Naproxen does not alter indices of muscle damage in resistance-exercise trained men

Brief research report: Repurposing pentoxifylline to treat intense acute swimming-Induced delayed-onset muscle soreness in mice: Targeting peripheral and spinal cord nociceptive mechanisms

In this study, we pursue determining the effect of pentoxifylline (Ptx) in delayed-onset muscle soreness (DOMS) triggered by exposing untrained mice to intense acute swimming exercise (120 min), which, to our knowledge, has not been investigated. Ptx treatment (1.5, 4.5, and 13.5 mg/kg; i.p., 30 min before and 12 h after the session) reduced intense acute swimming-induced mechanical hyperalgesia in a dose-dependent manner. The selected dose of Ptx (4.5 mg/kg) inhibited recruitment of neutrophils to the muscle tissue, oxidative stress, and both pro- and anti-inflammatory cytokine production in the soleus muscle and spinal cord. Furthermore, Ptx treatment also reduced spinal cord glial cell activation. In conclusion, Ptx reduces pain by targeting peripheral and spinal cord mechanisms of DOMS.

Role of macrophages during skeletal muscle regeneration and hypertrophy-Implications for immunomodulatory strategies

Skeletal muscle is a plastic tissue that regenerates ad integrum after injury and adapts to raise mechanical loading/contractile activity by increasing its mass and/or myofiber size, a phenomenon commonly refers to as skeletal muscle hypertrophy. Both muscle regeneration and hypertrophy rely on the interactions between muscle stem cells and their neighborhood, which include inflammatory cells, and particularly macrophages. This review first summarizes the role of macrophages in muscle regeneration in various animal models of injury and in response to exercise-induced muscle damage in humans. Then, the potential contribution of macrophages to skeletal muscle hypertrophy is discussed on the basis of both animal and human experiments. We also present a brief comparative analysis of the role of macrophages during muscle regeneration versus hypertrophy. Finally, we summarize the current knowledge on the impact of different immunomodulatory strategies, such as heat therapy, cooling, massage, nonsteroidal anti-inflammatory drugs and resolvins, on skeletal muscle regeneration and their potential impact on muscle hypertrophy.

ANTI-INFLAMMATORIES FOR DELAYED ONSET MUSCLE SORENESS: SYSTEMATIC REVIEW AND META-ANALYSIS

ABSTRACT Objective: To investigate the effectiveness of pharmacological interventions in the treatment of delayed onset muscle soreness (DOMS). Design: A systematic review and meta-analysis of randomized controlled clinical trials (RCTs). Data sources: The PubMed/MEDLINE, EMBASE, SPORTDiscus, Scielo and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched for RCTs published prior to August 3, 2020. Eligibility criteria for selecting studies: Studies that 1) used an RCT design; 2) evaluated the effectiveness of steroidal or nonsteroidal anti-inflammatory drugs (NSAIDs) in treating DOMS; and 3) therapeutically used drugs after exercise were included. Results: In total, 26 studies (patients = 934) were eligible for inclusion in the qualitative analysis on the treatment of DOMS. The results of the meta-analysis showed no superiority between the use and non-use of NSAIDs in the improvement of late muscle pain, as no statistically significant differences were verified (21 studies, n= 955; standard mean difference (SMD)= 0.02; 95% confidence interval (CI) −0.58, 0.63; p=0.94; I2=93%). The quality of the synthesized evidence was very low according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria, and there was significant heterogeneity among the included studies. Conclusion: The results demonstrate that NSAIDs are not superior to controls/placebos in treating DOMS. The inclusion of both studies with dose-response protocols and those with exercise protocols may have influenced the results. In addition, the high risk of bias identified reveals that limitations need to be considered when interpreting the results. Level of evidence I; ystematic review of RCT (Randomized and Controlled Clinical Trials).

Possible exercised-induced rhabdomyolysis associated with terbinafine

Introduction. Terbinafine is reported to be associated with rhabdomyolysis. We present a patient taking terbinafine who may have developed exercise-induced rhabdomyolysis. Case Report. A healthy 40-year-old female developed onychomycosis of the right first toe for which she was taking terbinafine. After an increase in her exercise regimen, she began experiencing notable myalgias of the triceps. During outpatient evaluation, the patient was found to have elevated and worsening creatine kinase (CK) and aspartate transaminase. At evaluation in the emergency department, CK was <5000 IU/L and had decreased. She did not have electrolyte abnormalities, kidney injury or kidney failure. Discussion. Patients may be at risk for exercise-induced rhabdomyolysis while on terbinafine and may need to be cautioned regarding the intensity of exercise.

Effect of NSAIDs on Recovery From Acute Skeletal Muscle Injury: A Systematic Review and Meta-analysis

BACKGROUND

There is debate as to whether the use of nonsteroidal anti-inflammatory drugs (NSAIDs) is beneficial after acute skeletal muscle injury. Some studies have suggested that NSAID use may be detrimental to injured muscle.

PURPOSE

To determine whether NSAID use affects recovery from skeletal muscle injury as assessed by strength loss, soreness, and/or blood creatine kinase level.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

An extensive systematic review was completed searching 16 databases (eg, PubMed, Cochrane Library, EMBASE). Inclusion criteria were (1) acute injury to skeletal muscle, (2) use of a control condition, (3) certainty of the NSAID dose administered, and (4) use of 1 or more of the 3 desired outcome measures. A total of 5343 study reports were screened, of which 41 studies were deemed suitable for inclusion. The standardized mean difference was used as the effect size (ES) and was calculated such that a positive ES indicated NSAID efficacy. Meta-analyses were run using a random-effects model.

RESULTS

For all studies, time points after injury, and injury markers combined, NSAID use was found to elicit a small to medium, significant decrease in the markers of injury (overall ES = +0.34; P = .0001). Because heterogeneity in study ES was apparent (ie, Q- df = 52.4, P = .000005; I² = 57%), subgroup meta-analyses and meta-regressions were run in an attempt to explain the heterogeneity. In human studies, study ESs were higher when lower body muscles were injured ( P = .045). In animal studies, study ESs were lower with longer NSAID administration durations ( P = .023) and at longer follow-up times after injury ( P = .010).

CONCLUSION

Overall, our analysis supports NSAID use for reducing strength loss, soreness, and blood creatine kinase level after an acute muscle injury, at least for humans and in the short term. Additional research is required to determine why NSAID use appears to be more effective when lower-body muscles in humans are injured. It would also be important to determine why NSAID use appears detrimental at later times after injury in animals but not humans.

Acute kidney injury associated with endurance events-is it a cause for concern? A systematic review

INTRODUCTION

A growing body of evidence suggests even small rises in serum creatinine (SCr) are of considerable clinical relevance. Given that participants in endurance events are exposed to potential (repeated) renal insults, a systematic review was undertaken to collate current evidence for acute kidney injury (AKI), complicating such events.

METHODS

A systematic review of studies and case reports meeting inclusion criteria on Medline and EMBASE (inception to October 2015). Included: studies with markers of renal function before and after endurance or ultraendurance events; case reports of severe AKI. Two reviewers assessed risk of bias using the Newcastle-Ottawa scale.

RESULTS

Eleven case report publications (n=27 individuals) of severe AKI, were retrieved, with risk factors including systemic illness or nephrotoxic medications usually identified. From 30 studies of endurance and ultraendurance events, mean rise in SCr was 29 (±12.3) µmol/L after marathon or ultramarathon (17 studies, n=568 participants) events. Where follow-up tests were conducted, SCr returned to baseline within 48 hours. Rises in biomarkers suggest potential parenchymal insult, rather than simply muscle breakdown. However, evidence of long-term deleterious effects is lacking.

CONCLUSIONS

Raised levels of SCr are reported immediately after endurance events. It is not clear whether this is either clinically significant, or if repeated participation predisposes to long-term sequelae. The aetiology of severe exercise-associated AKI is usually multifactorial, with risk factors generally identified in the rare cases reported. On-site biochemistry, urine analysis and biomarkers of AKI may help identify collapsed runners who are at significant short-term risk and allow suitable follow-up.

Effect of an acute dose of omega-3 fish oil following exercise-induced muscle damage

PURPOSE

The purpose of this double-blind, placebo-controlled study was to examine the effect of two fish oil supplements, one high in EPA (750 mg EPA, 50 mg DHA) and one low in EPA (150 mg EPA, 100 mg DHA), taken acutely as a recovery strategy following EIMD.

METHODS

Twenty-seven physically active males (26 ± 4 year, 1.77 ± 0.07 m, 80 ± 10 kg) completed 100 plyometric drop jumps to induce muscle damage. Perceptual (perceived soreness) and functional (isokinetic muscle strength at 60° and 180° s^-1, squat jump performance and countermovement jump performance) indices of EIMD were recorded before, and 1, 24, 48, 72, and 96h after the damaging protocol. Immediately after the damaging protocol, volunteers ingested either a placebo (Con), a low-EPA fish oil (Low EPA) or a high-EPA fish oil (High EPA) at a dose of 1 g per 10 kg body mass.

RESULTS

A significant group main effect was observed for squat jump, with the High EPA group performing better than Con and Low EPA groups (average performance decrement, 2.1, 8.3 and 9.8%, respectively), and similar findings were observed for countermovement jump performance, (average performance decrement, 1.7, 6.8 and 6.8%, respectively, p = 0.07). Significant time, but no interaction main effects were observed for all functional and perceptual indices measured, although large effect sizes demonstrate a possible ameliorating effect of high dose of EPA fish supplementation (effect sizes ≥0.14).

CONCLUSION

This study indicates that an acute dose of high-EPA fish oil may ameliorate the functional changes following EIMD.

Role of Redox Signaling and Inflammation in Skeletal Muscle Adaptations to Training

The inflammatory response to exercise-induced muscle damage has been extensively described. Exercise has important modulatory effects on immune function. These effects are mediated by diverse factors including pro-inflammatory cytokines, classical stress hormones, and hemodynamic effects leading to cell redistribution. As has been reported regarding oxidative stress, inflammation can have both detrimental and beneficial effects in skeletal muscle. In this review we will address the role of inflammation on protein metabolism in skeletal muscle. Specifically, we will review studies showing that treatment with cyclooxygenase-inhibiting drugs modulate the protein synthesis response to one bout of resistance exercise and to training. Understanding how these drugs work is important for the millions of individuals worldwide that consume them regularly. We will also discuss the importance of reactive oxygen species and inflammatory cytokines in muscle adaptations to exercise and the Janus faced of the use of antioxidant and anti-inflammatory drugs by athletes for optimizing their performance, especially during the periods in which muscle hypertrophy is expected.

Greater eccentric exercise-induced muscle damage by large versus small range of motion with the same end-point

Several factors can affect the magnitude of eccentric exercise (ECC)-induced muscle damage, but little is known regarding the effect of the range of motion (ROM) in ECC-induced muscle damage. The purpose of this study was to investigate whether elbow flexor ECC with 120° of ROM (from 60° of elbow flexion until elbow full extension - 180° [120ROM]) induces a greater magnitude of muscle damage compared with a protocol with 60° of ROM (120-180° of elbow flexion [60ROM]). Twelve healthy young men (age: 22 ± 3.1 years; height: 1.75 ± 0.05 m; body mass: 75.6 ± 13.6 kg) performed the ECC with 120ROM and 60ROM using different arms in a random order separated by 2 weeks and were tested before and 24, 48, 72 and 96 h after ECC for maximal voluntary isometric contraction torque (MVC-ISO), ROM and muscle soreness. The 120ROM protocol showed greater changes and effect sizes (ES) for MVC-ISO (-35%, ES: 1.97), ROM (-11.5°, ES: 1.27) and muscle soreness (19 mm, ES: 1.18) compared with the 60ROM protocol (-23%, ES: 0.93; -12%, ES: 0.56; 17°, ES: 0.63; 8 mm, ES: 1.07, respectively). In conclusion, ECC of the elbow flexors with 120° of ROM promotes a greater magnitude of muscle damage compared with a protocol with 60° of ROM, even when both protocols are performed at long muscle lengths.

Ibuprofen Ingestion Does Not Affect Markers of Post-exercise Muscle Inflammation

Purpose: We investigated if oral ingestion of ibuprofen influenced leucocyte recruitment and infiltration following an acute bout of traditional resistance exercise

Methods: Sixteen male subjects were divided into two groups that received the maximum over-the-counter dose of ibuprofen (1200mg d⁻¹) or a similarly administered placebo following lower body resistance exercise. Muscle biopsies were taken from m.vastus lateralis and blood serum samples were obtained before and immediately after exercise, and at 3 and 24 h after exercise. Muscle cross-sections were stained with antibodies against neutrophils (CD66b and MPO) and macrophages (CD68). Muscle damage was assessed via creatine kinase and myoglobin in blood serum samples, and muscle soreness was rated on a ten-point pain scale.

Results: The resistance exercise protocol stimulated a significant increase in the number of CD66b⁺ and MPO⁺ cells when measured 3 h post exercise. Serum creatine kinase, myoglobin and subjective muscle soreness all increased post-exercise. Muscle leucocyte infiltration, creatine kinase, myoglobin and subjective muscle soreness were unaffected by ibuprofen treatment when compared to placebo. There was also no association between increases in inflammatory leucocytes and any other marker of cellular muscle damage.

Conclusion: Ibuprofen administration had no effect on the accumulation of neutrophils, markers of muscle damage or muscle soreness during the first 24 h of post-exercise muscle recovery.

Single dose of intra-muscular platelet rich plasma reverses the increase in plasma iron levels in exercise-induced muscle damage: A pilot study

BACKGROUND

Platelet rich plasma (PRP) therapy is widely used in enhancing the recovery of skeletal muscle from injury. However, the impact of intramuscular delivery of PRP on hematologic and biochemical responses has not been fully elucidated in exercise-induced muscle damage. The purpose of this investigation the effects of intramuscular delivery of PRP on hematologic and biochemical responses and recovery strategy muscle damage induced by high intensity muscle exercise (exercise-induced muscle damage, EIMD).

METHODS

Moderately active male volunteers participated in this study and were assigned to a control group (control, n = 6) and PRP administration group (PRP, n = 6). The subjects performed exercise with a load of 80% one repetition maximum (1RM) maximal voluntary contraction of the elbow flexors until point of exhaustion of the non-dominant arm was reached. The arms were treated with saline or autologous PRP post-24 h EIMD. Venous blood samples were obtained in the morning to establish a baseline value and 1-4 days post-exercise and were analyzed for serum ferritin, iron, iron binding capacity (IBC), creatinine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT).

RESULTS

The baseline levels of plasma iron, ferritin, IBC, CK, LDH, AST, and ALT were similar in both the control and PRP groups. However, 24-h following exercise a significant increase in these parameters was observed in both groups between 1 and 4 days during the recovery period. Interestingly, PRP administration decreased plasma iron levels compared to the control on the second day post-exercise. Plasma IBC increased in PRP group from Days 2 to 4 post-exercise compared to the control group whilst PRP administration had no effect on plasma ferritin, CK, AST, ALT, or LDH.

CONCLUSION

Acute exhaustive exercise increased muscle damage markers, including plasma iron, IBC, and ferritin levels, indicating muscle damage induced by exercise. PRP administration improves inflammation by reversing the increase in the iron levels post-exercise without displaying any myotoxicity and may have a role to play in the recovery of exercise-induced muscle damage.

Muscle enzyme and fiber type-specific sarcomere protein increases in serum after inertial concentric-eccentric exercise

Muscle damage induced by inertial exercise performed on a flywheel device was assessed through the serum evolution of muscle enzymes, interleukin 6, and fiber type-specific sarcomere proteins such as fast myosin (FM) and slow myosin (SM). We hypothesized that a model of muscle damage could be constructed by measuring the evolution of serum concentration of muscle proteins following inertial exercise, according to their molecular weight and the fiber compartment in which they are located. Moreover, by measuring FM and SM, the type of fibers that are affected could be assessed. Serum profiles were registered before and 24, 48, and 144 h after exercise in 10 healthy and recreationally active young men. Creatine kinase (CK) and CK-myocardial band isoenzyme increased in serum early (24 h) and returned to baseline values after 48 h. FM increased in serum late (48 h) and remained elevated 144 h post-exercise. The increase in serum muscle enzymes suggests increased membrane permeability of both fast and slow fibers, and the increase in FM reveals sarcomere disruption as well as increased membrane permeability of fast fibers. Consequently, FM could be adopted as a fiber type-specific biomarker of muscle damage.

Monocyte/macrophage interactions with myogenic precursor cells during skeletal muscle regeneration

Adult skeletal muscle has the remarkable property of regenerating after damage, owing to satellite cells and myogenic precursor cells becoming committed to adult myogenesis to rebuild the muscle. This process is accompanied by the continuing presence of macrophages, from the phagocytosis of damaged myofibres to the full re-formation of new myofibres. In recent years, there has been huge progress in our understanding of the roles of macrophages during skeletal muscle regeneration, notably concerning their effects on myogenic precursor cells. Here, we review the most recent knowledge acquired on monocyte entry into damaged muscle, the various macrophage subpopulations, and their respective roles during the sequential phases of muscle repair. We also discuss the role of macrophages after exercise-induced muscle damage, notably in humans.

The effects of Lyprinol(®) on delayed onset muscle soreness and muscle damage in well trained athletes: a double-blind randomised controlled trial

OBJECTIVES

The aim of the study was to determine if Lyprinol(®) is effective in reducing pain, indicators of inflammation and muscle damage, and in turn improving performance in well trained athletes suffering from delayed onset muscle soreness (DOMS).

DESIGN

A double blind randomised placebo controlled trial.

SETTING

Twenty well trained male volunteers, matched by VO(2max) were randomly assigned to consume 200mg of Lyprinol(®) or an indistinguishable placebo daily for 8 weeks prior to a downhill treadmill running episode designed to induce DOMS.

MAIN OUTCOME MEASURES

Performance measures (Kin-Com, counter movement and squat jump), pain assessments (visual analogue scale, algometer) and blood analyses (Interleukin-1, Interleukin-6, Interleukin-10, tumour necrosis factor-α, C-reactive protein, myoglobin, creatine kinase) were assessed at 7 time points over 5 days (pre, post, 4, 24, 48, 72 and 96h after the downhill run).

RESULTS

No statistically significant differences were identified in any parameters between the active and placebo groups at any time point.

CONCLUSION

After 2 months ingestion of Lyprinol(®) at the currently recommended dosage (200mg/day) and a demanding eccentric exercise intervention, Lyprinol(®) did not convincingly affect DOMS and indicators of muscle damage.

Adenosine A(3) receptor stimulation induces protection of skeletal muscle from eccentric exercise-mediated injury

Effective therapy to reduce skeletal muscle injury associated with severe or eccentric exercise is needed. The purpose of this study was to determine whether adenosine receptor stimulation can mediate protection from eccentric exercise-induced muscle injury. Downhill treadmill exercise (-15 degrees ) was used to induce eccentric exercise-mediated skeletal muscle injury. Experiments were conducted in both normal wild-type (WT) mice and also in beta-sarcoglycan knockout dystrophic mice, animals that show an exaggerated muscle damage with the stress of exercise. In the vehicle-treated WT animals, eccentric exercise increased serum creatine kinase (CK) greater than 3-fold to 358.9 +/- 62.7 U/l (SE). This increase was totally abolished by stimulation of the A(3) receptor. In the dystrophic beta-sarcoglycan-null mice, eccentric exercise caused CK levels to reach 55,124 +/- 5,558 U/l. A(3) receptor stimulation in these animals reduced the CK response by nearly 50%. In the dystrophic mice at rest, 10% of the fibers were found to be damaged, as indicated by Evans blue dye staining. While this percentage was doubled after exercise, A(3) receptor stimulation eliminated this increase. Neither the A(1) receptor agonist 2-chloro-N(6)-cyclopentyladenosine (0.05 mg/kg) nor the A(2A) receptor agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine (0.07 mg/kg) protected skeletal muscle from eccentric exercise injury in WT or dystrophic mice. The protective effect of adenosine A(3) receptor stimulation was absent in mice, in which genes for phospholipase C beta2/beta3 (PLCbeta2/beta3) and beta-sarcoglycan were deleted. The present study elucidates a new protective role of the A(3) receptor and PLCbeta2/beta3 and points to a potentially effective therapeutic strategy for eccentric exercise-induced skeletal muscle injury.

Prevention of physical training-related injuries recommendations for the military and other active populations based on expedited systematic reviews

BACKGROUND

The Military Training Task Force of the Defense Safety Oversight Council chartered a Joint Services Physical Training Injury Prevention Working Group to: (1) establish the evidence base for making recommendations to prevent injuries; (2) prioritize the recommendations for prevention programs and policies; and (3) substantiate the need for further research and evaluation on interventions and programs likely to reduce physical training-related injuries.

EVIDENCE ACQUISITION

A work group was formed to identify, evaluate, and assess the level of scientific evidence for various physical training-related injury prevention strategies through an expedited systematic review process. Of 40 physical training-related injury prevention strategies identified, education, leader support, and surveillance were determined to be essential elements of a successful injury prevention program and not independent interventions. As a result of the expedited systematic reviews, one more essential element (research) was added for a total of four. Six strategies were not reviewed. The remaining 31 interventions were categorized into three levels representing the strength of recommendation: (1) recommended; (2) not recommended; and (3) insufficient evidence to recommend or not recommend.

EVIDENCE SYNTHESIS

Education, leadership support, injury surveillance, and research were determined to be critical components of any successful injury prevention program. Six interventions (i.e., prevent overtraining, agility-like training, mouthguards, semirigid ankle braces, nutrient replacement, and synthetic socks) had strong enough evidence to become working group recommendations for implementation in the military services. Two interventions (i.e., back braces and pre-exercise administration of anti-inflammatory medication) were not recommended due to evidence of ineffectiveness or harm, 23 lacked sufficient scientific evidence to support recommendations for all military services at this time, and six were not evaluated.

CONCLUSIONS

Six interventions should be implemented in all four military services immediately to reduce physical training-related injuries. Two strategies should be discouraged by all leaders at all levels. Of particular note, 23 popular physical training-related injury prevention strategies need further scientific investigation, review, and group consensus before they can be recommended to the military services or similar civilian populations. The expedited systematic process of evaluating interventions enabled the working group to build consensus around those injury prevention strategies that had enough scientific evidence to support a recommendation.

Use of prescription drugs in athletes

Although athletes are young and generally healthy, they use a variety of non-doping classified medicines to treat injuries, cure illnesses and obtain a competitive edge. Athletes and sports medicine physicians try to optimize the treatment of symptoms related to extreme training during an elite athlete's active career. According to several studies, the use of antiasthmatic medication is more frequent among elite athletes than in the general population. The type of training and the kind of sport influence the prevalence of asthma. Asthma is most common among those competing in endurance events, such as cycling, swimming, cross-country skiing and long-distance running. Recent studies show that athletes use also NSAIDs and oral antibacterials more commonly than age-matched controls, especially athletes competing in speed and power sports. Inappropriately high doses and concomitant use of several different NSAIDs has been observed. All medicines have adverse effects that may have deleterious effects on elite athletes' performance. Thus, any unnecessary medication use should be minimized in elite athletes. Inhaled beta(2)-agonists may cause tachycardia and muscle tremor, which are especially harmful in events requiring accuracy and a steady hand. In experimental animal models of acute injury, especially selective cyclo-oxygenase-2 inhibitors have been shown to be detrimental to tissue-level repair. They have been shown to impair mechanical strength return following acute injury to bone, ligament and tendon. This may have clinical implications for future injury susceptibility. However, it should be noted that the current animal studies have limited translation to the clinical setting. Adverse effects related to the CNS and gastrointestinal adverse reactions are commonly reported in connection with NSAID use also in elite athletes. In addition to the potential for adverse effects, recent studies have shown that NSAID use may negatively regulate muscle growth by inhibiting protein synthesis. Physicians and pharmacists taking care of athletes' medication need to be aware of the medicines that an athlete is taking and how those medicines interact with performance, exercise, environment and other medicines. Sport associations should repeatedly monitor not only the use of banned substances, but also the trends of use of legal medicines in athletes. Not only physicians and pharmacists, but also athletes and coaches should be better educated with respect to potential benefits and risks, and how each agent may affect an athlete's performance. The attitudes and beliefs leading to ample use of legal medicines in athletes is an interesting area of future research.

Effect of hydration state on resistance exercise-induced endocrine markers of anabolism, catabolism, and metabolism

Hypohydration (decreased total body water) exacerbates the catabolic hormonal response to endurance exercise with unclear effects on anabolic hormones. Limited research exists that evaluates the effect of hypohydration on endocrine responses to resistance exercise; this work merits attention as the acute postexercise hormonal environment potently modulates resistance training adaptations. The purpose of this study was to examine the effect of hydration state on the endocrine and metabolic responses to resistance exercise. Seven healthy resistance-trained men (age = 23 ± 4 yr, body mass = 87.8 ± 6.8 kg, body fat = 11.5 ± 5.2%) completed three identical resistance exercise bouts in different hydration states: euhydrated (EU), hypohydrated by ∼2.5% body mass (HY25), and hypohydrated by ∼5.0% body mass (HY50). Investigators manipulated hydration status via controlled water deprivation and exercise-heat stress. Cortisol, epinephrine, norepinephrine, testosterone, growth hormone, insulin-like growth factor-I, insulin, glucose, lactate, glycerol, and free fatty acids were measured during euhydrated rest, immediately preceding resistance exercise, immediately postexercise, and during 60 min of recovery. Body mass decreased 0.2 ± 0.4, 2.4 ± 0.4, and 4.8 ± 0.4% during EU, HY25, and HY50, respectively, supported by humoral and urinary changes that clearly indicated subjects achieved three distinct hydration states. Hypohydration significantly 1) increased circulating concentrations of cortisol and norepinephrine, 2) attenuated the testosterone response to exercise, and 3) altered carbohydrate and lipid metabolism. These results suggest that hypohydration can modify the hormonal and metabolic response to resistance exercise, influencing the postexercise circulatory milieu.

The magnitude of muscle damage induced by downhill backward walking

While various models for exercise-induced muscle damage (EIMD) have been introduced, many of them use maximal voluntary contractions of the elbow flexors and knee extensors performed on isokinetic dynamometers. Few studies have used exercise protocols that attempt to replicate submaximal eccentric muscle actions that commonly occur during daily activities. Downhill backwards walking has been used previously as an EIMD model. However, the common markers of muscle damage have not been systematically examined for this model. The purpose of this study was to determine the magnitude of muscle damage induced by downhill backward walking with regard to changes in commonly-used indirect markers of EIMD. Twenty subjects aged between 19 y and 42 y completed a bout of 60 min of downhill (-15%) backward walking in which a single limb performed submaximal eccentric actions at a stepping rate of 30 - 35 strides per min. A repeated measures ANOVA revealed significant (p < 0.05) increases from baseline for soreness (24 hr- 96 hr), tenderness (24 hr - 96 hr), and plasma creatine kinase activity (0.5 hr - 96 hr), and significant decreases (p < 0.05) in maximal voluntary isometric (approximately 25%) and isokinetic (-15%) strength (0.5 hr - 96 hr) post-walk for the exercised limb. The time course of observed changes in these markers was similar to that reported for EIMD models of the elbow flexors and knee extensors. However, the magnitude of muscle damage appeared more consistent with that demonstrated following submaximal eccentric exercise.

The Mechanisms of Massage and Effects on Performance, Muscle Recovery and Injury Prevention

Many coaches, athletes and sports medicine personnel hold the belief, based on observations and experiences, that massage can provide several benefits to the body such as increased blood flow, reduced muscle tension and neurological excitability, and an increased sense of well-being. Massage can produce mechanical pressure, which is expected to increase muscle compliance resulting in increased range of joint motion, decreased passive stiffness and decreased active stiffness (biomechanical mechanisms). Mechanical pressure might help to increase blood flow by increasing the arteriolar pressure, as well as increasing muscle temperature from rubbing. Depending on the massage technique, mechanical pressure on the muscle is expected to increase or decrease neural excitability as measured by the Hoffman reflex (neurological mechanisms). Changes in parasympathetic activity (as measured by heart rate, blood pressure and heart rate variability) and hormonal levels (as measured by cortisol levels) following massage result in a relaxation response (physiological mechanisms). A reduction in anxiety and an improvement in mood state also cause relaxation (psychological mechanisms) after massage. Therefore, these benefits of massage are expected to help athletes by enhancing performance and reducing injury risk. However, limited research has investigated the effects of pre-exercise massage on performance and injury prevention. Massage between events is widely investigated because it is believed that massage might help to enhance recovery and prepare athletes for the next event. Unfortunately, very little scientific data has supported this claim. The majority of research on psychological effects of massage has concluded that massage produces positive effects on recovery (psychological mechanisms). Post-exercise massage has been shown to reduce the severity of muscle soreness but massage has no effects on muscle functional loss. Notwithstanding the belief that massage has benefits for athletes, the effects of different types of massage (e.g. petrissage, effleurage, friction) or the appropriate timing of massage (pre-exercise vs post-exercise) on performance, recovery from injury, or as an injury prevention method are not clear. Explanations are lacking, as the mechanisms of each massage technique have not been widely investigated. Therefore, this article discusses the possible mechanisms of massage and provides a discussion of the limited evidence of massage on performance, recovery and muscle injury prevention. The limitations of previous research are described and further research is recommended.

Protection against muscle damage in competitive sports players: the effect of the immunomodulator AM3

Strenuous physical exercise of the limb muscles commonly results in damage, especially when that exercise is intense, prolonged and includes eccentric contractions. Many factors contribute to exercise-induced muscle injury and the mechanism is likely to differ with the type of exercise. Competitive sports players are highly susceptible to this type of injury. AM3 is an orally administered immunomodulator that reduces the synthesis of proinflammatory cytokines and normalizes defective cellular immune fractions. The ability of AM3 to prevent chronic muscle injury following strenuous exercise characterized by eccentric muscle contraction was evaluated in a double-blind and randomized pilot study. Fourteen professional male volleyball players from the First Division of the Spanish Volleyball League volunteered to take part. The participants were randomized to receive either placebo (n=7) or AM3 (n=7). The physical characteristics (mean+/-s) of the placebo group were as follows: age 25.7+/-2.1 years, body mass 87.2+/-4.1 kg, height 1.89+/-0.07 m, maximal oxygen uptake 65.3+/-4.2 ml.kg(-1).min(-1). Those of the AM3 group were as follows: age 26.1+/-1.9 years, body mass 85.8+/-6.1 kg, height 1.91+/-0.07 m, maximal oxygen uptake 64.6+/-4.5 ml.kg(-1).min(-1). All participants were evaluated for biochemical indices of muscle damage, including concentrations of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatine kinase (CK) and its MB fraction (CK-MB), myoglobin, lactate dehydrogenase, urea, creatinine and gamma-glutamyltranspeptidase, both before and 30 days after treatment (over the peak of the competitive season). In the placebo group, competitive exercise (i.e. volleyball) was accompanied by significant increases in creatine kinase (494+/-51 to 560+/-53 IU.l(-1), P < 0.05) and myoglobin (76.8+/-2.9 to 83.9+/-3.1 microg.l(-1), P < 0.05); aspartate aminotransferase (30.8+/-3.0 to 31.1+/-2.9 IU.l(-1)) and lactate dehydrogenase (380+/-31 to 376+/-29 IU.l(-1)) were relatively unchanged after the 30 days maximum effort. AM3 not only inhibited these changes, it led to a decrease from baseline serum concentrations of creatine kinase (503+/-49 to 316+/-37 IU.l(-1), P < 0.05) and myoglobin (80.1+/-3.2 to 44.1+/-2.6 IU.l(-1), P < 0.05), as well as aspartate aminotransferase (31.1+/-3.3 to 26.1+/-2.7 IU.l(-1), P < 0.05) and lactate dehydrogenase (368+/-34 to 310+/-3 IU.l(-1), P < 0.05). The concentration of CK-MB was also significantly decreased from baseline with AM3 treatment (11.6+/-1.2 to 5.0+/-0.7 IU.l(-1), P < 0.05), but not with placebo (11.4+/-1.1 to 10.8+/-1.4 IU.l(-1)). In conclusion, the use of immunomodulators, such as AM3, by elite sportspersons during competition significantly reduces serum concentrations of proteins associated with muscle damage.

Effects of local pressure and vibration on muscle pain from eccentric exercise and hypertonic saline

In human subjects the triceps surae of one leg was exercised eccentrically by asking subjects to walk backwards on an inclined treadmill. Before the exercise controlled local pressure, applied to the muscle with an electromagnet, produced mild soreness, which was reduced when the pressure was combined with vibration. When delayed-onset muscle soreness (DOMS) had set in, 24-48 h after the exercise, vibration increased pain from local pressure. Vibrating at different frequencies suggested 80 Hz as the optimal frequency. During 2-h testing post-exercise, evidence of a change in character of the effects of vibration was first detected at 6 h. It persisted up to 72 h post-exercise. When muscle pain was generated in an unexercised triceps by injection of hypertonic (5%) saline, controlled local pressure applied to the sore area increased pain levels by 32% while pressure plus vibration reduced this to 11%. In a subject with DOMS, local pressure again increased pain from saline by 32% but combining it with vibration increased pain further by an additional 20%. The effect of vibration on DOMS could be abolished with a large nerve fibre block applied to the sciatic nerve. It is concluded that the vibration effects are the result of stimulation of large-diameter mechanoreceptive afferents in the muscle which, it is speculated, play a role in generating DOMS.

Temporal relation between leukocyte accumulation in muscles and halted recovery 10-20 h after strength exercise

Effects of normal strength exercise on leukocyte accumulation were examined in 10 well-trained male subjects (27.2 +/- 2.7 yr). The workout, consisting of five maximal sets of three repetitions of leg press exercise and five maximal sets of six repetitions of knee extension exercise, was performed with the dominant leg, and the other leg served as control. Repeated maximal isokinetic knee extensions at 60 degrees /s were performed to evaluate neuromuscular fatigue and recovery after the workout. Accumulation of leukocytes was assessed with 99mTc-labeled cells, and repeated images of the thighs were taken 1-24 h after the workout. Maximal force-generating capacity in the exercised leg was reduced by 17 +/- 2% (P < 0.01) after the workout. The course of recovery followed a biphasic pattern characterized by halted recovery 10-23 h after exercise. The presence of leukocytes was approximately 10% higher in the exercised than in the control thigh 10 h after exercise (P < 0.05). This difference increased to approximately 15% at 20 h after exercise (P < 0.05). The retarded recovery of maximal force-generating capacity 10-20 h after exercise, together with a significant infiltration of leukocytes in exercised muscle during the same time interval, shows a temporal relation between leukocyte infiltration and impaired recovery.

Use of nonsteroidal anti-inflammatory drugs following exercise-induced muscle injury

The objective of this article is to examine the use of NSAIDs for attenuating exercise-induced muscle injuries (EIMI), with an emphasis on their safety and usefulness for improving muscle function and reducing soreness. NSAIDs are some of the most widely consumed medications in the world, and NSAID use as therapy for EIMI has increased dramatically over the last 20 years. However, there is a lack of agreement concerning NSAID effectiveness for this purpose. The lack of consensus about the efficacy of NSAID use in relation to EIMI has spawned a recent interest in sports medicine research regarding NSAIDs. The application of a variety of methods used to induce, assess and quantify muscle injury has contributed to the inconsistency among the findings regarding the efficacy of NSAIDs for EIMI. Therefore, future studies should focus on the evaluation of muscle injury and function, with the use of better functional measurement tools and more uniformity in the assessment tools used. However, from review of the current literature, it is concluded that NSAID use for brief periods of time is beneficial for short-term recovery of muscle function and is an important laboratory tool for the study of EIMI.

Preliminary comparison of bromelain and Ibuprofen for delayed onset muscle soreness management

OBJECTIVE

The purpose of this study was to determine whether a common bromelain regimen or common ibuprofen regimen are effective in resolving pain and muscle dysfunction associated with delayed onset muscle soreness of the elbow flexors.

DESIGN

A randomized, double-blinded, repeated measures design was used for this study.

SETTING

The study was performed in the Sports Injury Research Lab at an NCAA Division I university.

PARTICIPANTS

Forty subjects who had not participated in an upper body resistance-training program 3 months prior to the study, suffered pain or injury in the nondominant arm, or experienced an adverse response to nonsteroidal anti-inflammatory drugs or pineapple (bromelain source) were recruited. Thirty-nine subjects finished the study.

INTERVENTIONS

Active range of motion (ROM), perceived pain, and peak concentric torque measurements of the nondominant arm were taken prior to and 24, 48, 72, and 96 hours following an eccentric exercise protocol of the elbow flexors. Subjects were assigned to one of four treatment groups (bromelain 300 mg t.i.d., ibuprofen 400 mg t.i.d., placebo t.i.d., and control) and began treatment immediately following the exercise protocol.

MAIN OUTCOME MEASURES

No differences among treatments were observed for any of the dependent variables at any time. ROM deficits and pain peaked between 48 and 72 hours. Peak torque deficiencies were observed between 24 and 72 hours.

CONCLUSIONS

Ingestion of bromelain and ibuprofen had no effect on elbow flexor pain, loss of ROM, or loss of concentric peak torque as a result of an eccentric exercise regimen.

Metabolic myopathies and physical activity: when fatigue is more than simple exertion

Fatigue can have many causes in active people. A metabolic myopathy-though uncommonly identified as a cause of fatigue during sporting events-must be considered in certain circumstances, and the diagnosis may be helpful for preventive and genetic counseling. In general, symptoms of disorders of glycogen breakdown and glucose utilization (glycogen storage diseases) occur during high-intensity exercise. Symptoms of disorders of fatty acid transport or oxidation and mitochondrial disorders occur after endurance exercise. Important investigations include forearm ischemic testing, electromyographic and nerve conduction studies, muscle biopsy (histology, enzyme, and DNA testing), and exercise testing. Most patients with metabolic myopathies can participate in sports with appropriate exercise adaptations and dietary manipulation.

Effect of indomethacin on the development of eccentric exercise-induced localized sensitive region in the fascia of the rabbit

The effect of indomethacin on the development of delayed onset muscle soreness (DOMS) and localized sensitive region produced by eccentric exercise was examined in lightly anesthetized rabbits (n=12, 2.0-3.3 kg). Repeated eccentric contractions of the gastrocnemius (GS) muscle were made by manual extensions during the tetanic contractions induced by electrical stimulation of the tibial nerve. The development of DOMS was confirmed by evoked reflex EMG in the biceps femoris (BF) muscle elicited by a quantitative manual extension of the GS muscle. The distribution of thresholds for the evoked BF EMG was measured by focal electrical stimulations of the GS muscle. Indomethacin (5 mg/kg in 2% sodium bicarbonate) or a vehicle was injected subcutaneously before, during, and after the exercise (a total of 60 mg/kg in 12 doses). A clear ropy taut band was palpated at the GS muscle on the second day after the exercise and a localized sensitive region for evoked BF EMG was detected at the depth of the fascia of the band in the exercise and vehicle groups, whereas no such phenomena appeared in the control and indomethacin groups. The palpable band and sensitive region disappeared on the seventh day after the exercise. That indomethacin inhibits the development of DOMS and the localized sensitive region suggests that a sensitization of polymodal-type nociceptors in the fascia mediated by prostaglandins is a possible mechanism for the development of DOMS and the localized sensitive region.

Effect of ibuprofen and acetaminophen on postexercise muscle protein synthesis

We examined the effect of two commonly consumed over-the-counter analgesics, ibuprofen and acetaminophen, on muscle protein synthesis and soreness after high-intensity eccentric resistance exercise. Twenty-four males (25 +/- 3 yr, 180 +/- 6 cm, 81 +/- 6 kg, and 17 +/- 8% body fat) were assigned to one of three groups that received either the maximal over-the-counter dose of ibuprofen (IBU; 1,200 mg/day), acetaminophen (ACET; 4,000 mg/day), or a placebo (PLA) after 10-14 sets of 10 eccentric repetitions at 120% of concentric one-repetition maximum with the knee extensors. Postexercise (24 h) skeletal muscle fractional synthesis rate (FSR) was increased 76 +/- 19% (P < 0.05) in PLA (0.058 +/- 0.012%/h) and was unchanged (P > 0.05) in IBU (35 +/- 21%; 0.021 +/- 0.014%/h) and ACET (22 +/- 23%; 0.010 +/- 0.019%/h). Neither drug had any influence on whole body protein breakdown, as measured by rate of phenylalanine appearance, on serum creatine kinase, or on rating of perceived muscle soreness compared with PLA. These results suggest that over-the-counter doses of both ibuprofen and acetaminophen suppress the protein synthesis response in skeletal muscle after eccentric resistance exercise. Thus these two analgesics may work through a common mechanism to influence protein metabolism in skeletal muscle.

Large-fiber mechanoreceptors contribute to muscle soreness after eccentric exercise

Muscles subjected to eccentric exercise, in which the contracting muscle is forcibly lengthened, become sore the next day (delayed onset muscle soreness). In subjects who had their triceps surae of 1 leg exercised eccentrically by walking backwards on an inclined moving treadmill, mapping the muscle 48 hours later with a calibrated probe showed sensitive areas were localized but not restricted to the muscle-tendon junction. Injection of 5% sodium chloride into a sensitive site in the exercised leg did not produce more pain than injections into the unexercised leg, suggesting that nociceptor sensitization was not responsible. Applying controlled indentations to a sensitive area showed that the pain could be exacerbated by 20-Hz or 80-Hz vibration. In an unexercised muscle, vibration had the opposite effect; it reduced pain. Pain thresholds were measured before, during, and after a pressure block of the sciatic nerve. The block affected only large-diameter nerve fibers, as evidenced by disappearance of the H reflex and a weakened voluntary contraction, leaving painful heat and cold sensations unaltered. Pain thresholds increased significantly during the block. It is concluded that muscle mechanoreceptors, including muscle spindles, contribute to the soreness after eccentric exercise.

Nonsteroidal anti-inflammatory therapy after eccentric exercise in healthy older individuals

BACKGROUND

Aging is associated with greater susceptibility to muscle injury and soreness after exercise. Although elderly persons regularly consume nonsteroidal anti-inflammatory drugs (NSAIDs), it is not clear that NSAIDs alleviate muscle dysfunction and/or inflammation following injurious exercise.

METHODS

In this double-blind crossover study, 10 men and 5 women (aged 60 +/- 2 years, mean +/- SE) consumed naproxen sodium or placebo for 10 days after performing 64 unilateral eccentric (ECC) knee extensions using 75% of the ECC 1-repetition maximum. Strength was measured before, 3 days after, and 10 days after each bout. Injury and soreness were assessed using magnetic resonance images of m. quadriceps femoris (QF) and a visual analog scale.

RESULTS

Three days after exercise, concentric strength loss was greater for placebo (-32 +/- 9%) than NSAID (-6 +/- 8%; p =.0064). Likewise, isometric strength declined less for NSAID than placebo (-12 +/- 7% vs -24 +/- 4%; p =.0213), and thigh soreness while rising from a chair was greater for placebo (p < or =.0393) than NSAID (43 +/- 7 mm vs 26 +/- 7 mm). QF cross-sectional area (cm(2)) showing elevated T(2) was 27% and 35% greater (p < or =.0096) for placebo on Days 3 and 10, respectively.

CONCLUSIONS

Naproxen sodium attenuated muscle injury, strength loss, and soreness following ECC exercise in older individuals and may be beneficial during the early stages of increased physical activity.

Anabolic steroids increase exercise tolerance

The influence of an anabolic androgenic steroid (AAS) on thymidine and amino acid uptake in rat hindlimb skeletal muscles during 14 days after a single exhaustive bout of weight lifting was determined. Adult male rats were divided randomly into Control or Steroid groups. Nandrolone decanoate was administered to the Steroid group 1 wk before the exercise bout. [3H]thymidine and [14C]leucine labeling were used to determine the serial changes in cellular mitotic activity, amino acid uptake, and myosin synthesis. Serum creatine kinase (CK) activity, used as a measure of muscle damage, increased 30 and 60 min after exercise in both groups. The total amount of weight lifted was higher, whereas CK levels were lower in Steroid than in Control rats. [3H]thymidine uptake peaked 2 days after exercise in both groups and was 90% higher in Control than in Steroid rats, reflecting a higher level of muscle damage. [14C]leucine uptake was approximately 80% higher at rest and recovered 33% faster postexercise in Steroid than in Control rats. In a separate group of rats, the in situ isometric mechanical properties of the plantaris muscle were determined. The only significant difference was a higher fatigue resistance in the Steroid compared with the Control group. Combined, these results indicate that AAS treatment 1) ameliorates CK efflux and the uptake of [3H]thymidine and enhances the rate of protein synthesis during recovery after a bout of weight lifting, all being consistent with there being less muscle damage, and 2) enhances in vivo work capacity and the in situ fatigue resistance of a primary plantarflexor muscle.

Managing delayed-onset muscle soreness: lack of effect of selected oral systemic analgesics

OBJECTIVE

To investigate the efficacy of commonly available analgesics in the management of delayed-onset muscle soreness over an 11-day period.

DESIGN

Double-blind, placebo-controlled randomized trial.

SETTING

University laboratory.

PARTICIPANTS

Sixty healthy volunteers (30 men, 30 women) with no current arm pain or pathology completed the experimental procedure.

INTERVENTIONS

Subjects were randomly allocated to one of five experimental groups: control; placebo; aspirin (900 mg); codeine (60 mg); and paracetamol (1000 mg) (n = 12 in all groups). Delayed soreness was induced in the nondominant elbow flexors using a standardized exercise protocol of repeated eccentric contractions.

MAIN OUTCOME MEASURES

Pain (visual analogue scale; McGill pain questionnaire [MPQ]), range of extension, flexion and resting angle (universal goniometer), and mechanical pain threshold (pressure algometer). Measurements were taken before and after drug administration each day, except for the MPQ, which was completed on the first and third days of the experiment.

RESULTS

Analysis of results using repeated-measures analysis of variance and relevant post hoc tests provided no evidence of the effectiveness of any of the preparations.

CONCLUSION

There is no beneficial effect from the medications, at least at the doses stated, in the management of delayed-onset muscle soreness.

Anti-inflammatory treatment of muscular injuries in sport. An update of recent studies

Stretch-induced muscle injuries or strains, muscle contusions and delayed-onset muscle soreness (DOMS) are common muscle problems in athletes. Anti-inflammatory treatment is often used for the pain and disability associated with these injuries. The most recent studies on nonsteroidal anti-inflammatory drugs (NSAIDs) in strains and contusions suggest that the use of NSAIDs can result in a modest inhibition of the initial inflammatory response and its symptoms. However, this may be associated with some small negative effects later in the healing phase. Corticosteroids have generally been shown to adversely affect the healing of these acute injuries. Animal studies have suggested that anabolic steroids may actually aid in the healing process, but clinical studies are not yet available and the exact role of these drugs has yet to be determined. Studies on anti-inflammatory treatment of DOMS have yielded conflicting results. However, the effect of NSAIDs on DOMS appears small at best. Future research may have to focus on different aspects of these injuries as the emphasis on anti-inflammatory treatment has yielded somewhat disappointing results.