Effects Of Eccentric Exercise Research Articles

Clinical Outcomes and Central Pain Mechanisms are Improved After Upper Trapezius Eccentric Training in Female Computer Users With Chronic Neck/Shoulder Pain.

The effects of eccentric exercises on clinical outcomes and central pain mechanisms are unclear in neck/shoulder pain (NSP). The aims were to: (1) evaluate the clinical impact of unilateral eccentric training in female computer users with chronic NSP; (2) compare pressure pain sensitivity, temporal summation of pain (TSP); and conditioned pain modulation (CPM) in female office workers with and without NSP; and (3) assess sensitization and central pain responses after training. In part A, 20 females with NSP were compared with 20 controls. In part B, the NSP group underwent a 5-week upper trapezius eccentric training program. Participants reported their pain intensity and completed the Neck Disability Index, and the Disabilities of the Arm, Shoulder and Hand questionnaire. Pressure pain thresholds (PPTs) were assessed over the neck and forearm. Cuff algometry identified pain detection threshold (PDT) and pain tolerance thresholds (PTT). TSP was evaluated by visual analog scale pain scores during 10 repetitive cuff stimulations. CPM was calculated as the difference in PDT with and without a conditioning painful stimulus. Outcomes were measured at baseline and after intervention. Pain intensities were collected at 3- and 6-month follow-up. Pain and disability decreased after intervention (P<0.05) and at follow-ups (P=0.002). The NSP group showed reduced PTT (P≤0.02), but no differences in TSP (P=0.947) or CPM (P=0.059) compared with controls. After training, participants with NSP had improved CPM, PPTs, and PTT at the nontreated side (P<0.05). Eccentric training improved pain and disability, reduced sensitization, and enhanced CPM efficiency in female computer users with NSP.

OR-018 The study of acupuncture intervention on the dynamic changes of Ca2+, Na+, H2O2 flux at earlier time points of rat skeletal muscle regeneration following eccentric exercise

OR-018 The study of acupuncture intervention on the dynamic changes of Ca2+, Na+, H2O2 flux at earlier time points of rat skeletal muscle regeneration following eccentric exercise

The effect of eccentric exercise and delayed onset muscle soreness on the homologous muscle of the contralateral limb

High intensity eccentric exercise induces muscle fiber damage and associated delayed-onset muscle soreness (DOMS) resulting in an impaired ability of the muscle to generate voluntary force. This study investigates the extent to which DOMS, induced by high intensity eccentric exercise, can affect the activation and performance of the non-exercised homologous muscle of the contralateral limb. Healthy volunteers performed maximal voluntary contractions of knee extension and sustained isometric knee extension at 50% of maximal force until task failure on both the ipsilateral exercised limb and the contralateral limb. Surface electromyography (EMG) was recorded from the ipsilateral and contralateral knee extensor muscles (vastus medialis, rectus femoris, and vastus lateralis). Maximal isometric knee extension force (13.7% reduction) and time to task failure (38.1% reduction) of the contralateral non-exercised leg decreased immediately after eccentric exercise, and persisted 24 h and 48 h later (p < 0.05). Moreover, the amplitude of muscle activity recorded from the contralateral knee extensor muscles was significantly lower during the post exercise maximal and submaximal contractions following high intensity eccentric exercise of the opposite limb (p < 0.05). Unilateral high intensity eccentric exercise of the quadriceps can contribute to reduced neuromuscular activity and physical work capacity of the non-exercised homologous muscle in the contralateral limb.

Trapezius viscoelastic properties are heterogeneously affected by eccentric exercise

ObjectivesThe aim of this study was to investigate the influence of eccentric exercise (ECC) on the spatial mapping of muscle stiffness and creep of the upper trapezius, using a quantitative myotonometry device. DesignTwo groups of 16 subjects participated in the experimental sessions. In part A, the test–retest reliabilities of muscle stiffness and creep were assessed. In part B, muscle stiffness and muscle creep were mapped before, immediately after and 24h after ECC when post-exercise soreness had developed. MethodsThe ECC protocol consisted of 50 eccentric contractions divided into 5 bouts of 10 contractions at maximum force level. ResultsThe relative reliabilities of stiffness and creep measurements were found to be substantial to almost perfect. Muscle stiffness for musculotendinous sites increased at 24h after ECC while it decreased for muscle belly immediately after and 24h after ECC. Muscle creep for musculotendinous sites decreased, and for muscle belly sites increased, immediately after and 24h after ECC. ConclusionsFor the first time, the present study showed sign of discrepancies in the effects of ECC on muscle stiffness and creep, underlining opposite changes in the musculotendinous and muscle belly viscoelastic properties of upper trapezius.

Effectiveness of Eccentric Exercise and a Vibration or Cryotherapy Program in Enhancing Rectus Abdominis Muscle Thickness and Inter-Rectus Distance in Patients with Chronic Mid-Portion Achilles Tendinopathy: A Randomized Clinical Trial.

Purpose: Abdominal muscles are key in maintaining body stability and balance and an improvement in the functioning of these muscles could influence the rehabilitation process in lower limb pathologies such as Achilles Tendinopathy (AT). The aim was to explore whether calf eccentric exercise (EE) with vibration training was more effective at causing adaptation to the rectus anterior (RA) thickness and inter-rectus distance (IRD) than calf EE with cryotherapy.Methods: The investigation was a single-blinded, randomized, controlled clinical trial (NCT03515148). Sixty-one individuals diagnosed with mid-portion AT were recruited and divided in two groups: group A (n = 30) followed an EE with vibration program and group B (n = 31) an EE program with cryotherapy, for 12-weeks. RA muscle thickness and IRD were measured in maximal isometric contraction and at rest as an indication of superficial abdominal muscle activation.Results: IRD measures showed a significant (P < 0.05) decrease at baseline, 4 and at 12-weeks in both groups, but no significant differences were observed between the intervention groups. RA thickness was significantly increased (P < 0.05) in measures at baseline, 4 and 12-weeks showed a significant increase in maximal isometric contraction and at rest in favor of the EE vibration program group.Conclusions: The present study showed a RA thickness increase in both groups in favor of the EE vibration program with respect to cryotherapy added to EE in short and mid term in maximal isometric contraction and at rest in subjects with chronic mid-portion AT. IRD was decreased in both groups without between-groups differences.

The Effects of Eccentric Exercise on Muscle Damage and Blood Redox Status in Men and Women

The purpose of the present investigation was to study the possible differences between men and women in muscle damage indices and oxidative stress biomarkers in response to eccentric exercise. Ten males and ten females performed a bout of eccentric exercise using an isokinetic dynamometer. Muscle damage indices (i.e., isometric torque, range of movement, delayed onset muscle soreness, and creatine kinase (CK)) and oxidative stress biomarkers (i.e., protein carbonyls and glutathione) were measured before and 48 h after eccentric exercise. No significant main effect of group or time–group interaction was found for muscle damage indices and oxidative stress biomarkers. However, the main effect of time was significant for all measured parameters. The findings of the present investigation indicate that eccentric exercise caused muscle damage and oxidative stress (i.e., protein and glutathione oxidation) in both males and females with no significant differences between the two groups. It is concluded that there are no differences between males and females regarding muscle damage and oxidative stress after eccentric exercise.

The effect of eccentric exercise with blood flow restriction on neuromuscular activation, microvascular oxygenation, and the repeated bout effect.

To examine the effect of low-intensity eccentric contractions with and without blood flow restriction (BFR) on microvascular oxygenation, neuromuscular activation, and the repeated bout effect (RBE). Participants were randomly assigned to either low-intensity (LI), low-intensity with BFR (LI-BFR), or a control (CON) group. Participants in LI and LI-BFR performed a preconditioning bout of low-intensity eccentric exercise prior to about of maximal eccentric exercise. Participants reported 24, 48, 72, and 96h later to assess muscle damage and function. Surface electromyography (sEMG) and near-infrared spectroscopy (NIRS) were used to measure neuromuscular activation and microvascular deoxygenation (deoxy-[Hb + Mb]) and [total hemoglobin] ([THC]) during the preconditioning bout, respectively. During set-2, LI-BFR resulted in greater activation of the VM-RMS (47.7 ± 11.5% MVIC) compared to LI (67.0 ± 20.0% MVIC), as well as during set-3 (p < 0.05). LI-BFR resulted in a greater change in deoxy-[Hb + Mb] compared to LI during set-2 (LI-BFR 13.1 ± 5.2µM, LI 6.7 ± 7.9µM), set-3 (LI-BFR 14.6 ± 6µM, LI 6.9 ± 7.4µM), and set-4 (p < 0.05). [THC] was higher during LI-BFR compared to LI (p < 0.05). All groups showed a decrease in MVIC torque immediately after maximal exercise (LI 74.2 ± 14.1%, LI-BFR 75 ± 5.1%, CON 53 ± 18.6%). At 24, 48, 72, and 96h post maximal eccentric exercise, LI and LI-BFR force deficit was not different from baseline. This study suggests that the neuromuscular and deoxygenation (i.e., metabolic stress) responses were considerably different between LI and LI-BFR groups; however, these differences did not lead to improvements in the RBE inferred by performing LI and LI-BFR.

Effects of Eccentric Exercise and Extracorporeal Shock Wave Therapy on Rehabilitation of Patients with Noncalcific Rotator Cuff Tendinopathy

Objective: In this study, in order to establish a more effective therapeutic model for the patients with chronic rotator cuff tendinosis, the authors attempted to compare the therapeutic effects of general physical therapy, eccentric contraction exercise, extracorporeal shock wave therapy (ESWT) and their combination for patients with noncalcific subscapular tendinosis. Methods: 120 patients with subscapular tendinosis Grade II tendinopathy were divided randomly into four groups: I-IV, with 30 patients in each group. In group I (GI): the patients received conventional rehabilitation program, which included 20 minute of local hot packs, 15 min interferential electrotherapy and 10 min of passive range motion exercise three times weekly for 8 weeks; in Group II: the patients received eccentric contraction exercise three times per day and a rehabilitation program as in GI; in GIII: the patients received ESWT therapy weekly except for a rehabilitation program as in GI; in GIV: they received three combination therapies including a conventional rehabilitation program, three rounds of eccentric contraction exercises per day and weekly ESWT for 8 weeks. The outcome measurements include visual analogue pain scale (VAS), range of shoulder motion, subscapular muscle peak torques, and proprioception of the affected shoulder. Results: The results showed that the combination therapy group GII-IV all had more improvement than the conventional rehabilitation program group I. However, the integrated therapy group IV had the best improvement over GII and GIII in pain reduction and improvement of range of motion, proprioception and muscle peak torques. Additionally, group III and IV had better improvement of range of motion and muscle peak torques than did GII. Conclusion: Eccentric exercise and ESWT had benefit in rehabilitation of patients with noncalcific subscapular tendinosis, and conventional rehabilitation combined with these two therapies will result in more therapeutic effects.

Effect of Eccentric Exercise with Blood Flow Restriction on Muscle Activation and Microvascular Oxygenation

Effect of Eccentric Exercise with Blood Flow Restriction on Muscle Activation and Microvascular Oxygenation

Effect of acute and chronic eccentric exercise on FOXO1 mRNA expression as fiber type transition factor in rat skeletal muscles

Skeletal muscle is a highly elastic tissue which can respond to various functional demands by altering fiber-type composition. Exercise affects muscle fiber phenotype. One of the transcription factors that induce fiber-type transition is forkhead box O1 (FOXO1). Since eccentric contraction considered an essential part of exercise, so we are interested to see the effects of eccentric exercise (acute/chronic) on FOXO1 as an important factor of fiber-type transition in rat skeletal muscles. Twenty-four Sprague–Dawley rats (190–235g) were divided to 3 groups of 8 rats: 1) chronic eccentric exercise (CEE), 2) acute eccentric exercise (AEE), and 3) control (C). The exercise groups underwent downhill running protocol. CEE was running on treadmill in 3days of week for 9weeks, that slope and duration gradually managed from −4° to −16° and 15 to 90min, respectively. AEE group was running with 16m/min on −16° slope for 3 consecutive days that included 18 sets of 5min with rest interval of 2min in between. Soleus and super vastus lateralis (SVL) muscles mRNA were analyzed by real-time RT-PCR. SVL FOXO1 mRNA levels increased by 3.92-fold in the AEE and decreased 0.56-fold in the CEE group and were not significant in soleus muscle. In soleus muscle, myosin heavy chain (MHC) IIa, IIx, and IIb decreased in the AEE group and MHC IIa and IIx decreased in the CEE group. In SVL muscle, MHC I, IIa, and IIx increased in the AEE group and MHC IIa and IIX increased in the CEE group. In summary, both acute and chronic eccentric exercise could lead to change in FOXO1 mRNA only in fast SVL muscle of rat and so could induce fiber-type transition in both muscles regardless of changes in expression of FOXO1. So, oxidative stress can play important role in change of FOXO1.

Eccentric exercise slows in vivo microvascular reactivity during brief contractions in human skeletal muscle

Unaccustomed exercise involving eccentric contractions results in muscle soreness and an overall decline in muscle function, however, little is known about the effects of eccentric exercise on microvascular reactivity in human skeletal muscle. Fourteen healthy men and women performed eccentric contractions of the dorsiflexor muscles in one leg, while the contralateral leg served as a control. At baseline, and 24 and 48 h after eccentric exercise, the following were acquired bilaterally in the tibialis anterior muscle: 1) transverse relaxation time (T2)-weighted magnetic resonance images to determine muscle cross-sectional area (mCSA) and T2; 2) blood oxygen level-dependent (BOLD) images during and following brief, maximal voluntary contractions (MVC) to monitor the hyperemic responses with participants positioned supine in a 3T magnet; 3) muscle strength; and 4) pain pressure threshold. Compared with the control leg, eccentric exercise resulted in soreness, decline in strength (∼20%), increased mCSA (∼7%), and prolonged T2 (∼7%) at 24 and 48 h (P < 0.05). The BOLD response to a brief MVC was altered 24 and 48 h after eccentric exercise, such that time-to-peak (∼35%, P < 0.05) and time-to-half-recovery (∼23%, P < 0.05) were prolonged. The altered contraction-induced hyperemic response suggests slowed microvascular reactivity and altered matching of O2 delivery to O2 utilization within muscle tissue showing signs of muscle damage. These changes in microvascular regulation after eccentric exercise may impede rapid adjustments in muscle blood flow at exercise onset and during activities involving brief bursts of muscle activation, which may impair O2 delivery and contribute to reduced muscle function after eccentric exercise.

Effectiveness of Eccentric Exercise in Tennis Elbow - A Single Case Report

Lateral epicondylitis/lateral epicondylalgia, or tennis elbow or lateral elbow tendenopathy (LET) is a common pathology of both athletes and non-athletes, affecting 1 to 3 % of the population at large (Howitt, 226). This condition is most often associated with overuse or a repetitive stress, as opposed to an acute inflammatory reaction. Tennis elbow is a degenerative or failed healing tendon response characterized by the increased presence of fibroblasts, vascular hyperplasia,

The effect of eccentric exercise is dissimilar between superficial muscles of the quadriceps

The effect of eccentric exercise is dissimilar between superficial muscles of the quadriceps

Changes in Muscle Strength and Performance after a Plyometric Training Session in Children and Adults

Although the effects of eccentric exercise on muscular performance have been examined in adults, there is little research on the effects of plyometric training in children. PURPOSE: To evaluate the effects of a single session of plyometric training on the time-course of changes in maximal force and rate of force development (RFD) measured during maximal isometric and dynamic exercise METHODS: Seven moderately trained university students (age: 21.0±1.1 yrs, height: 173±5 cm, body mass: 74±8 kg) and four children (age 11.0±0.5 yrs, height: 151±5 cm, body mass: 38±3 kg) performed a plyometric training session comprised of 10 repetitions of the following 7 jumping exercises: drop, scissor, box, stride crossover and depth jumps and single leg steps and hops on the track (total volume: 70 jumps), with 1 min recovery between sets and 3 min between exercises. Maximal isometric strength and RFD of the knee extensors (knee angle set at 90o) and countermovement jump (CMJ) performance were measured using a force platform, before, 30 min after and 48 and 102 h after the plyometric training session. Data were analyzed using two-way ANOVA with repeated measures and Tukey’s post-hoc test. RESULTS: Maximal isometric force before training was higher in adults compared with children (2031±194 vs. 504±58 N, p<0.001) and remained unchanged in both adults and children at all time-points. RFD during isometric exercise was also higher in adults compared with children (6266±1665 vs. 970±262 N.s-1, p<0.001) and remained unchanged in children, but was decreased in adults by 17.3±5.6% (p=0.02) and 8.6±4.2% (p=0.04) 30 min and 48 h after training, respectively. CMJ performance was similarly decreased 30 min after training in adults and children (-13.9±3.8%, p<0.01 and (-10.2±2.9%, p=0.03, respectively), but 48 later, it remained below the pre-training values only in adults (-6.8±3.1%, p=0.05) and had fully recovered in children. CONCLUSION: A single training session of low volume plyometric jumping exercises does not affect maximal isometric force in both children and adults. However, RFD and CMJ performance 48 h after training are only decreased in adults, while children exhibit a faster muscular performance recovery which may be explained by their lower absolute strength and their fewer fast-twitch muscle fibres.

Effects of eccentric exercise in rehabilitation of phasic and tonic muscles after leg immobilization in rats

Eccentric exercise is an essential resource for skeletal muscle rehabilitation following muscle disuse however, abnormalities linked to the tissue recuperation require further research. Our aim was analyze the adaptation ability of rehabilitated muscular tissue in rats during different periods of eccentric training after 10 days of limb immobilization. Twenty-seven Wistar rats were divided into six groups: immobilized 10 days, immobilized and eccentric trained for 10 days, immobilized and eccentric trained for 21 days, and three age-matched control groups. After sacrifice, soleus and plantaris muscles were frozen, cut and stained for general histology using hematoxylin and eosin and Gomori trichrome methods and immunohistochemical methods for fiber typing (mATPase, NADH2-TR), for capillaries (CD31) and intermediate filaments (desmin, vimentin) and high resolution microscopy of resin embedded material. Immobilization resulted in more intense morphological alterations in soleus muscles such as formation of target fibers, nuclear centralization, a reduction in the number of type I fibers, diameter of type I, IIA, IIAD fibers, and capillaries. After 10 days of eccentric training, increases in the nuclear centralization and the number of lobulated fibers were observed. This period was insufficient to reestablish the capillary/fiber (C/F) ratio and distribution of fiber types as that observed in the control group. However, 21 days of rehabilitation allowed the reversal of all morphological and quantitative abnormalities. For the plantaris muscles, 10-days of training restored their basic characteristics. Despite the fact that immobilization affected soleus and plantaris muscles, 10 days of eccentric training was insufficient to restore the morphological characteristics of soleus muscles, which was not the case observed in plantaris muscle.

Effects of Eccentric and Concentric Exercises on Some Functional Activity Indexes of Patients With Diabetes Type 2

Background: Around 7% of the world population have diabetes and suffer from its extensive complications. Many studies are conducted on the positive effects of aerobic and resistance exercises on the reduction of body performances, but considering the available references, no specific study is conducted on the effect of eccentric exercises on patients with diabetes. Objectives: The current study aimed to evaluate and compare the effects of eccentric and concentric exercises on some functional activity indexes in patients with diabetes type 2. Patients and Methods: Twenty eight patients with diabetes type 2 were randomly divided into two groups of eccentric and concentric exercises using treadmill. Six Minute Walking and Time up and Go tests were performed before and after control and intervention periods. Results: Results of the current study showed that eccentric and concentric exercises significantly improved the two mentioned functional indexes. However, eccentric exercises in comparison with concentric exercises significantly improved the results of Six Minute Walking Test (P < 0.0001). Also, in the time up and go test, no significant difference was observed between the groups. Conclusions: Results of the current study showed that the eccentric exercises improve the functional activity of patients with diabetes.

Patellar Tendinopathy May not Be the Proper Term for Patients With Clinical Diagnosis of Patellar Tendon Disorder.

Dear Editor, Chronic patellar tendinopathy is a common clinical condition that is managed by physical therapists and is common among athletes and non-athletes alike. Patellar tendinopathy is characterized by the absence of inflammatory cells and prostaglandins and an increased presence of fibroblasts and disorganized collagen (1). Therefore, this condition is not inflammatory as physicians had thought but is a degenerative condition. Extrinsic factors such as inappropriate footwear, sport technique, training errors, and intrinsic factors such as muscle weakness and/or inflexibility, and misalignment are the main factors that lead to patellar tendinopathy (1-3). Functional activities such as squat or hop can cause pain in this condition (2, 3). The ideal term for clinical diagnosis is patellar tendinopathy because this term refers to the painful tendon without implying the pathology (1). Jumper’s knee was the first diagnostic term used for this condition. However, this condition can occur in people who are not athletes and athletes who do not perform jumping in their sports. Thus, jumper’s knee is not an appropriate term for clinical diagnosis (2). Patellar tendonitis is also an incorrect term for clinical diagnosis because the condition is not inflammatory but is degenerative as mentioned. The best diagnostic term may be the term patellar tendinosis because this term refers to the pathology of the tendon (1-3). The most common site of pain in patellar tendinopathy is the inferior pole of the patella. Patellar tendinopathy pain can also be reported at the tibial tuberosity, at the superior pole of the patella and at the midportion of the tendon (1-3). There are four sites of pain in this condition, and an appropriate diagnostic term is needed for each specific pain site. Therefore, the term patellar tendinopathy is a general diagnostic term and cannot be used for all the above-mentioned sites of pain. Moreover, it is unknown if the pathology of the above-mentioned sites are the same. Many physiotherapy techniques have been recommended for the treatment/rehabilitation of patellar tendinopathy such as electrotherapeutic (ultrasound, ESWT, laser, iontophoresis) and non-electrotherapeutic modalities (exercise programs, soft tissue manipulation, and acupuncture). All the above-mentioned treatments intend to improve symptoms (pain and function) of patellar tendinopathy but have totally different mechanisms of action. However, a treatment is effective when it reverses the pathology of the tendinopathy and not only improve the symptoms. Nowadays, eccentric training is the most common physiotherapy treatment for patients with patellar tendinopathy (1-3). The question that arises is whether eccentric training is effective for all sites of patellar tendinopathy? For example, eccentric training with dorsiflexion is effective for patients with mid-portion Achilles tendinopathy (4-9), but eccentric training without dorsiflexion has positive effects on patients with insertional Achilles tendinopathy (10). Therefore, different sites of Achilles tendinopathy are managed with different protocols of eccentric exercises. Eccentric training consisting of squats is an effective treatment approach when the patellar tendinopathy is at the inferior pole of the patella; however, no studies have investigated the effectiveness of eccentric training on other sites of patellar tendinopathy. Thus, studies determining the effectiveness of eccentric exercises at other sites of patellar tendinopathy are needed. Future well-designed studies are needed to find firstly, the most appropriate diagnostic term for each site of patellar tendinopathy and secondly, the appropriate protocol of eccentric training for each site of pain and the pathology of this disorder.

The Effects of Eccentric Exercise on Muscle Function and Proprioception of Individuals Being Overweight and Underweight

The aim of this study was to estimate the effect of being overweight or underweight on proprioception at rest and after muscle damaging eccentric exercise. Twelve lean, 12 overweight, and 8 underweight female participants performed an eccentric exercise session using the knee extensor muscles of the dominant leg. Muscle damage indices and proprioception were assessed up to 3 days postexercise. The results indicated that proprioception at baseline of the lean individuals was superior to that of the other 2 groups. The overweight individuals exhibited a smaller knee joint reaction angle to release than did the lean group, whereas the underweight individuals exhibited a larger reaction angle to release than did the lean group. After eccentric exercise, proprioception was affected more in the overweight and the underweight groups than in the lean group. The greater exercise-induced muscle damage appeared in the overweight group, and the deficient muscle mass of the underweight participants could explain in part the greater disturbances that appeared in proprioception in these 2 groups than for the lean counterparts. In conclusion, deviating from the normal body mass is associated with significant disturbances in the proprioception of the legs at rest and after participation in activities involving eccentric actions.

Delayed Hypoalgesia to a Heat Stimulus is Induced by Eccentric Exercise and is Greater for Red- than Dark-Haired Women

AbstractObjectives: This study sought to examine the potential delayed effect of eccentric exercise on pain perceptions of heat stimuli presented to red-haired and dark-haired women.Methods: Healthy college-aged women capable of physical exercise were sought for participation in the study. They were to assess pain intensity and unpleasantness of thermal stimuli [at 45, 47 and 49 °C] applied to their forearm and posterior lower leg before and 24 and 48 h after 18 eccentric actions of the non-dominant elbow flexors at an intensity of maximal voluntary concentric contraction strength. Women of similar age and ability served as controls and the exercise for the controls (n=6) was concentric exercise, resulting in little or no muscle injury.Results: Eighteen healthy adult women participated. Twelve [five with bright red hair and five with dark hair] subjects performed eccentric exercise. At 24- and 48-h after the eccentric exercise, the volume of the exercised arm increased by 2.2% [±1.5%] and by 5.0% [±2.2%],...

Effects of eccentric exercise on branched‐chain amino acid profiles in rat serum and skeletal muscle

Supplementation of branched-chain amino acid (BCAA) is often used to attenuate exercise-induced skeletal muscle damage and promote adaptation, but no definitive conclusion on the benefits of BCAA on muscle recovery after injurious exercise can be drawn. Exploration of the systematic BCAA alteration in muscular injury-repair stage per se without any BCAA supplement should provide some useful information in favour of BCAA application in muscle regeneration after injury. One bout of 90-min downhill-running exercise was performed to cause rat skeletal muscle injury. After exercise, myofibrillar BCAA concentrations showed minor changes compared with exercise before, while serum concentrations of BCAA were lower after exercise. Especially, serum leucine, isoleucine and total BCAA concentrations 2 weeks post-run were significantly lower than normal values of exercise before (p = 0.008, p = 0.041, p = 0.015). The data demonstrate that a single eccentric exercise can significantly decrease the serum BCAA concentrations, which mean high utilization of BCAA for myogenesis after injurious exercise.