Markers Of Exercise-induced Muscle Damage Research Articles

Fascicle Lengthening During Eccentric Exercise Determines The Magnitude Of Muscle Damage

The characteristics of the muscle-tendon interaction during eccentric contractions suggests that tendon properties and the magnitude of fascicle lengthening contribute to the extent and the variability of exercise-induced muscle damage (EIMD). The mechanical processes which predispose the severity of EIMD remains unclear. PURPOSE: To determine whether; 1) patella tendon stiffness, at rest and during eccentric contractions, 2) the magnitude of vastus lateralis (VL) fascicle lengthening during eccentric contractions, and/or 3) eccentric torque, are determinants of EIMD. METHODS: Combining dynamometry, electromyography and ultrasonography, patella tendon properties and VL architectural properties were measured pre and during the first of 6 sets of 12 maximal voluntary eccentric knee extensions (range of motion 20 - 90°, 0° = full extension). The eccentric phase of the contraction was performed at an isokinetic angular velocity of 30°s-1 and the concentric phase was performed passively at an angular velocity of 60°s-1. Maximal isometric torque loss and creatine kinase (CK) activity were measured pre-damage (-48 h), 48, 96 and 168 h post-damage as markers of EIMD. RESULTS: Compared to pre-damage, a significant reduction in maximal isometric torque (264 ± 35 Nm, 221.0 ± 48.4 Nm, p = 0.004) and a significant increase in CK (136 ± 114, 796 ± 723 UL, p = 0.014) was reported 48 and 96 hrs post EIMD respectively. Relative changes in CK correlated with the relative change in fascicle length during eccentric contractions (r = 0.53, p = 0.02) and eccentric torque (r = 0.50, p = 0.02). Additionally, the relative change in CK tended to correlate with estimated patella tendon lengthening during eccentric contractions (r = -0.41, p < 0.10). However, relative change in CK did not correlate with resting measures of patella tendon properties or VL properties. Similarly, torque loss did not correlate with any patella tendon or VL properties at rest or during eccentric contractions. CONCLUSION: The extent of fascicle lengthening during eccentric contractions is related to the magnitude of the CK response. Furthermore, at rest, patella tendon properties are not determinants of indices of EIMD. During eccentric contractions of the VL, the patella tendon might play a modulatory role during exercise, to the susceptibility of EIMD.

A Reduction in Maximal Incremental Exercise Test Duration 48 h Post Downhill Run Is Associated with Muscle Damage Derived Exercise Induced Pain.

Purpose: To examine whether exercise induced muscle damage (EIMD) and muscle soreness reduce treadmill maximal incremental exercise (MIE) test duration, and true maximal physiological performance as a consequence of exercise induced pain (EIP) and perceived effort.Methods: Fifty (14 female), apparently healthy participants randomly allocated into a control group (CON, n = 10), or experimental group (EXP, n = 40) visited the laboratory a total of six times: visit 1 (familiarization), visit 2 (pre 1), visit 3 (pre 2), visit 4 (intervention), visit 5 (24 h post) and visit 6 (48 h post). Both groups performed identical testing during all visits, except during visit 4, where only EXP performed a 30 min downhill run and CON performed no exercise. During visits 2, 3, and 6 all participants performed MIE, and the following measurements were obtained: time to exhaustion (TTE), EIP, maximal oxygen consumption , rate of perceived exertion (RPE), maximum heart rate (HRmax), maximum blood lactate (BLamax), and the contribution of pain to terminating the MIE (assessed using a questionnaire). Additionally during visits 1, 2, 3, 5, and 6 the following markers of EIMD were obtained: muscle soreness, maximum voluntary contraction (MVC), voluntary activation (VA), creatine kinase (CK).Results: There were no significant differences (p ≥ 0.32) between any trials for any of the measures obtained during MIE for CON. In EXP, TTE decreased by 34 s (3%), from pre 2 to 48 h post (p < 0.001). There was a significant association between group (EXP, CON) and termination of the MIE due to “pain” during 48 h post (χ2 = 14.7, p = 0.002).Conclusion: EIMD resulted in premature termination of a MIE test (decreased TTE), which was associated with EIP, MVC, and VA. The exact mechanisms responsible for this require further investigation.

Plasma Actin, Gelsolin and Orosomucoid Levels after Eccentric Exercise.

The present study investigated the acute effect of eccentric exercise on blood plasma actin, gelsolin (GSN) and orosomucoid (AGP) levels in untrained and moderately trained individuals, and their correlation with exercise induced muscle damage (EIMD) markers (CK, intensity of muscle soreness and maximal voluntary contraction torque deficit). Healthy physical education students (6 untrained, 12 moderately trained) participated in this research. Actin, GSN, AGP and CK levels were measured in blood plasma at baseline, immediately, 1 h, 6 h and 24 h post-exercise comprising 90 eccentric quadriceps contractions performed on a dynamometer. There was significant time main effect for GSN, AGP, CK and significant difference was found between baseline and the lowest value of post-exercise GSN (p < 0.05), as well as baseline and the highest value of post-exercise AGP (p < 0.05). Relationships were found between GSN levels and other indirect EIMD markers (between all GSN levels at post-exercise and CK activity at 6 h, p < 0.05; GSNMIN and muscle soreness at post-exercise, p < 0.04), GSN and AGP; however, actin did not correlate at any time points with GSN. Actin, GSN, AGP and CK responses after eccentric exercise do not seem sensitive to training status. The plasma actin level is used as an indicator of injury, however, our results suggest that it is not an accurate marker of EIMD, while plasma GSN concentrations show a better relationship with EIMD and the post-exercise inflammatory process. The elevated plasma AGP and the correlation between GSN and AGP seem to be promising for assessment of exercise-induced muscle injury.

ACTN3 genotype influences exercise-induced muscle damage during a marathon competition

Exercise-induced muscle damage has been identified as one of the main causes of the progressive decrease in running and muscular performance in marathoners. The aim of this investigation was to determine the influence of the ACTN3 genotype on exercise-induced muscle damage produced during a marathon. Seventy-one experienced runners competed in a marathon race. Before and after the race, a sample of venous blood was obtained and maximal voluntary leg muscle power was measured during a countermovement jump. In the blood samples, the ACTN3 genotype (R577X) and the changes in serum creatine kinase and myoglobin concentrations were measured. Data from RX heterozygotes and XX mutant homozygotes were grouped as X allele carriers and compared to RR homozygotes. At the end of the race, X allele carriers presented higher serum myoglobin (774 ± 852 vs 487 ± 367 UL-1; P = 0.02) and creatine kinase concentrations (508 ± 346 vs 359 ± 170ngmL-1; P = 0.04) than RR homozygotes. Pre-to-post-race maximal voluntary leg muscle power reduction was more pronounced in X allele carriers than RR homozygotes (-34.4 ± 16.1 vs -27.3 ± 15.4%; P = 0.05). X allele carriers self-reported higher levels of lower limb muscle pain (7 ± 2 vs 6 ± 2cm; P = 0.02) than RR homozygotes at the end of the race. In comparison to RR homozygotes, X allele carriers for the R577X polymorphism of the ACTN3 gene presented higher values for typical markers of exercise-induced muscle damage during a competitive marathon. Thus, the absence of a functional α-actinin-3 produced by the X allele might induce higher levels of muscle breakdown during prolonged running events.

Effects of low-level laser therapy applied before or after plyometric exercise on muscle damage markers: randomized, double-blind, placebo-controlled trial.

Promising effects of phototherapy on markers of exercise-induced muscle damage has been already demonstrated in constant load or isokinetic protocols. However, its effects on more functional situations, such as plyometric exercises, and when is the best moment to apply this treatment (pre- or post-exercise) remain unclear. Therefore, the purpose of this study was to investigate the effect of low-level laser therapy (LLLT) before or after plyometric exercise on quadriceps muscle damage markers. A randomized, double-blinded, placebo-controlled trial was conducted with 24 healthy men, 12 at pre-exercise treatment group and 12 at post-exercise treatment group. Placebo and LLLT (810nm, 200mW per diode, 6J per diode, 240J per leg) were randomly applied on right/left knee extensor muscles of each volunteer before/after a plyometric exercise protocol. Muscular echo intensity (ultrasonography images), soreness (visual analogue scale -VAS), and strength impairment (maximal voluntary contraction -MVC) were assessed at baseline, 24, 48, and 72h post-exercise. Legs treated with LLLT before or after exercise presented significantly smaller increments of echo intensity (values up to 1%) compared to placebo treatments (increased up to ∼7%). No significant treatment effect was found for VAS and MVC, although a trend toward better results on LLLT legs have been found for VAS (mean values up to 30% lesser than placebo leg). In conclusion, LLLT applied before or after plyometric exercise reduces the muscle echo intensity response and possibly attenuates the muscle soreness. However, these positive results were not observed on strength impairment.

Acute Inflammatory Response to Low-, Moderate-, and High-Load Resistance Exercise in Women With Breast Cancer-Related Lymphedema.

Background. Resistance exercise is emerging as a potential adjunct therapy to aid in the management of breast cancer–related lymphedema (BCRL). However, the mechanisms underlying the relationships between the acute and long-term benefits of resistance exercise on BCRL are not well understood. Purpose. To examine the acute inflammatory response to upper-body resistance exercise in women with BCRL and to compare these effects between resistance exercises involving low, moderate, and high loads. The impact on lymphedema status and associated symptoms was also compared. Methods. A total of 21 women, 62 ± 10 years old, with BCRL participated in the study. Participants completed low-load (15-20 repetition maximum [RM]), moderate-load (10-12 RM), and high-load (6-8 RM) exercise sessions consisting of 3 sets of 6 upper-body resistance exercises. Sessions were completed in a randomized order separated by a 7- to 10-day wash-out period. Venous blood samples were obtained to assess markers of exercise-induced muscle damage and inflammation. Lymphedema status was assessed using bioimpedance spectroscopy and arm circumferences, and associated symptoms were assessed using Visual Analogue Scales for pain, heaviness, and tightness. Measurements were conducted before and 24 hours after the exercise sessions. Results. No significant changes in creatine kinase, C-reactive protein, interleukin-6, and tumor necrosis factor-α were observed following the 3 resistance exercise sessions. There were no significant changes in arm swelling or symptom severity scores across the 3 resistance exercise conditions. Conclusions. The magnitude of acute exercise-induced inflammation following upper-body resistance exercise in women with BCRL does not vary between resistance exercise loads.

Effects of far infrared rays emitting clothing on recovery after an intense plyometric exercise bout applied to elite soccer players: a randomized double-blind placebo-controlled trial.

The aim was to investigate the effects of far infrared (FIR) ray emitting clothes on indirect markers of exercise-induced muscle damage and physical performance recovery after a plyometric bout applied to soccer players. Twenty-one male players (18.9±0.6 years; 70.8±5.01 kg; 178.3±0.06 cm) performed 100 drop-jumps. Six hours after the bout, athletes put on FIR clothes (FIR) (density of 225 g·m-2, 88% far infrared rays emitting polyamide 66 Emana yarn (PA66) fibre, 12% Spandex, emissivity of 0.88 and power emitted of 341 W/m2µm at 37°C in the 5-20 µm wavelength range, patent WO 2009/077834 A2) (N = 10) or placebo clothes (PLA) (N = 11). Mid-thigh circumferences, creatine kinase (CK), and delayed-onset muscle soreness (DOMS) were assessed before, immediately after and 24, 48, and 72 h after the bout. Squat (SJ) and countermovement jump (CMJ) heights were measured before and at 24, 48, and 72 h after, while 1RM leg press (maximum strength) was measured before and at 72 h after the plyometrics. No differences between groups were found in mid-thigh circumferences, SJ, CMJ or 1RM. CK increased significantly 24 h after the plyometrics in comparison to before (p < 0.05) in both groups. PLA showed significant DOMS increases at 24, 48, and 72 h, while FIR showed significant increases at 24 and 48 h (p < 0.05). DOMS effect sizes were greater in FIR (moderate at 48 h, ES = 0.737 and large at 72 h, ES = 0.844), suggesting that FIR clothes may reduce perceived DOMS after an intense plyometric session performed by soccer players.

Susceptibility to Exercise-Induced Muscle Damage: a Cluster Analysis with a Large Sample.

We investigated the responses of indirect markers of exercise-induced muscle damage (EIMD) among a large number of young men (N=286) stratified in clusters based on the largest decrease in maximal voluntary contraction torque (MVC) after an unaccustomed maximal eccentric exercise bout of the elbow flexors. Changes in MVC, muscle soreness (SOR), creatine kinase (CK) activity, range of motion (ROM) and upper-arm circumference (CIR) before and for several days after exercise were compared between 3 clusters established based on MVC decrease (low, moderate, and high responders; LR, MR and HR). Participants were allocated to LR (n=61), MR (n=152) and HR (n=73) clusters, which depicted significantly different cluster centers of 82%, 61% and 42% of baseline MVC, respectively. Once stratified by MVC decrease, all muscle damage markers were significantly different between clusters following the same pattern: small changes for LR, larger changes for MR, and the largest changes for HR. Stratification of individuals based on the magnitude of MVC decrease post-exercise greatly increases the precision in estimating changes in EIMD by proxy markers such as SOR, CK activity, ROM and CIR. This indicates that the most commonly used markers are valid and MVC orchestrates their responses, consolidating the role of MVC as the best EIMD indirect marker.

The Relationship Between Match-Play Characteristics of Elite Rugby League and Indirect Markers of Muscle Damage.

While exercise-induced muscle damage (EIMD) after rugby league match play has been well documented, the specific match actions that contribute to EIMD are unclear. Accordingly, the purpose of this study was to investigate the positional demands of elite rugby league matches and examine their relationship with subsequent EIMD. Twenty-eight performances (from 17 participants) were captured using 10-Hz global positioning systems over 4 competitive matches. Upper- and lower-body neuromuscular fatigue, creatine kinase (CK), and perceived muscle soreness were assessed 24 h before and at 12, 36, and 60 h after matches. High-intensity running was moderately higher in backs (6.6 ± 2.6 m/min) than in forwards (5.1 ± 1.6 m/min), whereas total collisions were moderately lower (31.1 ± 13.1 vs 54.1 ± 37.0). Duration (r = .90, CI: .77-.96) and total (r = .86, CI: .70-.95) and high-intensity distance covered (r = .76, CI: .51-.91) were associated (P < .05) with increased CK concentration postmatch. Total collisions and repeated high-intensity efforts were associated (P < .05) with large decrements in upper-body neuromuscular performance (r = -.48, CI: -.74 to .02; r = -.49, CI: -.77 to .05, respectively), muscle soreness (r = -.68, CI: -.87 to -.10, r = -.66, CI: -.89 to .21, respectively), and CK concentration (r = .67, CI: .42-.85; r = .73, CI: .51-.87, respectively). All EIMD markers returned to baseline within 60 h. Match duration, high-intensity running, and collisions were associated with variations in EIMD markers, suggesting that recovery is dependent on individual match demands.

Perfil neuromuscular de atletas de handebol durante curta competição no Brasil

The aim of this study was to assess the neuromuscular profile of handball (TH) players during a short-term condensed competition. Nine TH athletes (age: 23 ± 3 years; height: 176.2 ± 10.5 cm; mass: 75.3 ± 8.6 kg) played 5 handball matches in 5 consecutive days and had exercise-induced muscle damage (EIMD) markers such as soreness (SOR), thigh circumference (CIR), knee range of motion (ROM) and countermovement jump height (CMJ) collected before the first match and at the end of each day of competition. Changes over time in these markers were analyzed. Significant changes were found for all EIMD markers assessed. CMJ significantly decreased at the fourth day of competition when compared to baseline (0.41 ± 0.03 m vs. 0.45 ± 0.02 m). ROM decreased on the first day of competition and remained stable until the last day of competition (baseline: 126.5 ± 7.2o; 1st day: 115.8 ± 5.9o; 2nd day: 115 ± 7o; 3rd day: 113.9 ± 8.8o; 4th day: 114.4 ± 8.6o). SOR and CIR were increased at the second day of competition and remained altered thereafter. It was concluded that the characteristics of short-term condensed competition have led TH athletes to significant EIMD. If not avoided, EIMD might lead to reductions in performance in the most important (final) matches.

Precipitation Of Muscle Damage In Females Following A Sport-specific Bout Of Repeated Sprints

High intensity eccentric contractions can result in exercise-induced muscle damage (EIMD), the symptoms of which are temporary, but last for several days following the initial bout. Although the responses have been well described in the literature, there is a paucity of data surrounding this response in females. PURPOSE: The aim of this study was to examine the damage responses from a sport-specific bout of repeated sprints on well-trained collegiate female athletes. METHODS: Eleven well-trained females (mean ± SD; age 22 ± 3 y, height 166.6 ± 5.7 cm, mass 62.7 ± 4.5 kg) took part in a repeated sprint protocol designed to induce EIMD (15 by 30 m sprints, with an enforced deceleration, and a 60 s rest period between repetitions). Markers of EIMD were assessed before and up to 72 hours following the repeated sprint protocol. These included creatine kinase (CK), jump height (CMJ), maximum voluntary contractions (MVC), sprint times, limb girth and muscle soreness (DOMS). All participants were tested throughout the luteal phase of the menstrual cycle. RESULTS: CK was elevated at 24, 48 and 72 h (p≤0.035), peaking at 24 h (+418%) and returning towards baseline at 72 h. CMJ significantly reduced immediately post, 24 and 48 h (p<0.05) post exercise, with a mean jump height decline of 12% from pre exercise (26.4 ± 3.3 cm) to immediately post exercise (23.4 ± 4 cm). Sprint performance was also negatively affected immediately post, 24 h, 48 h and 72 h post exercise, nadir at 48 h (5.25 ± 0.4 s) equating to a 6 % increase from pre exercise times. Muscle soreness peaked at 48 h (p<0.001) and stayed significantly elevated at 72 h post exercise (p<0.003). Limb girth or MVC did not alter over time. CONCLUSIONS: The current study demonstrates that a sport specific bout of repeated sprints precipitates EIMD in trained females and has the potential to negatively affect performance in the subsequent days, which is evidenced by decrements in muscle function and soreness. Further research is needed to examine the damage responses in this population following other damaging exercise paradigms, and importantly if the menstrual cycle influences the EIMD response.

Effects of tadalafil administration on plasma markers of exercise-induced muscle damage, IL6 and antioxidant status capacity.

Physical exercise is associated with enhanced production of reactive oxygen species, which if uncontrolled can result in tissue injury. Phosphodiesterase type 5 inhibitors (PDE5i) exhibit protective effect against oxidative stress, both in animals and healthy/unhealthy humans. However, the effect of a chronic administration of PDE5i, particularly combined with physical exercise, has never been investigated. The present study was designed to evaluate the effect of the long-acting PDE5i tadalafil on oxidative status and muscle damage after exhaustive exercise in healthy males included in a double-blind crossover trial. Tadalafil, having a putative antioxidant activity, may reduce oxidative damage after strenuous exercise. Each volunteer randomly received two tablets of placebo or tadalafil (20 mg/day) with 36 h of interval before performing exhaustive exercise. After 2 weeks of washout, the volunteers were crossed over. Blood samples were collected immediately before exercise, immediately after, and during recovery (15, 30, 60 min). Plasma total antioxidant status, glutathione homeostasis (GSH/GSSG), malondialdehyde (MDA), protein carbonyls, creatine kinase (CK), lactate dehydrogenase (LDH) and the inflammatory cytokine interleukin 6 were assessed. Tadalafil administration per se affected redox homeostasis (GSH/GSSG -36%; p < 0.05), cellular (CK +75% and LDH +36%; p < 0.05) and oxidative damage (MDA +41% and protein carbonyls +50%; p < 0.05) markers. The exhaustive exercise increased all the above-reported biochemical parameters, with subjects from the tadalafil group showing significantly higher values with respect to the placebo group. A prolonged exposure to tadalafil decreases antioxidant capacity at resting condition, therefore making subjects more susceptible to the oxidative stress induced by an exhaustive bout of exercise.

Influence of Compression Garments on Recovery After Marathon Running

Strenuous physical activity can result in exercise-induced muscle damage. The purpose of this study was to investigate the efficacy of a lower limb compression garment in accelerating recovery from a marathon run. Twenty four subjects (female, n = 7; male, n = 17) completed a marathon run before being assigned to a treatment group or a sham treatment group. The treatment group wore lower limb compression tights for 72 hours after the marathon run, the sham treatment group received a single treatment of 15 minutes of sham ultrasound after the marathon run. Perceived muscle soreness, maximal voluntary isometric contraction (MVIC), and serum markers of creatine kinase (CK) and C-reactive protein (C-RP) were assessed before, immediately after, and 24, 48, and 72 hours after the marathon run. Perceived muscle soreness was significantly lower (p ≤ 0.05) in the compression group at 24 hours after marathon when compared with the sham group. There were no significant group effects for MVIC, CK, and C-RP (p > 0.05). The use of a lower limb compression garment improved subjective perceptions of recovery; however, there was neither a significant improvement in muscular strength nor a significant attenuation in markers of exercise-induced muscle damage and inflammation.

Plasma Matrix Metalloproteinase-9 Response to Downhill Running in Humans

Matrix metalloproteinase-9 is a proteolytic enzyme capable of degrading proteins of the muscle extracellular matrix. Systemic levels of MMP-9 or its inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), have the potential to serve as blood markers of exercise-induced muscle damage. The purpose of this study was to determine if an eccentrically-dominated task, downhill running (DHR), produces changes in plasma MMP-9 or TIMP-1 and examine the relationship between MMP-9/TIMP-1 levels and indirect indicators of muscle damage. Subjects were sedentary (SED, n=12) or had a history of concentrically-biased training (CON, n=9). MMP-9 and TIMP-1 were measured before (Pre-Ex), immediately after (Post-Ex), and 1-, 2-, 4-, and 7-days post-DHR (-10°), and compared to discomfort ratings, creatine kinase activity and strength loss. At 1-day Post-Ex, discomfort increased (5.6 ± 7.8 to 45.5 ± 19.9 mm; 0-100 mm scale), strength decreased (-6.9 ± 1.6%) and CK increased (162.9 ± 177.2%). MMP-9 was modestly but significantly increased at Post-Ex in both CONC and SED (32.7 ± 33.6%) and at 4-days in SED (66.9 ± 88.1%), Individual responses were variable, however. There were no correlations between MMPs and discomfort ratings, plasma CK or strength. While plasma MMP-9 changes may be detectable in the systemic circulation after DHR, they are small and do not correspond to other markers of damage.

Effects of exercise-induced muscle damage on resting metabolic rate, sub-maximal running and post-exercise oxygen consumption

Exercise-induced muscle damage (EIMD), described as the acute weakness of the musculature after unaccustomed eccentric exercise, increases oxidative metabolism at rest and during endurance exercise. However, it is not known whether oxygen uptake during recovery from endurance exercise is increased when experiencing symptoms of EIMD. Therefore, the purpose of this study was to investigate the effects of EIMD on physiological and metabolic responses before, during and after sub-maximal running. After a 12 h fast, eight healthy male participants completed baseline measurements comprising resting metabolic rate (RMR), indirect markers of EIMD, 10 min of sub-maximal running and 30 min of recovery to ascertain excess post-exercise oxygen consumption (EPOC). Measurements were then repeated at 24 and 48 h after 100 Smith-machine squats. Data analysis revealed significant (P<0.05) increases in muscle soreness and creatine kinase (CK) and decreases in peak knee extensor torque at 24 and 48 h after squatting exercise. Moreover, RMR, physiological, metabolic and perceptual responses during sub-maximal running and EPOC were increased in the two days after squatting exercise (P<0.05). It is suggested that the elevated RMR was a consequence of a raised energy requirement for the degradation and resynthesis of damaged muscle fibres. The increased oxygen demand during sub-maximal running after muscle damage was responsible for the increase in EPOC. Individuals engaging in unaccustomed resistance exercise that results in muscle damage should be mindful of the increases in resting energy expenditure and increased metabolic demand to exercise in the days that follow.

Effect of single bout versus repeated bouts of stretching on muscle recovery following eccentric exercise

To analyze the effects of a single bout and repeated bouts of stretching on indirect markers of exercise-induced muscle damage. A randomized controlled clinical trial at a university human research laboratory was conducted. Fifty-six untrained males were randomly divided into four groups. (I) a single stretching group underwent a single bout of stretching on the quadriceps muscle; (II) an eccentric exercised group underwent eccentric quadriceps muscle contractions until exhaustion; (III) an eccentric exercise group followed by a single bout of stretching; (IV) an eccentric exercised group submitted to repeated bouts of stretching performed immediately and 24, 48, and 72 h post-exercise. Muscle stiffness, muscle soreness, maximal concentric peak torque, and plasma creatine kinase activity were assessed before exercise and 1, 24, 48, 72, and 96 h post-exercise. All exercised groups showed significant reduction in maximal concentric peak torque and significant increases in muscle soreness, muscle stiffness, and plasma creatine kinase. There were no differences between these groups in all assessed variables, with the exception of markers of muscle stiffness, which were significantly lower in the eccentric exercise group followed by single or repeated bouts. The single stretching group showed no change in any assessed variables during the measurement period. Muscle stretching performed after exercise, either as single bout or as repeated bouts, does not influence the levels of the main markers of exercise-induced muscle damage; however, repeated bouts of stretching performed during the days following exercise may have favorable effects on muscle stiffness.

β-Hydroxy-β-methylbutyrate free acid reduces markers of exercise-induced muscle damage and improves recovery in resistance-trained men

The purpose of the present study was to determine the effects of short-term supplementation with the free acid form of b-hydroxyb-methylbutyrate (HMB-FA) on indices of muscle damage, protein breakdown, recovery and hormone status following a high-volume resistance training session in trained athletes. A total of twenty resistance-trained males were recruited to participate in a high-volume resistance training session centred on full squats, bench presses and dead lifts. Subjects were randomly assigned to receive either 3 g/d of HMB-FA or a placebo. Immediately before the exercise session and 48 h post-exercise, serum creatine kinase (CK), urinary 3-methylhistadine (3-MH), testosterone, cortisol and perceived recovery status (PRS) scale measurements were taken. The results showed that CK increased to a greater extent in the placebo (329%) than in the HMB-FA group (104%) (P¼0·004, d ¼ 1·6). There was also a significant change for PRS, which decreased to a greater extent in the placebo (9·1 (SEM 0·4) to 4·6 (SEM 0·5)) than in the HMB-FA group (9·1 (SEM 0·3) to 6·3 (SEM 0·3)) (P¼0·005, d ¼ 20·48). Muscle protein breakdown, measured by 3-MH analysis, numerically decreased with HMB-FA supplementation and approached significance (P¼0·08, d ¼ 0·12). There were no acute changes in plasma total or free testosterone, cortisol or C-reactive protein. In conclusion, these results suggest that an HMB-FA supplement given to trained athletes before exercise can blunt increases in muscle damage and prevent declines in perceived readiness to train following a high-volume, muscle-damaging resistance-training session.

Efeitos de um tratamento combinado (vitamina C pré-exercício e alongamento FNP, tratamento com ultrassom pós-exercício) sobre marcadores de dano muscular induzido por exercício

CONTEXTO: Várias estratégias de recuperação têm sido utilizadas na tentativa de minimizar os sintomas da dor muscular de início tardio (DMIT). Contudo, evidências científicas que apoiem este efeito profilático (pré-exercício) e terapêutico (pós-exercício) de um tratamento combinado (FNP e vitamina C, ultrassom) no dano muscular são inexistentes. OBJETIVO: Investigar os efeitos de um tratamento combinado (FNP e vitamina C, ultrassom) nos marcadores bioquímicos (níveis enzimáticos) e funcionais (ângulo do cotovelo, circunferência de braço, taxa de dor) de dano muscular induzido por exercício. MÉTODO: Amostra randomizada controlada. LOCAL: Laboratório da Universidade. PARTICIPANTES: Alunos universitários masculinos participaram voluntariamente do estudo, o qual não reportou nenhuma dor muscular de início tardio por no mínimo seis meses antes do estudo. Posteriormente, os sujeitos foram agrupados aleatoriamente em subgrupos com mão controle e mão experimental. INTERVENÇÃO(ÕES): Programa de exercício para indução de dano muscular induzido por exercício envolvendo o teste de bíceps Scott (contração excêntrica com duas mãos). PROCEDIMENTO(S) PRINCIPAL(IS): Circunferência de braço relaxado, circunferência de braço flexionado, ângulo de cotovelo em descanso, circunferência de antebraço, amplitude de movimento de cotovelo flexionado, amplitude de movimento de cotovelo estendido, dano muscular induzido por exercício, força máxima voluntária isométrica e isocinética foram registrados basal, imediatamente após exercício e 24, 48, 72 e 96 horas após exercício. RESULTADOS: O subgrupo experimental manifestou redução de sintomas de DMIT em menor amplitude de movimento de cotovelo flexionado e amplitude de movimento de cotovelo estendido, menor perda de força isométrica e isocinética voluntária máxima (P &lt; 0,05) em comparação com o subgrupo controle. Contudo, nenhum efeito na circunferência de braço relaxado, circunferência de braço flexionado, ângulo de cotovelo em descanso ou circunferência de antebraço foi observado (P &gt;0,05). CONCLUSÃO: Este tratamento combinado foi eficiente em contração máxima voluntária isométrica, dor muscular de início tardio e taxa de intensidade de dor ao longo do tempo. Finalmente, os resultados sugerem que os tratamentos combinados são eficientes na manutenção de força isométrica e diminuição de dor muscular de início tardio e taxa de intensidade de dor.

Effect of volume of milk consumed on the attenuation of exercise-induced muscle damage

Exercise-induced muscle damage (EIMD) leads to decrements in muscle performance, increases in intramuscular proteins and delayed-onset of muscle soreness (DOMS). Previous research demonstrated that one litre of milk-based protein-carbohydrate (CHO) consumed immediately following muscle damaging exercise can limit changes in markers of EIMD possibly due to attenuating protein degradation and/or increasing protein synthesis. If the attenuation of EIMD is derived from changes in protein metabolism then it can be hypothesised that consuming a smaller volume of CHO and protein will elicit similar effects. Three independent matched groups of 8 males consumed 500 mL of milk, 1,000 mL of milk or a placebo immediately following muscle damaging exercise. Passive and active DOMS, isokinetic muscle performance, creatine kinase (CK), myoglobin and interleukin-6 were assessed immediately before and 24, 48 and 72 h after EIMD. After 72 h 1,000 mL of milk had a likely benefit for limiting decrements in peak torque compared to the placebo. After 48 h, 1,000 mL of milk had a very likely benefit of limiting increases in CK in comparison to the placebo. There were no differences between consuming 500 or 1,000 mL of milk for changes in peak torque and CK. In conclusion, decrements in isokinetic muscle performance and increases in CK can be limited with the consumption of 500 mL of milk.

Time-course of changes in inflammatory response after whole-body cryotherapy multi exposures following severe exercise.

The objectives of the present investigation was to analyze the effect of two different recovery modalities on classical markers of exercise-induced muscle damage (EIMD) and inflammation obtained after a simulated trail running race. Endurance trained males (n = 11) completed two experimental trials separated by 1 month in a randomized crossover design; one trial involved passive recovery (PAS), the other a specific whole body cryotherapy (WBC) for 96 h post-exercise (repeated each day). For each trial, subjects performed a 48 min running treadmill exercise followed by PAS or WBC. The Interleukin (IL) -1 (IL-1), IL-6, IL-10, tumor necrosis factor alpha (TNF-α), protein C-reactive (CRP) and white blood cells count were measured at rest, immediately post-exercise, and at 24, 48, 72, 96 h in post-exercise recovery. A significant time effect was observed to characterize an inflammatory state (Pre vs. Post) following the exercise bout in all conditions (p<0.05). Indeed, IL-1β (Post 1 h) and CRP (Post 24 h) levels decreased and IL-1ra (Post 1 h) increased following WBC when compared to PAS. In WBC condition (p<0.05), TNF-α, IL-10 and IL-6 remain unchanged compared to PAS condition. Overall, the results indicated that the WBC was effective in reducing the inflammatory process. These results may be explained by vasoconstriction at muscular level, and both the decrease in cytokines activity pro-inflammatory, and increase in cytokines anti-inflammatory.