Markers Of Muscle Damage Research Articles

Changes in Factors Regulating Serum Sodium Homeostasis During Two Ultra-Endurance Mountain Races of Different Distances: 69km vs. 121km.

Overdrinking and non-osmotic arginine vasopressin release are the main risk factors for exercise-associated hyponatremia (EAH) in ultra-marathon events. However, particularly during ultra-marathon running in mountainous regions, eccentric exercise and hypoxia, which have been shown to modulate inflammation, hormones regulating fluid homeostasis (hypoxia), and oxidative stress, could contribute to serum sodium changes in a dose-dependent manner. To the best of our knowledge, the contribution of these factors, the extent of which depends on the duration and geographical location of the race, has not been well studied. Twelve male participants (11 finishers) of the short (69km, 4,260m elevation-gain) and 15 male participants (seven finishers) of the long (121km, 7,554m elevation-gain) single-stage Südtirol Ultra Sky-Race took part in this observational field study. Venous blood was drawn immediately before and after the race. Analyses included serum sodium concentration, copeptin (a stable marker for vasopressin), markers of inflammation, muscle damage and oxidative stress. Heart rate was measured during the race and race time was obtained from the race office. During the short and the long competition two and one finishers, respectively showed serum sodium concentrations >145mmol/L. During the long competition, one athlete showed serum sodium concentrations <135mmol/L. Only during the short competition percent changes in serum sodium concentrations of the finishers were related to percent changes in body mass (r=−0.812, p=0.002), total time (r=−0.608, p=0.047) and training impulse (TRIMP) (r=−0.653, p=0.030). Data show a curvilinear (quadratic) relationship between percent changes in serum sodium concentration and body mass with race time when including all runners (short, long, finishers and non-finishers). The observed prevalence of hypo- and hypernatremia is comparable to literature reports, as is the relationship between serum sodium changes and race time, race intensity and body mass changes of the finishers of the short race. The curvilinear relationship indicates that there might be a turning point of changes in serum sodium and body mass changes after a race time of approximately 20h. Since the turning point is represented mainly by non-finishers, regardless of race duration slight decrease in body mass and a slight increase in serum sodium concentration should be targeted to complete the race. Drinking to the dictate of thirst seems an adequate approach to achieve this goal.

Muscle Damage Indicated by Maximal Voluntary Contraction Strength Changes From Immediately to 1 Day After Eccentric Exercise of the Knee Extensors.

The present study examined if the magnitude of changes in indirect muscle damage markers could be predicted by maximal voluntary isometric contraction (MVIC) torque changes from immediately to 1 day after eccentric exercise. Twenty-eight young men performed 100 maximal isokinetic (60°/s) eccentric contractions of the knee extensors. MVIC torque, potentiated doublet torque, voluntary activation (VA) during MVIC, shear modulus of rectus femoris (RF), vastus medialis and lateralis, and muscle soreness of these muscles were measured before, immediately after, and 1–3 days post-exercise. Based on the recovery rate of the MVIC torque from immediately to 1-day post-exercise, the participants were placed to a recovery group that showed an increase in the MVIC torque (11.3–79.9%, n = 15) or a no-recovery group that showed no recovery (−71.9 to 0%, n = 13). No significant difference in MVIC torque decrease immediately post-exercise was found between the recovery (−33 ± 12%) and no-recovery (−32 ± 9%) groups. At 1–3 days, changes in MVIC torque (−40 to −26% vs. −22 to −12%), potentiated doublet torque (−37 to −22% vs. −20 to −9%), and proximal RF shear modulus (29–34% vs. 8–15%) were greater (p < 0.05) for the no-recovery than recovery group. No significant group differences were found for muscle soreness. The recovery rate of MVIC torque was correlated (p < 0.05) with the change in MVIC torque from baseline to 2 (r = 0.624) or 3 days post-exercise (r = 0.526), or peak change in potentiated doublet torque at 1–3 days post-exercise from baseline (r = 0.691), but not correlated with the changes in other dependent variables. These results suggest that the recovery rate of MVIC torque predicts changes in neuromuscular function but not muscle soreness and stiffness following eccentric exercise of the knee extensors.

Phytoecdysteroids Accelerate Recovery of Skeletal Muscle Function Following in vivo Eccentric Contraction-Induced Injury in Adult and Old Mice.

Background: Eccentric muscle contractions are commonly used in exercise regimens, as well as in rehabilitation as a treatment against muscle atrophy and weakness. If repeated multiple times, eccentric contractions may result in skeletal muscle injury and loss of function. Skeletal muscle possesses the remarkable ability to repair and regenerate after an injury or damage; however, this ability is impaired with aging. Phytoecdysteroids are natural plant steroids that possess medicinal, pharmacological, and biological properties, with no adverse side effects in mammals. Previous research has demonstrated that administration of phytoecdysteroids, such as 20-hydroxyecdysone (20E), leads to an increase in protein synthesis signaling and skeletal muscle strength.Methods: To investigate whether 20E enhances skeletal muscle recovery from eccentric contraction-induced damage, adult (7–8 mo) and old (26–27 mo) mice were subjected to injurious eccentric contractions (EC), followed by 20E or placebo (PLA) supplementation for 7 days. Contractile function via torque-frequency relationships (TF) was measured three times in each mouse: pre- and post-EC, as well as after the 7-day recovery period. Mice were anesthetized with isoflurane and then electrically-stimulated isometric contractions were performed to obtain in vivo muscle function of the anterior crural muscle group before injury (pre), followed by 150 EC, and then again post-injury (post). Following recovery from anesthesia, mice received either 20E (50 mg•kg−1 BW) or PLA by oral gavage. Mice were gavaged daily for 6 days and on day 7, the TF relationship was reassessed (7-day).Results: EC resulted in significant reductions of muscle function post-injury, regardless of age or treatment condition (p < 0.001). 20E supplementation completely recovered muscle function after 7 days in both adult and old mice (pre vs. 7-day; p > 0.05), while PLA muscle function remained reduced (pre vs. 7-day; p < 0.01). In addition, histological markers of muscle damage appear lower in damaged muscle from 20E-treated mice after the 7-day recovery period, compared to PLA.Conclusions: Taken together, these findings demonstrate that 20E fully recovers skeletal muscle function in both adult and old mice just 7 days after eccentric contraction-induced damage. However, the underlying mechanics by which 20E contributes to the accelerated recovery from muscle damage warrant further investigation.

Can Skin Temperature Be Altered After Different Magnitudes of Eccentric Exercise-Induced Muscle Damage?

ABSTRACT Purpose: This study aimed to assess skin temperature (Tsk) changes after different magnitudes of exercise-induced muscle damage (EIMD) of the elbow flexor muscles and investigate whether Tsk is related to indirect markers of EIMD. Methods: Thirty healthy active men were randomly allocated to the mild (MiDG) (n = 15) or moderate (MoDG) (n = 15) muscle damage group. Muscle damage in elbow flexor muscles was induced by 10 (for MiDG) or 30 (for MoDG) maximal eccentric isokinetic contractions at 60 degrees/s. Tsk, maximal voluntary isometric contraction (MVIC), delayed-onset muscle soreness (DOMS), plasma creatine kinase (CK) activity, range of motion (ROM), and pressure pain threshold (PPT) were measured before and up to 72 hr after EIMD. Results: Tsk increased only immediately after EIMD (p < .05; f = 1.44) in the MoDG (4.2%) and MiDG (4.6%), returning to near baseline values 30 min after EIMD and remaining so thereafter. In addition, there was no intergroup difference (p > .05) at any of the times analyzed, or correlation between Tsk and most indirect markers of EIMD. Conclusions: In conclusion, Tsk should not be considered an indirect marker of mild or moderate muscle damage in active men, since alterations in this variable last less than 30 min after damaging exercise and showed no correlation with most indirect markers of EIMD.

A Practical Approach to Monitoring Biomarkers of Inflammation and Muscle Damage in Youth Soccer Players During a 6‐Month Training Cycle

The aim of the study was to determine the effects of a 6-month training cycle on muscle damage and inflammatory markers in youth male soccer players. Twenty-one soccer players were tested four times: at the beginning (T1) and immediately after the pre-season period (T2), in the middle (T3) and at the end of the competitive period (T4). Muscle damage and inflammatory markers were determined in blood taken 36 hours after the match. Throughout the training cycle significant increases (p < 0.05) of creatine kinase (T1: 254.4 U·L-1; T4: 304.2 U·L-1) and lactate dehydrogenase (T1: 382.8 U·L-1; T4: 453.2 U·L-1) activities were observed. Significant changes (p < 0.05) in platelet count (T1: 210.5·109·L-1; T4: 234.2·109·L-1), percentage of lymphocyte (T1: 39.80%; T4: 42.97%), monocyte (T1: 6.88%; T4: 9.99%) and granulocyte (T1: 53.32%; T4: 47.05%) as well as in granulocyte-to-lymphocyte (T1: 1.41; T4: 1.17) and lymphocyte-to-monocyte (T1: 6.21; T4: 4.46) ratios were noted. The correlation analysis revealed statistically significant relationships (p < 0.05) between: myoglobin and the percentage of leukocyte subpopulations and the granulocyte to lymphocyte ratio; lactate dehydrogenase and the percentage of monocyte; lactate and leukocyte count. In conclusion, the reported muscle damage and inflammatory markers in T3 and T4 indicate the need for fatigue status monitoring in youth soccer players, especially in the competitive period. Moreover granulocyte to lymphocyte and lymphocyte to monocyte ratios proved to be sensitive to fatigue changes and therefore can provide coaches and sport scientists with a broader perspective on the biochemical monitoring of training status in soccer players.

중년 남성의 근 체력 및 염증 수준과 백혈구 텔로미어 길이와의 관련성

This study was to investigate the effects of muscular fitness and inflammation level on telomere length in middle aged men. This study was conducted on 106 middle aged men. We examined muscle fitness, such as muscle mass, grip strength and maximal knee eccentric isometric strength (MKEIS), inflammation level including c-reactive protein (CRP) and lactate dehydrogenase (LDH), and telomere length. LDH level has shown a negative correlation with telomere length (r=-.289, p＜.01). When adjusted for age and muscle fitness related factors, as LDH level increased by 1 UI/L, the telomere length (T/S ratio) decreased by 0.0013 (p＜.01). When adjusted for age and obesity related factor such as BMI, percent of body fat, and waist circumference, as LDH level increased by 1 UI/L, telomere length (T/S ratio) decreased by 0.0014(p＜.01). When adjusted for all variable, as LDH level increased by 1 UI/L, telomere length (T/S ratio) decreased by 0.0012 (p＜.01). Overall, LDH as muscle damage marker influenced telomere length in middle-aged men.

Performance, muscle damage, and inflammatory responses to repeated high-intensity exercise following a 40-min nap

ABSTRACT The purpose of this study was to examine the effect of a 40-min nap opportunity (N40) on performance during, markers of muscle damage and inflammation, and the perception of fatigue and recovery, in response to a 5-m shuttle run test (5msrt). Fifteen male amateur athletes performed the 5msrt under two conditions: N40 and no-nap condition (NN). Blood biomarkers were collected at rest and after the 5msrt to measure muscle damage (i.e., creatinine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (ASAT), and alanine aminotransferase (ALAT)) and inflammation (i.e., C-reactive protein (CRP)). RPE was determined immediately after each repetition of the test and PRS and DOMS were determined 5 min, thereafter. Compared to NN, N40 improved the highest distance (p<0.001, Δ=+7.9%) and the total distance (p<0.001, Δ=+7.2%) attained during the 5msrt. Pre and post the 5msrt, participants presented lower muscle damage (i.e., CK, LDH, ASAT and ALAT) and inflammation (i.e., CRP) (p<0.05) values in the N40 compared to NN. Concerning RPE, DOMS, and PRS, there was a positive effect in the N40 vs. NN (p<0.01). N40 represents an effective method for improving repeated high intensity short-term maximal performance, PRS, and associated muscle damage and inflammation, and reducing RPE and DOMS.

Time Course and Role of Exercise-Induced Cytokines in Muscle Damage and Repair After a Marathon Race.

Endurance exercise induces an increase in the expression of exercise-induced peptides that participate in the repair and regeneration of skeletal muscles. The present study aimed to evaluate the time course and role of exercise-induced cytokines in muscle damage and repair after a marathon race. Fifty-seven Brazilian male amateur marathon finishers, aged 30–55 years, participated in this study. The blood samples were collected 24 h before, immediately after, and 24 and 72 h after the São Paulo International Marathon. The leukogram and muscle damage markers were analyzed using routine automated methodology in the clinical laboratory. The plasma levels of the exercise-induced cytokines were determined using the Human Magnetic Bead Panel or enzyme-linked immunosorbent assays [decorin and growth differentiation factor 15 (GDF-15)]. A muscle damage was characterized by an increase in plasma myocellular proteins and immune changes (leukocytosis and neutrophilia). Running the marathon increased interleukin (IL)-6 (4-fold), IL-8 (1.5-fold), monocyte chemoattractant protein-1 (2.4-fold), tumor necrosis factor alpha (TNF-α) (1.5-fold), IL-10 (11-fold), decorin (1.9-fold), GDF-15 (1.8-fold), brain-derived neurotrophic factor (BDNF) (2.7-fold), follistatin (2-fold), and fibroblast growth factor (FGF-21) (3.4-fold) plasma levels. We also observed a reduction in musclin, myostatin, IL-15, and apelin levels immediately after the race (by 22–36%), 24 h (by 26–52%), and 72 h after the race (by 25–53%). The changes in BDNF levels were negatively correlated with the variations in troponin levels (r = −0.36). The variations in IL-6 concentrations were correlated with the changes in follistatin (r = 0.33) and FGF-21 (r = 0.31) levels after the race and with myostatin and irisin levels 72 h after the race. The changes in IL-8 and IL-10 levels had positive correlation with variation in musclin (p < 0.05). Regeneration of exercise-induced muscle damage involves the participation of classical inflammatory mediators, as well as GDF-15, BDNF, follistatin, decorin, and FGF-21, whose functions include myogenesis, mytophagia, satellite cell activation, and downregulation of protein degradation. The skeletal muscle damage markers were not associated to myokines response. However, BDNF had a negative correlation with a myocardial damage marker. The classical anti-inflammatory mediators (IL-10, IL-8, and IL-6) induced by exercise are associated to myokines response immediately after the race and in the recovery period and may affect the dynamics of muscle tissue repair.

The effect of branched-chain amino acid on muscle damage markers and performance following strenuous exercise: a systematic review and meta-analysis.

This systematic review and meta-analysis determined whether the ergogenic effects of branched-chain amino acids (BCAA) ameliorated markers of muscle damage and performance following strenuous exercise. In total, 25 studies were included, consisting of 479 participants (age 24.3 ± 8.3 years, height 1.73 ± 0.06 m, body mass 70.8 ± 9.5 kg, females 26.3%). These studies were rated as fair to excellent following the PEDro scale. The outcome measures were compared between the BCAA and placebo conditions at 24 and 48 hours following muscle-damaging exercises, using standardised mean differences and associated p-values via forest plots. Our meta-analysis demonstrated significantly lower levels of indirect muscle damage markers (creatine kinase, lactate dehydrogenase and myoglobin) at 48 hours post-exercise (standardised mean difference [SMD] = -0.41; p < 0.05) for the BCAA than placebo conditions, whilst muscle soreness was significant at 24 hours post-exercise (SMD = -0.28 ≤ d ≤ -0.61; p < 0.05) and 48 hours post-exercise (SMD = -0.41 ≤ d≤ -0.92; p < 0.01). However, no significant differences were identified between the BCAA and placebo conditions for muscle performance at 24 or 48 hours post-exercise (SMD = 0.08 ≤ d ≤ 0.21; p > 0.05). Overall, BCAA reduced the level of muscle damage biomarkers and muscle soreness following muscle-damaging exercises. However, the potential benefits of BCAA for muscle performance recovery is questionable and warrants further investigation to determine the practicality of BCAA for ameliorating muscle damage symptoms in diverse populations. PROSPERO registration number: CRD42020191248. Novelty: BCAA reduces the level of creatine kinase and muscle soreness following strenuous exercise with a dose-response relationship. BCAA does not accelerate recovery for muscle performance.

Impact of varying doses of omega-3 supplementation on muscle damage and recovery after eccentric resistance exercise

BackgroundExercise-induced muscle damage (EIMD) commonly occurs following intense resistance exercise and is associated with decrements in exercise performance and delayed muscle recovery. Thus, practical methods to attenuate EIMD would prove useful to both training and athletic populations. Omega-3 (n-3) supplementation has been shown to mitigate EIMD with evidence of increasing efficacy at higher doses (up to 6 g/day). However, data of its efficacy in trained individuals is limited. Therefore, this study investigated the effects of 6 and 8 g of n-3 supplementation on markers of muscle damage and muscle recovery after eccentric resistance exercise in resistance-trained males. MethodsUsing a double-blind, randomized, placebo-controlled design, 26 resistance trained males (23 ± 4 years; 173.6 ± 20.5 cm; 81.9 ± 9.7 kg; 14.2 ± 3.7% body fat) supplemented with 6 (n=10) or 8 g (n=7) of n-3 polyunsaturated fatty acids, or placebo (n=9) for 33 days. On day 30, participants performed a lower body muscle-damaging eccentric resistance exercise bout. Measures of muscle performance, soreness, and damage were taken pre-exercise on day 30 as well as on days 31–33, including vertical jump height (VJH), perceived muscle soreness (PMS), hip and knee range of motion (ROM), repetitions to fatigue (RTF) at 70% 1-RM, and serum creatine kinase (CK) while participants continued to supplement until day 33. ResultsThere were significant differences in VJH, PMS, and serum CK following the muscle-damaging exercise bout compared to pre-exercise (p<0.05). However, there were no significant (p>0.05) differences between supplementation groups (6 g, 8 g, and placebo) at any time point post-exercise (day 31–33). There were no changes in hip and knee ROM or RTF at any time point or between groups. Vertical jump height and PMS returned to pre-exercise levels despite CK remaining elevated post-exercise. ConclusionsThirty-three days of 6 and 8 g of n-3 supplementation did not attenuate EIMD or enhance muscle recovery following muscle-damaging eccentric resistance exercise in resistance-trained males. Further research using various n-3 supplementation durations, doses, and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations may be needed to establish its efficacy in attenuating EIMD, which may vary between trained and untrained individuals. Furthermore, while circulating CK is commonly used to assess muscle damage, elevated CK levels may not reflect muscle recovery status following muscle-damaging exercise.

Influence of Female Sex Hormones on Ultra-Running Performance and Post-Race Recovery: Role of Testosterone.

In recent years, increasing numbers of women have participated in extremely long races. In adult males, there is a clear association between physiological levels of endogenous sex hormones and physical performance. However, the influence of plasmatic sex hormones and the effects of different types of hormonal contraception (HC) on the modulation of physical performance in adult females remain to be fully clarified. Eighteen female ultra-endurance athletes were recruited to participate in the study. Different variables were studied, including hematological parameters, body mass index, and body composition. Strength measurements were obtained using the squat-jump and hand-grip test. A repeated-measures analysis demonstrated significant differences in hematological values of CK and LDH pre-race as compared to immediately post-race and after 24/48 h. Furthermore, statistical differences were found in squat-jump and hand-grip test results after the ultramarathon. Testosterone, estradiol, and the testosterone/estrogen ratio were significantly correlated with muscle fatigue and were found to be indirect markers of muscle damage. A multivariate analysis demonstrated the protective role of testosterone against muscle damage and severe fatigue. Fluctuations in endogenous testosterone levels were correlated with greater fatigability and muscle damage after the competition. Adjusting the menstrual cycle with HC would not provide any further benefit to the athlete’s competitive capacity.

Effect of omega-3 fatty acids supplementation on indirect blood markers of exercise-induced muscle damage: Systematic review and meta-analysis of randomized controlled trials.

BackgroundOmega 3 fatty acids supplementation may have an attenuative effect on exercise‐induced muscle damage (EIMD) through the cell membrane stabilization. The purpose of the present meta‐analysis was to evaluate the effects of omega 3 fatty acids supplementation, on indirect blood markers of muscle damage following EIMD in trained and untrained individuals.MethodsScopus, Medline, and Google scholar systematically searched up to January 2021. The Cochrane Collaboration tool was used for the quality of studies. Random‐effects model, weighted mean difference (WMD), and 95% confidence interval (CI) were applied for the overall effect estimating. The heterogeneity between studies was evaluated applying the chi‐squared and I2 statistic.ResultsThe outcomes showed a significant effect of omega 3 supplementation on reducing creatine kinase (CK), lactate dehydrogenase (LDH), and myoglobin (Mb) concentrations. In addition, a subgroup analysis indicated a significant reduction in CK, LDH, and Mb concentrations, based on follow‐ups after exercise, studies duration, time of supplementation, and training status.ConclusionThe current meta‐analysis indicated an efficacy of omega 3 in reducing CK, LDH, and Mb serum concentration among healthy individuals, overall and in subgroups analysis. Thus, omega 3 should be considered as a priority EIMD recovery agent in interventions.

Effects of Zembrin® (Sceletium tortuosum) Supplementation on Mood, Soreness, and Performance Following Unaccustomed Resistance Exercise: A Pilot Study

The purpose of this study was to investigate acute Zembrin® (Sceletium tortuosum) supplementation on muscle soreness, markers of muscle damage, mood, and exercise performance following unaccustomed resistance exercise. Untrained females (n = 16) were divided into two groups with a different three-day treatment regimen: (1) placebo (PL) and (2) Zembrin® (ZEM). During the initial visit, baseline perceived soreness, range of motion (ROM), mood state (profile of mood states (POMS) questionnaire), and plasma lactate dehydrogenase concentrations (LDH) were measured followed by the performance of an eccentric bicep curl protocol with their non-dominant arm. The total repetitions and rate of perceived exertion (RPE) were recorded throughout the exercise. The participants then supplemented with the corresponding treatment immediately following, the subsequent day, and 30 min prior to completing a 48 h follow-up visit. For the 48 h visit, all procedures were repeated and comparisons were drawn for perceived soreness, ROM, LDH, mood scores, total repetitions, and RPE. The findings indicate that short-term ZEM supplementation resulted in lower perceived soreness (p = 0.020) and a greater preservation of ROM (p = 0.028) at 48 h versus the PL group. Mood worsened from the baseline to 48 h regardless of the treatment (p = 0.043) but the decrements were exacerbated in the PL group compared with the ZEM group (p &lt; 0.001). LDH levels (p = 0.019) and RPE (p = 0.008) were higher and total repetitions were lower (p &lt; 0.001) at 48 h irrespective of the treatment. Although short-term dietary enrichment with ZEM did not alter the exercise performance or biomarkers of muscle damage, the current results suggest ZEM supplementation may be effective in reducing the markers of soreness and preserve mood following unaccustomed eccentric exercise.

The influence of external load variables on creatine kinase change during preseason training period.

The aim of the present study was to analyse the relationships between creatine kinase (CK) concentration, an indirect marker of muscle damage, and global positioning system (GPS)-derived metrics of a continuous two-week-long preseason training period in elite football. Twenty-one elite male professional soccer players were assessed during a 14-day preseason preparatory period. CK concentrations were determined each morning, and a GPS system was used to quantify the external load. A generalized estimating equation (GEE) model was established to determine the extent to which the external load parameter explained post-training CK levels. The GEE model found that higher numbers of decelerations (χ 2 = 7.83, P = 0.005) were most strongly associated with the post-training CK level. Decelerations and accelerations accounted for 62% and 11% of the post-training CK level, respectively, and considerable interindividual variability existed in the data. The use of GPS to predict muscle damage could be of use to coaches and practitioners in prescribing recovery practices. Based on GPS data, more individualized strategies could be devised and could potentially result in better subsequent performance.

Acute Inflammatory, Anthropometric, and Perceptual (Muscle Soreness) Effects of Postresistance Exercise Water Immersion in Junior International and Subelite Male Volleyball Athletes.

Horgan, BG, West, NP, Tee, N, Drinkwater, EJ, Halson, SL, Vider, J, Fonda, CJ, Haff, GG, and Chapman, DW. Acute inflammatory, anthropometric, and perceptual (muscle soreness) effects of postresistance exercise water immersion in junior international and subelite male volleyball athletes. J Strength Cond Res 36(12): 3473-3484, 2022-Athletes use water immersion strategies to recover from training and competition. This study investigated the acute effects of postexercise water immersion after resistance exercise. Eighteen elite and subelite male volleyball athletes participated in an intervention using a randomized cross-over design. On separate occasions after resistance exercise, subjects completed 1 of 4 15-minute interventions: control (CON), cold water immersion (CWI), contrast water therapy (CWT), or hot water immersion (HWI). Significance was accepted at p ≤ 0.05. Resistance exercise induced significant temporal changes (time effect) for inflammatory, anthropometric, perceptual, and performance measures. Serum creatine kinase was reduced ( g = 0.02-0.30) after CWI ( p = 0.007), CWT ( p = 0.006), or HWI ( p < 0.001) vs. CON, whereas it increased significantly ( g = 0.50) after CWI vs. HWI. Contrast water therapy resulted in significantly higher ( g = 0.56) interleukin-6 concentrations vs. HWI. Thigh girth increased ( g = 0.06-0.16) after CWI vs. CON ( p = 0.013) and HWI ( p < 0.001) and between CWT vs. HWI ( p = 0.050). Similarly, calf girth increased ( g = 0.01-0.12) after CWI vs. CON ( p = 0.039) and CWT ( p = 0.018), and HWI vs. CON ( p = 0.041) and CWT ( p = 0.018). Subject belief in a postexercise intervention strategy was associated with HSP72 ("believer">"nonbeliever," p = 0.026), muscle soreness ("believer">"nonbeliever," p = 0.002), and interleukin-4 ("nonbeliever">"believer," p = 0.002). There were no significant treatment × time (interaction effect) pairwise comparisons. Choice of postexercise water immersion strategy (i.e., cold, contrast, or hot) combined with a belief in the efficacy of that strategy to enhance recovery or performance improves biological and perceptual markers of muscle damage and soreness. On same or subsequent days where resistance exercise bouts are performed, practitioners should consider athlete beliefs when prescribing postexercise water immersion, to reduce muscle soreness.

L-Citrulline Supplementation and Exercise in the Management of Sarcopenia

Sarcopenia is a process associated to aging. Persistent inflammation and oxidative stress in muscle favour muscle wasting and decreased ability to perform physical activity. Controlled exercise can optimize blood flux and moderate the production of reactive oxygen species. Therefore, supplements that can work as a vasodilators and control oxidative stress, might be beneficial for active elders. In this context, we have tested citrulline supplementation in a group of 44 participants aged from 60–73 years that followed a physical activity program adapted to their age and capacities. Volunteers were divided in two groups: placebo (n = 22) and citrullline supplemented (n = 22). Different physical tests and blood extractions were performed at the beginning and at the end of intervention (six weeks). Strength and endurance showed a tendency to increase in the citrulline supplemented group, with no significant differences respect to placebo. However, walking speed in the citrulline supplemented group improved significantly compared to placebo. Markers of muscle damage as well as circulating levels of testosterone, cortisol and vitamin D showed no significant changes, but a tendency to improve at the end of intervention in the supplemented group compared to placebo. Additional studies are necessary to confirm the effect of citrulline supplementation in sarcopenia delay.

Bioelectrical Phase Angle, Muscle Damage Markers and Inflammatory Response After a Competitive Match in Professional Soccer Players

Abstract Introduction. The purposes of this study were 1) to evaluate changes from baseline levels in bioelectrical phase angle (PhA) and markers of muscle damage and inflammation in professional players 36 h after a soccer match, and 2) to analyze the relationships between PhA and markers of muscle damage and inflammation in order to investigate if PhA might be a useful parameter to monitor recovery. Material and methods. Eighteen male professional soccer players participated in this study. Plasma lactate dehydrogenase (LDH) and creatine kinase (CK) activities, plasma C-reactive protein (CRP) and interleukin-6 (IL-6) concentrations, and PhA were measured before and 36 h after a competitive match. Results. Changes in LDH and CK 36 h after the match were greater than their reference change values (RCV). Changes in CRP and IL-6 were, however, lower than their corresponding RCV. 36 h after the match, significant correlations were observed between PhA and LDH (r = 0.714, p = 0.001), PhA and CK (r = 0.787, p = 0.000), and PhA and CRP (r = 0.554, p = 0.017). Conclusions. Although IL-6 and CRP have been traditionally analyzed together to monitor inflammation after intense exercise, since 36 h after the match they have already returned or started to return to baseline levels, the use of them alone is not a good option to monitor inflammation throughout recovery. PhA might be used as a predictor of muscle damage and inflammation, but further studies covering the whole recovery period are warranted.

The influence of age on the recovery from worksite resistance exercise in career firefighters.

To examine the changes in indirect markers of muscle damage in young and older firefighters following a feasible worksite resistance exercise routine. Nineteen young (25.5±3.4years) and 19 older male career firefighters (50.3±3.5years) completed pre-testing, an acute bout of resistance exercise, and post-testing at 24, 48, and 72h post-exercise at their fire station. Prior to all testing, firefighters completed a work-related fatigue (WRF) questionnaire to account for potential unanticipated differences in previous shift workloads. Testing included perceived muscle soreness, ultrasonography to quantify muscle size and echo intensity (EI) of the vastus lateralis (VL) and biceps brachii (BB), countermovement jump (CMJ) height and velocity, upper body (UB) peak force (PF), lower body (LB) PF and rapid force, and electromyographic (EMG) amplitude of the VL. The resistance training session included 3 sets of 8-10 repetitions of a deadlift, shoulder press, lunge, and upright row exercise at 80% 1-RM. All recovery variables were analyzed using a linear mixed model, controlling for WRF. There was no interaction (age × time) for any of the variables and a similar training volume were completed between groups (P≥0.171). Muscle soreness, CMJ height and velocity, UB PF, LB rapid force and EMG amplitude at later time intervals (100-200ms), and VL and BB muscle size were altered from baseline (P≤0.044) for 48, 24, 48, 72, and 72h post-exercise, respectively. Young firefighters exhibited greater CMJ height and velocity, LB PF, LB rapid force (200ms), and lower VL EI values than the older firefighters (P≤0.047). Age did not influence the recovery from an acute bout of worksite resistance exercise in firefighters. However, UB muscle strength, CMJ performance, and LB rapid force production were reduced 24-72h post-exercise. Appropriately scheduled and chronic on-duty resistance training may mitigate these decrements.

Regional Differences of Mechanical Properties in a Biceps Brachii Following Eccentric Exercise

PURPOSE: This study aimed to examine the effects of eccentric exercise (ECC) on the indices of mechanical properties together with markers of exercise-induced muscle damage (EIMD) in different sites of the biceps brachii (BB) muscle.METHODS: ECC using an elbow joint was performed in 13 non-trained, college men. Global symptoms of EIMD were identified through changes in muscle soreness and serum creatine kinase (CK) activity, including muscle function following ECC. To evaluate regional EIMD, muscle swelling and tenderness as well as muscular echo intensity were measured at distal (4 cm above the elbow joint) and middle (30% of the distance from the antecubital crease to the acromion) sites within the BB muscle. A handheld myotonometer was used to estimate changes in mechanical properties, that is, oscillation frequency (F), dynamic stiffness (S), and relaxation time (R), of BB muscles after ECC.RESULTS: A significant difference in the major markers of EIMD, such as muscle soreness and serum CK activity, along with parameters of muscle function, was observed after ECC compared to baseline. Although all indirect markers of regional muscle damage demonstrated meaningful differences between before and after ECC, no statistically significant interaction between the distal and middle sites was observed in any of the markers. After ECC, both distal and middle sites showed significant changes in F, S, and R, but no statistical differences in changes in muscle mechanical properties were observed between localized muscle sites within BB muscles.CONCLUSIONS: Changes in mechanical properties, including regional muscle damage, seem to be uniformly influenced by different anatomical locations within the BB muscle, such as elbow flexors, following ECC.

Circulating MicroRNAs as Biomarkers of Accelerated Sarcopenia in Chronic Heart Failure.

Background:Sarcopenia is a critical finding in patients with chronic heart failure (CHF). However, the search for a definitive biomarker to predict muscle and functional decline in CHF remains elusive.Objectives:We aimed to correlate the circulating levels of selected miRs with the indexes of sarcopenia during healthy aging and in patients with CHF.Methods:We analyzed the association of circulating microRNAs (miRs) levels including miR-21, miR-434-3p, miR424-5p, miR-133a, miR-455-3p and miR-181a with sarcopenia indexes in male, 61–73 years old healthy controls and patients with CHF (N = 89–92/group).Results:Patients with CHF had lower hand-grip strength (HGS), appendicular skeletal mass index (ASMI) and physical capacity than healthy controls. Circulating miR-21 levels were higher and miR-181a, miR-133a, miR-434-3p and miR-455-3p levels were lower in patients with CHF than healthy controls. Among the sarcopenia indexes, HGS showed the strongest correlation with miR-133a while ASMI showed the strongest correlations with miR-133a, miR-434-3p and miR-455-3p. Among the miRs, miR-434-3p showed the highest area under the curve in testing for sensitivity and specificity for CHF. These changes were associated with higher expressions of the markers of inflammation, oxidative stress and muscle damage in CHF patients.Conclusion:Taken together, our data show that circulating miRs can be useful markers of muscle health and physical capacity in the sarcopenic elderly with CHF.