of motion induces greater muscle damage than partial range of motion in elbow flexion exercise with free weights. J Strength Cond Res 31(8): 2223-2230, 2017-Load and range of motion (ROM) applied in resistance training (RT) affect the muscle damage magnitude and the recovery time-course. Because exercises performed with partial ROM allow a higher load compared with those with full ROM, this study investigated the acute effect of a traditional RT exercise using full ROM or partial ROM on muscle damage markers. Fourteen healthy men performed 4 sets of 10 concentric-eccentric repetitions of unilateral elbow flexion on the Scott bench. Arms were randomly assigned to partial-ROM (50-100°) and full-ROM (0-130°) conditions, and load was determined as 80% of 1 repetition maximum (1RM) in the full- and partial-ROM tests. Muscle damage markers were assessed preexercise, immediately, and 24, 48, and 72 hours after exercise. Primary outcomes were peak torque, muscle soreness during palpation and elbow extension, arm circumference, and joint ROM. The load lifted in the partial-ROM condition (1RM = 19.1 ± 3.0 kg) was 40 ± 18% higher compared with the full-ROM condition (1RM = 13.7 ± 2.2 kg). Seventy-two hours after exercise, the full-ROM condition led to significant higher soreness sensation during elbow extension (1.3-4.1 cm vs. 1.0-1.9 cm) and smaller ROM values (97.5-106.1° vs. 103.6-115.7°). Peak torque, soreness from palpation, and arm circumference were statistically similar between conditions, although mean values in all time points of these outcomes have suggested more expressive muscle damage for the full-ROM condition. In conclusion, elbow flexion exercise with full ROM seems to induce greater muscle damage than partial-ROM exercises, even though higher absolute load was achieved with partial ROM.

Influence of pre-exercise muscle glycogen content on exercise-induced transcriptional regulation of metabolic genes

DEFF Research Database (Denmark)

Pilegaard, Henriette; Keller, Charlotte; Steensberg, Adam

2002-01-01

Transcription of metabolic genes is transiently induced during recovery from exercise in skeletal muscle of humans. To determine whether pre-exercise muscle glycogen content influences the magnitude and/or duration of this adaptive response, six male subjects performed one-legged cycling exercise...... to lower muscle glycogen content in one leg and then, the following day, completed 2.5 h low intensity two-legged cycling exercise. Nuclei and mRNA were isolated from biopsies obtained from the vastus lateralis muscle of the control and reduced glycogen (pre-exercise glycogen = 609 +/- 47 and 337 +/- 33...... mmol kg(-1) dry weight, respectively) legs before and after 0, 2 and 5 h of recovery. Exercise induced a significant (P glycogen leg only. Although PDK4...

Does granulocyte colony-stimulating factor exacerbate radiation-induced acute lung injury in rats?

International Nuclear Information System (INIS)

Miura, Gouji; Awaya, Hitomi; Matsumoto, Tsuneo; Tanaka, Nobuyuki; Matsunaga, Naofumi

2000-01-01

Radiation pneumonitis (RP) frequently occurs as a complication of thoracic irradiation. However, the mechanism of RP is not well known. Activated neutrophils are a possible pathogenesis of RP. Neutrophil activation induced by granulocyte colony-stimulating factor (G-CSF) may exacerbate RP. We studied the effects of recombinant human G-CSF on acute lung injury induced by thoracic irradiation using rats. Animals were divided into three groups: sham irradiation with saline control, irradiation alone, and irradiation with G-CSF. Actual irradiation was given as a single fraction of 16 Gy delivered to the right hemithorax. G-CSF at a dose of 12 μg/body was administered subcutaneously once a day from 14 to 18 days after actual irradiation. Lung injury was evaluated 21 days after irradiation by bronchoalveolar lavage (BAL) fluid findings and the lung wet/dry weight (W/D) ratio. Neutrophil and lymphocyte counts in BAL fluid and the W/D ratio were significantly increased in the irradiation alone and the irradiation with G-CSF groups compared with those of the sham irradiation+saline control group. However, there was no significant difference observed between the irradiation alone and irradiation with G-CSF groups. In conclusion, this study suggests that postradiation administration of G-CSF does not exacerbate acute lung injury induced by thoracic irradiation in rats. (author)

Does granulocyte colony-stimulating factor exacerbate radiation-induced acute lung injury in rats?

Energy Technology Data Exchange (ETDEWEB)

Miura, Gouji; Awaya, Hitomi; Matsumoto, Tsuneo; Tanaka, Nobuyuki; Matsunaga, Naofumi [Yamaguchi Univ., Ube (Japan). School of Medicine

2000-08-01

Radiation pneumonitis (RP) frequently occurs as a complication of thoracic irradiation. However, the mechanism of RP is not well known. Activated neutrophils are a possible pathogenesis of RP. Neutrophil activation induced by granulocyte colony-stimulating factor (G-CSF) may exacerbate RP. We studied the effects of recombinant human G-CSF on acute lung injury induced by thoracic irradiation using rats. Animals were divided into three groups: sham irradiation with saline control, irradiation alone, and irradiation with G-CSF. Actual irradiation was given as a single fraction of 16 Gy delivered to the right hemithorax. G-CSF at a dose of 12 {mu}g/body was administered subcutaneously once a day from 14 to 18 days after actual irradiation. Lung injury was evaluated 21 days after irradiation by bronchoalveolar lavage (BAL) fluid findings and the lung wet/dry weight (W/D) ratio. Neutrophil and lymphocyte counts in BAL fluid and the W/D ratio were significantly increased in the irradiation alone and the irradiation with G-CSF groups compared with those of the sham irradiation+saline control group. However, there was no significant difference observed between the irradiation alone and irradiation with G-CSF groups. In conclusion, this study suggests that postradiation administration of G-CSF does not exacerbate acute lung injury induced by thoracic irradiation in rats. (author)

Muscle activity during knee-extension strengthening exercise performed with elastic tubing and isotonic resistance.

Science.gov (United States)

Jakobsen, Markus Due; Sundstrup, Emil; Andersen, Christoffer H; Bandholm, Thomas; Thorborg, Kristian; Zebis, Mette K; Andersen, Lars L

2012-12-01

While elastic resistance training, targeting the upper body is effective for strength training, the effect of elastic resistance training on lower body muscle activity remains questionable. The purpose of this study was to evaluate the EMG-angle relationship of the quadriceps muscle during 10-RM knee-extensions performed with elastic tubing and an isotonic strength training machine. 7 women and 9 men aged 28-67 years (mean age 44 and 41 years, respectively) participated. Electromyographic (EMG) activity was recorded in 10 muscles during the concentric and eccentric contraction phase of a knee extension exercise performed with elastic tubing and in training machine and normalized to maximal voluntary isometric contraction (MVC) EMG (nEMG). Knee joint angle was measured during the exercises using electronic inclinometers (range of motion 0-90°). When comparing the machine and elastic resistance exercises there were no significant differences in peak EMG of the rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM) during the concentric contraction phase. However, during the eccentric phase, peak EMG was significantly higher (ptubing (5.7±0.6) compared with knee extensions performed in training machine (5.9±0.5). Knee extensions performed with elastic tubing induces similar high (>70% nEMG) quadriceps muscle activity during the concentric contraction phase, but slightly lower during the eccentric contraction phase, as knee extensions performed using an isotonic training machine. During the concentric contraction phase the two different conditions displayed reciprocal EMG-angle patterns during the range of motion. 5.

Exercise and chemotherapy-induced amenorrhea.

Science.gov (United States)

Mathis, Katlynn M; Sturgeon, Kathleen M; Winkels, Renate M; Wiskemann, Joachim; Williams, Nancy I; Schmitz, Kathryn

2018-07-01

Chemotherapy-induced amenorrhea (CIA) is the temporary or permanent loss of menses experienced by premenopausal women undergoing chemotherapy treatment for cancer. Two possible mechanisms through which chemotherapy induces CIA have been identified: systemic endothelial dysfunction, resulting in decreased blood flow to the ovaries, and increased oxidative stress within the ovaries, both of which are proposed to lead to apoptosis of follicles. Endothelial dysfunction in ovarian arteries in women undergoing or who have undergone chemotherapy treatment is characterized by prothrombotic changes and thickening of the vascular wall. These changes result in occlusion of the blood vessels. Oxidative stress is increased and antioxidants decreased in the ovaries secondary to chemotherapy drugs, specifically cyclophosphamide. It is hypothesized that low to moderate intensity aerobic exercise during chemotherapy may prevent these changes and lessen the risk for developing CIA in premenopausal women. Low to moderate intensity aerobic exercise has been shown to improve endothelial function and blood flow in patients with cardiovascular disease-a disease state characterized by endothelial dysfunction and for which patients who have undergone chemotherapy are at increased risk. In mice, moderate intensity aerobic exercise has been shown to decrease the amount of oxidative stress within the ovaries, and in humans, chronic aerobic exercise has been shown to increase antioxidant production systemically. This hypothesis should be tested in both a mouse model, using sedentary and exercising mice treated with chemotherapy drugs that commonly result in CIA, as well as a human model to determine the effects of low to moderate intensity aerobic exercise on ovarian function in premenopausal women undergoing chemotherapy. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of acute augmented feedback on between limb asymmetries and eccentric knee flexor strength during the Nordic hamstring exercise

Directory of Open Access Journals (Sweden)

Wade J. Chalker

2018-06-01

Full Text Available Background Hamstring strain injuries (HSI are one of the most prevalent and serious injuries affecting athletes, particularly those in team ball sports or track and field. Recent evidence demonstrates that eccentric knee flexor weakness and between limb asymmetries are possible risk factors for HSIs. While eccentric hamstring resistance training, e.g. the Nordic hamstring exercise (NHE significantly increases eccentric hamstring strength and reduces HSI risk, little research has examined whether between limb asymmetries can be reduced with training. As augmented feedback (AF can produce significant acute and chronic increases in muscular strength and reduce injury risk, one way to address the limitation in the eccentric hamstring training literature may be to provide athletes real-time visual AF of their NHE force outputs with the goal to minimise the between limb asymmetry. Methods Using a cross over study design, 44 injury free, male cricket players from two skill levels performed two NHE sessions on a testing device. The two NHE sessions were identical with the exception of AF, with the two groups randomised to perform the sessions with and without visual feedback of each limb’s force production in real-time. When performing the NHE with visual AF, the participants were provided with the following instructions to ‘reduce limb asymmetries as much as possible using the real-time visual force outputs displayed in front them’. Between limb asymmetries and mean peak force outputs were compared between the two feedback conditions (FB1 and FB2 using independent t-tests to ensure there was no carryover effect, and to determine any period and treatment effects. The magnitude of the differences in the force outputs were also examined using Cohen d effect size. Results There was a significant increase in mean peak force production when feedback was provided (mean difference, 21.7 N; 95% CI [0.2–42.3 N]; P = 0.048; d = 0.61 and no significant

Corticosteroid or placebo injection combined with deep transverse friction massage, Mills manipulation, stretching and eccentric exercise for acute lateral epicondylitis: a randomised, controlled trial.

Science.gov (United States)

Olaussen, Morten; Holmedal, Øystein; Mdala, Ibrahimu; Brage, Søren; Lindbæk, Morten

2015-05-20

Lateral epicondylitis of the elbow is a frequent condition with long-lasting symptoms. Corticosteroid injection is increasingly discouraged and there is little knowledge on the combined effect of corticosteroid injection and physiotherapy for acute conditions. We wanted to investigate the efficacy of physiotherapy alone and combined with corticosteroid injection for acute lateral epicondylitis. A randomized, controlled study with one-year follow-up was conducted in a general practice setting in Sarpsborg, Norway. We included 177 men and women aged 18 to 70 with clinically diagnosed lateral epicondylitis of recent onset (2 weeks to 3 months). They were randomly assigned to one of three treatments: physiotherapy with two corticosteroid injections, physiotherapy with two placebo injections or wait-and-see (control). Physiotherapy consisted of deep transverse friction massage, Mills manipulation, stretching, and eccentric exercises. We used double blind injection of corticosteroid and single blind assessments. The main outcome measure was treatment success defined as patients rating themselves completely recovered or much better on a six-point scale. One hundred fifty-seven patients (89 %) completed the trial. Placebo injection with physiotherapy showed no significant difference compared to control or to corticosteroid injection with physiotherapy at any follow-up. Corticosteroid injection with physiotherapy had a 10.6 times larger odds for success at six weeks (odds ratio 10.60, p lateral epicondylitis is a self-limiting condition where 3/4 of patients recover within 52 weeks. Physiotherapy with deep transverse friction massage, Mills manipulation, stretching, and eccentric exercises showed no clear benefit, and corticosteroid injection gave no added effect. Corticosteroid injections combined with physiotherapy might be considered for patients needing a quick improvement, but intermediate (12 to 26 weeks) worsening of symptoms makes the treatment difficult to

Caffeine-induced increase in voluntary activation and strength of the quadriceps muscle during isometric, concentric and eccentric contractions.

Science.gov (United States)

Behrens, Martin; Mau-Moeller, Anett; Weippert, Matthias; Fuhrmann, Josefin; Wegner, Katharina; Skripitz, Ralf; Bader, Rainer; Bruhn, Sven

2015-05-13

This study investigated effects of caffeine ingestion (8 mg/kg) on maximum voluntary torque (MVT) and voluntary activation of the quadriceps during isometric, concentric and eccentric contractions. Fourteen subjects ingested caffeine and placebo in a randomized, controlled, counterbalanced, double-blind crossover design. Neuromuscular tests were performed before and 1 h after oral caffeine and placebo intake. MVTs were measured and the interpolated twitch technique was applied during isometric, concentric and eccentric contractions to assess voluntary activation. Furthermore, normalized root mean square of the EMG signal was calculated and evoked spinal reflex responses (H-reflex evoked at rest and during weak isometric voluntary contraction) as well as twitch torques were analyzed. Caffeine increased MVT by 26.4 N m (95%CI: 9.3-43.5 N m, P = 0.004), 22.5 N m (95%CI: 3.1-42.0 N m, P = 0.025) and 22.5 N m (95%CI: 2.2-42.7 N m, P = 0.032) for isometric, concentric and eccentric contractions. Strength enhancements were associated with increases in voluntary activation. Explosive voluntary strength and voluntary activation at the onset of contraction were significantly increased following caffeine ingestion. Changes in spinal reflex responses and at the muscle level were not observed. Data suggest that caffeine ingestion induced an acute increase in voluntary activation that was responsible for the increased strength regardless of the contraction mode.

Decline eccentric squats increases patellar tendon loading compared to standard eccentric squats

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Kongsgaard, M; Aagaard, P; Roikjaer, S

2006-01-01

Recent studies have shown excellent clinical results using eccentric squat training on a 25 degrees decline board to treat patellar tendinopathy. It remains unknown why therapeutic management of patellar tendinopathy using decline eccentric squats offer superior clinical efficacy compared...

Gene expression in response to exercise in patients with chronic fatigue syndrome: a pilot study.

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Andrew Keech

2016-09-01

Full Text Available Chronic fatigue syndrome (CFS is a debilitating disorder of unknown pathogenesis, characterised by fatigue, which is exacerbated after minimal exercise. We examined the effect of a single bout of aerobic exercise on leucocyte mRNA expression of genes putatively linked to exaggerated afferent signalling as an under-pinning of the fatigue state. A carefully-characterised sample of patients with CFS (N = 10 and healthy matched control participants (N = 12 were included. Participant ratings of fatigue and other symptoms, as well as blood samples, were obtained at baseline, and five other time-points up to 72 hours after 25 minutes of moderate-intensity cycling exercise. Leucocyte mRNA of 19 metabolite-sensing, adrenergic, immune and neurotransmission genes was examined using quantitative polymerase chain reaction. Patients with CFS reported substantial fatigue, functional impairment and poor sleep at baseline (all p < 0.02, and exercise immediately induced worsened patients’ fatigue (effect size, ES = 1.17. There were no significant changes in gene expression after exercise and patients did not differ from control participants at any time point. Higher levels of expression of ficolin (FCN1 and a purinergic receptor (P2RX4 in patients with CFS were found when all time points were combined. Patients with CFS did not show significant exercise-induced changes in leucocyte mRNA of 19 metabolite-sensing, adrenergic, immune and neurotransmission genes despite a prominent exacerbation of fatigue.

Preventive effect of eccentric training on acute hamstring injuries in men's soccer: A cluster-randomized controlled trial

DEFF Research Database (Denmark)

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

2011-01-01

Background: The incidence of acute hamstring injuries is high in several sports, including the different forms of football. Purpose: The authors investigated the preventive effect of eccentric strengthening of the hamstring muscles using the Nordic hamstring exercise compared with no additional h...

Exercisers achieve greater acute exercise-induced mood enhancement than nonexercisers.

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Hoffman, Martin D; Hoffman, Debi Rufi

2008-02-01

To determine whether a single session of exercise of appropriate intensity and duration for aerobic conditioning has a different acute effect on mood for nonexercisers than regular exercisers. Repeated-measures design. Research laboratory. Adult nonexercisers, moderate exercisers, and ultramarathon runners (8 men, 8 women in each group). Treadmill exercise at self-selected speeds to induce a rating of perceived exertion (RPE) of 13 (somewhat hard) for 20 minutes, preceded and followed by 5 minutes at an RPE of 9 (very light). Profile of Mood States before and 5 minutes after exercise. Vigor increased by a mean +/- standard deviation of 8+/-7 points (95% confidence interval [CI], 5-12) among the ultramarathon runners and 5+/-4 points (95% CI, 2-9) among the moderate exercisers, with no improvement among the nonexercisers. Fatigue decreased by 5+/-6 points (95% CI, 2-8) for the ultramarathon runners and 4+/-4 points (95% CI, 1-7) for the moderate exercisers, with no improvement among the nonexercisers. Postexercise total mood disturbance decreased by a mean of 21+/-16 points (95% CI, 12-29) among the ultramarathon runners, 16+/-10 points (95% CI, 7-24) among the moderate exercisers, and 9+/-13 points (95% CI, 1-18) among the nonexercisers. A single session of moderate aerobic exercise improves vigor and decreases fatigue among regular exercisers but causes no change in these scores for nonexercisers. Although total mood disturbance improves postexercise in exercisers and nonexercisers, regular exercisers have approximately twice the effect as nonexercisers. This limited postexercise mood improvement among nonexercisers may be an important deterrent for persistence with an exercise program.

The Accumulative Effect of Concentric‐Biased and Eccentric‐ Biased Exercise on Cardiorespiratory and Metabolic Responses to Subsequent Low‐Intensity Exercise: A Preliminary Study

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Gavin James Peter

2015-12-01

Full Text Available The study investigated the accumulative effect of concentric-biased and eccentric-biased exercise on cardiorespiratory, metabolic and neuromuscular responses to low-intensity exercise performed hours later. Fourteen young men cycled at low-intensity (~60 rpm at 50% maximal oxygen uptake for 10 min before, and 12 h after: concentric-biased, single-leg cycling exercise (CON (performed ~19:30 h and eccentric-biased, double-leg knee extension exercise (ECC (~06:30 h the following morning. Respiratory measures were sampled breath-by-breath, with oxidation values derived from stoichiometry equations. Knee extensor neuromuscular function was assessed before and after CON and ECC. Cardiorespiratory responses during low-intensity cycling were unchanged by accumulative CON and ECC. The RER was lower during low-intensity exercise 12 h after CON and ECC (0.88 ± 0.08, when compared to baseline (0.92 ± 0.09; p = 0.02. Fat oxidation increased from baseline (0.24 ± 0.2 g·min1 to 12 h after CON and ECC (0.39 ± 0.2 g·min1; p = 0.01. Carbohydrate oxidation decreased from baseline (1.59 ± 0.4 g·min-1 to 12 h after CON and ECC (1.36 ± 0.4 g·min1; p = 0.03. These were accompanied by knee extensor force loss (right leg: -11.6%, p < 0.001; left leg: -10.6%, p = 0.02 and muscle soreness (right leg: 2.5 ± 0.9, p < 0.0001; left leg: 2.3 ± 1.2, p < 0.01. Subsequent concentric-biased and eccentric-biased exercise led to increased fat oxidation and decreased carbohydrate oxidation, without impairing cardiorespiration, during low-intensity cycling. An accumulation of fatiguing and damaging exercise increases fat utilisation during low intensity exercise performed as little as 12 h later.

Vitamin E supplementation inhibits muscle damage and inflammation after moderate exercise in hypoxia.

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Santos, S A; Silva, E T; Caris, A V; Lira, F S; Tufik, S; Dos Santos, R V T

2016-08-01

Exercise under hypoxic conditions represents an additional stress in relation to exercise in normoxia. Hypoxia induces oxidative stress and inflammation as mediated through tumour necrosis factor (TNF)-α release that might be exacerbated through exercise. In addition, vitamin E supplementation might attenuate oxidative stress and inflammation resulting from hypoxia during exercise. The present study aimed to evaluate the effects of vitamin E supplementation (250 mg) on inflammatory parameters and cellular damage after exercise under hypoxia simulating an altitude of 4200 m. Nine volunteers performed three sessions of 60 min of exercise (70% maximal oxygen uptake) interspersed for 1 week under normoxia, hypoxia and hypoxia after vitamin E supplementation 1 h before exercise. Blood was collected before, immediately after and at 1 h after exercise to measure inflammatory parameters and cell damage. Percentage oxygen saturation of haemoglobin decreased after exercise and recovered 1 h later in the hypoxia + vitamin condition (P exercise (P exercise in hypoxia increased interleukin (IL)-6, TNF-α, IL-1ra and IL-10 immediately after exercise (P exercise in hypoxia without supplementation (P exercise reduces cell damage markers after exercise in hypoxia and changes the concentration of cytokines, suggesting a possible protective effect against inflammation induced by hypoxia during exercise. © 2016 The British Dietetic Association Ltd.

Innate immune activation by inhaled lipopolysaccharide, independent of oxidative stress, exacerbates silica-induced pulmonary fibrosis in mice.

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David M Brass

Full Text Available Acute exacerbations of pulmonary fibrosis are characterized by rapid decrements in lung function. Environmental factors that may contribute to acute exacerbations remain poorly understood. We have previously demonstrated that exposure to inhaled lipopolysaccharide (LPS induces expression of genes associated with fibrosis. To address whether exposure to LPS could exacerbate fibrosis, we exposed male C57BL/6 mice to crystalline silica, or vehicle, followed 28 days later by LPS or saline inhalation. We observed that mice receiving both silica and LPS had significantly more total inflammatory cells, more whole lung lavage MCP-1, MIP-2, KC and IL-1β, more evidence of oxidative stress and more total lung hydroxyproline than mice receiving either LPS alone, or silica alone. Blocking oxidative stress with N-acetylcysteine attenuated whole lung inflammation but had no effect on total lung hydroxyproline. These observations suggest that exposure to innate immune stimuli, such as LPS in the environment, may exacerbate stable pulmonary fibrosis via mechanisms that are independent of inflammation and oxidative stress.

A Standardized "Rescue" Exercise Program for Symptomatic Flare-up of Knee Osteoarthritis

DEFF Research Database (Denmark)

Bartholdy, Cecilie; Klokker, Louise; Bandak, Elisabeth

2016-01-01

the implementation of standardized rescue exercises for patients with pain exacerbations and to assess whether performing these benefit or further worsen symptoms in patients with exacerbated symptoms of knee OA. Methods The data from 2 randomized controlled studies of exercise in patients with knee OA were used......Study Design Secondary analysis of clinical trial data. Background Knee osteoarthritis (OA) management has changed significantly over recent decades toward nonpharmacological treatments, particularly exercise. However, the optimal exercise program remains to be established. Objective To describe....... A supervised, standard exercise program that included standardized "rescue" exercises to be performed in the event of symptomatic exacerbation, defined as knee pain of greater than 5 on a 0-to-10 numeric pain-rating scale, was conducted for 12 weeks at 3 sessions per week. Pain ratings were obtained before...

Exercise-induced maximum metabolic rate scaled to body mass by ...

African Journals Online (AJOL)

Exercise-induced maximum metabolic rate scaled to body mass by the fractal ... rate scaling is that exercise-induced maximum aerobic metabolic rate (MMR) is ... muscle stress limitation, and maximized oxygen delivery and metabolic rates.

Exercise Promotes Healthy Aging of Skeletal Muscle.

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Cartee, Gregory D; Hepple, Russell T; Bamman, Marcas M; Zierath, Juleen R

2016-06-14

Primary aging is the progressive and inevitable process of bodily deterioration during adulthood. In skeletal muscle, primary aging causes defective mitochondrial energetics and reduced muscle mass. Secondary aging refers to additional deleterious structural and functional age-related changes caused by diseases and lifestyle factors. Secondary aging can exacerbate deficits in mitochondrial function and muscle mass, concomitant with the development of skeletal muscle insulin resistance. Exercise opposes deleterious effects of secondary aging by preventing the decline in mitochondrial respiration, mitigating aging-related loss of muscle mass and enhancing insulin sensitivity. This review focuses on mechanisms by which exercise promotes "healthy aging" by inducing modifications in skeletal muscle. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of 12-wk eccentric calf muscle training on muscle-tendon glucose uptake and SEMG in patients with chronic Achilles tendon pain

DEFF Research Database (Denmark)

Masood, Tahir; Kalliokoski, Kari; Magnusson, S Peter

2014-01-01

High-load eccentric exercises have been a key component in the conservative management of chronic Achilles tendinopathy. This study investigated the effects of a 12-wk progressive, home-based eccentric rehabilitation program on ankle plantar flexors' glucose uptake (GU) and myoelectric activity......, while the asymptomatic leg displayed higher uptake for medial gastrocnemius and flexor hallucis longus (P tendon GU than the controls (P effect on the tendon GU. Concerning SEMG, at baseline, soleus showed more relative...... within- or between-group differences. Eccentric rehabilitation was effective in decreasing subjective severity of Achilles tendinopathy. It also resulted in redistribution of relative electrical activity, but not metabolic activity, within the triceps surae muscle....

What are the Physiological Mechanisms for Post-Exercise Cold Water Immersion in the Recovery from Prolonged Endurance and Intermittent Exercise?

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Ihsan, Mohammed; Watson, Greig; Abbiss, Chris R

2016-08-01

training performances. The efficacy of CWI for attenuating the secondary effects of EIMD seems dependent on the mode of exercise utilised. For instance, CWI application seems to demonstrate limited recovery benefits when EIMD was induced by single-joint eccentrically biased contractions. In contrast, CWI seems more effective in ameliorating effects of EIMD induced by whole body prolonged endurance/intermittent based exercise modalities.

Exercise-induced rhabdomyolysis from stationary biking: a case report.

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Inklebarger, J; Galanis, N; Kirkos, J; Kapetanos, G

2010-10-01

There are several reports concerning exercise and rabdomyolysis. There has been no report in the English literature of exercise induced rabdomyolisis from a stationary bike.A 63-year-old female recreational athlete presented to our hospital seeking treatment for lower back, leg pain and stiffness after exercising on a stationary bicycle one day prior. Blood work showed a raised CK of 38,120 U/L, a myoglobin of 5330 and an AST 495 U/L with normal urea and electrolytes. Urinalysis remained negative. She was admitted for oral and intravenous hydration and fluid balance monitoringThis is a very rare case of rhabdomyolysis due to exercise. This study highlights the difficulties faced by accident and emergency teams in distinguishing delayed onset muscle soreness (DOMS) from exercise-induced rhabdomyolysis, and reinforces the concept that rhabdomyolysis can occur at any level of exercise intensity.

Enhanced Glycogen Storage of a Subcellular Hot Spot in Human Skeletal Muscle during Early Recovery from Eccentric Contractions

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Nielsen, Joachim; Farup, Jean; Rahbek, Stine Klejs

2015-01-01

Unaccustomed eccentric exercise is accompanied by muscle damage and impaired glucose uptake and glycogen synthesis during subsequent recovery. Recently, it was shown that the role and regulation of glycogen in skeletal muscle are dependent on its subcellular localization, and that glycogen synthe...

Suppression of Ghrelin Exacerbates HFCS-Induced Adiposity and Insulin Resistance.

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Ma, Xiaojun; Lin, Ligen; Yue, Jing; Wu, Chia-Shan; Guo, Cathy A; Wang, Ruitao; Yu, Kai-Jiang; Devaraj, Sridevi; Murano, Peter; Chen, Zheng; Sun, Yuxiang

2017-06-19

High fructose corn syrup (HFCS) is widely used as sweetener in processed foods and soft drinks in the United States, largely substituting sucrose (SUC). The orexigenic hormone ghrelin promotes obesity and insulin resistance; ghrelin responds differently to HFCS and SUC ingestion. Here we investigated the roles of ghrelin in HFCS- and SUC-induced adiposity and insulin resistance. To mimic soft drinks, 10-week-old male wild-type (WT) and ghrelin knockout ( Ghrelin -/- ) mice were subjected to ad lib. regular chow diet supplemented with either water (RD), 8% HFCS (HFCS), or 10% sucrose (SUC). We found that SUC-feeding induced more robust increases in body weight and body fat than HFCS-feeding. Comparing to SUC-fed mice, HFCS-fed mice showed lower body weight but higher circulating glucose and insulin levels. Interestingly, we also found that ghrelin deletion exacerbates HFCS-induced adiposity and inflammation in adipose tissues, as well as whole-body insulin resistance. Our findings suggest that HFCS and SUC have differential effects on lipid metabolism: while sucrose promotes obesogenesis, HFCS primarily enhances inflammation and insulin resistance, and ghrelin confers protective effects for these metabolic dysfunctions.

Suppression of Ghrelin Exacerbates HFCS-Induced Adiposity and Insulin Resistance

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Xiaojun Ma

2017-06-01

Full Text Available High fructose corn syrup (HFCS is widely used as sweetener in processed foods and soft drinks in the United States, largely substituting sucrose (SUC. The orexigenic hormone ghrelin promotes obesity and insulin resistance; ghrelin responds differently to HFCS and SUC ingestion. Here we investigated the roles of ghrelin in HFCS- and SUC-induced adiposity and insulin resistance. To mimic soft drinks, 10-week-old male wild-type (WT and ghrelin knockout (Ghrelin−/− mice were subjected to ad lib. regular chow diet supplemented with either water (RD, 8% HFCS (HFCS, or 10% sucrose (SUC. We found that SUC-feeding induced more robust increases in body weight and body fat than HFCS-feeding. Comparing to SUC-fed mice, HFCS-fed mice showed lower body weight but higher circulating glucose and insulin levels. Interestingly, we also found that ghrelin deletion exacerbates HFCS-induced adiposity and inflammation in adipose tissues, as well as whole-body insulin resistance. Our findings suggest that HFCS and SUC have differential effects on lipid metabolism: while sucrose promotes obesogenesis, HFCS primarily enhances inflammation and insulin resistance, and ghrelin confers protective effects for these metabolic dysfunctions.

Eccentric, nonspinning, inspiral, Gaussian-process merger approximant for the detection and characterization of eccentric binary black hole mergers

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Huerta, E. A.; Moore, C. J.; Kumar, Prayush; George, Daniel; Chua, Alvin J. K.; Haas, Roland; Wessel, Erik; Johnson, Daniel; Glennon, Derek; Rebei, Adam; Holgado, A. Miguel; Gair, Jonathan R.; Pfeiffer, Harald P.

2018-01-01

We present ENIGMA, a time domain, inspiral-merger-ringdown waveform model that describes nonspinning binary black holes systems that evolve on moderately eccentric orbits. The inspiral evolution is described using a consistent combination of post-Newtonian theory, self-force and black hole perturbation theory. Assuming eccentric binaries that circularize prior to coalescence, we smoothly match the eccentric inspiral with a stand-alone, quasicircular merger, which is constructed using machine learning algorithms that are trained with quasicircular numerical relativity waveforms. We show that ENIGMA reproduces with excellent accuracy the dynamics of quasicircular compact binaries. We validate ENIGMA using a set of Einstein Toolkit eccentric numerical relativity waveforms, which describe eccentric binary black hole mergers with mass-ratios between 1 ≤q ≤5.5 , and eccentricities e0≲0.2 ten orbits before merger. We use this model to explore in detail the physics that can be extracted with moderately eccentric, nonspinning binary black hole mergers. In particular, we use ENIGMA to show that the gravitational wave transients GW150914, GW151226, GW170104, GW170814 and GW170608 can be effectively recovered with spinning, quasicircular templates if the eccentricity of these events at a gravitational wave frequency of 10 Hz satisfies e0≤{0.175 ,0.125 ,0.175 ,0.175 ,0.125 }, respectively. We show that if these systems have eccentricities e0˜0.1 at a gravitational wave frequency of 10 Hz, they can be misclassified as quasicircular binaries due to parameter space degeneracies between eccentricity and spin corrections. Using our catalog of eccentric numerical relativity simulations, we discuss the importance of including higher-order waveform multipoles in gravitational wave searches of eccentric binary black hole mergers.

Creep and cracking of concrete hinges: insight from centric and eccentric compression experiments.

Science.gov (United States)

Schlappal, Thomas; Schweigler, Michael; Gmainer, Susanne; Peyerl, Martin; Pichler, Bernhard

2017-01-01

Existing design guidelines for concrete hinges consider bending-induced tensile cracking, but the structural behavior is oversimplified to be time-independent. This is the motivation to study creep and bending-induced tensile cracking of initially monolithic concrete hinges systematically. Material tests on plain concrete specimens and structural tests on marginally reinforced concrete hinges are performed. The experiments characterize material and structural creep under centric compression as well as bending-induced tensile cracking and the interaction between creep and cracking of concrete hinges. As for the latter two aims, three nominally identical concrete hinges are subjected to short-term and to longer-term eccentric compression tests. Obtained material and structural creep functions referring to centric compression are found to be very similar. The structural creep activity under eccentric compression is significantly larger because of the interaction between creep and cracking, i.e. bending-induced cracks progressively open and propagate under sustained eccentric loading. As for concrete hinges in frame-like integral bridge construction, it is concluded (i) that realistic simulation of variable loads requires consideration of the here-studied time-dependent behavior and (ii) that permanent compressive normal forces shall be limited by 45% of the ultimate load carrying capacity, in order to avoid damage of concrete hinges under sustained loading.

Comparison of the Force-, Velocity- and Power-Time Curves Between the Concentric-Only and Eccentric-Concentric Bench Press Exercises.

Science.gov (United States)

Pérez-Castilla, Alejandro; Comfort, Paul; McMahon, John J; Pestaña-Melero, Francisco Luis; García-Ramos, Amador

2018-01-17

The aim of this study was to compare the temporal and mechanical variables between the concentric-only and eccentric-concentric bench press (BP) variants. Twenty-one men (age: 22.0±4.2 years, body mass: 73.4±7.7 kg, height: 177.2±8.0 cm; one-repetition maximum [1RM]: 1.12±0.12 kg⋅kg) were evaluated during the concentric-only and eccentric-concentric BP variants using 80% 1RM. Temporal (concentric phase duration, propulsive phase duration, and time to reach the maximum values of force, velocity, and power) and mechanical variables (force, velocity, and power), determined using a linear velocity transducer, were compared between both BP variants. All temporal variables were significantly lower during the eccentric-concentric BP compared to the concentric-only BP (P velocity and power were significantly higher for the eccentric-concentric BP compared to the concentric-only BP (all P velocity (ES: 0.40) and power (ES: 0.41). The stretch-shortening cycle (i.e., eccentric-concentric BP) mainly enhanced force production at the early portion of the concentric phase, but this potentiation effect gradually reduced over the latter part of the movement. Finally, force was higher for the concentric-only BP during 49% of the concentric phase duration. These results suggest that both BP variants should be included during resistance training programs in order to optimize force output at different points of the concentric phase.

Comparisons of eccentric knee flexor strength and asymmetries across elite, sub-elite and school level cricket players

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Wade J. Chalker

2016-02-01

Full Text Available Background. There has been a continual increase in injury rates in cricket, with hamstring strain injuries (HSIs being the most prominent. Eccentric knee flexor weakness and bilateral asymmetries are major modifiable risk factors for future HSIs. However, there is a lack of data relating to eccentric hamstring strength in cricket at any skill level. The objective of this study was to compare eccentric knee flexor strength and bilateral asymmetries in elite, sub-elite and school level cricket players; and to determine if playing position and limb role influenced these eccentric knee flexor strength indices. Methods. Seventy four male cricket players of three distinct skill levels performed three repetitions of the Nordic hamstring exercise on the experimental device. Strength was assessed as the absolute and relative mean peak force output for both limbs, with bilateral asymmetries. Differences in mean peak force outputs between skill level and playing positions were measured. Results. There were no significant differences between elite, sub-elite and school level athletes for mean peak force and bilateral asymmetries of the knee flexors. There were no significant differences observed between bowler’s and batter’s mean peak force and bilateral asymmetries. There were no significant differences between front and back limb mean peak force outputs. Discussion. Skill level, playing position and limb role appeared to have no significant effect on eccentric knee flexor strength and bilateral asymmetries. Future research should seek to determine whether eccentric knee flexor strength thresholds are predictive of HSIs in cricket and if specific eccentric knee flexor strengthening can reduce these injuries.

Beneficial effects of neuropeptide galanin on reinstatement of exercise-induced somatic and psychological trauma.

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He, Biao; Fang, Penghua; Guo, Lili; Shi, Mingyi; Zhu, Yan; Xu, Bo; Bo, Ping; Zhang, Zhenwen

2017-04-01

Galanin is a versatile neuropeptide that is distinctly upregulated by exercise in exercise-related tissues. Although benefits from exercise-induced upregulation of this peptide have been identified, many issues require additional exploration. This Review summarizes the information currently available on the relationship between galanin and exercise-induced physical and psychological damage. On the one hand, body movement, exercise damage, and exercise-induced stress and pain significantly increase local and circulatory galanin levels. On the other hand, galanin plays an exercise-protective role to inhibit the flexor reflex and prevent excessive movement of skeletal muscles through enhancing response threshold and reducing acetylcholine release. Additionally, elevated galanin levels can boost repair of the exercise-induced damage in exercise-related tissues, including peripheral nerve, skeletal muscle, blood vessel, skin, bone, articulation, and ligament. Moreover, elevated galanin levels may serve as effective signals to buffer sport-induced stress and pain via inhibiting nociceptive signal transmission and enhancing pain threshold. This Review deepens our understanding of the profitable roles of galanin in exercise protection, exercise injury repair, and exercise-induced stress and pain. Galanin and its agonists may be used to develop a novel preventive and therapeutic strategy to prevent and treat exercise-induced somatic and psychological trauma. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Inhibition of IKKβ in enterocytes exacerbates sepsis-induced intestinal injury and worsens mortality.

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Dominguez, Jessica A; Samocha, Alexandr J; Liang, Zhe; Burd, Eileen M; Farris, Alton B; Coopersmith, Craig M

2013-10-01

Nuclear factor-κB is a critical regulator of cell-survival genes and the host inflammatory response. The purpose of this study was to investigate the role of enterocyte-specific NF-kB in sepsis through selective ablation of IkB kinase. Prospective, randomized controlled study. Animal laboratories in university medical centers. Mice lacking functional NF-kB in their intestinal epithelium (Vil-Cre/Ikkβ) and wild-type mice were subjected to sham laparotomy or cecal ligation and puncture. Animals were killed at 24 hours or followed 7 days for survival. Septic wild-type mice had decreased villus length compared with sham mice, whereas villus atrophy was further exacerbated in septic Vil-Cre/Ikkβ mice. Sepsis induced an increase in intestinal epithelial apoptosis compared with sham mice, which was further exacerbated in Vil-Cre/Ikkβ mice. Sepsis induced intestinal hyperpermeability in wild-type mice compared with sham mice, which was further exacerbated in septic Vil-Cre/Ikkβ mice. This was associated with increased intestinal expression of claudin-2 in septic wild-type mice, which was further increased in septic Vil-Cre/Ikkβ mice. Both, pro-inflammatory and anti-inflammatory cytokines were increased in serum following cecal ligation and puncture, and interleukin 10 and monocyte chemoattractant protein-1 levels were higher in septic Vil-Cre/Ikkβ mice than in septic wild-type mice. All septic mice were bacteremic, but no differences in bacterial load were identified between wild-type and Vil-Cre/Ikkβ mice. To determine the functional significance of these results, animals were followed for survival. Septic wild-type mice had lower mortality than septic Vil-Cre/Ikkβ mice (47% vs 80%, p<0.05). Antitumor necrosis factor administration decreased intestinal apoptosis, permeability, and mortality in wild-type septic mice, and a similar improvement in intestinal integrity and survival were seen when antitumor necrosis factor was given to Vil-Cre/Ikkβ mice. Enterocyte

Inhibition of IKKß in enterocytes exacerbates sepsis-induced intestinal injury and worsens mortality

Science.gov (United States)

Dominguez, Jessica A.; Samocha, Alexandr J.; Liang, Zhe; Burd, Eileen M.; Farris, Alton B.; Coopersmith, Craig M.

2013-01-01

Objective NF-kB is a critical regulator of cell survival genes and the host inflammatory response. The purpose of this study was to investigate the role of enterocyte-specific NF-kB in sepsis through selective ablation of IkB kinase (IKK)-ß. Design Prospective, randomized, controlled study. Setting Animal laboratories in university medical centers. Subjects and Interventions Mice lacking functional NF-kB in their intestinal epithelium (Vil-Cre/Ikkßf/Δ) and wild type (WT) mice were subjected to sham laparotomy or cecal ligation and puncture (CLP). Animals were sacrified at 24 hours or followed seven days for survival. Measurements and Main Results Septic WT mice had decreased villus length compared to sham mice while villus atrophy was further exacerbated in septic Vil-Cre/Ikkßf/Δ mice. Sepsis induced an increase in intestinal epithelial apoptosis compared to sham mice which was further exacerbated in Vil-Cre/Ikkßf/Δ mice. Sepsis induced intestinal hyperpermeability in WT mice compared to sham mice, which was further exacerbated in septic Vil-Cre/Ikkßf/Δ mice. This was associated with increased intestinal expression of claudin-2 in septic WT mice, which was further increased in septic Vil-Cre/Ikkßf/Δ mice. Both, pro-inflammatory and anti-inflammatory cytokines were increased in serum following CLP, and IL-10 and MCP-1 levels were higher in septic Vil-Cre/Ikkßf/Δ mice than septic WT mice. All septic mice were bacteremic, but no differences in bacterial load were identified between WT and Vil-Cre/Ikkßf/Δ mice. To determine the functional significance of these results, animals were followed for survival. Septic WT mice had lower mortality than septic Vil-Cre/Ikkßf/Δ mice (47% vs. 80%, p<0.05). Anti-TNF administration decreased intestinal apoptosis, permeability and mortality in WT septic mice and a similar improvement in intestinal integrity and survival were seen when anti-TNF was given to Vil-Cre/Ikkßf/Δ mice. Conclusions Enterocyte-specific NF

Exercise-induced metallothionein expression in human skeletal muscle fibres

DEFF Research Database (Denmark)

Penkowa, Milena; Keller, Pernille; Keller, Charlotte

2005-01-01

in both type I and II muscle fibres. This is the first report demonstrating that MT-I + II are significantly induced in human skeletal muscle fibres following exercise. As MT-I + II are antioxidant factors that protect various tissues during pathological conditions, the MT-I + II increases post exercise......Exercise induces free oxygen radicals that cause oxidative stress, and metallothioneins (MTs) are increased in states of oxidative stress and possess anti-apoptotic effects. We therefore studied expression of the antioxidant factors metallothionein I and II (MT-I + II) in muscle biopsies obtained...... in response to 3 h of bicycle exercise performed by healthy men and in resting controls. Both MT-I + II proteins and MT-II mRNA expression increased significantly in both type I and II muscle fibres after exercise. Moreover, 24 h after exercise the levels of MT-II mRNA and MT-I + II proteins were still highly...

Oxidative Stress and Antioxidant Defense Mechanisms Linked to Exercise During Cardiopulmonary and Metabolic Disorders

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Kelsey Fisher-Wellman

2009-01-01

Full Text Available Oxidative stress has been implicated in the pathophysiology of multiple human diseases, in addition to the aging process. Although various stimuli exist, acute exercise is known to induce a transient increase in reactive oxygen and nitrogen species (RONS, evident by several reports of increased oxidative damage following acute bouts of aerobic and anaerobic exercise. Although the results are somewhat mixed and appear disease dependent, individuals with chronic disease experience an exacerbation in oxidative stress following acute exercise when compared to healthy individuals. However, this increased oxidant stress may serve as a necessary “signal” for the upregulation in antioxidant defenses, thereby providing protection against subsequent exposure to prooxidant environments within susceptible individuals. Here we present studies related to both acute exercise-induced oxidative stress in those with disease, in addition to studies focused on adaptations resulting from increased RONS exposure associated with chronic exercise training in persons with disease.

Exercise-Induced Oxidative Stress Responses in the Pediatric Population

Directory of Open Access Journals (Sweden)

Alexandra Avloniti

2017-01-01

Full Text Available Adults demonstrate an upregulation of their pro- and anti-oxidant mechanisms in response to acute exercise while systematic exercise training enhances their antioxidant capacity, thereby leading to a reduced generation of free radicals both at rest and in response to exercise stress. However, less information exists regarding oxidative stress responses and the underlying mechanisms in the pediatric population. Evidence suggests that exercise-induced redox perturbations may be valuable in order to monitor exercise-induced inflammatory responses and as such training overload in children and adolescents as well as monitor optimal growth and development. The purpose of this review was to provide an update on oxidative stress responses to acute and chronic exercise in youth. It has been documented that acute exercise induces age-specific transient alterations in both oxidant and antioxidant markers in children and adolescents. However, these responses seem to be affected by factors such as training phase, training load, fitness level, mode of exercise etc. In relation to chronic adaptation, the role of training on oxidative stress adaptation has not been adequately investigated. The two studies performed so far indicate that children and adolescents exhibit positive adaptations of their antioxidant system, as adults do. More studies are needed in order to shed light on oxidative stress and antioxidant responses, following acute exercise and training adaptations in youth. Available evidence suggests that small amounts of oxidative stress may be necessary for growth whereas the transition to adolescence from childhood may promote maturation of pro- and anti-oxidant mechanisms. Available evidence also suggests that obesity may negatively affect basal and exercise-related antioxidant responses in the peripubertal period during pre- and early-puberty.

Exercise does not protect against MPTP-induced neurotoxicity in BDNF haploinsufficient mice.

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Kim M Gerecke

Full Text Available Exercise has been demonstrated to potently protect substantia nigra pars compacta (SN dopaminergic neurons from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP-induced neurotoxicity. One mechanism proposed to account for this neuroprotection is the upregulation of neurotrophic factors. Several neurotrophic factors, including Brain Derived Neurotrophic Factor (BDNF, have been shown to upregulate in response to exercise. In order to determine if exercise-induced neuroprotection is dependent upon BDNF, we compared the neuroprotective effects of voluntary exercise in mice heterozygous for the BDNF gene (BDNF+/- with strain-matched wild-type (WT mice. Stereological estimates of SNpc DA neurons from WT mice allowed 90 days exercise via unrestricted running demonstrated complete protection against the MPTP-induced neurotoxicity. However, BDNF+/- mice allowed 90 days of unrestricted exercise were not protected from MPTP-induced SNpc DA neuron loss. Proteomic analysis comparing SN and striatum from 90 day exercised WT and BDNF+/- mice showed differential expression of proteins related to energy regulation, intracellular signaling and trafficking. These results suggest that a full genetic complement of BDNF is critical for the exercise-induced neuroprotection of SNpc DA neurons.

The Eccentric Behavior of Nearly Frozen Orbits

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Sweetser, Theodore H.; Vincent, Mark A.

2013-01-01

Frozen orbits are orbits which have only short-period changes in their mean eccentricity and argument of periapse, so that they basically keep a fixed orientation within their plane of motion. Nearly frozen orbits are those whose eccentricity and argument of periapse have values close to those of a frozen orbit. We call them "nearly" frozen because their eccentricity vector (a vector whose polar coordinates are eccentricity and argument of periapse) will stay within a bounded distance from the frozen orbit eccentricity vector, circulating around it over time. For highly inclined orbits around the Earth, this distance is effectively constant over time. Furthermore, frozen orbit eccentricity values are low enough that these orbits are essentially eccentric (i.e., off center) circles, so that nearly frozen orbits around Earth are bounded above and below by frozen orbits.

Food-Dependent, Exercise-Induced Anaphylaxis: Diagnosis and Management in the Outpatient Setting.

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Feldweg, Anna M

Food-dependent, exercise-induced anaphylaxis is a disorder in which anaphylaxis develops most predictably during exercise, when exercise takes place within a few hours of ingesting a specific food. IgE to that food should be demonstrable. It is the combination of the food and exercise that precipitates attacks, whereas the food and exercise are each tolerated independently. Recently, it was demonstrated that exercise is not essential for the development of symptoms, and that if enough of the culprit food is ingested, often with additional augmentation factors, such as alcohol or acetylsalicylic acid, symptoms can be induced at rest in the challenge setting. Thus, food-dependent, exercise-induced anaphylaxis appears to be more correctly characterized as a food allergy syndrome in which symptoms develop only in the presence of various augmentation factors, with exercise being the primary one. However, additional factors are not usually present when the patient exercises normally, so ongoing investigation is needed into the physiologic and cellular changes that occur during exercise to facilitate food-induced anaphylaxis. Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Exercise reverses metabolic syndrome in high-fat diet-induced obese rats.

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Touati, Sabeur; Meziri, Fayçal; Devaux, Sylvie; Berthelot, Alain; Touyz, Rhian M; Laurant, Pascal

2011-03-01

Chronic consumption of a high-fat diet induces obesity. We investigated whether exercise would reverse the cardiometabolic disorders associated with obesity without it being necessary to change from a high- to normal-fat diet. Sprague-Dawley rats were placed on a high-fat (HFD) or control diet (CD) for 12 wk. HFD rats were then divided into four groups: sedentary HFD (HFD-S), exercise trained (motor treadmill for 12 wk) HFD (HFD-Ex), modified diet (HFD to CD; HF/CD-S), and exercise trained with modified diet (HF/CD-Ex). Cardiovascular risk parameters associated with metabolic syndrome were measured, and contents of aortic Akt, phospho-Akt at Ser (473), total endothelial nitric oxide synthase (eNOS), and phospho-eNOS at Ser (1177) were determined by Western blotting. Chronic consumption of HFD induced a metabolic syndrome. Exercise and dietary modifications reduced adiposity, improved glucose and insulin levels and plasma lipid profile, and exerted an antihypertensive effect. Exercise was more effective than dietary modification in improving plasma levels of thiobarbituric acid-reacting substance and in correcting the endothelium-dependent relaxation to acetylcholine and insulin. Furthermore, independent of the diet used, exercise increased Akt and eNOS phosphorylation. Metabolic syndrome induced by HFD is reversed by exercise and diet modification. It is demonstrated that exercise training induces these beneficial effects without the requirement for dietary modification, and these beneficial effects may be mediated by shear stress-induced Akt/eNOS pathway activation. Thus, exercise may be an effective strategy to reverse almost all the atherosclerotic risk factors linked to obesity, particularly in the vasculature.

Thyroid Echography-induced Thyroid Storm and Exacerbation of Acute Heart Failure.

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Nakabayashi, Keisuke; Nakazawa, Naomi; Suzuki, Toshiaki; Asano, Ryotaro; Saito, Hideki; Nomura, Hidekimi; Isomura, Daichi; Okada, Hisayuki; Sugiura, Ryo; Oka, Toshiaki

2016-01-01

Hyperthyroidism and thyroid storm affect cardiac circulation in some conditions. Several factors including trauma can induce thyroid storms. We herein describe the case of a 57-year-old woman who experienced a thyroid storm and exacerbation of acute heart failure on thyroid echography. She initially demonstrated a good clinical course after medical rate control for atrial fibrillation; however, thyroid echography for evaluating hyperthyroidism led to a thyroid storm and she collapsed. A multidisciplinary approach stabilized her thyroid hormone levels and hemodynamics. Thus, the medical staff should be prepared for a deterioration in the patient's condition during thyroid echography in heart failure patients with hyperthyroidism.

Exercise-induced arteriovenous intrapulmonary shunting in dogs.

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Stickland, Michael K; Lovering, Andrew T; Eldridge, Marlowe W

2007-08-01

We have previously shown, using contrast echocardiography, that intrapulmonary arteriovenous pathways are inducible in healthy humans during exercise; however, this technique does not allow for determination of arteriovenous vessel size or shunt magnitude. The purpose of this study was to determine whether large-diameter (more than 25 microm) intrapulmonary arteriovenous pathways are present in the dog, and whether exercise recruits these conduits. Through the right forelimb, 10.8 million 25-microm stable isotope-labeled microspheres (BioPAL, Inc., Worcester, MA) were injected either at rest (n = 8) or during high-intensity exercise (6- 8 mph, 10-15% grade, n = 6). Systemic arterial blood was continuously sampled during and for 3 minutes after injection. After euthanasia, tissue samples were obtained from the heart, liver, kidney, and skeletal muscle. In addition, 25- and 50-microm microspheres were infused into four isolated dog lungs that were ventilated and perfused at constant pressures similar to exercise. Blood and tissue samples were commercially analyzed for the presence of microspheres. No microspheres were detected in the arterial blood or tissue samples from resting dogs. In contrast, five of six exercising dogs showed evidence of exercise-induced intrapulmonary arteriovenous shunting, as microspheres were detected in arterial blood and/or tissue. Furthermore, shunt magnitude was calculated to be 1.4 +/- 0.8% of cardiac output (n = 3). Evidence of intrapulmonary arteriovenous anastomoses was also found in three of four isolated lungs. Consistent with previous human findings, these data demonstrate that intrapulmonary arteriovenous pathways are functional in the dog and are recruited with exercise.

Self-selected music-induced reduction of perceived exertion during moderate-intensity exercise does not interfere with post-exercise improvements in inhibitory control.

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Tanaka, Daichi; Tsukamoto, Hayato; Suga, Tadashi; Takenaka, Saki; Hamaoka, Takafumi; Hashimoto, Takeshi; Isaka, Tadao

2018-05-26

Acute aerobic exercise improves inhibitory control (IC). This improvement is often associated with increases in perceived exertion during exercise. However, listening to music during aerobic exercise mitigates an exercise-induced increase in perceived exertion. Thus, it is hypothesized that such effects of music may interfere with exercise-induced improvements in IC. To test this hypothesis, we examined the effect of music on post-exercise IC improvements that were induced by moderate-intensity exercise. Fifteen healthy young men performed cycle ergometer exercise with music or non-music. The exercise was performed using a moderate-intensity of 60% of VO 2 peak for 30 min. The music condition was performed while listening to self-selected music. The non-music condition involved no music. To evaluate IC, the Stroop task was administered before exercise, immediately after exercise, and during the 30-min post-exercise recovery period. The rate of perceived exertion immediately before moderate-intensity exercise completed was significantly lower in music condition than in non-music condition. The IC significantly improved immediately after exercise and during the post-exercise recovery period compared to before exercise in both music and non-music conditions. The post-exercise IC improvements did not significantly differ between the two conditions. These findings indicate that self-selected music-induced mitigation of the increase in perceived exertion during moderate-intensity exercise dose not interfere with exercise-induced improvements in IC. Therefore, we suggest that listening to music may be a beneficial strategy in mitigating the increase in perceived exertion during aerobic exercise without decreasing the positive effects on IC. Copyright © 2018 Elsevier Inc. All rights reserved.

A STRANGE STAR SCENARIO FOR THE FORMATION OF ECCENTRIC MILLISECOND PULSAR/HELIUM WHITE DWARF BINARIES

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Jiang, Long; Li, Xiang-Dong [Department of Astronomy, Nanjing University, Nanjing 210046 (China); Dey, Jishnu; Dey, Mira, E-mail: lixd@nju.edu.cn [Department of Physics, Presidency University, 86/1, College Street, Kolkata 700 073 (India)

2015-07-01

According to the recycling scenario, millisecond pulsars (MSPs) have evolved from low-mass X-ray binaries (LMXBs). Their orbits are expected to be circular due to tidal interactions during binary evolution, as observed in most binary MSPs. There are some peculiar systems that do not fit this picture. Three recent examples are the PSRs J2234+06, J1946+3417, and J1950+2414, all of which are MSPs in eccentric orbits but with mass functions compatible with expected He white dwarf (WD) companions. It has been suggested these MSPs may have formed from delayed accretion-induced collapse of massive WDs, or the eccentricity may be induced by dynamical interaction between the binary and a circumbinary disk. Assuming that the core density of accreting neutron stars (NSs) in LMXBs may reach the density of quark deconfinement, which can lead to phase transition from NSs to strange quark stars, we show that the resultant MSPs are likely to have an eccentric orbit, due to the sudden loss of the gravitational mass of the NS during the transition. The eccentricities can be reproduced with a reasonable estimate of the mass loss. This scenario might also account for the formation of the youngest known X-ray binary Cir X–1, which also possesses a low-field compact star in an eccentric orbit.

Eccentric strengthening effect of hip-adductor training with elastic bands in soccer players

DEFF Research Database (Denmark)

Jensen, Jesper; Hölmich, Per; Bandholm, Thomas

2014-01-01

programme, including one hip-adduction exercise, on eccentric and isometric hip-adduction strength, using elastic bands as external load. METHODS: Thirty-four healthy, sub-elite soccer players, mean (±SD) age of 22.1 (±3.3) years, were randomised to either training or control. During the mid-season break......BACKGROUND: Soccer players with weak hip-adductor muscles are at increased risk of sustaining groin injuries. Therefore, a simple hip-adductor strengthening programme for prevention of groin injuries is needed. OBJECTIVE: We aimed to investigate the effect of an 8-week hip-adductor strengthening...... sessions per week (weeks 7-8) with 3×8 RM. Eccentric hip-adduction (EHAD), isometric hip-adduction (IHAD) and isometric hip-abduction (IHAB) strength, and the IHAD/IHAB ratio were measured assessor-blinded preintervention and postintervention, using reliable hand-held dynamometry procedures. RESULTS...

Exercise facilitates early recognition of cardiac and vascular remodeling in chronic thromboembolic pulmonary hypertension in swine.

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Stam, Kelly; van Duin, Richard W B; Uitterdijk, André; Cai, Zongye; Duncker, Dirk J; Merkus, Daphne

2018-03-01

Chronic thromboembolic pulmonary hypertension (CTEPH) develops in 4% of patients after pulmonary embolism and is accompanied by an impaired exercise tolerance, which is ascribed to the increased right ventricular (RV) afterload in combination with a ventilation/perfusion (V/Q) mismatch in the lungs. The present study aimed to investigate changes in arterial Po 2 and hemodynamics in response to graded treadmill exercise during development and progression of CTEPH in a novel swine model. Swine were chronically instrumented and received multiple pulmonary embolisms by 1) microsphere infusion (Spheres) over 5 wk, 2) endothelial dysfunction by administration of the endothelial nitric oxide synthase inhibitor N ω -nitro-l-arginine methyl ester (L-NAME) for 7 wk, 3) combined pulmonary embolisms and endothelial dysfunction (L-NAME + Spheres), or 4) served as sham-operated controls (sham). After a 9 wk followup, embolization combined with endothelial dysfunction resulted in CTEPH, as evidenced by mean pulmonary artery pressures of 39.5 ± 5.1 vs. 19.1 ± 1.5 mmHg (Spheres, P swine to result in an exercise-induced increase in cardiac index. In conclusion, embolization in combination with endothelial dysfunction results in CTEPH in swine. Exercise increased RV afterload, exacerbated the V/Q mismatch, and unmasked RV dysfunction. NEW & NOTEWORTHY Here, we present the first double-hit chronic thromboembolic pulmonary hypertension swine model. We show that embolization as well as endothelial dysfunction is required to induce sustained pulmonary hypertension, which is accompanied by altered exercise hemodynamics and an exacerbated ventilation/perfusion mismatch during exercise.

Putative benefits of microalgal astaxanthin on exercise and human health

Directory of Open Access Journals (Sweden)

Marcelo P. Barros

2011-04-01

Full Text Available Astaxanthin (ASTA is a pinkish-orange carotenoid produced by microalgae, but also commonly found in shrimp, lobster and salmon, which accumulate ASTA from the aquatic food chain. Numerous studies have addressed the benefits of ASTA for human health, including the inhibition of LDL oxidation, UV-photoprotection and prophylaxis of bacterial stomach ulcers. ASTA is recognized as a powerful scavenger of reactive oxygen species (ROS, especially those involved in lipid peroxidation. Both aerobic and anaerobic exercise are closely related to overproduction of ROS in muscle tissue. Post-exercise inflammatory processes can even exacerbate the oxidative stress imposed by exercise. Thus, ASTA is suggested here as a putative nutritional alternative/coadjutant for antioxidant therapy to afford additional protection to muscle tissues against oxidative damage induced by exercise, as well as for an (overall integrative redox re-balance and general human health.

Size, shape, and stamina: the impact of left ventricular geometry on exercise capacity.

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Lam, Carolyn S P; Grewal, Jasmine; Borlaug, Barry A; Ommen, Steve R; Kane, Garvan C; McCully, Robert B; Pellikka, Patricia A

2010-05-01

Although several studies have examined the cardiac functional determinants of exercise capacity, few have investigated the effects of structural remodeling. The current study evaluated the association between cardiac geometry and exercise capacity. Subjects with ejection fraction > or = 50% and no valvular disease, myocardial ischemia, or arrhythmias were identified from a large prospective exercise echocardiography database. Left ventricular mass index and relative wall thickness were used to classify geometry into normal, concentric remodeling, eccentric hypertrophy, and concentric hypertrophy. All of the subjects underwent symptom-limited treadmill exercise according to standard Bruce protocol. Maximal exercise tolerance was measured in metabolic equivalents. Of 366 (60+/-14 years; 57% male) subjects, 166 (45%) had normal geometry, 106 (29%) had concentric remodeling, 40 (11%) had eccentric hypertrophy, and 54 (15%) had concentric hypertrophy. Geometry was related to exercise capacity: in descending order, the maximum achieved metabolic equivalents were 9.9+/-2.8 in normal, 8.9+/-2.6 in concentric remodeling, 8.6+/-3.1 in eccentric hypertrophy, and 8.0+/-2.7 in concentric hypertrophy (all P<0.02 versus normal). Left ventricular mass index and relative wall thickness were negatively correlated with exercise tolerance in metabolic equivalents (r=-0.14; P=0.009 and r=-0.21; P<0.001, respectively). Augmentation of heart rate and ejection fraction with exercise were blunted in concentric hypertrophy compared with normal, even after adjusting for medications. In conclusion, the pattern of ventricular remodeling is related to exercise capacity among low-risk adults. Subjects with concentric hypertrophy display the greatest limitation, and this is related to reduced systolic and chronotropic reserve. Reverse remodeling strategies may prevent or treat functional decline in patients with structural heart disease.

Moderate exercise prevents neurodegeneration in D-galactose-induced aging mice

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Li Li

2016-01-01

Full Text Available D-galactose has been widely used in aging research because of its efficacy in inducing senescence and accelerating aging in animal models. The present study investigated the benefits of exercise for preventing neurodegeneration, such as synaptic plasticity, spatial learning and memory abilities, in mouse models of aging. D-galactose-induced aging mice were administered daily subcutaneous injections of D-galactose at the base of the neck for 10 consecutive weeks. Then, the mice were subjected to exercise training by running on a treadmill for 6 days a week. Shortened escape latency in a Morris water maze test indicated that exercise improved learning and memory in aging mice. The ameliorative changes were likely induced by an upregulation of Bcl-2 and brain-derived neurotrophic factor, the repression of apoptosis factors such as Fas and Bax, and an increase in the activity of glucose transporters-1 and 4. The data suggest moderate exercise may retard or inhibit neurodegeneration in D-galactose-induced aging mice.

Reduced firing rates of high threshold motor units in response to eccentric overload.

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Balshaw, Tom G; Pahar, Madhu; Chesham, Ross; Macgregor, Lewis J; Hunter, Angus M

2017-01-01

Acute responses of motor units were investigated during submaximal voluntary isometric tasks following eccentric overload (EO) and constant load (CL) knee extension resistance exercise. Ten healthy resistance-trained participants performed four experimental test sessions separated by 5 days over a 20 day period. Two sessions involved constant load and the other two used eccentric overload. EO and CL used both sessions for different target knee eccentric extension phases; one at 2 sec and the other at 4 sec. Maximal voluntary contractions (MVC) and isometric trapezoid efforts for 10 sec at 70% MVC were completed before and after each intervention and decomposed electromyography was used to measure motor unit firing rate. The firing rate of later recruited, high-threshold motor units declined following the 2-sec EO but was maintained following 2sec CL (P motor units were maintained for both loading types following 4-sec extension phases. MVC and rate of force development where maintained following both EO and CL and 2 and 4 sec phases. This study demonstrates a slower firing rate of high-threshold motor units following fast eccentric overload while MVC was maintained. This suggests that there was a neuromuscular stimulus without cost to the force-generating capacity of the knee extensors. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

An increase in the number of admitted patients with exercise-induced rhabdomyolysis.

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Aalborg, Christian; Rød-Larsen, Cecilie; Leiro, Ingjerd; Aasebø, Willy

2016-10-01

Rhabdomyolysis may lead to serious complications, and treatment is both time-consuming and costly. The condition can be caused by many factors, including intense exercise. The purpose of this study was to investigate whether the number of hospitalisations due to exercise-induced rhabdomyolysis has changed in recent years. We describe the disease course in hospitalised patients, and compare disease course in individuals with exercise-induced rhabdomyolysis and rhabdomyolysis due to other causes. The study is a systematic review of medical records from Akershus University Hospital for the years 2008 and 2011 – 14. All hospitalised patients with diagnostic codes M62.8, M62.9 and T79.6 and creatine kinase levels > 5 000 IU/l were included. The cause of the rhabdomyolysis was recorded in addition to patient characteristics and the results of various laboratory tests. Of 161 patients who were hospitalised with rhabdomyolysis during the study period, 44 cases (27  %) were classified as exercise-induced. In 2008 there were no admissions due to exercise-induced rhabdomyolysis; in 2011 and 2012 there were six and four admissions respectively, while in 2014 there were 22. This gives an estimated incidence of 0.8/100 000 in 2012 and 4.6/100 000 in 2014. Strength-training was the cause of hospitalisation in 35 patients (80  % of the exercise-induced cases). Three patients (7  % of the exercise-induced cases) had transient stage 1 kidney injury, but there were no cases with stage 2 or stage 3 injury. By comparison, 52  % of patients with rhabdomyolysis due to another cause had kidney injury, of which 28  % was stage 2 or 3. The number of persons hospitalised with exercise-induced rhabdomyolysis has increased four-fold from 2011 to 2014, possibly due to changes in exercise habits in the population. None of the patients with exercise-induced rhabdomyolysis had serological signs of kidney injury upon hospital discharge.

Effects of adding a weekly eccentric-overload training session on strength and athletic performance in team-handball players.

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Sabido, Rafael; Hernández-Davó, Jose Luis; Botella, Javier; Navarro, Angel; Tous-Fajardo, Julio

2017-06-01

To investigate the influence of adding a weekly eccentric-overload training (EOT) session in several athletic performance's tests, 18 team-handball players were assigned either to an EOT (n = 11) or a Control (n = 7) group. Both groups continued to perform the same habitual strength training, but the EOT group added one session/week during a 7-week training programme consisting of four sets of eight repetitions for the bilateral half-squat and unilateral lunge exercises. The test battery included handball throwing velocity, maximum dynamic strength (1RM), countermovement jump (CMJ), 20 m sprint, triple hop for distance, and eccentric/concentric power in both the half-squat and lunge exercises. Data were analysed using magnitude-based inferences. Both groups improved their 1RM in the half squat, 20 m sprint time, and CMJ performance to a similar extent, but the EOT group showed a beneficial effect for both right [(42/58/0), possibly positive] and left [(99/1/0), very likely positive] triple hop for distance performance. In addition, the EOT group showed greater power output improvements in both eccentric and concentric phases of the half-squat (difference in percent of change ranging from 6.5% to 22.0%) and lunge exercises (difference in per cent of change ranging from 13.1% to 24.9%). Nevertheless, no group showed changes in handball throwing velocity. Selected variables related to team-handball performance (i.e. functional jumping performance, power output) can be improved by adding a single EOT session per week, highlighting the usefulness of this low-volume/high-intensity training when aiming at optimizing dynamic athletic performance.

The effect of exercise repetition on the frequency characteristics of motor output force: implications for Achilles tendinopathy rehabilitation.

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Grigg, Nicole L; Wearing, Scott C; O'Toole, John M; Smeathers, James E

2014-01-01

To investigate the frequency characteristics of the ground reaction force (GRF) recorded throughout the eccentric Achilles tendon rehabilitation programme described by Alfredson. Controlled laboratory study, longitudinal. Nine healthy adult males performed six sets (15 repetitions per set) of eccentric ankle exercise. Ground reaction force was recorded throughout the exercise protocol. For each exercise repetition the frequency power spectrum of the resultant ground reaction force was calculated and normalised to total power. The magnitude of peak relative power within the 8-12 Hz bandwidth and the frequency at which this peak occurred was determined. The magnitude of peak relative power within the 8-12 Hz bandwidth increased with each successive exercise set and following the 4th set (60 repetitions) of exercise the frequency at which peak relative power occurred shifted from 9 to 10 Hz. The increase in magnitude and frequency of ground reaction force vibrations with an increasing number of exercise repetitions is likely connected to changes in muscle activation with fatigue and tendon conditioning. This research illustrates the potential for the number of exercise repetitions performed to influence the tendons' mechanical environment, with implications for tendon remodelling and the clinical efficacy of eccentric rehabilitation programmes for Achilles tendinopathy. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Introducing Earth's Orbital Eccentricity

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Oostra, Benjamin

2015-01-01

Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

Doxorubicin induced myocardial injury is exacerbated following ischaemic stress via opening of the mitochondrial permeability transition pore

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Gharanei, M.; Hussain, A. [Department of Biomolecular and Sport Sciences, Coventry University, Cox Street, Coventry, CV1 5FB (United Kingdom); Janneh, O. [Department of Biomolecular and Sport Sciences, Coventry University, Cox Street, Coventry, CV1 5FB (United Kingdom); Pharmacology Research Laboratories, 70, Pembroke Place, The University of Liverpool, Liverpool. L69 3GF (United Kingdom); Maddock, H.L., E-mail: h.maddock@coventry.ac.uk [Department of Biomolecular and Sport Sciences, Coventry University, Cox Street, Coventry, CV1 5FB (United Kingdom)

2013-04-15

Chemotherapeutic agents such as doxorubicin are known to cause or exacerbate cardiovascular cell death when an underlying heart condition is present. However, the mechanism of doxorubicin-induced cardiotoxicity is unclear. Here we assess the cardiotoxic effects of doxorubicin in conditions of myocardial ischaemia reperfusion and the mechanistic basis of protection, in particular the role of the mitochondrial permeability transition pore (mPTP) in such protection. The effects of doxorubicin (1 μM) ± cyclosporine A (CsA, 0.2 μM; inhibits mPTP) were investigated in isolated male Sprague–Dawley rats using Langendorff heart and papillary muscle contraction models subjected to simulated ischaemia and reperfusion injury. Isolated rat cardiac myocytes were used in an oxidative stress model to study the effects of drug treatment on mPTP by confocal microscopy. Western blot analysis evaluated the effects of drug treatment on p-Akt and p-Erk 1/2 levels. Langendorff and the isometric contraction models showed a detrimental effect of doxorubicin throughout reperfusion/reoxygenation as well as increased p-Akt and p-Erk levels. Interestingly, CsA not only reversed the detrimental effects of doxorubicin, but also reduced p-Akt and p-Erk levels. In the sustained oxidative stress assay to study mPTP opening, doxorubicin decreased the time taken to depolarization and hypercontracture, but these effects were delayed in the presence of CsA. Collectively, our data suggest for the first that doxorubicin exacerbates myocardial injury in an ischaemia reperfusion model. If the inhibition of mPTP ameliorates the cardiotoxic effects of doxorubicin, then more selective inhibitors of mPTP should be further investigated for their utility in patients receiving doxorubicin. - Highlights: ► Doxorubicin exacerbates myocardial ischaemia reperfusion injury. ► Co-treatment with CsA protects against doxorubicin induced myocardial injury. ► CsA delays doxorubicin induced mPTP opening in laser

Doxorubicin induced myocardial injury is exacerbated following ischaemic stress via opening of the mitochondrial permeability transition pore

International Nuclear Information System (INIS)

Gharanei, M.; Hussain, A.; Janneh, O.; Maddock, H.L.

2013-01-01

Chemotherapeutic agents such as doxorubicin are known to cause or exacerbate cardiovascular cell death when an underlying heart condition is present. However, the mechanism of doxorubicin-induced cardiotoxicity is unclear. Here we assess the cardiotoxic effects of doxorubicin in conditions of myocardial ischaemia reperfusion and the mechanistic basis of protection, in particular the role of the mitochondrial permeability transition pore (mPTP) in such protection. The effects of doxorubicin (1 μM) ± cyclosporine A (CsA, 0.2 μM; inhibits mPTP) were investigated in isolated male Sprague–Dawley rats using Langendorff heart and papillary muscle contraction models subjected to simulated ischaemia and reperfusion injury. Isolated rat cardiac myocytes were used in an oxidative stress model to study the effects of drug treatment on mPTP by confocal microscopy. Western blot analysis evaluated the effects of drug treatment on p-Akt and p-Erk 1/2 levels. Langendorff and the isometric contraction models showed a detrimental effect of doxorubicin throughout reperfusion/reoxygenation as well as increased p-Akt and p-Erk levels. Interestingly, CsA not only reversed the detrimental effects of doxorubicin, but also reduced p-Akt and p-Erk levels. In the sustained oxidative stress assay to study mPTP opening, doxorubicin decreased the time taken to depolarization and hypercontracture, but these effects were delayed in the presence of CsA. Collectively, our data suggest for the first that doxorubicin exacerbates myocardial injury in an ischaemia reperfusion model. If the inhibition of mPTP ameliorates the cardiotoxic effects of doxorubicin, then more selective inhibitors of mPTP should be further investigated for their utility in patients receiving doxorubicin. - Highlights: ► Doxorubicin exacerbates myocardial ischaemia reperfusion injury. ► Co-treatment with CsA protects against doxorubicin induced myocardial injury. ► CsA delays doxorubicin induced mPTP opening in laser

Effectiveness of Hamstring Knee Rehabilitation Exercise Performed in Training Machine vs. Elastic Resistance Electromyography Evaluation Study

DEFF Research Database (Denmark)

Jakobsen, M. D.; Sundstrup, E.; Andersen, C. H.

2014-01-01

Objective The aim of this study was to evaluate muscle activity during hamstring rehabilitation exercises performed in training machine compared with elastic resistance. Design Six women and 13 men aged 28-67 yrs participated in a crossover study. Electromyographic (EMG) activity was recorded...... inclinometers. Results Training machines and elastic resistance showed similar high levels of muscle activity (biceps femoris and semitendinosus peak normalized EMG >80%). EMG during the concentric phase was higher than during the eccentric phase regardless of exercise and muscle. However, compared with machine.......001) during hamstring curl performed with elastic resistance (7.58 +/- 0.08) compared with hamstring curl performed in a machine (5.92 +/- 0.03). Conclusions Hamstring rehabilitation exercise performed with elastic resistance induces similar peak hamstring muscle activity but slightly lower EMG values at more...

Cerebral responses to exercise and the influence of heat stress in human fatigue.

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Robertson, Caroline V; Marino, Frank E

2017-01-01

There are a number of mechanisms thought to be responsible for the onset of fatigue during exercise-induced hyperthermia. A greater understanding of the way in which fatigue develops during exercise could be gleaned from the studies which have examined the maintenance of cerebral blood flow through the process of cerebral autoregulation. Given that cerebral blood flow is a measure of the cerebral haemodynamics, and might reflect a level of brain activation, it is useful to understand the implications of this response during exercise and in the development of fatigue. It is known that cerebral blood flow is significantly altered under certain conditions such as altitude and exacerbated during exercise induced - hyperthermia. In this brief review we consider the processes of cerebral autoregulation predominantly through the measurement of cerebral blood flow and contrast these responses between exercise undertaken in normothermic versus heat stress conditions in order to draw some conclusions about the role cerebral blood flow might play in determining fatigue. Copyright © 2016. Published by Elsevier Ltd.

Dietary quercetin exacerbates the development of estrogen-induced breast tumors in female ACI rats

International Nuclear Information System (INIS)

Singh, Bhupendra; Mense, Sarah M.; Bhat, Nimee K.; Putty, Sandeep; Guthiel, William A.; Remotti, Fabrizio; Bhat, Hari K.

2010-01-01

Phytoestrogens are plant compounds that structurally mimic the endogenous estrogen 17β-estradiol (E 2 ). Despite intense investigation, the net effect of phytoestrogen exposure on the breast remains unclear. The objective of the current study was to examine the effects of quercetin on E 2 -induced breast cancer in vivo. Female ACI rats were given quercetin (2.5 g/kg food) for 8 months. Animals were monitored weekly for palpable tumors, and at the end of the experiment, rats were euthanized, breast tumor and different tissues excised so that they could be examined for histopathologic changes, estrogen metabolic activity and oxidant stress. Quercetin alone did not induce mammary tumors in female ACI rats. However, in rats implanted with E 2 pellets, co-exposure to quercetin did not protect rats from E 2 -induced breast tumor development with 100% of the animals developing breast tumors within 8 months of treatment. No changes in serum quercetin levels were observed in quercetin and quercetin + E 2 -treated groups at the end of the experiment. Tumor latency was significantly decreased among rats from the quercetin + E 2 group relative to those in the E 2 group. Catechol-O-methyltransferase (COMT) activity was significantly downregulated in quercetin-exposed mammary tissue. Analysis of 8-isoprostane F 2α (8-iso-PGF 2α ) levels as a marker of oxidant stress showed that quercetin did not decrease E 2 -induced oxidant stress. These results indicate that quercetin (2.5 g/kg food) does not confer protection against breast cancer, does not inhibit E 2 -induced oxidant stress and may exacerbate breast carcinogenesis in E 2 -treated ACI rats. Inhibition of COMT activity by quercetin may expose breast cells chronically to E 2 and catechol estrogens. This would permit longer exposure times to the carcinogenic metabolites of E 2 and chronic exposure to oxidant stress as a result of metabolic redox cycling to estrogen metabolites, and thus quercetin may exacerbate E 2 -induced

Effects of eccentric-focused and conventional resistance training on strength and functional capacity of older adults.

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Dias, Caroline Pieta; Toscan, Rafael; de Camargo, Mainara; Pereira, Evelyn Possobom; Griebler, Nathália; Baroni, Bruno Manfredini; Tiggemann, Carlos Leandro

2015-10-01

The aim of the study was to assess the effect of eccentric training using a constant load with longer exposure time at the eccentric phase on knee extensor muscle strength and functional capacity of elderly subjects in comparison with a conventional resistance training program. Twenty-six healthy elderly women (age = 67 ± 6 years) were randomly assigned to an eccentric-focused training group (ETG; n = 13) or a conventional training group (CTG; n = 13). Subjects underwent 12 weeks of resistance training twice a week. For the ETG, concentric and eccentric phases were performed using 1.5 and 4.5 s, respectively, while for CTG, each phase lasted 1.5 s. Maximum dynamic strength was assessed by the one-repetition maximum (1RM) test in the leg press and knee extension exercises, and for functional capacity, subjects performed specific tests (6-m walk test, timed up-and-go test, stair-climbing test, and chair-rising test). Both groups improved knee extension 1RM (24-26 %; p = 0.021), timed up-and-go test (11-16 %; p training volume and intensity does not promote different adaptations in strength or functional capacity compared to conventional resistance training in elderly woman.

[Benefits of Decumanum Phlebodium intake on the muscle damage in the response to intense physical exercise in sedentary subjects].

Science.gov (United States)

Vargas Corzo, M C; Aguilar Cordero, M J; de Teresa Galván, C; Segura Millán, D; Miranda Leon, M T; Castillo Rueda, G; Guisado Barrilao, R

2014-06-01

Intense physical exercise provoke muscle damage, that in sedentary people can increase cardiovascular risk. Phlebodium decumanum (PD) has shown to have immunomodulator effects in models of moderate intense physical activities in well conditioned groups. To evaluate the PD effects during eccentric exercise, as a model of muscle inflammation protocol, on a sedentary population with cardiovascular risk. This is an experimental, double-blind, multigroup randomized study. Experimental Group 1 (n = 17)received PD, 9 doses of 400 mg (total amount 3.6 g) every 8 hours during 3 days, and Control Group 2 (n = 16)received a placebo. All the subjects performed two treadmill ergoespirometry tests: first, a modified Bruce protocol to discard ischemic responses during exercise and to evaluate VO2max before the experimental phase;and second, with an eccentric protocol (14% descending ramp test) during 10 minutes in stable state at 70-80%VO2max, as experimental inflammatory protocol.We compared intra and inter groups to evaluate differences in the pre and post-test differences results on blood muscle damage variables. The study shown statistically significant differences in all pre-post intra-groups results in muscle damage variables (CK, LDH and Myoglobin, but not in Cardiac Troponin), and in functional lower-limb test (SJand CMJ). The comparison of inter-group results shown less muscle damage and less functional lower-limb deterioration in Group 1 compared with Control group, with statistical significance in both cases. Differences in handgrip dynamometry were no statistically significant. The eccentric exercise protocol in that study has proven to be a good model to induce muscle and functional damage in sedentary people. Short PD treatment has shown to reduce muscle and functional acute damages compared with placebo control group in this specific population. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Exercise-induced circulating extracellular vesicles protect against cardiac ischemia-reperfusion injury.

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Bei, Yihua; Xu, Tianzhao; Lv, Dongchao; Yu, Pujiao; Xu, Jiahong; Che, Lin; Das, Avash; Tigges, John; Toxavidis, Vassilios; Ghiran, Ionita; Shah, Ravi; Li, Yongqin; Zhang, Yuhui; Das, Saumya; Xiao, Junjie

2017-07-01

Extracellular vesicles (EVs) serve an important function as mediators of intercellular communication. Exercise is protective for the heart, although the signaling mechanisms that mediate this cardioprotection have not been fully elucidated. Here using nano-flow cytometry, we found a rapid increase in plasma EVs in human subjects undergoing exercise stress testing. We subsequently identified that serum EVs were increased by ~1.85-fold in mice after 3-week swimming. Intramyocardial injection of equivalent quantities of EVs from exercised mice and non-exercised controls provided similar protective effects against acute ischemia/reperfusion (I/R) injury in mice. However, injection of exercise-induced EVs in a quantity equivalent to the increase seen with exercise (1.85 swim group) significantly enhanced the protective effect. Similarly, treatment with exercise-induced increased EVs provided additional anti-apoptotic effect in H 2 O 2 -treated H9C2 cardiomyocytes mediated by the activation of ERK1/2 and HSP27 signaling. Finally, by treating H9C2 cells with insulin-like growth factor-1 to mimic exercise stimulus in vitro, we found an increased release of EVs from cardiomyocytes associated with ALIX and RAB35 activation. Collectively, our results show that exercise-induced increase in circulating EVs enhances the protective effects of endogenous EVs against cardiac I/R injury. Exercise-derived EVs might serve as a potent therapy for myocardial injury in the future.

Effect of lemon verbena supplementation on muscular damage markers, proinflammatory cytokines release and neutrophils' oxidative stress in chronic exercise.

Science.gov (United States)

Funes, Lorena; Carrera-Quintanar, Lucrecia; Cerdán-Calero, Manuela; Ferrer, Miguel D; Drobnic, Franchek; Pons, Antoni; Roche, Enrique; Micol, Vicente

2011-04-01

Intense exercise is directly related to muscular damage and oxidative stress due to excessive reactive oxygen species (ROS) in both, plasma and white blood cells. Nevertheless, exercise-derived ROS are essential to regulate cellular adaptation to exercise. Studies on antioxidant supplements have provided controversial results. The purpose of this study was to determine the effect of moderate antioxidant supplementation (lemon verbena extract) in healthy male volunteers that followed a 90-min running eccentric exercise protocol for 21 days. Antioxidant enzymes activities and oxidative stress markers were measured in neutrophils. Besides, inflammatory cytokines and muscular damage were determined in whole blood and serum samples, respectively. Intense running exercise for 21 days induced antioxidant response in neutrophils of trained male through the increase of the antioxidant enzymes catalase, glutathione peroxidase and glutathione reductase. Supplementation with moderate levels of an antioxidant lemon verbena extract did not block this cellular adaptive response and also reduced exercise-induced oxidative damage of proteins and lipids in neutrophils and decreased myeloperoxidase activity. Moreover, lemon verbena supplementation maintained or decreased the level of serum transaminases activity indicating a protection of muscular tissue. Exercise induced a decrease of interleukin-6 and interleukin-1β levels after 21 days measured in basal conditions, which was not inhibited by antioxidant supplementation. Therefore, moderate antioxidant supplementation with lemon verbena extract protects neutrophils against oxidative damage, decreases the signs of muscular damage in chronic running exercise without blocking the cellular adaptation to exercise.

A new kinematical definition of orbital eccentricity

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Ninković S.

2009-01-01

Full Text Available A new concept of orbital eccentricity is given. The dimensionless quantities proposed in the present paper to serve as orbital eccentricities have a kinematical nature. The purpose is to use them in describing the motion for the case of three-dimensional orbits. A comparison done for nearly planar orbits shows that the values of the eccentricities proposed here do not differ significantly from those corresponding to the eccentricities of geometric nature usually applied.

Association of Exercise Training with Tobacco Smoking Prevents Fibrosis but has Adverse Impact on Myocardial Mechanics.

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Reis Junior, Dermeval; Antonio, Ednei Luiz; de Franco, Marcello Fabiano; de Oliveira, Helenita Antonia; Tucci, Paulo José Ferreira; Serra, Andrey Jorge

2016-12-01

There was no data for cardiac repercussion of exercise training associated with tobacco smoking. This issue is interesting because some smoking people can be enrolled in an exercise-training program. Thus, we evaluated swimming training effects on the function and structural myocardial in rats exposed to tobacco smoking. Male Wistar rats were assigned to one of four groups: C, untrained rats without exposure to tobacco smoking; E, exercised rats without exposure to tobacco smoking; CS, untrained rats exposed to tobacco smoking; ECS, exercised rats exposed to tobacco smoking. Rats swam five times a week twice daily (60min per session) for 8 weeks. Before each bout exercise, rats breathed smoke from 20 cigarettes for 60min. Twenty-four hours after the last day of the protocol, papillary muscles were isolated for in vitro analysis of myocardial mechanics. The myocardial mass and nuclear cardiomyocyte volume were used as hypertrophy markers, and collagen content was determined by picrosirius red staining. There was a well-pronounced myocardial hypertrophic effect for two interventions. The exercise blunted myocardial collagen increases induced by tobacco smoking. However, exercise and tobacco-smoking association was deleterious to myocardial performance. Thereby, in vitro experiments with papillary muscles contracting in isometric showed impairment myocardial inotropism in exercised rats exposed to tobacco smoking. This work presents novel findings on the role of exercise training on cardiac remodeling induced by tobacco smoking. Although exercise has mitigated tissue fibrosis, their association with tobacco smoking exacerbated hypertrophy and in vitro myocardial dysfunction. This is first study to show that the association of an aerobic exercise training with tobacco smoking intensifies the phenotype of pathological cardiac hypertrophy. Therefore, the combination of interventions resulted in exacerbated myocardial hypertrophy and contractility dysfunction. These

Systemic Exercise-Induced Hypoalgesia Following Isometric Exercise Reduces Conditioned Pain Modulation.

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Alsouhibani, Ali; Vaegter, Henrik Bjarke; Hoeger Bement, Marie

2018-04-03

Physically active individuals show greater conditioned pain modulation (CPM) compared with less active individuals. Understanding the effects of acute exercise on CPM may allow for a more targeted use of exercise in the management of pain. This study investigated the effects of acute isometric exercise on CPM. In addition, the between-session and within-session reliability of CPM was investigated. Experimental, randomized crossover study. Laboratory at Marquette University. Thirty healthy adults (19.3±1.5 years, 15 males). Subjects underwent CPM testing before and after isometric exercise (knee extension, 30% maximum voluntary contraction for three minutes) and quiet rest in two separate experimental sessions. Pressure pain thresholds (PPTs) at the quadriceps and upper trapezius muscles were assessed before, during, and after ice water immersions. PPTs increased during ice water immersion (i.e., CPM), and quadriceps PPT increased after exercise (P CPM decreased similarly following exercise and quiet rest (P > 0.05). CPM within-session reliability was fair to good (intraclass correlation coefficient [ICC] = 0.43-0.70), and the between-session reliability was poor (ICC = 0.20-0.35). Due to the variability in the systemic exercise-induced hypoalgesia (EIH) response, participants were divided into systemic EIH responders (N = 9) and nonresponders (N = 21). EIH responders experienced attenuated CPM following exercise (P = 0.03), whereas the nonresponders showed no significant change (P > 0.05). Isometric exercise decreased CPM in individuals who reported systemic EIH, suggesting activation of shared mechanisms between CPM and systemic EIH responses. These results may improve the understanding of increased pain after exercise in patients with chronic pain and potentially attenuated CPM.

Astragalus membranaceus Improves Exercise Performance and Ameliorates Exercise-Induced Fatigue in Trained Mice

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Tzu-Shao Yeh

2014-03-01

Full Text Available Astragalus membranaceus (AM is a popular “Qi-tonifying” herb with a long history of use as a Traditional Chinese Medicine with multiple biological functions. However, evidence for the effects of AM on exercise performance and physical fatigue is limited. We evaluated the potential beneficial effects of AM on ergogenic and anti-fatigue functions following physiological challenge. Male ICR strain mice were randomly assigned to four groups (n = 10 per group for treatment: (1 sedentary control and vehicle treatment (vehicle control; (2 exercise training with vehicle treatment (exercise control; and (3 exercise training with AM treatment at 0.615 g/kg/day (Ex-AM1 or (4 3.075 g/kg/day (Ex-AM5. Both the vehicle and AM were orally administered for 6 weeks. Exercise performance and anti-fatigue function were evaluated by forelimb grip strength, exhaustive swimming time, and levels of serum lactate, ammonia, glucose, and creatine kinase after 15-min swimming exercise. Exercise training combined with AM supplementation increased endurance exercise capacity and increased hepatic and muscle glycogen content. AM reduced exercise-induced accumulation of the byproducts blood lactate and ammonia with acute exercise challenge. Moreover, we found no deleterious effects from AM treatment. Therefore, AM supplementation improved exercise performance and had anti-fatigue effects in mice. It may be an effective ergogenic aid in exercise training.

Effects of fast-velocity eccentric resistance training on early and late rate of force development

DEFF Research Database (Denmark)

Oliveira, Anderson S.C.; Corvino, Rogério Bulhões; Caputo, Fabrizio

2016-01-01

This study examined whether short-term maximal resistance training employing fast-velocity eccentric knee extensor actions would induce improvements in maximal isometric torque and rate of force development (RFD) at early (phases (>100 ms) of rising torque. Twenty healthy men were......, no changes in the late phase of incremental RFD were observed in TG. No changes were found in the CG. In summary, we have demonstrated, in active individuals, that a short period of resistance training performed with eccentric fast-velocity isokinetic muscle contractions is able to enhance RFDINC and RFDREL...... assigned to two experimental groups: eccentric resistance training (TG) or control (CG). Participants on the TG trained three days a week for a total of eight weeks. Training consisted of maximal unilateral eccentric knee extensors actions performed at 180°s-1. Maximal isometric knee extensor torque (MVC...

The profile of psychiatric symptoms exacerbated by methamphetamine use.

Science.gov (United States)

McKetin, Rebecca; Dawe, Sharon; Burns, Richard A; Hides, Leanne; Kavanagh, David J; Teesson, Maree; McD Young, Ross; Voce, Alexandra; Saunders, John B

2016-04-01

Methamphetamine use can produce symptoms almost indistinguishable from schizophrenia. Distinguishing between the two conditions has been hampered by the lack of a validated symptom profile for methamphetamine-induced psychiatric symptoms. We use data from a longitudinal cohort study to examine the profile of psychiatric symptoms that are acutely exacerbated by methamphetamine use. 164 methamphetamine users, who did not meet DSM-IV criteria for a lifetime primary psychotic disorder, were followed monthly for one year to assess the relationship between days of methamphetamine use and symptom severity on the 24-item Brief Psychiatric Rating Scale. Exacerbation of psychiatric symptoms with methamphetamine use was quantified using random coefficient models. The dimensions of symptom exacerbation were examined using principal axis factoring and a latent profile analysis. Symptoms exacerbated by methamphetamine loaded on three factors: positive psychotic symptoms (suspiciousness, unusual thought content, hallucinations, bizarre behavior); affective symptoms (depression, suicidality, guilt, hostility, somatic concern, self-neglect); and psychomotor symptoms (tension, excitement, distractibility, motor hyperactivity). Methamphetamine use did not significantly increase negative symptoms. Vulnerability to positive psychotic and affective symptom exacerbation was shared by 28% of participants, and this vulnerability aligned with a past year DSM-IV diagnosis of substance-induced psychosis (38% vs. 22%, χ(2)(df1)=3.66, p=0.056). Methamphetamine use produced a symptom profile comprised of positive psychotic and affective symptoms, which aligned with a diagnosis of substance-induced psychosis, with no evidence of a negative syndrome. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Eccentric crank variable compression ratio mechanism

Science.gov (United States)

Lawrence, Keith Edward [Kobe, JP; Moser, William Elliott [Peoria, IL; Roozenboom, Stephan Donald [Washington, IL; Knox, Kevin Jay [Peoria, IL

2008-05-13

A variable compression ratio mechanism for an internal combustion engine that has an engine block and a crankshaft is disclosed. The variable compression ratio mechanism has a plurality of eccentric disks configured to support the crankshaft. Each of the plurality of eccentric disks has at least one cylindrical portion annularly surrounded by the engine block. The variable compression ratio mechanism also has at least one actuator configured to rotate the plurality of eccentric disks.

Exercise-Induced Pulmonary Edema in a Triathlon

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Hirotomo Yamanashi

2015-01-01

Full Text Available Introduction. Family physicians have more opportunities to attend athletic competitions as medical staff at first-aid centers because of the increasing popularity of endurance sports. Case. A 38-year-old man who participated in a triathlon race experienced difficulty in breathing after swimming and was moved to a first-aid center. His initial oxygen saturation was 82% and a thoracic computed tomography scan showed bilateral ground glass opacity in the peripheral lungs. His diagnosis was noncardiogenic pulmonary edema associated with exercise or swimming: exercise-induced pulmonary edema (EIPE or swimming-induced pulmonary edema (SIPE. Treatment with furosemide and corticosteroid relieved his symptoms of pulmonary edema. Discussion. Noncardiogenic pulmonary edema associated with endurance sports is not common, but knowledge about EIPE/SIPE or neurogenic pulmonary edema associated with hyponatremia, which is called Ayus-Arieff syndrome, is crucial. Knowledge and caution for possible risk factors, such as exposure to cold water or overhydration, are essential for both medical staff and endurance athletes. Conclusion. To determine the presence of pulmonary edema associated with strenuous exercise, oxygen saturation should be used as a screening tool at a first-aid center. To avoid risks for EIPE/SIPE, knowledge about these diseases is essential for medical staff and for athletes who perform extreme exercise.

A single bout of exercise with a flexible pole induces significant cardiac autonomic responses in healthy men

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Cristiane M. Ogata

2014-09-01

Full Text Available OBJECTIVES: Flexible poles can provide rapid eccentric and concentric muscle contractions. Muscle vibration is associated with a "tonic vibration reflex” that is stimulated by a sequence of rapid muscle stretching, activation of the muscle spindles and stimulation of a response that is similar to the myotatic reflex. Literature studies analyzing the acute cardiovascular responses to different exercises performed with this instrument are lacking. We investigated the acute effects of exercise with flexible poles on the heart period in healthy men. METHOD: The study was performed on ten young adult males between 18 and 25 years old. We evaluated the heart rate variability in the time and frequency domains. The subjects remained at rest for 10 min. After the rest period, the volunteers performed the exercises with the flexible poles. Immediately after the exercise protocol, the volunteers remained seated at rest for 30 min and their heart rate variability was analyzed. RESULTS: The pNN50 was reduced at 5-10 and 15-20 min after exercise compared to 25-30 min after exercise (p = 0.0019, the SDNN was increased at 25-30 min after exercise compared to at rest and 0-10 min after exercise (p = 0.0073 and the RMSSD was increased at 25-30 min after exercise compared to 5-15 min after exercise (p = 0.0043. The LF in absolute units was increased at 25-30 min after exercise compared to 5-20 min after exercise (p = 0.0184. CONCLUSION: A single bout of exercise with a flexible pole reduced the heart rate variability and parasympathetic recovery was observed approximately 30 min after exercise.

Effects of Uric Acid on Exercise-induced Oxidative Stress

OpenAIRE

平井, 富弘

2001-01-01

We studied effects of uric acid on exercise― induced oxidative stress in humans based on a hypothesis that uric acid acts as an antioxidant to prevent from exercise―induced oxidative stress. Relation between uric acid level in plasma and increase of thiobarbituric acid reactive substance (TBARS)after the cycle ergometer exercise was examined. Thiobarbituricacid reactive substance in plasma increased after the ergometer exercise. High uric acid in plasma did not result in low increase of TBARS...

Overexpression of Hypoxia-Inducible Factor-1α Exacerbates Endothelial Barrier Dysfunction Induced by Hypoxia

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Pei Wang

2013-09-01

Full Text Available Background/Aims: The mechanisms involved in endothelial barrier dysfunction induced by hypoxia are incompletely understood. There is debate about the role of hypoxia-inducible factor-1α (HIF-1α in endothelial barrier disruption. The aim of this study was to investigate the effect of genetic overexpression of HIF-1α on barrier function and the underlying mechanisms in hypoxic endothelial cells. Methods: The plasmid pcDNA3.1/V5-His-HIF-1α was stably transfected into human endothelial cells. The cells were exposed to normoxia or hypoxia. The mRNA and protein expressions of HIF-1α were detected by RT-PCR and Western blot respectively. The barrier function was assessed by measuring the transendothelial electrical resistance (TER. The Western blot analysis was used to determine the protein expression of glucose transporter-1 (GLUT-1, zonular occludens-1 (ZO-1, occludin, and myosin light chain kinase (MLCK in endothelial cells. The mRNA expression of proinflammatory cytokines was detected by qRT-PCR. Results: Genetic overexpression of HIF-1α significantly increased the mRNA and protein expression of HIF-1α in endothelial cells. The overexpression of HIF-1α enhanced the hypoxia-induced increase of HIF-1α and GLUT-1 protein expression. HIF-1α overexpression not only exacerbated hypoxia-induced endothelial barrier dysfunction but also augmented hypoxia-induced up-regulation of MLCK protein expression. HIF-1α overexpression also enhanced IL-1β, IL-6 and TNF-α mRNA expression. Conclusion: We provide evidence that genetic overexpression of HIF-1α aggravates the hypoxia-induced endothelial barrier dysfunction via enhancing the up-regulation of MLCK protein expression caused by hypoxia, suggesting a potential role for HIF-1α in the pathogenesis of endothelial barrier dysfunction in hypoxia.

Reducing orbital eccentricity in binary black hole simulations

International Nuclear Information System (INIS)

Pfeiffer, Harald P; Brown, Duncan A; Kidder, Lawrence E; Lindblom, Lee; Lovelace, Geoffrey; Scheel, Mark A

2007-01-01

Binary black hole simulations starting from quasi-circular (i.e., zero radial velocity) initial data have orbits with small but nonzero orbital eccentricities. In this paper, the quasi-equilibrium initial-data method is extended to allow nonzero radial velocities to be specified in binary black hole initial data. New low-eccentricity initial data are obtained by adjusting the orbital frequency and radial velocities to minimize the orbital eccentricity, and the resulting (∼5 orbit) evolutions are compared with those of quasi-circular initial data. Evolutions of the quasi-circular data clearly show eccentric orbits, with eccentricity that decays over time. The precise decay rate depends on the definition of eccentricity; if defined in terms of variations in the orbital frequency, the decay rate agrees well with the prediction of Peters (1964 Phys. Rev. 136 1224-32). The gravitational waveforms, which contain ∼8 cycles in the dominant l = m = 2 mode, are largely unaffected by the eccentricity of the quasi-circular initial data. The overlap between the dominant mode in the quasi-circular evolution and the same mode in the low-eccentricity evolution is about 0.99

Black Hole Mergers in Galactic Nuclei Induced by the Eccentric Kozai–Lidov Effect

Science.gov (United States)

Hoang, Bao-Minh; Naoz, Smadar; Kocsis, Bence; Rasio, Frederic A.; Dosopoulou, Fani

2018-04-01

Nuclear star clusters around a central massive black hole (MBH) are expected to be abundant in stellar black hole (BH) remnants and BH–BH binaries. These binaries form a hierarchical triple system with the central MBH, and gravitational perturbations from the MBH can cause high-eccentricity excitation in the BH–BH binary orbit. During this process, the eccentricity may approach unity, and the pericenter distance may become sufficiently small so that gravitational-wave emission drives the BH–BH binary to merge. In this work, we construct a simple proof-of-concept model for this process, and specifically, we study the eccentric Kozai–Lidov mechanism in unequal-mass, soft BH–BH binaries. Our model is based on a set of Monte Carlo simulations for BH–BH binaries in galactic nuclei, taking into account quadrupole- and octupole-level secular perturbations, general relativistic precession, and gravitational-wave emission. For a typical steady-state number of BH–BH binaries, our model predicts a total merger rate of ∼1–3 {Gpc} ‑3 {yr} ‑1, depending on the assumed density profile in the nucleus. Thus, our mechanism could potentially compete with other dynamical formation processes for merging BH–BH binaries, such as the interactions of stellar BHs in globular clusters or in nuclear star clusters without an MBH.

Chronic high-fat diet-induced obesity decreased survival and increased hypertrophy of rats with experimental eccentric hypertrophy from chronic aortic regurgitation.

Science.gov (United States)

Dhahri, Wahiba; Drolet, Marie-Claude; Roussel, Elise; Couet, Jacques; Arsenault, Marie

2014-09-24

The composition of a diet can influence myocardial metabolism and development of left ventricular hypertrophy (LVH). The impact of a high-fat diet in chronic left ventricular volume overload (VO) causing eccentric LVH is unknown. This study examined the effects of chronic ingestion of a high-fat diet in rats with chronic VO caused by severe aortic valve regurgitation (AR) on LVH, function and on myocardial energetics and survival. Male Wistar rats were divided in four groups: Shams on control or high-fat (HF) diet (15 rats/group) and AR rats fed with the same diets (ARC (n = 56) and ARHF (n = 32)). HF diet was started one week before AR induction and the protocol was stopped 30 weeks later. As expected, AR caused significant LV dilation and hypertrophy and this was exacerbated in the ARHF group. Moreover, survival in the ARHF group was significantly decreased compared the ARC group. Although the sham animals on HF also developed significant obesity compared to those on control diet, this was not associated with heart hypertrophy. The HF diet in AR rats partially countered the expected shift in myocardial energy substrate preference usually observed in heart hypertrophy (from fatty acids towards glucose). Systolic function was decreased in AR rats but HF diet had no impact on this parameter. The response to HF diet of different fatty acid oxidation markers as well as the increase in glucose transporter-4 translocation to the plasma membrane compared to ARC was blunted in AR animals compared to those on control diet. HF diet for 30 weeks decreased survival of AR rats and worsened eccentric hypertrophy without affecting systolic function. The expected adaptation of myocardial energetics to volume-overload left ventricle hypertrophy in AR animals seemed to be impaired by the high-fat diet suggesting less metabolic flexibility.

Eccentricity from transit photometry

DEFF Research Database (Denmark)

Van Eylen, Vincent; Albrecht, Simon

2015-01-01

and can be described by a Rayleigh distribution with $\\sigma$ = 0.049 $\\pm$ 0.013. This is in full agreement with solar system eccentricities, but in contrast to the eccentricity distributions previously derived for exoplanets from radial velocity studies. Our findings are helpful in identifying which...... (TTVs), and we present some previously unreported TTVs. Finally transit durations help distinguish between false positives and true planets and we use our measurements to confirm six new exoplanets....

Mechanisms and management of exercise-induced asthma in elite athletes

DEFF Research Database (Denmark)

Ali, Zarqa; Norsk, Peter; Ulrik, Charlotte Suppli

2012-01-01

Asthma is often reported by elite athletes, especially endurance athletes. The aim of this article is to review current knowledge of mechanisms and management of exercise-induced asthma (EIA) in adult elite athletes.......Asthma is often reported by elite athletes, especially endurance athletes. The aim of this article is to review current knowledge of mechanisms and management of exercise-induced asthma (EIA) in adult elite athletes....

Safe and effective prescription of exercise in acute exacerbations of chronic obstructive pulmonary disease: rationale and methods for an integrated knowledge translation study.

Science.gov (United States)

Camp, Pat; Reid, W Darlene; Yamabayashi, Cristiane; Brooks, Dina; Goodridge, Donna; Chung, Frank; Marciniuk, Darcy D; Neufeld, Andrea; Hoens, Alsion

2013-01-01

Patients hospitalized with an acute exacerbation of chronic obstructive pulmonary disease (AECOPD) engage in low levels of activity, putting them at risk for relapse and future readmissions. There is little direction for health care providers regarding the parameters for safe exercise during an AECOPD that is effective for increasing activity tolerance before discharge from hospital, especially for patients with associated comorbid conditions. To report the rationale for and methods of a study to develop evidence-informed care recommendations that guide health care providers in the assessment, prescription, monitoring and progression of exercise for patients hospitalized with AECOPD. The present study was a multicomponent knowledge translation project incorporating evidence from systematic reviews of exercise involving populations with chronic obstructive pulmonary disease and⁄or common comorbidities. A Delphi process was then used to obtain expert opinion from clinicians, academics and patients to identify the parameters of safe and effective exercise for patients with AECOPD. Clinical decision-making tool(s) for patients and practitioners supported by a detailed knowledge dissemination, implementation and evaluation framework. The present study addressed an important knowledge gap: the lack of availability of parameters to guide safe and effective exercise prescription for hospitalized patients with AECOPD, with or without comorbid conditions. In the absence of such parameters, health care professionals may adopt an 'activity as tolerated' approach, which may not improve physical activity levels in their patients. The present study synthesizes the best available evidence and expert opinion, and will generate decision-making tools for use by patients and their health care providers.

Overexpression of IL-38 protein in anticancer drug-induced lung injury and acute exacerbation of idiopathic pulmonary fibrosis.

Science.gov (United States)

Tominaga, Masaki; Okamoto, Masaki; Kawayama, Tomotaka; Matsuoka, Masanobu; Kaieda, Shinjiro; Sakazaki, Yuki; Kinoshita, Takashi; Mori, Daisuke; Inoue, Akira; Hoshino, Tomoaki

2017-09-01

Interleukin (IL)-38, a member of the IL-1 family, shows high homology to IL-1 receptor antagonist (IL-1Ra) and IL-36 receptor antagonist (IL-36Ra). Its function in interstitial lung disease (ILD) is still unknown. To determine the expression pattern of IL-38 mRNA, a panel of cDNAs derived from various tissues was analyzed by quantitative real-time PCR. Immunohistochemical reactivity with anti-human IL-38 monoclonal antibody (clone H127C) was evaluated semi-quantitatively in lung tissue samples from 12 patients with idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP), 5 with acute exacerbation of IPF, and 10 with anticancer drug-induced ILD (bleomycin in 5 and epidermal growth factor receptor-tyrosine kinase inhibitor in 5). Control lung tissues were obtained from areas of normal lung in 22 lung cancer patients who underwent extirpation surgery. IL-38 transcripts were strongly expressed in the lung, spleen, synoviocytes, and peripheral blood mononuclear cells, and at a lower level in pancreas and muscle. IL-38 protein was not strongly expressed in normal pulmonary alveolar tissues in all 22 control lungs. In contrast, IL-38 was overexpressed in the lungs of 4 of 5 (80%) patients with acute IPF exacerbation and 100% (10/10) of the patients with drug-induced ILD. IL-38 overexpression was limited to hyperplastic type II pneumocytes, which are considered to reflect regenerative change following diffuse alveolar damage in ILD. IL-38 may play an important role in acute and/or chronic inflammation in anticancer drug-induced lung injury and acute exacerbation of IPF. Copyright © 2017 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Motor imagery during action observation increases eccentric hamstring force: an acute non-physical intervention.

Science.gov (United States)

Scott, Matthew; Taylor, Stephen; Chesterton, Paul; Vogt, Stefan; Eaves, Daniel Lloyd

2018-06-01

Rehabilitation professionals typically use motor imagery (MI) or action observation (AO) to increase physical strength for injury prevention and recovery. Here we compared hamstring force gains for MI during AO (AO + MI) against two pure MI training groups. Over a 3-week intervention physically fit adults imagined Nordic hamstring exercises in both legs and synchronized this with a demonstration of the same action (AO + MI), or they purely imagined this action (pure MI), or imagined upper-limb actions (pure MI-control). Eccentric hamstring strength gains were assessed using ANOVAs, and magnitude-based inference (MBI) analyses determined the likelihood of clinical/practical benefits for the interventions. Hamstring strength only increased significantly following AO + MI training. This effect was lateralized to the right leg, potentially reflecting a left-hemispheric dominance in motor simulation. MBIs: The right leg within-group treatment effect size for AO + MI was moderate and likely beneficial (d = 0.36), and only small and possibly beneficial for pure MI (0.23). Relative to pure MI-control, effects were possibly beneficial and moderate for AO + MI (0.72), although small for pure MI (0.39). Since hamstring strength predicts injury prevalence, our findings point to the advantage of combined AO + MI interventions, over and above pure MI, for injury prevention and rehabilitation. Implications for rehabilitation While hamstring strains are the most common injury across the many sports involving sprinting and jumping, Nordic hamstring exercises are among the most effective methods for building eccentric hamstring strength, for injury prevention and rehabilitation. In the acute injury phase it is crucial not to overload damaged soft tissues, and so non-physical rehabilitation techniques are well suited to this phase. Rehabilitation professionals typically use either motor imagery or action observation techniques to safely improve physical

Alfredson versus Silbernagel exercise therapy in chronic midportion Achilles tendinopathy: study protocol for a randomized controlled trial.

Science.gov (United States)

Habets, Bas; van Cingel, Robert E H; Backx, Frank J G; Huisstede, Bionka M A

2017-07-11

Midportion Achilles tendinopathy (AT) is a common overuse injury, usually requiring several months of rehabilitation. Exercise therapy of the ankle plantar flexors (i.e. tendon loading) is considered crucial during conservative rehabilitation. Alfredson's isolated eccentric and Silbernagel's combined concentric-eccentric exercise programs have both shown beneficial results, but it is unknown whether any of these programs is superior for use in clinical practice. Therefore, the primary objective of this study is to compare the effectiveness of both programs on clinical symptoms. Secondary objectives are to compare the effectiveness of both programs on quality of life and functional outcome measures, to investigate the prognostic value of baseline characteristics, to investigate differences in cost-effectiveness. Eighty-six recreational athletes (21-60 years of age) with unilateral chronic midportion AT (i.e. ≥ 3 months) will be included in this multicenter assessor blinded randomized controlled trial. They will be randomly allocated to either a group performing the Alfredson isolated eccentric training program (n = 43), or a group performing the Silbernagel combined concentric-eccentric program (n = 43). In the Alfredson group, participants will perform eccentric heel-drops on their injured side, twice daily for 12 weeks, whereas in the Silbernagel group, participants perform various concentric-eccentric heel-raise exercises, once daily for 12 weeks. Primary outcome measure will be the Victorian Institute of Sport Assessment - Achilles (VISA-A) questionnaire. Secondary outcomes will be a visual analogue scale (VAS) for pain during daily activities and sports, duration of morning stiffness, global perceived effect, the 12-item Short Form Health Survey and the Euroqol instrument, and functional performance measured with the heel-raise test and the countermovement jump. Additionally, alongside the RCT, a cost-effectiveness analysis will be performed

Shedding light on the eccentricity valley: Gap heating and eccentricity excitation of giant planets in protoplanetary disks

International Nuclear Information System (INIS)

Tsang, David; Cumming, Andrew; Turner, Neal J.

2014-01-01

We show that the first order (non-co-orbital) corotation torques are significantly modified by entropy gradients in a non-barotropic protoplanetary disk. Such non-barotropic torques can dramatically alter the balance that, for barotropic cases, results in the net eccentricity damping for giant gap-clearing planets embedded in the disk. We demonstrate that stellar illumination can heat the gap enough for the planet's orbital eccentricity to instead be excited. We also discuss the 'Eccentricity Valley' noted in the known exoplanet population, where low-metallicity stars have a deficit of eccentric planets between ∼0.1 and ∼1 AU compared to metal-rich systems. We show that this feature in the planet distribution may be due to the self-shadowing of the disk by a rim located at the dust sublimation radius ∼0.1 AU, which is known to exist for several T Tauri systems. In the shadowed region between ∼0.1 and ∼1 AU, lack of gap insolation allows disk interactions to damp eccentricity. Outside such shadowed regions stellar illumination can heat the planetary gaps and drive eccentricity growth for giant planets. We suggest that the self-shadowing does not arise at higher metallicity due to the increased optical depth of the gas interior to the dust sublimation radius.

Shedding light on the eccentricity valley: Gap heating and eccentricity excitation of giant planets in protoplanetary disks

Energy Technology Data Exchange (ETDEWEB)

Tsang, David; Cumming, Andrew [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Turner, Neal J., E-mail: dtsang@physics.mcgill.ca [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2014-02-20

We show that the first order (non-co-orbital) corotation torques are significantly modified by entropy gradients in a non-barotropic protoplanetary disk. Such non-barotropic torques can dramatically alter the balance that, for barotropic cases, results in the net eccentricity damping for giant gap-clearing planets embedded in the disk. We demonstrate that stellar illumination can heat the gap enough for the planet's orbital eccentricity to instead be excited. We also discuss the 'Eccentricity Valley' noted in the known exoplanet population, where low-metallicity stars have a deficit of eccentric planets between ∼0.1 and ∼1 AU compared to metal-rich systems. We show that this feature in the planet distribution may be due to the self-shadowing of the disk by a rim located at the dust sublimation radius ∼0.1 AU, which is known to exist for several T Tauri systems. In the shadowed region between ∼0.1 and ∼1 AU, lack of gap insolation allows disk interactions to damp eccentricity. Outside such shadowed regions stellar illumination can heat the planetary gaps and drive eccentricity growth for giant planets. We suggest that the self-shadowing does not arise at higher metallicity due to the increased optical depth of the gas interior to the dust sublimation radius.

The Curious Question of Exercise-Induced Pulmonary Edema

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Melissa L. Bates

2011-01-01

Full Text Available The question of whether pulmonary edema develops during exercise on land is controversial. Yet, the development of pulmonary edema during swimming and diving is well established. This paper addresses the current controversies that exist in the field of exercise-induced pulmonary edema on land and with water immersion. It also discusses the mechanisms by which pulmonary edema can develop during land exercise, swimming, and diving and the current gaps in knowledge that exist. Finally, this paper discusses how these fields can continue to advance and the areas where clinical knowledge is lacking.

Exercise-induced heat stress disrupts the shear-dilatory relationship.

Science.gov (United States)

Ives, Stephen J; Lefferts, Wesley K; Wharton, Margret; Fehling, Patricia C; Smith, Denise L

2016-12-01

What is the central question of this study? Although heat stress is known to increase cardiovascular strain, no study, to date, had explored the potential impact of exercise-induced heat stress on vascular function. What is the main finding and its importance? We found that acute exercise tended to reduce flow-mediated dilatation (FMD), owing in part to reduced reactive hyperaemia/shear stimulus; thus, when FMD is normalized to shear no postexercise deficit exists. Exercise-induced heat stress increased reactive hyperaemia, shear rate, coupled with a sustained FMD postexercise, suggests that exercise-induced heat stress increases the amount of shear stimulus to elicit a similar response, indicating reduced vascular responsiveness, or reserve, which might increase cardiovascular susceptibility. Heat stress increases cardiovascular strain and is of particular concern in occupations, such as firefighting, in which individuals are required to perform strenuous work while wearing personal protective equipment. Sudden cardiac events are associated with strenuous activity and are the leading cause of duty-related death among firefighters, accounting for ∼50% of duty-related fatalities per year. Understanding the acute effects of exercise-induced heat stress (EIHS) on vascular endothelial function may provide insight into the mechanisms precipitating acute coronary events in firefighters. The purpose of this study, therefore, was to determine the effects of EIHS on vascular endothelial function. Using a balanced crossover design, 12 healthy men performed 100 min of moderate-intensity, intermittent exercise with and without EIHS (personal protective equipment or cooling vest, respectively). Measurements of flow-mediated dilatation (FMD), reactive hyperaemia and shear rate area under the curve (SR AUC ) were performed pre- and postexercise. During EIHS, core temperature was significantly higher (38 ± 0.1 versus 37 ± 0.1°C). Postexercise FMD tended to be suppressed

Global Proteome Changes in the Rat Diaphragm Induced by Endurance Exercise Training.

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Kurt J Sollanek

Full Text Available Mechanical ventilation (MV is a life-saving intervention for many critically ill patients. Unfortunately, prolonged MV results in the rapid development of diaphragmatic atrophy and weakness. Importantly, endurance exercise training results in a diaphragmatic phenotype that is protected against ventilator-induced diaphragmatic atrophy and weakness. The mechanisms responsible for this exercise-induced protection against ventilator-induced diaphragmatic atrophy remain unknown. Therefore, to investigate exercise-induced changes in diaphragm muscle proteins, we compared the diaphragmatic proteome from sedentary and exercise-trained rats. Specifically, using label-free liquid chromatography-mass spectrometry, we performed a proteomics analysis of both soluble proteins and mitochondrial proteins isolated from diaphragm muscle. The total number of diaphragm proteins profiled in the soluble protein fraction and mitochondrial protein fraction were 813 and 732, respectively. Endurance exercise training significantly (P<0.05, FDR <10% altered the abundance of 70 proteins in the soluble diaphragm proteome and 25 proteins of the mitochondrial proteome. In particular, key cytoprotective proteins that increased in relative abundance following exercise training included mitochondrial fission process 1 (Mtfp1; MTP18, 3-mercaptopyruvate sulfurtransferase (3MPST, microsomal glutathione S-transferase 3 (Mgst3; GST-III, and heat shock protein 70 kDa protein 1A/1B (HSP70. While these proteins are known to be cytoprotective in several cell types, the cyto-protective roles of these proteins have yet to be fully elucidated in diaphragm muscle fibers. Based upon these important findings, future experiments can now determine which of these diaphragmatic proteins are sufficient and/or required to promote exercise-induced protection against inactivity-induced muscle atrophy.

Impact of exercise selection on hamstring muscle activation.

Science.gov (United States)

Bourne, Matthew N; Williams, Morgan D; Opar, David A; Al Najjar, Aiman; Kerr, Graham K; Shield, Anthony J

2017-07-01

To determine which strength training exercises selectively activate the biceps femoris long head (BF LongHead ) muscle. We recruited 24 recreationally active men for this two-part observational study . Part 1: We explored the amplitudes and the ratios of lateral (BF) to medial hamstring (MH) normalised electromyography (nEMG) during the concentric and eccentric phases of 10 common strength training exercises. Part 2: We used functional MRI (fMRI) to determine the spatial patterns of hamstring activation during two exercises which (1) most selectively and (2) least selectively activated the BF in part 1. Eccentrically, the largest BF/MH nEMG ratio occurred in the 45° hip-extension exercise; the lowest was in the Nordic hamstring (Nordic) and bent-knee bridge exercises. Concentrically, the highest BF/MH nEMG ratio occurred during the lunge and 45° hip extension; the lowest was during the leg curl and bent-knee bridge. fMRI revealed a greater BF (LongHead) to semitendinosus activation ratio in the 45° hip extension than the Nordic (phamstring muscles (p≤0.002). We highlight the heterogeneity of hamstring activation patterns in different tasks. Hip-extension exercise selectively activates the long hamstrings, and the Nordic exercise preferentially recruits the semitendinosus. These findings have implications for strategies to prevent hamstring injury as well as potentially for clinicians targeting specific hamstring components for treatment (mechanotherapy). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

ALDH2 restores exhaustive exercise-induced mitochondrial dysfunction in skeletal muscle

International Nuclear Information System (INIS)

Zhang, Qiuping; Zheng, Jianheng; Qiu, Jun; Wu, Xiahong; Xu, Yangshuo; Shen, Weili; Sun, Mengwei

2017-01-01

Background: Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is highly expressed in heart and skeletal muscles, and is the major enzyme that metabolizes acetaldehyde and toxic aldehydes. The cardioprotective effects of ALDH2 during cardiac ischemia/reperfusion injury have been recognized. However, less is known about the function of ALDH2 in skeletal muscle. This study was designed to evaluate the effect of ALDH2 on exhaustive exercise-induced skeletal muscle injury. Methods: We created transgenic mice expressing ALDH2 in skeletal muscles. Male wild-type C57/BL6 (WT) and ALDH2 transgenic mice (ALDH2-Tg), 8-weeks old, were challenged with exhaustive exercise for 1 week to induce skeletal muscle injury. Animals were sacrificed 24 h post-exercise and muscle tissue was excised. Results: ALDH2-Tg mice displayed significantly increased treadmill exercise capacity compared to WT mice. Exhaustive exercise caused an increase in mRNA levels of the muscle atrophy markers, Atrogin-1 and MuRF1, and reduced mitochondrial biogenesis and fusion in WT skeletal muscles; these effects were attenuated in ALDH2-Tg mice. Exhaustive exercise also enhanced mitochondrial autophagy pathway activity, including increased conversion of LC3-I to LC3-II and greater expression of Beclin1 and Bnip3; the effects of which were mitigated by ALDH2 overexpression. In addition, ALDH2-Tg reversed the increase of an oxidative stress biomarker (4-hydroxynonenal) and decreased levels of mitochondrial antioxidant proteins, including manganese superoxide dismutase and NAD(P)H:quinone oxidoreductase 1, in skeletal muscle induced by exhaustive exercise. Conclusion: ALDH2 may reverse skeletal muscle mitochondrial dysfunction due to exhaustive exercise by regulating mitochondria dynamic remodeling and enhancing the quality of mitochondria. - Highlights: • Skeletal muscle ALDH2 expression and activity declines during exhaustive exercise. • ALDH2 overexpression enhances physical performance and restores muscle

Fatty acid-inducible ANGPTL4 governs lipid metabolic response to exercise

DEFF Research Database (Denmark)

Catoire, Milène; Alex, Sheril; Paraskevopulos, Nicolas

2014-01-01

Physical activity increases energy metabolism in exercising muscle. Whether acute exercise elicits metabolic changes in nonexercising muscles remains unclear. We show that one of the few genes that is more highly induced in nonexercising muscle than in exercising human muscle during acute exercis...

Characterisation of exacerbation risk and exacerbator phenotypes in the POET-COPD trial.

Science.gov (United States)

Beeh, Kai M; Glaab, Thomas; Stowasser, Susanne; Schmidt, Hendrik; Fabbri, Leonardo M; Rabe, Klaus F; Vogelmeier, Claus F

2013-10-29

Data examining the characteristics of patients with frequent exacerbations of chronic obstructive pulmonary disease (COPD) and associated hospitalisations and mortality are scarce. Post-hoc analysis of the Prevention Of Exacerbations with Tiotropium in COPD (POET-COPD) trial, targeting exacerbations as the primary endpoint. Patients were classified as non-, infrequent, and frequent exacerbators (0, 1, or ≥ 2 exacerbations during study treatment), irrespective of study treatment. A multivariate Cox regression model assessed the effect of covariates on time to first exacerbation. In total, 7376 patients were included in the analysis: 63.5% non-exacerbators, 22.9% infrequent, 13.6% frequent exacerbators. Factors significantly associated with exacerbation risk were age, sex, body mass index, COPD duration and severity, smoking history, baseline inhaled corticosteroid use, and preceding antibiotic or systemic corticosteroid courses. Frequent exacerbators had greater severity and duration of COPD, received more pulmonary medication, and ≥ 2 systemic corticosteroid or antibiotic courses in the preceding year, and were more likely to be female and ex-smokers. The small proportion of frequent exacerbators (13.6%) accounted for 56.6% of exacerbation-related hospitalisations, which, overall, were associated with a three-fold increase in mortality. The frequent exacerbator phenotype was closely associated with exacerbation-related hospitalisations, and exacerbation-related hospitalisations were associated with poorer survival. NCT00563381; Study identifier: BI 205.389.

The Effects of Adding Whey Protein and Branched-chain Amino Acid to Carbohydrate Beverages on Indices of Muscle Damage after Eccentric Resistance Exercise in Untrained Young Males

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Foad Asjodi

2017-07-01

Full Text Available Abstract Background: The aim of this study was to evaluate the effects of supplementation of Branched-Chain Amino Acids (BCAAs plus carbohydrate (CHO and whey protein plus CHO on muscle damage indices after eccentric resistant exercise. Materials and Methods: Twenty four untrained healthy males participated in this study. They were randomly divided into three groups, BCAA +glucose (0.1+0.1g/kg supplement group (n=8, Whey+glucose (0.1+0.1g/kg supplement group (n=8, and placebo (malto dextrin 0.2g/kg group (n=8. Each subject consumed a carbohydrate beverage with addition of whey protein or branched-chain amino acid or placebo 30 minutes before exercise in a randomized,double-blind fashion. Serum levels of Creatine Kinase (CK, Lactate dehydrogenase (LDH, and muscle pain were measured before, 24, 48, 72 h after exercise. Follow-up analyses included 1-way repeated measures ANOVAs, and Bonferroni post hoc comparisons. Results: 24 h after test, serum levels of CK, LDH and muscle pain in both supplement groups were increased less than placebo group (0.015, 0.001 and 0.001, respectively. Also, the levels of CK and LDH showed significant changes in both intervention groups compared to placebo group at 24 h (0.001, 0. 015, respectively. Similarly, significant differences in the levels of CK and LDH between groups were observed. Conclusion: These data indicate that muscle damage and pain after resistant exercise were reduced by an ingestion of either BCAA drink or whey protein drink.

Exercise Does Not Protect against MPTP-Induced Neurotoxicity in BDNF Happloinsufficent Mice

OpenAIRE

Gerecke, Kim M.; Jiao, Yun; Pagala, Viswajeeth; Smeyne, Richard J.

2012-01-01

Exercise has been demonstrated to potently protect substantia nigra pars compacta (SN) dopaminergic neurons from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity. One mechanism proposed to account for this neuroprotection is the upregulation of neurotrophic factors. Several neurotrophic factors, including Brain Derived Neurotrophic Factor (BDNF), have been shown to upregulate in response to exercise. In order to determine if exercise-induced neuroprotection is depende...

Antibiotics usefulness and choice in BPCO acute exacerbation

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Bruno Tartaglino

2005-10-01

Full Text Available Although the debate on the role of bacterial infections and antibiotic treatment in AE-COPD remains open, there is evidence that the persistence of bacteria after acute exacerbation (residual bacterial colony influences the frequency and severity of subsequent acute exacerbation and that antibiotic treatment that induces faster and more complete eradication produces better clinical outcomes. New aspects must now be considered, given that COPD is a chronic illness subject to acute exacerbations of varying frequencies and that acute exacerbations correspond to functional respiratory deterioration. One of the parameters that is currently acquiring clinical relevance is the interval free of infection (IFI, the period that elapses between one acute exacerbation and the next, caused by bacterial infection. Another guiding concept in the choice of antibiotic treatment is that not all patients benefit in the same way; those requiring more aggressive treatment are most likely to be those with FEV1 < 50%, frequent exacerbations (> 3/year treated with antibiotics, relevant co-morbidity, under chronic steroid treatment, etc., for these patients it is recommended to administer antibiotics active on the three most common pathogens (in particular H. influenzae, considering the resistance acquired in recent years, and on Pseudomomias aeruginosa.

Exercise-induced asthma: critical analysis of the protective role of montelukast

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Terrence W Carver Jr

2009-10-01

Full Text Available Terrence W Carver JrThe Children’s Mercy Hospital and Clinics, Kansas City, MO, USAAbstract: Exercise-induced asthma/exercise-induced bronchospasm (EIA/EIB is a prevalent and clinically important disease affecting young children through older adulthood. These terms are often used interchangeably and the differences are not clearly defined in the literature. The pathogenesis of EIA/EIB may be different in those with persistent asthma compared to those with exercise-induced symptoms only. The natural history of EIA is unclear and may be different for elite athletes. Leukotriene biology has helped the understanding of EIB. The type and intensity of exercise are important factors for EIB. Exercise participation is necessary for proper development and control of EIA is recommended. Symptoms of EIB should be confirmed by proper testing. Biologic markers may also be helpful in diagnosis. Not all exercise symptoms are from EIB. Many medication and nonpharmacologic treatments are available. Asthma education is an important component of managing EIA. Many medications have been tested and the comparisons are complicated. Montelukast is a US Food and Drug Administration-approved asthma and EIB controller and has a number of potential advantages to other asthma medications including short onset of action, ease of use, and lack of tolerance. Not all patients improve with montelukast and rescue medication should be available.Keywords: exercise, asthma, montelukast, Singulair, bronchospasm, leukotrienes

THE ECCENTRIC KOZAI MECHANISM FOR A TEST PARTICLE

International Nuclear Information System (INIS)

Lithwick, Yoram; Naoz, Smadar

2011-01-01

We study the dynamical evolution of a test particle that orbits a star in the presence of an exterior massive planet, considering octupole-order secular interactions. In the standard Kozai mechanism (SKM), the planet's orbit is circular and so the particle conserves vertical angular momentum. As a result, the particle's orbit oscillates periodically, exchanging eccentricity for inclination. However, when the planet's orbit is eccentric, the particle's vertical angular momentum varies and its Kozai oscillations are modulated on longer timescales—we call this the eccentric Kozai mechanism (EKM). The EKM can lead to behavior that is dramatically different from the SKM. In particular, the particle's orbit can flip from prograde to retrograde and back again, and it can reach arbitrarily high eccentricities given enough time. We map out the conditions under which this dramatic behavior (flipping and extreme eccentricities) occurs and show that when the planet's eccentricity is sufficiently high, it occurs quite generically. For example, when the planet's eccentricity exceeds a few percent of the ratio of semimajor axes (outer to inner), around half of randomly oriented test particle orbits will flip and reach extreme eccentricities. The SKM has often been invoked for bringing pairs of astronomical bodies (star-star, planet-star, compact-object pairs) close together. Including the effect of the EKM will enhance the rate at which such matchmaking occurs.

Eccentric figure-eight coils for transcranial magnetic stimulation.

Science.gov (United States)

Sekino, Masaki; Ohsaki, Hiroyuki; Takiyama, Yoshihiro; Yamamoto, Keita; Matsuzaki, Taiga; Yasumuro, Yoshihiro; Nishikawa, Atsushi; Maruo, Tomoyuki; Hosomi, Koichi; Saitoh, Youichi

2015-01-01

Previously we proposed an eccentric figure-eight coil that can cause threshold stimulation in the brain at lower driving currents. In this study, we performed numerical simulations and magnetic stimulations to healthy subjects for evaluating the advantages of the eccentric coil. The simulations were performed using a simplified spherical brain model and a realistic human brain model. We found that the eccentric coil required a driving current intensity of approximately 18% less than that required by the concentric coil to cause comparable eddy current densities within the brain. The eddy current localization of the eccentric coil was slightly higher than that of the concentric coil. A prototype eccentric coil was designed and fabricated. Instead of winding a wire around a bobbin, we cut eccentric-spiral slits on the insulator cases, and a wire was woven through the slits. The coils were used to deliver magnetic stimulation to healthy subjects; among our results, we found that the current slew rate corresponding to motor threshold values for the concentric and eccentric coils were 86 and 78 A/µs, respectively. The results indicate that the eccentric coil consistently requires a lower driving current to reach the motor threshold than the concentric coil. Future development of compact magnetic stimulators will enable the treatment of some intractable neurological diseases at home. © 2014 Wiley Periodicals, Inc.

Eccentric Knee Flexor Strength and Risk of Hamstring Injuries in Rugby Union: A Prospective Study.

Science.gov (United States)

Bourne, Matthew N; Opar, David A; Williams, Morgan D; Shield, Anthony J

2015-11-01

Hamstring strain injuries (HSIs) represent the most common cause of lost playing time in rugby union. Eccentric knee flexor weakness and between-limb imbalance in eccentric knee flexor strength are associated with a heightened risk of HSIs in other sports; however, these variables have not been explored in rugby union. To determine if lower levels of eccentric knee flexor strength or greater between-limb imbalance in this parameter during the Nordic hamstring exercise are risk factors for HSIs in rugby union. Cohort study; Level of evidence, 2. This prospective study was conducted over the 2014 Super Rugby and Queensland Rugby Union seasons. In total, 178 rugby union players (mean age, 22.6 ± 3.8 years; mean height, 185.0 ± 6.8 cm; mean weight, 96.5 ± 13.1 kg) had their eccentric knee flexor strength assessed using a custom-made device during the preseason. Reports of previous hamstring, quadriceps, groin, calf, and anterior cruciate ligament injuries were also obtained. The main outcome measure was the prospective occurrence of HSIs. Twenty players suffered at least 1 HSI during the study period. Players with a history of HSIs had a 4.1-fold (95% CI, 1.9-8.9; P = .001) greater risk of subsequent HSIs than players without such a history. Between-limb imbalance in eccentric knee flexor strength of ≥15% and ≥20% increased the risk of HSIs by 2.4-fold (95% CI, 1.1-5.5; P = .033) and 3.4-fold (95% CI, 1.5-7.6; P = .003), respectively. Lower eccentric knee flexor strength and other prior injuries were not associated with an increased risk of future HSIs. Multivariate logistic regression revealed that the risk of reinjuries was augmented in players with strength imbalances. Previous HSIs and between-limb imbalance in eccentric knee flexor strength were associated with an increased risk of future HSIs in rugby union. These results support the rationale for reducing imbalance, particularly in players who have suffered a prior HSI, to mitigate the risk of future

Effects of 12-wk eccentric calf muscle training on muscle-tendon glucose uptake and SEMG in patients with chronic Achilles tendon pain.

Science.gov (United States)

Masood, Tahir; Kalliokoski, Kari; Magnusson, S Peter; Bojsen-Møller, Jens; Finni, Taija

2014-07-15

High-load eccentric exercises have been a key component in the conservative management of chronic Achilles tendinopathy. This study investigated the effects of a 12-wk progressive, home-based eccentric rehabilitation program on ankle plantar flexors' glucose uptake (GU) and myoelectric activity and Achilles tendon GU. A longitudinal study design with control (n = 10) and patient (n = 10) groups was used. Surface electromyography (SEMG) from four ankle plantar flexors and GU from the same muscles and the Achilles tendon were measured during submaximal intermittent isometric plantar flexion task. The results indicated that the symptomatic leg was weaker (P eccentric rehabilitation. Additionally, the rehabilitation resulted in greater GU in both soleus (P tendon GU than the controls (P effect on the tendon GU. Concerning SEMG, at baseline, soleus showed more relative activity in the symptomatic leg compared with both the asymptomatic and control legs (P Eccentric rehabilitation was effective in decreasing subjective severity of Achilles tendinopathy. It also resulted in redistribution of relative electrical activity, but not metabolic activity, within the triceps surae muscle. Copyright © 2014 the American Physiological Society.

Antibiotics usefulness and choice in BPCO acute exacerbation

OpenAIRE

Bruno Tartaglino

2005-01-01

Although the debate on the role of bacterial infections and antibiotic treatment in AE-COPD remains open, there is evidence that the persistence of bacteria after acute exacerbation (residual bacterial colony) influences the frequency and severity of subsequent acute exacerbation and that antibiotic treatment that induces faster and more complete eradication produces better clinical outcomes. New aspects must now be considered, given that COPD is a chronic illness subject to acute exacerbatio...

Flow Mode Magnetorheological Dampers with an Eccentric Gap

OpenAIRE

Young-Tai Choi; Norman M. Wereley

2014-01-01

This paper analyzes flow mode magnetorheological (MR) dampers with an eccentric annular gap (i.e., a nonuniform annular gap). To this end, an MR damper analysis for an eccentric annular gap is constructed based on approximating the eccentric annular gap using a rectangular duct with a variable gap, as well as a Bingham-plastic constitutive model of the MR fluid. Performance of flow mode MR dampers with an eccentric gap was assessed analytically using both field-dependent damping force and dam...

Eccentric-Overload Training in Team-Sport Functional Performance: Constant Bilateral Vertical Versus Variable Unilateral Multidirectional Movements.

Science.gov (United States)

Gonzalo-Skok, Oliver; Tous-Fajardo, Julio; Valero-Campo, Carlos; Berzosa, César; Bataller, Ana Vanessa; Arjol-Serrano, José Luis; Moras, Gerard; Mendez-Villanueva, Alberto

2017-08-01

To analyze the effects of 2 different eccentric-overload training (EOT) programs, using a rotational conical pulley, on functional performance in team-sport players. A traditional movement paradigm (ie, squat) including several sets of 1 bilateral and vertical movement was compared with a novel paradigm including a different exercise in each set of unilateral and multi-directional movements. Forty-eight amateur or semiprofessional team-sport players were randomly assigned to an EOT program including either the same bilateral vertical (CBV, n = 24) movement (squat) or different unilateral multidirectional (VUMD, n = 24) movements. Training programs consisted of 6 sets of 1 exercise (CBV) or 1 set of 6 exercises (VUMD) × 6-10 repetitions with 3 min of passive recovery between sets and exercises, biweekly for 8 wk. Functional-performance assessment included several change-of-direction (COD) tests, a 25-m linear-sprint test, unilateral multidirectional jumping tests (ie, lateral, horizontal, and vertical), and a bilateral vertical-jump test. Within-group analysis showed substantial improvements in all tests in both groups, with VUMD showing more robust adaptations in pooled COD tests and lateral/horizontal jumping, whereas the opposite occurred in CBV respecting linear sprinting and vertical jumping. Between-groups analyses showed substantially better results in lateral jumps (ES = 0.21), left-leg horizontal jump (ES = 0.35), and 10-m COD with right leg (ES = 0.42) in VUMD than in CBV. In contrast, left-leg countermovement jump (ES = 0.26) was possibly better in CBV than in VUMD. Eight weeks of EOT induced substantial improvements in functional-performance tests, although the force-vector application may play a key role to develop different and specific functional adaptations.

Food-dependent exercise-induced anaphylaxis with a high level of plasma noradrenaline.

Science.gov (United States)

Kato, Yukihiko; Nagai, Ayako; Saito, Masuyoshi; Ito, Tomonobu; Koga, Michiyuki; Tsuboi, Ryoji

2007-02-01

Ingesting certain foods sometimes triggers anaphylaxis when followed by exercise (food-dependent exercise-induced anaphylaxis, FDEIA). Specific food-induced mucocutaneous urticaria may also progress to anaphylaxis (oral allergy syndrome, OAS). A positive skin test and/or radioallergosorbent test (RAST) to the foods suggest involvement of immunoglobulin (Ig)E-anaphylaxis in both disorders. The triggering foods and initial target organs are usually different in each case. In the present study, a 32-year-old male reported dyspnea accompanied by wheals, and symptoms of low blood pressure while walking after eating Chinese noodles and donuts. He also reported uncomfortable sensations in his mouth and throat after ingesting melon. Exercise challenge tests were administered. Serum histamine, plasma adrenaline, noradrenaline and dopamine were measured pre- and post-test. No symptoms were induced by exercise or by the ingestion of any single food item before exercise. However, numerous wheals appeared when exercise followed the combined ingestion of foods. Likewise, the sequence of eating pancakes and then exercising resulted in numerous wheals and anaphylaxis. Olopatadine hydrochloride and ketotifen fumarate completely inhibited this anaphylaxis. The skin prick tests resulted in fruit-induced erythema and wheals. The results of these tests with wheat, butter and sugar were negative, and no symptoms were induced by the exercise test after ingestion of watermelon, melon or apple. The anaphylactoid symptoms were accompanied by a significant increase of plasma noradrenaline. In this case, not only wheat, but sugar and butter may induce the onset of FDEIA. There was no significant correlation between the intensity of the symptoms and the serum histamine levels in the present case. Noradrenaline may be involved in the onset of FDEIA, since noradrenaline may selectively inhibit T-helper (Th)1 functions while favoring Th2 responses. The tests showed no cross-reactivity between the

Longitudinal changes in reproductive hormones and menstrual cyclicity in cynomolgus monkeys during strenuous exercise training: abrupt transition to exercise-induced amenorrhea.

Science.gov (United States)

Williams, N I; Caston-Balderrama, A L; Helmreich, D L; Parfitt, D B; Nosbisch, C; Cameron, J L

2001-06-01

Cross-sectional studies of exercise-induced reproductive dysfunction have documented a high proportion of menstrual cycle disturbances in women involved in strenuous exercise training. However, longitudinal studies have been needed to examine individual susceptibility to exercise-induced reproductive dysfunction and to elucidate the progression of changes in reproductive function that occur with strenuous exercise training. Using the female cynomolgus monkey (Macaca fascicularis), we documented changes in menstrual cyclicity and patterns of LH, FSH, estradiol, and progesterone secretion as the animals developed exercise-induced amenorrhea. As monkeys gradually increased running to 12.3 +/- 0.9 km/day, body weight did not change significantly although food intake remained constant. The time spent training until amenorrhea developed varied widely among animals (7-24 months; mean = 14.3 +/- 2.2 months) and was not correlated with initial body weight, training distance, or food intake. Consistent changes in function of the reproductive axis occurred abruptly, one to two menstrual cycles before the development of amenorrhea. These included significant declines in plasma reproductive hormone concentrations, an increase in follicular phase length, and a decrease in luteal phase progesterone secretion. These data document a high level of interindividual variability in the development of exercise-induced reproductive dysfunction, delineate the progression of changes in reproductive hormone secretion that occur with exercise training, and illustrate an abrupt transition from normal cyclicity to an amenorrheic state in exercising individuals, that is not necessarily associated with weight loss.

Effect of deep stripping massage alone or with eccentric resistance on hamstring length and strength.

Science.gov (United States)

Forman, Jeffrey; Geertsen, Lisbeth; Rogers, Michael E

2014-01-01

Many studies have evaluated the effects of different interventions on hamstring length. However, little research has been conducted on the effects of deep stripping massage strokes (DSMS) alone, or combined with eccentric resistance, on hamstring length and strength. To determine: 1) if DSMS have an effect on hamstring length and strength and 2) if the effects on hamstring length and strength are any different when DSMS are combined with eccentric exercise. 89 Community College students and community members between the ages of 18 and 62 volunteered for the study. Of these, 64 demonstrated tight hamstrings on either one or both sides as defined by supine, passive terminal knee extension of ≤75° and participated in the study. Strength was assessed by pressing the posterior calcaneus into a strain gauge for approximately 5 s while seated with the knee flexed to 90°. On their tighter side, participants were administered longitudinal DSMS during 15, 10-s bouts of eccentric resistance with an elastic resistance band. On their other hamstring, participants were administered 15, 10-s longitudinal DSMS while lying passive. All massage strokes were performed at a depth of 7 out of 10 on a verbal pressure scale index. Afterwards, the hamstring flexibility and strength tests were repeated. Both DSMS with eccentric resistance (10.7%) and DSMS alone (6.3%) resulted in improved (p alone. Strength was not significantly affected by either treatment. These results suggest that DSMS increases hamstring length in less than 3 min but has no affect on strength. Furthermore, combining DSMS with eccentric resistance produces more hamstring flexibility gains than DSMS alone and does not affect strength. Copyright © 2013 Elsevier Ltd. All rights reserved.

Flow Mode Magnetorheological Dampers with an Eccentric Gap

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Young-Tai Choi

2014-07-01

Full Text Available This paper analyzes flow mode magnetorheological (MR dampers with an eccentric annular gap (i.e., a nonuniform annular gap. To this end, an MR damper analysis for an eccentric annular gap is constructed based on approximating the eccentric annular gap using a rectangular duct with a variable gap, as well as a Bingham-plastic constitutive model of the MR fluid. Performance of flow mode MR dampers with an eccentric gap was assessed analytically using both field-dependent damping force and damping coefficient, which is the ratio of equivalent viscous field-on damping to field-off damping. In addition, damper capabilities of flow mode MR dampers with an eccentric gap were compared to a concentric gap (i.e., uniform annular gap.

Increased pain sensitivity but normal function of exercise induced analgesia in hip and knee osteoarthritis - treatment effects of neuromuscular exercise and total joint replacement

DEFF Research Database (Denmark)

Kosek, E; Roos, Ewa M.; Ageberg, E

2013-01-01

To assess exercise induced analgesia (EIA) and pain sensitivity in hip and knee osteoarthritis (OA) and to study the effects of neuromuscular exercise and surgery on these parameters.......To assess exercise induced analgesia (EIA) and pain sensitivity in hip and knee osteoarthritis (OA) and to study the effects of neuromuscular exercise and surgery on these parameters....

Exercise-induced muscle-derived cytokines inhibit mammary cancer cell growth.

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Hojman, Pernille; Dethlefsen, Christine; Brandt, Claus; Hansen, Jakob; Pedersen, Line; Pedersen, Bente Klarlund

2011-09-01

Regular physical activity protects against the development of breast and colon cancer, since it reduces the risk of developing these by 25-30%. During exercise, humoral factors are released from the working muscles for endocrinal signaling to other organs. We hypothesized that these myokines mediate some of the inhibitory effects of exercise on mammary cancer cell proliferation. Serum and muscles were collected from mice after an exercise bout. Incubation with exercise-conditioned serum inhibited MCF-7 cell proliferation by 52% and increased caspase activity by 54%. A similar increase in caspase activity was found after incubation of MCF-7 cells with conditioned media from electrically stimulated myotubes. PCR array analysis (CAPM-0838E; SABiosciences) revealed that seven genes were upregulated in the muscles after exercise, and of these oncostatin M (OSM) proved to inhibit MCF-7 proliferation by 42%, increase caspase activity by 46%, and induce apoptosis. Blocking OSM signaling with anti-OSM antibodies reduced the induction of caspase activity by 51%. To verify that OSM was a myokine, we showed that it was significantly upregulated in serum and in three muscles, tibialis cranialis, gastronemius, and soleus, after an exercise bout. In contrast, OSM expression remained unchanged in subcutaneous and visceral adipose tissue, liver, and spleen (mononuclear cells). We conclude that postexercise serum inhibits mammary cancer cell proliferation and induces apoptosis of these cells. We suggest that one or more myokines secreted from working muscles may be mediating this effect and that OSM is a possible candidate. These findings emphasize that role of physical activity in cancer treatment, showing a direct link between exercise-induced humoral factors and decreased tumor cell growth.

Maintenance of exercise-induced benefits in physical functioning and bone among elderly women.

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Karinkanta, S; Heinonen, A; Sievänen, H; Uusi-Rasi, K; Fogelholm, M; Kannus, P

2009-04-01

This study showed that about a half of the exercise-induced gain in dynamic balance and bone strength was maintained one year after cessation of the supervised high-intensity training of home-dwelling elderly women. However, to maintain exercise-induced gains in lower limb muscle force and physical functioning, continued training seems necessary. Maintenance of exercise-induced benefits in physical functioning and bone structure was assessed one year after cessation of 12-month randomized controlled exercise intervention. Originally 149 healthy women 70-78 years of age participated in the 12-month exercise RCT and 120 (81%) of them completed the follow-up study. Self-rated physical functioning, dynamic balance, leg extensor force, and bone structure were assessed. During the intervention, exercise increased dynamic balance by 7% in the combination resistance and balance-jumping training group (COMB). At the follow-up, a 4% (95% CI: 1-8%) gain compared with the controls was still seen, while the exercise-induced isometric leg extension force and self-rated physical functioning benefits had disappeared. During the intervention, at least twice a week trained COMB subjects obtained a significant 2% benefit in tibial shaft bone strength index compared to the controls. A half of this benefit seemed to be maintained at the follow-up. Exercise-induced benefits in dynamic balance and rigidity in the tibial shaft may partly be maintained one year after cessation of a supervised 12-month multi-component training in initially healthy elderly women. However, to maintain the achieved gains in muscle force and physical functioning, continued training seems necessary.

Effect of birth weight and 12 weeks of exercise training on exercise-induced AMPK signaling in human skeletal muscle

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Mortensen, Brynjulf; Hingst, Janne Rasmuss; Frederiksen, Nicklas

2013-01-01

. We investigated 21 LBW and 21 normal birth weight (NBW) subjects during 1 hour of acute exercise performed at the same relative workload before and after 12 weeks of exercise training. Multiple skeletal muscle biopsies were obtained before and after exercise. Protein levels and phosphorylation status......Subjects with a low birth weight (LBW) display increased risk of developing type 2 diabetes (T2D). We hypothesized that this is associated with defects in muscle adaptations following acute and regular physical activity, evident by impairments in the exercise-induced activation of AMPK signaling...... were determined by Western blotting. AMPK activities were measured using activity assays. Protein levels of AMPK isoforms a1 and ¿1 were significantly increased while ¿3 levels decreased with training independent of group. The LBW group had higher exercise-induced AMPK Thr(172) phosphorylation before...

The effect of positive expiratory pressure (PEP) therapy on symptoms, quality of life and incidence of re-exacerbation in patients with acute exacerbations of chronic obstructive pulmonary disease: a multicentre, randomised controlled trial.

Science.gov (United States)

Osadnik, Christian R; McDonald, Christine F; Miller, Belinda R; Hill, Catherine J; Tarrant, Ben; Steward, Ranjana; Chao, Caroline; Stodden, Nicole; Oliveira, Cristino C; Gagliardi, Nadia; Holland, Anne E

2014-02-01

Positive expiratory pressure (PEP) is a technique used to enhance sputum clearance during acute exacerbations of chronic obstructive pulmonary disease (AECOPD). The impact of PEP therapy during acute exacerbations on clinically important outcomes is not clear. This study sought to determine the effect of PEP therapy on symptoms, quality of life and future exacerbations in patients with AECOPD. 90 inpatients (58 men; mean age 68.6 years, FEV(1) 40.8% predicted) with AECOPD and sputum expectoration were randomised to receive usual care (including physical exercise)±PEP therapy. The Breathlessness, Cough and Sputum Scale (BCSS), St George's Respiratory Questionnaire (SGRQ) and BODE index (Body mass index, airflow Obstruction, Dyspnoea, Exercise tolerance) were measured at discharge, 8 weeks and 6 months following discharge, and analysed via linear mixed models. Exacerbations and hospitalisations were recorded using home diaries. There were no significant between-group differences over time for BCSS score [mean (SE) at discharge 5.2 (0.4) vs 5.0 (0.4) for PEP and control group, respectively; p=0.978] or SGRQ total score [41.6 (2.6) vs 40.8 (2.8) at 8 weeks, p=0.872]. Dyspnoea improved more rapidly in the PEP group over the first 8 weeks (p=0.006), however these benefits were not observed at 6 months. Exacerbations (p=0.986) and hospitalisations (p=0.359) did not differ between groups. We found no evidence that PEP therapy during AECOPD improves important short-term or long-term outcomes. There does not appear to be a routine role for PEP therapy in the management of such individuals.

Aging exacerbates obesity-induced oxidative stress and inflammation in perivascular adipose tissue in mice: a paracrine mechanism contributing to vascular redox dysregulation and inflammation.

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Bailey-Downs, Lora C; Tucsek, Zsuzsanna; Toth, Peter; Sosnowska, Danuta; Gautam, Tripti; Sonntag, William E; Csiszar, Anna; Ungvari, Zoltan

2013-07-01

Obesity in the elderly individuals is increasing at alarming rates and there is evidence suggesting that elderly individuals are more vulnerable to the deleterious cardiovascular effects of obesity than younger individuals. However, the specific mechanisms through which aging and obesity interact to promote the development of cardiovascular disease remain unclear. The present study was designed to test the hypothesis that aging exacerbates obesity-induced inflammation in perivascular adipose tissue, which contributes to increased vascular oxidative stress and inflammation in a paracrine manner. To test this hypothesis, we assessed changes in the secretome, reactive oxygen species production, and macrophage infiltration in periaortic adipose tissue of young (7 month old) and aged (24 month old) high-fat diet-fed obese C57BL/6 mice. High-fat diet-induced vascular reactive oxygen species generation significantly increased in aged mice, which was associated with exacerbation of endothelial dysfunction and vascular inflammation. In young animals, high-fat diet-induced obesity promoted oxidative stress in the perivascular adipose tissue, which was associated with a marked proinflammatory shift in the profile of secreted cytokines and chemokines. Aging exacerbated obesity-induced oxidative stress and inflammation and significantly increased macrophage infiltration in periaortic adipose tissue. Using cultured arteries isolated from young control mice, we found that inflammatory factors secreted from the perivascular fat tissue of obese aged mice promote significant prooxidative and proinflammatory phenotypic alterations in the vascular wall, mimicking the aging phenotype. Overall, our findings support an important role for localized perivascular adipose tissue inflammation in exacerbation of vascular oxidative stress and inflammation in aging, an effect that likely enhances the risk for development of cardiovascular diseases from obesity in the elderly individuals.

Nonpharmacologic strategies to manage exercise-induced bronchoconstriction

DEFF Research Database (Denmark)

Dickinson, John; Amirav, Israel; Hostrup, Morten

2018-01-01

Pharmacologic management of exercise-induced bronchoconstriction (EIB) is the mainstay of preventative therapy. There are some nonpharmacologic interventions, however, that may assist the management of EIB. This review discusses these nonpharmacologic interventions and how they may be applied to ...

Does chronic smoking affect induced-exercise catecholamine release?

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Gökhan İpekoğlu

2017-04-01

Full Text Available This study was performed to investigate the acute effect of the submaximal aerobic exercise upon epinephrine and nor-epinephrine levels in chronic smokers and non-smoker.  The study was carried out upon 10 regular (15> cigarettes/day smoker untrained male along five years and 10 never smoker untrained male. Subjects performed an endurance exercise that continues 40 minutes at 70% maximal heart rate. There were 15cc venous blood samples extracted from the forearm pre-exercise (PRE, post-exercise (POST, post-exercise 2 hours (2h, post-exercise 24 hours (24h to measure of epinephrine and nor-epinephrine levels. The plasma level of each hormone increased after exercise and the tendency of rise was similar between groups as it seen in which 55,6% and 54,68% for epinephrine and 27,1% and 35,7% for norepinephrine. In this respect no group-time relationship has been found (p>0,05.  But in between-group analyses, basal and after exercise levels were different (p<0,05. The study revealed the fact that, smokers have higher plasma levels of epinephrine and norepinephrine before and after exercise. The results demonstrate that long-term smoking induces elevate baseline and post-aerobic submaximal exercise plasma epinephrine and nor-epinephrine levels.  The sympatho-adrenal activity appears to be disrupt with long-term smoking which effect the glycolytic and fat metabolism during exercise.

THREE-DIMENSIONAL ATMOSPHERIC CIRCULATION OF HOT JUPITERS ON HIGHLY ECCENTRIC ORBITS

International Nuclear Information System (INIS)

Kataria, T.; Showman, A. P.; Lewis, N. K.; Fortney, J. J.; Marley, M. S.; Freedman, R. S.

2013-01-01

Of the over 800 exoplanets detected to date, over half are on non-circular orbits, with eccentricities as high as 0.93. Such orbits lead to time-variable stellar heating, which has major implications for the planet's atmospheric dynamical regime. However, little is known about the fundamental dynamical regime of such planetary atmospheres, and how it may influence the observations of these planets. Therefore, we present a systematic study of hot Jupiters on highly eccentric orbits using the SPARC/MITgcm, a model which couples a three-dimensional general circulation model (the MITgcm) with a plane-parallel, two-stream, non-gray radiative transfer model. In our study, we vary the eccentricity and orbit-average stellar flux over a wide range. We demonstrate that the eccentric hot Jupiter regime is qualitatively similar to that of planets on circular orbits; the planets possess a superrotating equatorial jet and exhibit large day-night temperature variations. As in Showman and Polvani, we show that the day-night heating variations induce momentum fluxes equatorward to maintain the superrotating jet throughout its orbit. We find that as the eccentricity and/or stellar flux is increased (corresponding to shorter orbital periods), the superrotating jet strengthens and narrows, due to a smaller Rossby deformation radius. For a select number of model integrations, we generate full-orbit light curves and find that the timing of transit and secondary eclipse viewed from Earth with respect to periapse and apoapse can greatly affect what we see in infrared (IR) light curves; the peak in IR flux can lead or lag secondary eclipse depending on the geometry. For those planets that have large temperature differences from dayside to nightside and rapid rotation rates, we find that the light curves can exhibit 'ringing' as the planet's hottest region rotates in and out of view from Earth. These results can be used to explain future observations of eccentric transiting exoplanets.

High Prevalence of Exercise-Induced Laryngeal Obstruction in Athletes

DEFF Research Database (Denmark)

Walsted Nielsen, Emil; Hull, James H; Backer, Vibeke

2013-01-01

INTRODUCTION: Unexplained respiratory symptoms reported by athletes are often incorrectly considered secondary to exercise-induced asthma. We hypothesised that this may be related to exercise induced laryngeal obstruction (EILO). This study evaluates the prevalence of EILO in an unselected cohort......-one percent of athletes with EILO and negative bronchoprovocation and bronchodilator reversibility tests used regular asthma medication at referral. CONCLUSION: In athletes with unexplained respiratory symptoms, EILO is an important differential diagnosis not discerned from other aetiologies by clinical...... features. These findings have important implications for the assessment and management of athletes presenting with persistent respiratory symptoms despite asthma therapy....

EXTRACTING PLANET MASS AND ECCENTRICITY FROM TTV DATA

International Nuclear Information System (INIS)

Lithwick, Yoram; Xie Jiwei; Wu Yanqin

2012-01-01

Most planet pairs in the Kepler data that have measured transit time variations (TTVs) are near first-order mean-motion resonances. We derive analytical formulae for their TTV signals. We separate planet eccentricity into free and forced parts, where the forced part is purely due to the planets' proximity to resonance. This separation yields simple analytical formulae. The phase of the TTV depends sensitively on the presence of free eccentricity: if the free eccentricity vanishes, the TTV will be in phase with the longitude of conjunctions. This effect is easily detectable in current TTV data. The amplitude of the TTV depends on planet mass and free eccentricity, and it determines planet mass uniquely only when the free eccentricity is sufficiently small. We analyze the TTV signals of six short-period Kepler pairs. We find that three of these pairs (Kepler 18, 24, 25) have a TTV phase consistent with zero. The other three (Kepler 23, 28, 32) have small TTV phases, but ones that are distinctly non-zero. We deduce that the free eccentricities of the planets are small, ∼< 0.01, but not always vanishing. Furthermore, as a consequence of this, we deduce that the true masses of the planets are fairly accurately determined by the TTV amplitudes, within a factor of ∼< 2. The smallness of the free eccentricities suggests that the planets have experienced substantial dissipation. This is consistent with the hypothesis that the observed pile-up of Kepler pairs near mean-motion resonances is caused by resonant repulsion. But the fact that some of the planets have non-vanishing free eccentricity suggests that after resonant repulsion occurred there was a subsequent phase in the planets' evolution when their eccentricities were modestly excited, perhaps by interplanetary interactions.

Does eccentric training of hamstring muscles reduce acute injuries in soccer?

Science.gov (United States)

Nichols, Andrew W

2013-01-01

To investigate the effectiveness of a 10-week hamstring exercise training program in reducing the incidence and severity of new and recurrent hamstring injuries among male soccer players. Cluster-randomized (by team)controlled trial, stratified by level of play and geographic location. Sample size was calculated with 80% power to show a relative risk reduction for injury of 50% at P ≤ 0.05. Soccer community study in Denmark during the period January to December 2008. Teams in the top 5 soccer divisions (2 professional and 3 amateur)were invited to participate. The exclusion criterion for teams was that they already used eccentric hamstring exercises, and for participants was that they joined the teams after the beginning of the season. Of 116 teams, 54 were eligible and willing to be randomized and 50 were included in the analysis (942 players). Teams in both the intervention and control groups followed their normal training programs. At the beginning of the study period, the intervention teams added 27 sessions of the Nordicham string exercise (after warm-up) during the 10-week period of the mid-season break. The exercise begins with the player kneeling with the torso upright and rigid, and the feet held down to the ground by a partner. The player lowers his torso forwards toward the ground braking with his hamstring muscles until the chest reaches the ground (eccentric phase). He returns to the upright position, pushing with his hands to minimize the concentric phase load. Sessions per week and sets and repetitions per session increased to 3, 3, and 12, respectively. Team coaches supervised the sessions. A hamstring injury was defined as an acute occurrence of a “physical complaint in the region of the posterior thigh sustained during a soccer match or training, irrespective of the need for medical attention or time loss from soccer activities.” Injuries were recorded by the teams’ medical staff on standardized forms. Only first injuries during the season

Experience affects exercise-induced changes in catecholamines, glucose, and FFA

NARCIS (Netherlands)

Scheurink, A.J.W.; Steffens, A.B.; Dreteler, G.H.; Benthem, L.; Bruntink, R.

The interference of the experimental conditions on the exercise-induced alterations in plasma catecholamines, plasma free fatty acids, and glucose and insulin concentrations was investigated in rats. Exercise consisted of strenuous swimming against a countercurrent (0.22 m/s) for 15 min in a pool

Effect of Submaximal Warm-up Exercise on Exercise-induced Asthma in African School Children.

Science.gov (United States)

Mtshali, B F; Mokwena, K; Oguntibeju, O O

2015-03-01

Regular physical activity has long been regarded as an important component of a healthy lifestyle. Exercise-induced asthma (EIA) is one of the major problems interfering with the performance of exercise. A warm-up exercise programme has been cited as a non-pharmacologic means of reducing EIA, but its effect has not been fully elucidated. The aims of this study were to determine the prevalence of unrecognized EIA in Pretoria primary school children, determine the effect of a warm-up exercise programme on EIA and to establish the relationship between history of allergy, family history of asthma and EIA. A random sample of 640 school children was selected. The study was divided into three phases. In phase one, a descriptive cross-sectional study was done using the standardized European Community Respiratory Health Survey (ECRHS) questionnaire. In phase two, non-asthmatic participants that returned a completed questionnaire were included in the field study. Pre-test and post-test experimental designs were used, where peak expiratory flow rate (PEFR) was measured at baseline and within ten minutes after exercise. A total of 340 subjects completed the Free Running Asthma Screening Test (FRAST); EIA was defined as a decrease in baseline PEFR ≥ 10% after exercise and 75 children (22%) had EIA. In phase three, 29 of the 75 subjects participated in the warm-up programme which was performed in the laboratory and subjects acted as their own controls. Predefined protocols for the study were followed. Seventy-five (22%) of the 340 participants had EIA. The mean age, height and weight were 10.51 years, 139.26 cm and 33.45 kg, respectively. Exercise-induced asthma symptoms were cough (25%), chest pain (16%), wheeze (12%) and chest tightness (12%). The history of allergy was 75%, family history of allergy 40% and positive history of allergy when near animals, feathers or in dusty areas 38%. Wheezing during or after exercise, wheezing when near animals, feathers or in dusty areas

Exercise-Induced Bronchospasm and Allergy

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Serena Caggiano

2017-06-01

Full Text Available Sport is an essential part of childhood, with precious and acknowledged positive health effects but the impact of exercise-induced bronchoconstriction (EIB significantly reduces participation in physical activity. It is important to recognize EIB, differentiating EIB with or without asthma if the transient narrowing of the airways after exercise is associated with asthmatic symptoms or not, in the way to select the most appropriate treatment among the many treatment options available today. Therapy is prescribed based on symptoms severity but diagnosis of EIB is established by changes in lung function provoked by exercise evaluating by direct and indirect tests. Sometimes, in younger children it is difficult to obtain the registration of difference between the preexercise forced expiratory volume in the first second (FEV1 value and the lowest FEV1 value recorded within 30 min after exercise, defined as the gold standard, but interrupter resistance, in association with spirometry, has been showed to be a valid alternative in preschool age. Atopy is the main risk factor, as demonstrated by epidemiologic data showing that among the estimated pediatric population with EIB up to 40% of them have allergic rhinitis and 30% of these patients may develop adult asthma, according with atopic march. Adopting the right treatment and prevention, selecting sports with no marked hyperventilation and excessive cooling of the airways, children with EIB can be able to take part in physical activity like all others.

Quasi-eccentricity error modeling and compensation in vision metrology

Science.gov (United States)

Shen, Yijun; Zhang, Xu; Cheng, Wei; Zhu, Limin

2018-04-01

Circular targets are commonly used in vision applications for its detection accuracy and robustness. The eccentricity error of the circular target caused by perspective projection is one of the main factors of measurement error which needs to be compensated in high-accuracy measurement. In this study, the impact of the lens distortion on the eccentricity error is comprehensively investigated. The traditional eccentricity error turns to a quasi-eccentricity error in the non-linear camera model. The quasi-eccentricity error model is established by comparing the quasi-center of the distorted ellipse with the true projection of the object circle center. Then, an eccentricity error compensation framework is proposed which compensates the error by iteratively refining the image point to the true projection of the circle center. Both simulation and real experiment confirm the effectiveness of the proposed method in several vision applications.

Low-dose cadmium exposure exacerbates polyhexamethylene guanidine-induced lung fibrosis in mice.

Science.gov (United States)

Kim, Min-Seok; Kim, Sung-Hwan; Jeon, Doin; Kim, Hyeon-Young; Han, Jin-Young; Kim, Bumseok; Lee, Kyuhong

2018-01-01

Cadmium (Cd) is a toxic metal present in tobacco smoke, air, food, and water. Inhalation is an important route of Cd exposure, and lungs are one of the main target organs for metal-induced toxicity. Cd inhalation is associated with an increased risk of pulmonary diseases. The present study aimed to assess the effects of repeated exposure to low-dose Cd in a mouse model of polyhexamethylene guanidine (PHMG)-induced lung fibrosis. Mice were grouped into the following groups: vehicle control (VC), PHMG, cadmium chloride (CdCl 2 ), and PHMG + CdCl 2 . Animals in the PHMG group exhibited increased numbers of total cells and inflammatory cells in the bronchoalveolar lavage fluid (BALF) accompanied by inflammation and fibrosis in lung tissues. These parameters were exacerbated in mice in the PHMG + CdCl 2 group. In contrast, mice in the CdCl 2 group alone displayed only minimal inflammation in pulmonary tissue. Expression of inflammatory cytokines and fibrogenic mediators was significantly elevated in lungs of mice in the PHMG group compared with that VC. Further, expression of these cytokines and mediators was enhanced in pulmonary tissue in mice administered PHMG + CdCl 2 . Data demonstrate that repeated exposure to low-dose Cd may enhance the development of PHMG-induced pulmonary fibrosis.

The Effect of Body Mass on Eccentric Knee-Flexor Strength Assessed With an Instrumented Nordic Hamstring Device (Nordbord) in Football Players.

Science.gov (United States)

Buchheit, Martin; Cholley, Yannick; Nagel, Mark; Poulos, Nicholas

2016-09-01

To examine the effect of body mass (BM) on eccentric knee-flexor strength using the Nordbord and offer simple guidelines to control for the effect of BM on knee-flexor strength. Data from 81 soccer players (U17, U19, U21, senior 4th French division, and professionals) and 41 Australian Football League (AFL) players were used for analysis. They all performed 1 set of 3 maximal repetitions of the bilateral Nordic hamstring exercise, with the greatest strength measure used for analysis. The main regression equation obtained from the overall sample was used to predict eccentric knee-flexor strength from a given BM (moderate TEE, 22%). Individual deviations from the BM-predicted score were used as a BM-free index of eccentric knee- flexor strength. There was a large (r = .55, 90% confidence limits .42;.64) correlation between eccentric knee-flexor strength and BM. Heavier and older players (professionals, 4th French division, and AFL) outperformed their lighter and younger (U17-U21) counterparts, with the soccer professionals presenting the highest absolute strength. Professional soccer players were the only ones to show strength values likely slightly greater than those expected for their BM. Eccentric knee-flexor strength, as assessed with the Nordbord, is largely BM-dependent. To control for this effect, practitioners may compare actual test performances with the expected strength for a given BM, using the following predictive equation: Eccentric strength (N) = 4 × BM (kg) + 26.1. Professional soccer players with specific knee-flexor-training history and enhanced neuromuscular performance may show higher than expected values.

Spred-2 deficiency exacerbates lipopolysaccharide-induced acute lung inflammation in mice.

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