Muscle Damage Responses Research Articles

Influence of preliminary exercise training on muscle damage indices in rats after one bout of prolonged treadmill exercise.

[Purpose] The purpose of this study was to investigate the effects of exercise on muscle damage indices in male Sprague-Dawley rats. Two groups of rats were trained in either moderate- or high-intensity treadmill running for 4 weeks. Subsequently, the concentrations of creatine kinase, lactate dehydrogenase, and high-sensitivity C-reactive protein were examined following a single bout of prolonged (3-h) intensive exercise. [Subjects and Methods] The study included forty 6-week-old male Sprague-Dawley rats weighing 150–180 g each. The aerobic exercise group was divided into high-intensity (28 m/min) and moderate-intensity (15 m/min) subgroups. Both subgroups were trained for 35 min daily for 6 days per week (excluding Sunday) over a 4-week period. Following training, the high- and moderate-intensity exercise groups and a non-exercise group performed one bout of prolonged (3-h) treadmill exercise for 3 hours at a speed of 15 m/min. [Results] Creatine kinase and lactate dehydrogenase levels differed significantly among the groups. [Conclusion] The preliminary exercise groups showed lower muscle damage and inflammatory response levels than the non-exercise group after the bout of prolonged intensive exercise.

Muscle Damage Response in Female Collegiate Athletes After Repeated Sprint Activity

Exercise-induced muscle damage (EIMD) is a well-investigated area, however there is a paucity of data surrounding the damage response in females. The aim of this study was to examine the damage responses from a sport-specific bout of repeated sprints in female athletes. Eleven well-trained females (mean ± SD; age: 22 ± 3 years; height: 166.6 ± 5.7 cm; mass: 62.7 ± 4.5 kg) in the luteal phase of the menstrual cycle completed a repeated sprint protocol designed to induce EIMD (15 × 30 m sprints). Creatine kinase, countermovement jump height, knee extensor maximal voluntary isometric contraction (MVIC) force, delayed onset muscle soreness (DOMS), 30-m sprint time, and limb girth were recorded before, after, 24, 48, and 72 hours after exercise. Creatine kinase was elevated at 24, 48, and 72 hours (p ≤ 0.05), peaking at 24 hours (+418%) and returning toward baseline at 72 hours. Countermovement jump height was reduced immediately after, 24, and 48 hours (p ≤ 0.05). Sprint performance was also negatively affected immediately after, 24, 48, and 72 hours after exercise. Muscle soreness peaked at 48 hours (p < 0.01) and remained significantly elevated at 72 hours after exercise (p < 0.01). Limb girth and MVIC did not alter over time. This study provides new information on the EIMD response in trained females after a sport-specific bout of repeated sprints. Importantly, this damage response has the potential to negatively affect performance for several days after exercise.

Muscle damage, inflammatory, immune and performance responses to three football games in 1 week in competitive male players.

We examined effects of a three-game, 1-week microcycle (G1, G2, G3) on recovery of performance and inflammatory responses in professional male footballers. Players were randomized into an experimental (EXP; N = 20) and a control group (CON; N = 20). Blood was drawn and repeated sprint ability (RSA), muscle soreness and knee range of motion (KJRM) were determined pre- and post-games and during recovery. High-intensity running during G2 was 7-14% less compared to G1 and G3. RSA declined in EXP by 2-9% 3 days post-game with G2 causing the greatest performance impairment. In EXP, game play increased muscle soreness (~sevenfold) compared to CON with G2 inducing the greatest rise, while KJRM was attenuated post-game in EXP compared to CON (5-7%) and recovered slower post G2 and G3 than G1. CK, CRP, sVCAM-1, sP-Selectin and cortisol peaked 48 h post-games with G2 eliciting the greatest increase. Leukocyte count, testosterone, IL-1β and IL6 responses, although altered 24 h post each game, were comparable among games. Plasma TBARS and protein carbonyls rose by ~50% post-games with G2 eliciting the greatest increase 48 h of recovery. Reduced to oxidized glutathione ratio declined for 24 h post all games with G2 displaying the slowest recovery. Total antioxidant capacity and glutathione peroxidase activity increased (9-56%) for 48 h in response to game play. In summary, post-game performance recovery and inflammatory adaptations in response to a three-game weekly microcycle displayed a different response pattern, with strong indications of a largest physiological stress and fatigue after the middle game that was preceded by only a 3-day recovery.

Effect of elastic-band exercise on muscle damage and inflammatory responses in Taekwondo athletes

INTRODUCTION: Elastic bands offer variable elastic resistance (ER) throughout a range of motion and their incorporation with exercise movements has been used for variable strength training and rehabilitation purposes. Objective: Investigate the effect of acute bout of progressive elastic-band exercise on muscle damage and inflammatory response in Taekwondo athletes (TKD) compared with untrained ones.METHODS: Fourteen (TKD, n = 7 and untrained, n = 7) men performed 3 sets of progressive resistance elastic exercise. Blood samples were taken pre-exercise and also immediately and 24h post exercise. Delayed onset muscle soreness (DOMS), creatine kinase (CK) and lactate dehydrogenase (LDH) activity, total leukocyte counts, interleukin-6 and C-reactive protein (CRP) were analyzed.RESULTS: Only DOMS increased in untrained group, but elevation of DOMS was observed in both groups (TKD and untrained) at 24h after exercise (p&lt;0.05). CK and LDH activity increased in both groups significantly. Also TKD group only showed CK increasing 24h post exercise (p&lt;0.05). Total circulating leukocyte counts increased immediately in post exercise experiments and decreased in 24h ones in both groups (p&lt;0.05). Serum IL-6 immediately increased in both groups and 24h post exercises but there was no significant difference between immediate and 24h post exercise experiments in TKD group. Furthermore, CRP just increased 24h after exercise in both groups (p&lt;0.05).CONCLUSION: Progressive resistance elastic exercise induced muscle damage and inflammation in TKD athletes, but also had smaller changes in comparison with untrained group and other forms of exercise.

Muscle Damage, Inflammatory, And Performance Responses To Submaximal, Metabolically-Matched Load Carriage And Non-Weight Bearing Endurance Exercise

PURPOSE: Metabolic and mechanical stressors elicited during submaximal load carriage (LC) and non-weight bearing, conventional endurance (CE) exercise differ, potentially influencing patterns of post-exercise muscle damage, inflammation, soreness, and performance. This study characterized muscle damage, inflammation, soreness, and lower-body muscular performance during recovery from submaximal LC and CE. METHODS: Forty adults (mean ± SD, 22 ± 4 y, 80 ± 10 kg, 4.0 ± 0.5 L·min-1) were randomly assigned (n = 20 per group), to perform either a 90 min submaximal, (2.2 ± 0.1 L·m-1) LC (24 ± 3 kg load) or metabolically-matched non-weight bearing (cycle ergometry), CE bout. Muscle damage, inflammation, ratings of soreness (deltoids, gluteus, quadriceps, and gastrocnemius/soleus), and quadriceps isometric and isokinetic peak force (PF), rate of force development (RFD), and total work were measured at baseline, 3, 24, 48, and 72 h post-exercise. RESULTS: Myoglobin (ng/mL) peaked 3 h post-exercise (70 ± 45) and remained elevated 72 h post-exercise (31 ± 10) compared to baseline (27 ± 8; P < 0.05). Overall, mean myoglobin levels were higher (P < 0.05) with LC (43 ± 31) than CE (34 ± 17). Creatine kinase (IU/L) increased similarly 3, 24, and 48 h post-exercise for LC and CE, but remained elevated 72 h post-exercise (327 ± 128) compared to baseline (205 ± 173) for LC only (mode-by-time, P < 0.05). Lactate dehydrogenase increased to a peak 3 h post-exercise and returned to baseline levels by 24 h, regardless of mode (P < 0.05). Post-exercise (24 and 48 h) interleukin-6 and C-reactive protein levels, which increased post-exercise relative to baseline, were 54% and 61% higher, respectively, for CE than LC (mode-by-time, P < 0.05). Post-exercise quadriceps and gastrocnemius/soleus soreness were similar between LC and CE, whereas gluteal soreness was higher for CE than LC, and deltoid soreness was greater for LC than CE (mode-by-time, P < 0.05). Independent of exercise mode, PF at 60°/sec at 24 h and RFD at 48 h decreased 5% and 13% lower (P < 0.05), respectively. No other differences in performance were observed. CONCLUSION: Although muscle damage, inflammatory, and soreness responses to metabolically-matched LC and CE were different, neither submaximal exercise bout produced meaningful decrements in lower-body, maximal muscular performance. Supported by U.S. Army Medical Research and Material Command.

The influence of estradiol on muscle damage and leg strength after intense eccentric exercise.

To examine the influence of estradiol on muscle damage and leg strength after intense eccentric exercise. Eight men (MEN), eight normally menstruating women (WomenNM), and eight women using oral contraceptives (WomenOC) participated in this study. Subjects performed 240 maximal-effort bilateral eccentric contractions of the quadriceps muscle groups designed to elicit exercise-induced muscle damage (EiMD). Serum creatine kinase (CK), myoglobin (Mb), and fatty acid-binding protein (FABP) concentrations were measured before (pre-) EiMD, as well as 0, 6, 24, and 48 h post-EiMD. Peak isometric quadriceps torque (i.e., leg strength) was measured pre-EiMD, as well as 24 and 48 h post-EiMD. The increases in CK, Mb, and FABP concentrations from pre- to post-EiMD were greater in MEN (10-fold, 15-fold, and fourfold, respectively) and WomenOC (sevenfold, 11-fold, and ninefold) compared with WomenNM (five-, six-, and threefold; p < 0.05). The decline in leg strength was about 10 % pre- to 24 h post-EiMD in all groups and decreased a further 10-15 % by 48 h post-EiMD in the MEN and WomenOC only. Our findings suggest an important role of estradiol in blunting the muscle damage response to intense eccentric exercise and preserving muscle function after EiMD.

Docosahexaenoic acid affects markers of inflammation and muscle damage after eccentric exercise.

The effect of docosahexaenoic acid (DHA) on inflammatory and muscle damage response to acute eccentric exercise and to the subsequent initiation of a resistance training program was studied in 41 untrained men. Subjects consumed either 2 g·d of either DHA or placebo (PL) for 28 days before a 17-day exercise phase (day 1 to day 17) that began with an eccentric exercise bout of the elbow flexors (day 1). For analysis, the exercise period was further divided into an acute response phase (day 1-4). Isometric muscle strength (STR), range of motion (ROM), and delayed onset muscle soreness (DOMS) were measured on days 1, 2, 3, 4, 7, 12, and 17. Fasted blood was measured for interleukin 6 (IL-6), interleukin 1 receptor antagonist, C-reactive protein (CRP), and creatine kinase (CK) on days 1, 2, and 4. Serum CK and CRP were also measured in blood collected on days 7, 12, and 17. In the acute phase, DHA significantly reduced the serum CK (12.5%) and the IL-6 response (32%) but did not affect STR or DOMS. Over the entire 17-day resistance exercise period, DOMS area under the curve was 183.2 ± 96.2 for DHA and 203.2 ± 120.9 for PL (p = 0.054) and the CK response was numerically lower for DHA (p = 0.093). Docosahexaenoic acid supplementation reduced some but not all indicators of muscle damage and inflammation in the 4 days after an acute eccentric exercise bout but did not significantly affect the response to initiation of resistance exercise.

The Effects of High Intensity Short Rest Resistance Exercise on Muscle Damage Markers in Men and Women

Within and between sexes, universal load prescription (as assigned in extreme conditioning programs) creates extreme ranges in individual training intensities. Exercise intensity has been proposed to be the main factor determining the degree of muscle damage. Thus, the purpose of this study was to examine markers of muscle damage in resistance-trained men (n = 9) and women (n = 9) from a high intensity (HI) short rest (SR) (HI/SR) resistance exercise protocol. The HI/SR consisted of a descending pyramid scheme starting at 10 repetitions, decreasing 1 repetition per set for the back squat, bench press, and deadlift, as fast as possible. Blood was drawn pre-exercise (pre), immediately postexercise (IP), 15 minutes postexercise (+15), 60 minutes postexercise (+60), and 24 hours postexercise (+24). Women demonstrated significant increases in interleukin 6 (IL-6; IP), creatine kinase (CK; +24), myoglobin (IP, +15, +60), and a greater relative increase when compared with men (+15, +60). Men demonstrated significant increases in myoglobin (IP, +15, +60, +24), IL-6 (IP, +15), CK (IP, +60, +24), and testosterone (IP, +15). There were significant sex interactions observed in CK (IP, +60, +24) and testosterone (IP, +15, +60, +24). Women completed the protocol faster (women: 34:04 ± 9:40 minutes, men: 39:22 ± 14:43 minutes), and at a slightly higher intensity (women: 70.1 ± 3.5%, men 68.8 ± 3.1%); however, men performed significantly more work (men: 14384.6 ± 1854.5 kg, women: 8774.7 ± 1612.7 kg). Overall, women demonstrated a faster inflammatory response with increased acute damage, whereas men demonstrated a greater prolonged damage response. Therefore, strength and conditioning professionals need to be aware of the level of stress imposed on individuals when creating such volitional high intensity metabolic type workouts and allow for adequate progression and recovery from such workouts.

Muscle damage responses and adaptations to eccentric-overload resistance exercise in men and women

This study assessed markers of muscle damage and training adaptations to eccentric-overload flywheel resistance exercise (RE) in men and women. Dynamic strength (1 RM), jump performance, maximal power at different percentages of 1 RM, and muscle mass in three different portions of the thigh were assessed in 16 men and 16 women before and after 6 weeks (15 sessions) of flywheel supine squat RE training. Plasma creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations were measured before, 24, 48 and 72 h after the first and the last training session. After training, increases in 1 RM were somewhat greater (interaction P < 0.001) in men (25 %) than in women (20 %). Squat and drop jump height and power performance at 50, 60, 70 and 80 % of 1 RM increased after training in both sexes (P < 0.05). Power improvement at 80 % of 1 RM was greater (interaction P < 0.02) in men than women. Muscle mass increased ~5 % in both groups (P < 0.05). CK increased in men after the first training session (P < 0.001), whereas the response in women was unaltered. In both sexes, LDH concentration was greater after the first training session compared with basal values (P < 0.05). After the last session, CK and LDH remained at baseline in both groups. These results suggest that although improvements in maximal strength and power at high loads may be slightly greater for men, eccentric-overload RE training induces comparable and favorable gains in strength, power, and muscle mass in both men and women. Equally important, it appears muscle damage does not interfere with the adaptations triggered by this training paradigm.

In Memoriam

In Memoriam

Inflammatory responses after different velocities of eccentric exercise

OBJECTIVE: The present study aimed to verify the indirect markers of muscle damage and inflammatory response following different velocities of eccentric exercise in women. METHODS: Nine women performed isokinetic eccentric actions at a slow velocity (Ecc30 group, 23.8 ± 2.0 years; 57.8 ± 7.0 Kg; 1.6 ± 0.5 m) and another ten women performed at high velocity (Ecc210 group, 22.2 ± 3.9 years; 56.4 ± 6.0 Kg; 1.6 ± 0.5 m). Maximal voluntary isometric contraction (MVIC), range of motion (ROM), upper-arm circumference, muscle soreness, creatine kinase (CK),tumor necrosis factor-alpha (TNF-α),interleukin-6 (IL-6) and interleukin-10 (IL-10) weremeasured before, immediately after (except CK and cytokines), and 24, 48 and 72 h following exercise. Normalized changes in the variables following exercise were compared between velocities by a mixed model. RESULTS: The Ecc30 demonstrated greater CK activity than the Ecc210 (group vs. time interaction, P< 0.001). A group effect for circumference and ROM ( P< 0.001) and a time effect for circumference (P = 0.003), ROM (P = 0.004), soreness ( P< 0.001), TNF-α(P = 0.004), IL-6 (P = 0.001) and IL-10 (P = 0.041) were found. The Ecc30 showed large effect sizes for TNF-α and IL-6 compared to Ecc210, which presented small and moderate effect sizes, respectively. IL-10 showed a moderate effect size for both groups. CONCLUSIONS: The velocity of the eccentric exercise does not modulate the systemic anti-inflammatory response, at least for a low number of muscle contractions performed by a small muscle group in women.

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

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

Changes in metabolic and muscle damage indicators following a single bout of jump training on stair versus at level

We hypothesized that stair-jump exercise would induce less muscle damage and greater acute metabolic responses than level-jumps. Trained males executed 100 unilateral jumps on stairs with one leg, and at level with the other leg, with two weeks hiatus. Maximal isometric voluntary torque (MVC) and rate of torque development (RTD)in the quadriceps, and unilateral vertical jump height (VJ) were determined in the trained leg at pre-exercise,immediately at post- (IP), 24 h and 48 h after exercise. Serum creatine kinase (CK) level and delayed onset muscle soreness (DOMS) were evaluated at pre-exercise, 24 h and 48 h. Acute lactate and heart rate responses were also measured. Lactate and heart rate at IP increased similarly under the two conditions. CK was elevated and MVC was depressed while RTD and VJ remained unchanged at 24 h in both types of training. MVC recovered at 48 h only after stair-jump exercise. DOMS developed only after level-jumps. Except DOMS, no effects of condition were found in any other variables. We conclude that vigorous stair-jump exercise highly stresses the aerobic and the anaerobic energy system, and it preserves power and rapid torque generating ability 24 h after exercise. Stair-jump could be one alternative exercise to prevent muscle soreness.

Explosive type of moderate-resistance training induces functional, cardiovascular, and molecular adaptations in the elderly

Current recommendations aimed at reducing neuromuscular and functional loss in aged muscle have identified muscle power as a key target for intervention trials, although little is known about the biological and cardiovascular systemic response in the elderly. This study investigated the effects of 12weeks of low-frequency, moderate-intensity, explosive-type resistance training (EMRT) on muscle strength and power in old community-dwelling people (70-75years), monitoring functional performance linked to daily living activities (ADL) and cardiovascular response, as well as biomarkers of muscle damage, cardiovascular risk, and cellular stress response. The present study provides the first evidence that EMRT was highly effective in achieving a significant enhancement in muscular strength and power as well as in functional performance without causing any detrimental modification in cardiovascular, inflammatory, and damage parameters. Moreover, trained elderly subjects showed an adaptive response at both systemic and cellular levels by modulation of antioxidant and stress-induced markers such as myeloperoxidase (MPO), heat shock protein 70 (Hsp70) and 27 (Hsp27), and thioredoxin reductase 1 (TrxR1).

Metabolic and Muscle Damage Profiles of Concentric versus Repeated Eccentric Cycling

Eccentric cycling is an exercise modality that could elicit multiple health benefits with low metabolic cost, but unaccustomed performance results in significant muscle damage. It is not known whether muscle damage is attenuated when eccentric cycling is repeated; thus, this study compared metabolic and muscle damage responses to concentric (CONC) and two consecutive eccentric (ECC1 and ECC2) cycling bouts. Ten men (28 ± 8 yr) performed each cycling bout for 30 min at 60% of the maximal concentric power output at 60 rpm, with 2 wk between bouts. HR, oxygen consumption (V˙O2), blood lactate (BLa), RPE, and muscle activity (EMG) data were collected during cycling. Maximal voluntary isometric knee extensor (MVC) strength, squat (SJ), countermovement jump (CMJ) height, muscle soreness indicators, and plasma creatine kinase (CK) activity were measured before, immediately after, and 1-4 d after exercise. Average HR, V˙O2, BLa, and RPE were lower (P < 0.05) during ECC1 than CONC, and EMG amplitude was also lower during ECC1 than CONC. Decreases in MVC, CMJ, and SJ and the increase in muscle soreness were greater (P x0003C; 0.05) after ECC1 than CONC. Increases in creatine kinase were minimal after all bouts. When comparing ECC1 and ECC2, HR and BLa were lower (P < 0.05) during ECC2 than ECC1, and decreases in MVC, CMJ, and SJ and the increase in muscle soreness were greater (P < 0.05) after ECC1 than ECC2. After ECC2, MVC, CMJ, and SJ did not change and no muscle soreness was developed. Eccentric cycling was less metabolically demanding than concentric cycling, and HR and BLa were further reduced during ECC2. Muscle damage is minimal after ECC2 and should not influence the choice to undertake eccentric cycling training.

Interleukin-6 − 174G/C gene polymorphism affects muscle damage response to acute eccentric resistance exercise in elderly obese women

The IL-6 gene polymorphism has been associated with disease prevalence and different physiological responses to exercise. Eccentric resistance exercise (ERE) is considered a nonpharmacological tool to prevent the chronic degenerative profile associated with aging and obesity. Consequently, the aim of the present study was to investigate the influence of IL-6 −174G/C polymorphism on acute interleukin-6 (IL-6) and creatine kinase (CK) temporal response to ERE in elderly obese women. Ninety women completed seven sets of ten repetitions (eccentric only) of an acute ERE session at 110% of the ten repetitions maximum (10RM). IL-6 genotypes displayed no difference at baseline. ERE induced changes in CK concentration over time occurred only in the GG group, F(2.619, 136.173)=5.199, p=0.003, with CK activity increased from 106.8±6.9U/l pre-intervention to 122.7±11.2U/l at 24h and 131.9±14.4U/l at 48h post-exercise. IL-6 concentration in the GG group was lower than the CC/CG group only at 0h post-exercise (3.78±0.58pg/ml versus 6.51±1.91pg/ml, p=0.030). Only the GG genotype group had higher CK activity 24–48h following ERE and greater CK integral values, while IL-6 activity over 48h was higher in the CC/CG genotype group. In conclusion, IL-6 genotype affects CK and IL-6 in response to ERE. It is of interest that the ERE protocol induced an elevation in CK, indicating possible muscle damage without exacerbating IL-6 and CK for the GG genotype.

Ballet dancers cardiorespiratory, oxidative and muscle damage responses to classes and rehearsals

This study aimed to describe and compare ballet dancers' cardiorespiratory responses, muscle damage and oxidative stress levels during a ballet class (practice of isolated ballet exercises performed with barre/hand-rail support and across-the-floor movements to improve technical skills) and rehearsal (practice of ballet choreography involving technical-artistic skills to improve dancers' performance for shows). The 12 advanced female ballet dancers undertook three exercise sessions: maximum effort test, class and rehearsal. Heart rate (HR) and oxygen consumption (V̇O2) were continuously measured. Lactate was determined before 15 min and after class and rehearsal. Blood was sampled pre, post and 48 h after class and rehearsal for creatine kinase (CK), lipid peroxides (LPO) and glutathione analysis (GSSG/GSH). Class was of lower intensity than rehearsal as shown by V̇O2, HR and lactate values: V̇O2 (mL.kg−1.min−1): 14.5±2.1 vs 19.1±1.7 (p < 0.001); HR (bpm.min−1): 145.7±17.9 vs 174.5±13.8 (p < 0.001); lactate (mmol.L−1): 4.2±1.1 vs 5.5±2.7 (p = 0.049). CK (IU) increased following class and rehearsal, remaining high 48 h after: class (pre = 109.3±48.5; post = 144±60; 48 h = 117.2±64.6); rehearsal (pre = 78.6±52.1; post = 122±70.7; 48 h = 104.9±89.5). LPO (µM) increased from pre-class (1.27±0.19) to post-class (1.41±0.19) and went down after 48 h (1.20±0.22). No LPO time-course changes followed the rehearsal. GSSG/GSH decreased 48 h after class and rehearsal. Greater increases in LPO post-class suggest it promotes CK release by an oxidative membrane-damage mechanism. Physiological increases of LPO and CK in class indicate it prepares the dancers for exercise-induced oxidative stress and muscle damage during rehearsals. Ballet dancers' muscle damage and oxidative stress responses seem not to be dependent on exercise intensity based on V̇O2 responses.

Metabolic Profile of Brazilian Elite Boxing Athletes

Elite athletes present a peculiar profile that demands specific performance assessment, including training, dietary recommendations and metabolic stress repercussion.This study aimed to assess the metabolic impairment regarding nutritional intake, eletrolytes, gluconeogenesis (urea cycle) and muscle damage responses of Brazilian elite boxing athletes.For RMR evaluation, a portable analyzer was used in 11 athletes (7 males/4 females; 25,5±3yrs); nutritional pattern was analyzed using daily 24h records, with specific software for qualitative datas. They were submitted to blood tests analysis for acute and chronic biochemical markers of stress.RMR was 1341,2±423,2, higher in males (1496,7±109,2; 1069,2±646,4). Caloric intake was 2038,6±575,2, higher in females (2323,2±786,8; 1874,78±394,6). Qualitative analysis showed lower carbohydrate intake (91% of the athletes). 36% showed high protein intake. Eletrolytes intake, such as sodium and pottasium were abnormal in 100% of the athletes. CK values were abnormal in 90% of the athletes; Urea was elevated in 25% of the athletes. Sodium and potassium were above the DRI, and the serum levels were in normal range (138±18mg/dL; 4± 10.8mg/dL).The present study evidences abnormalities that should be focused on the multidisciplinary matter, avoiding deleterious atitudes such as dehydration and malnutrition, wich could lead to decrease in performance.

Do Fat Supplements Increase Physical Performance?

Fish oil and conjugated linoleic acid (CLA) belong to a popular class of food supplements known as “fat supplements”, which are claimed to reduce muscle glycogen breakdown, reduce body mass, as well as reduce muscle damage and inflammatory responses. Sport athletes consume fish oil and CLA mainly to increase lean body mass and reduce body fat. Recent evidence indicates that this kind of supplementation may have other side-effects and a new role has been identified in steroidogenensis. Preliminary findings demonstrate that fish oil and CLA may induce a physiological increase in testosterone synthesis. The aim of this review is to describe the effects of fish oil and CLA on physical performance (endurance and resistance exercise), and highlight the new results on the effects on testosterone biosynthesis. In view of these new data, we can hypothesize that fat supplements may improve the anabolic effect of exercise.

The time-frame of acute resistance exercise effects on football skill performance: The impact of exercise intensity

The purpose of this study was to determine the recovery rate of football skill performance following resistance exercise of moderate or high intensity. Ten elite football players participated in three different trials: control, low-intensity resistance exercise (4 sets, 8–10 repetitions/set, 65–70% 1 repetition maximum [1RM]) and high-intensity resistance exercise (4 sets, 4–6 repetitions/set, 85–90% 1RM) in a counterbalanced manner. In each experimental condition, participants were evaluated pre, post, and at 24, 48, 72 h post exercise time points. Football skill performance was assessed through the Loughborough Soccer Passing Test, long passing, dribbling, shooting and heading. Delayed onset muscle soreness, knee joint range of motion, and muscle strength (1RM) in squat were considered as muscle damage markers. Blood samples analysed for creatine kinase activity, C-reactive protein, and leukocyte count. Passing and shooting performance declined (P < 0.05) post-exercise following resistance exercise. Strength declined post-exercise following high-intensity resistance exercise. Both trials induced only a mild muscle damage and inflammatory response in an intensity-dependent manner. These results indicate that football skill performance is minimally affected by acute resistance exercise independent of intensity suggesting that elite players may be able to participate in a football practice or match after only 24 h following a strength training session.