Contraction-induced muscle damage is unaffected by vitamin E supplementation

Vitamin E Does not Favor Recovery After Exercises: Systematic Review and Meta-analysis

This review aimed to verify the effects of vitamin E supplementation on oxidative stress, inflammatory response, muscle damage, soreness, and strength in healthy adults after exercise. We searched the MEDLINE, EMBASE, SPORTDiscus, Cochrane CENTRAL, and Web of Science from inception to August 2023, with no language restrictions. We included randomized placebo-controlled trials evaluating the supplementation of vitamin E on the abovementioned outcomes after a bout of physical exercise in healthy participants (no restriction for publication year or language). Meta-analyses were conducted to compare vitamin E and placebo supplementations to obtain a 95% confidence interval (95%IC). Twenty studies were included (n=298 participants). The effect of supplementation was assessed between 0 h and 96 h after the exercise. Compared to placebo, vitamin E had no effects on lipid (95%IC= -0.09 to 0.42), protein (-2.44 to 3.11), SOD (-1.05 to 0.23), interleukin-6 (-0.18 to 1.16), creatine kinase (-0.33 to 0.27), muscle soreness (-1.92 to 0.69), and muscle strength (-1.07 to 0.34). Heterogeneity for the analyses on carbonyls, interleukin-6 (1 h and 3 h), and muscle soreness ranged between 70 to 94%. Supplementing with vitamin E should not be recommended to support the recovery process in healthy individuals after exercise, given the lack of efficacy in the analyzed variables following an exercise session.

Antioxidants and Sports Performance

The role of reactive oxygen species and antioxidant response in training adaptations and sports performance has been a large issue investigated in the last few years. The present review aims to analyze the role of reactive oxygen species and antioxidant response in sports performance. For this aim, the production of reactive oxygen species in physical activities, the effect of reactive oxygen species on sports performance, the relationship between reactive oxygen species and training adaptations, inflammation, and the microbiota, the effect of antioxidants on recovery and sports performance, and strategies to use antioxidants supplementations will be discussed. Finally, practical applications derived from this information are discussed. The reactive oxygen species (ROS) production during physical activity greatly influences sports performance. This review concludes that ROS play a critical role in the processes of training adaptation induced by resistance training through a reduction in inflammatory mediators and oxidative stress, as well as appropriate molecular signaling. Additionally, it has been established that micronutrients play an important role in counteracting free radicals, such as reactive oxygen species, which cause oxidative stress, and the effects of antioxidants on recovery, sports performance, and strategies for using antioxidant supplements, such as vitamin C, vitamin E, resveratrol, coenzyme Q10, selenium, and curcumin to enhance physical and mental well-being.

Molecular Mechanisms Through Which Cannabidiol May Affect Skeletal Muscle Metabolism, Inflammation, Tissue Regeneration, and Anabolism: A Narrative Review

Background: Cannabidiol (CBD), a nonintoxicating constituent of the cannabis plant, recently gained a lot of interest among athletes, since it is no longer considered as a prohibited substance by the World Anti-Doping Agency. The increasing prevalence of CBD use among athletes is driven by a perceived improvement in muscle recovery and a reduction in pain. However, compelling evidence from intervention studies is lacking and the precise mechanisms through which CBD may improve muscle recovery remain unknown. This highlights the need for more scientific studies and an evidence-based background. In the current review, the state-of-the-art knowledge on the effects of CBD on skeletal muscle tissue is summarized with special emphasis on the underlying mechanisms and molecular targets. More specifically, the large variety of receptor families that are believed to be involved in CBD's physiological effects are discussed. Furthermore, in vivo and in vitro studies that investigated the actual effects of CBD on skeletal muscle metabolism, inflammation, tissue regeneration, and anabolism are summarized, together with the functional effects of CBD supplementation on muscle recovery in human intervention trials. Overall, CBD was effective to increase the expression of metabolic regulators in muscle of obese mice (e.g., Akt, glycogen synthase kinase-3). CBD treatment in rodents reduced muscle inflammation following eccentric exercise (i.e., nuclear factor kappa B [NF-κB]), in a model of muscle dystrophy (e.g., interleukin-6, tumor necrosis factor alpha) and of obesity (e.g., COX-2, NF-κB). In addition, CBD did not affect in vitro or in vivo muscle anabolism, but improved satellite cell differentiation in dystrophic muscle. In humans, there are some indications that CBD supplementation improved muscle recovery (e.g., creatine kinase) and performance (e.g., squat performance). However, CBD doses were highly variable (between 16.7 and 150 mg) and there are some methodological concerns that should be considered. Conclusion: CBD has the prospective to become an adequate supplement that may improve muscle recovery. However, this research domain is still in its infancy and future studies addressing the molecular and functional effects of CBD in response to exercise are required to further elucidate the ergogenic potential of CBD.

THE VITAMIN E CONSUMPTION EFFECT ON MUSCLE DAMAGE AND OXIDATIVE STRESS: A SYSTEMATIC REVIEW AND META-ANALYSIS OF RANDOMIZED CONTROLLED TRIALS

ABSTRACT Introduction: Vitamin E supplementation may protect against exercise-induced muscle damage (EIMD) through possible inhibition of free radical formation and cell membrane stabilization. However, there is no systematic review of this topic. This fact maintains academic stalemates that may have a resolution. Objective: This systematic review with meta-analysis aims to provide a comprehensive literature review on the hypothesis of the benefit of vitamin E supplementation on oxidative stress and muscle damage induced by aerobic exercise. Methods: A random-effects model was used, weighted mean difference (WMD) and 95% confidence interval (CI) were applied to estimate the overall effect. Results: The results revealed a significant effect of vitamin E supplementation on reducing creatine kinase (CK) and lactate dehydrogenase (LDH). In addition, a subgroup analysis resulted in a significant decrease in CK concentrations in trials with immediate and <24 hours post-exercise CK measurement; <1000 at daily vitamin E intake; ≤1 at weekly intake; 1 at six weeks and >6 weeks experimental duration, studies on aerobic exercise and training were part of the crossover study. Conclusion: Vitamin E can be seen as a priority agent for recovery from muscle damage. Evidence Level II; Therapeutic Studies – Investigating the results.

Local and systemic transcriptomic responses from acute exercise induced muscle damage of the human knee extensors

Skeletal muscle is adaptable to a direct stimulus of exercise-induced muscle damage (EIMD). Local muscle gene networks and systemic circulatory factors respond to EIMD within days, mediating anti-inflammation and cellular proliferation. Here we show in humans that local EIMD of one muscle group is associated with a systemic response of gene networks that regulate muscle structure and cellular development in non-local homologous muscle not directly altered by EIMD. In the non-dominant knee-extensors of seven males, EIMD was induced through voluntary contractions against an electric motor that lengthened muscles. Neuromuscular assessments, vastus lateralis muscle biopsies and blood draws occurred at two days prior, and one and two days post the EIMD intervention. From the muscle and blood plasma samples, RNA-seq measured transcriptome changes of differential expression using bioinformatic analyses.Relative to the time of the EIMD intervention, local muscle that was mechanically damaged had 475 genes differentially expressed, as compared to 33 genes in the non-local homologous muscle. Gene and network analysis showed that activity of the local muscle was related to structural maintenance, repair, and energetic processes, whereas gene and network activity of the non-local muscle (that was not directly modified by the EIMD) were related to muscle cell development, stress response, and structural maintenance. Altered expression of two novel miRNAs related to the EIMD response supported that systemic factors were active. Together, these results indicate that the expression of genes and gene networks that control muscle contractile structure can be modified in response to non-local EIMD in humans.

Strength Training in Swimming

This narrative review deals with the topic of strength training in swimming, which has been a controversial issue for decades. It is not only about the importance for the performance at start, turn and swim speed, but also about the question of how to design a strength training program. Different approaches are discussed in the literature, with two aspects in the foreground. On the one hand is the discussion about the optimal intensity in strength training and, on the other hand, is the question of how specific strength training should be designed. In addition to a summary of the current state of research regarding the importance of strength training for swimming, the article shows which physiological adaptations should be achieved in order to be able to increase performance in the long term. Furthermore, an attempt is made to explain why some training contents seem to be rather unsuitable when it comes to increasing strength as a basis for higher performance in the start, turn and clean swimming. Practical training consequences are then derived from this. Regardless of the athlete's performance development, preventive aspects should also be considered in the discussion. The article provides a critical overview of the abovementioned key issues. The most important points when designing a strength training program for swimming are a sufficiently high-load intensity to increase maximum strength, which in turn is the basis for power, year-round strength training, parallel to swim training and working on the transfer of acquired strength skills in swim training, and not through supposedly specific strength training exercises on land or in the water.

Effects of Functional Phenolics Dietary Supplementation on Athletes' Performance and Recovery: A Review

In recent years, many efforts have been made to identify micronutrients or nutritional strategies capable of preventing, or at least, attenuating, exercise-induced muscle damage and oxidative stress, and improving athlete performance. The reason is that most exercises induce various changes in mitochondria and cellular cytosol that lead to the generation of reactive species and free radicals whose accumulation can be harmful to human health. Among them, supplementation with phenolic compounds seems to be a promising approach since their chemical structure, composed of catechol, pyrogallol, and methoxy groups, gives them remarkable health-promoting properties, such as the ability to suppress inflammatory processes, counteract oxidative damage, boost the immune system, and thus, reduce muscle soreness and accelerate recovery. Phenolic compounds have also already been shown to be effective in improving temporal performance and reducing psychological stress and fatigue. Therefore, the aim of this review is to summarize and discuss the current knowledge on the effects of dietary phenolics on physical performance and recovery in athletes and sports practitioners. Overall, the reports show that phenolics exert important benefits on exercise-induced muscle damage as well as play a biological/physiological role in improving physical performance.

Micronutrients and athletic performance: A review

Optimising nutrition intake is a key component for supporting athletic performance and supporting adaption to training. Athletes often use micronutrient supplements in order to correct vitamin and mineral deficiencies, improve immune function, enhance recovery and or to optimise their performance. The aim of this review was to investigate the recent literature regarding micronutrients (specifically iron, vitamin C, vitamin E, vitamin D, calcium) and their effects on physical performance. Over the past ten years, several studies have investigated the impacts of these micronutrients on aspects of athletic performance, and several reviews have aimed to provide an overview of current use and effectiveness. Currently the balance of the literature suggests that micronutrient supplementation in well-nourished athletes does not enhance physical performance. Excessive intake of dietary supplements may impair the body's physiological responses to exercise that supports adaptation to training stress. In some cases, micronutrient supplementation is warranted, for example, with a diagnosed deficiency, when energy intake is compromised, or when training and competing at altitude, however these micronutrients should be prescribed by a medical professional. Athletes are encouraged to obtain adequate micronutrients from a wellbalanced and varied dietary intake.

Consumption of New Zealand Blackcurrant Extract Improves Recovery from Exercise-Induced Muscle Damage in Non-Resistance Trained Men and Women: A Double-Blind Randomised Trial

Background: Blackcurrant is rich in anthocyanins that may protect against exercise-induced muscle damage (EIMD) and facilitate a faster recovery of muscle function. We examined the effects of New Zealand blackcurrant (NZBC) extract on indices of muscle damage and recovery following a bout of strenuous isokinetic resistance exercise. Methods: Using a double-blind, randomised, placebo controlled, parallel design, twenty-seven healthy participants received either a 3 g·day⁻¹ NZBC extract (n = 14) or the placebo (PLA) (n = 13) for 8 days prior to and 4 days following 60 strenuous concentric and eccentric contractions of the biceps brachii muscle on an isokinetic dynamometer. Muscle soreness (using a visual analogue scale), maximal voluntary contraction (MVC), range of motion (ROM) and blood creatine kinase (CK) were assessed before (0 h) and after (24, 48, 72 and 96 h) exercise. Results: Consumption of NZBC extract resulted in faster recovery of baseline MVC (p = 0.04), attenuated muscle soreness at 24 h (NZBC: 21 ± 10 mm vs. PLA: 40 ± 23 mm, p = 0.02) and 48 h (NZBC: 22 ± 17 vs. PLA: 44 ± 26 mm, p = 0.03) and serum CK concentration at 96 h (NZBC: 635 ± 921 UL vs. PLA: 4021 ± 4319 UL, p = 0.04) following EIMD. Conclusions: Consumption of NZBC extract prior to and following a bout of eccentric exercise attenuates muscle damage and improves functional recovery. These findings are of practical importance in recreationally active and potentially athletic populations, who may benefit from accelerated recovery following EIMD.

An Antioxidant Nanoparticle Enhances Exercise Performance in Rat High-intensity Running Models

Although the adverse effects of excessively generated reactive oxygen species (ROS) on the body during aerobic exercise have been debated, there are few reports on the remarkable effects of the application of conventional antioxidants on exercise performance. The conventional antioxidants could not enhance exercise performance due to their rapid excretion from the body and serious adverse effects on the cellular respiratory system. In this study, impact of the original antioxidant self-assembling nanoparticle, redox-active nanoparticle (RNP), is investigated on the exercise performance of rats during running experiments. With an increase in the dose of the administered RNP, the all-out time of the rat running extends in a dose-dependent manner. In contrast, with an increase in the dose of the low-molecular-weight (LMW) antioxidant, the all-out running time of the rats decreases. The control group and LMW antioxidant treated group decrease in the number of red blood cells (RBCs) and increase oxidative stress after running. However, the RNP group maintains a similar RBC level and oxidative stress as that of the sedentary group. The results suggest that RNP, which shows long-blood circulation without disturbance of mitohormesis, effectively removes ROS from the bloodstream to suppresses RBC oxidative stress and damage, thus improving exercise performance.

Antioxidant supplements and endurance exercise: Current evidence and mechanistic insights

Antioxidant supplements are commonly consumed by endurance athletes to minimize exercise-induced oxidative stress, with the intention of enhancing recovery and improving performance. There are numerous commercially available nutritional supplements that are targeted to athletes and health enthusiasts that allegedly possess antioxidant properties. However, most of these compounds are poorly investigated with respect to their in vivo redox activity and efficacy in humans. Therefore, this review will firstly provide a background to endurance exercise-related redox signalling and the subsequent adaptations in skeletal muscle and vascular function. The review will then discuss commonly available compounds with purported antioxidant effects for use by athletes. N-acetyl cysteine may be of benefit over the days prior to an endurance event; while chronic intake of combined 1000 mg vitamin C + vitamin E is not recommended during periods of heavy training associated with adaptations in skeletal muscle. Melatonin, vitamin E and α-lipoic acid appear effective at decreasing markers of exercise-induced oxidative stress. However, evidence on their effects on endurance performance are either lacking or not supportive. Catechins, anthocyanins, coenzyme Q10 and vitamin C may improve vascular function, however, evidence is either limited to specific sub-populations and/or does not translate to improved performance. Finally, additional research should clarify the potential benefits of curcumin in improving muscle recovery post intensive exercise; and the potential hampering effects of astaxanthin, selenium and vitamin A on skeletal muscle adaptations to endurance training. Overall, we highlight the lack of supportive evidence for most antioxidant compounds to recommend to athletes.

Do Antioxidant Vitamins Prevent Exercise-Induced Muscle Damage? A Systematic Review

Free radicals produced during exercise play a role in modulating cell signaling pathways. High doses of antioxidants may hamper adaptations to exercise training. However, their benefits are unclear. This review aims to examine whether vitamin C (VitC) and/or vitamin E (VitE) supplementation (SUP) prevents exercise-induced muscle damage. The PubMed, Web of Science, Medline, CINAHL, and SPORTDiscus databases were searched, and 21 articles were included. Four studies examined the effects of acute VitC SUP given pre-exercise: in one study, lower CK levels post-exercise was observed; in three, no difference was recorded. In one study, acute VitE SUP reduced CK activity 1 h post-exercise in conditions of hypoxia. In three studies, chronic VitE SUP did not reduce CK activity after an exercise session. Chronic VitE SUP did not reduce creatine kinase (CK) concentrations after three strength training sessions, but it was effective after 6 days of endurance training in another study. Chronic SUP with VitC + E reduced CK activity post-exercise in two studies, but there was no such effect in four studies. Finally, three studies described the effects of chronic VitC + E SUP and long-term exercise, reporting dissimilar results. To conclude, although there is some evidence of a protective effect of VitC and/or VitE against exercise-induced muscle damage, the available data are not conclusive.

Antifatigue Activity and Exercise Performance of Phenolic-Rich Extracts from Calendula officinalis, Ribes nigrum, and Vaccinium myrtillus

Calendula officinalis, Ribes nigrum, and Vaccinium myrtillus (CRV) possess a high phenolic compound content with excellent antioxidant activity. Dietary antioxidants can reduce exercise-induced oxidative stress. Consumption of large amounts of phenolic compounds is positively correlated with reduction in exercise-induced muscle damage. Research for natural products to improve exercise capacity, relieve fatigue, and accelerate fatigue alleviation is ongoing. Here, CRV containing a large total phenolic content (13.4 mg/g of CRV) demonstrated antioxidant activity. Ultra-performance liquid chromatography quantification revealed 1.95 ± 0.02 mg of salidroside in 1 g of CRV. In the current study, CRV were administered to mice for five weeks, and the antifatigue effect of CRV was evaluated using the forelimb grip strength test; weight-loaded swimming test; and measurement of fatigue-related biochemical indicators, such as blood lactate, ammonia, glucose, blood urea nitrogen (BUN), and creatine kinase (CK) activity; and muscle and liver glycogen content. The results indicated that in CRV-treated mice, the forelimb grip strength significantly increased; weight-loaded swimming time prolonged; their lactate, ammonia, BUN, and CK activity decreased, and muscle and liver glucose and glycogen content increased compared with the vehicle group. Thus, CRV have antifatigue activity and can increase exercise tolerance.

Effects of pomegranate supplementation on exercise performance and post-exercise recovery in healthy adults: a systematic review

The functional significance of pomegranate (POM) supplementation on physiological responses during and following exercise is currently unclear. This systematic review aimed (i) to evaluate the existing literature assessing the effects of POM supplementation on exercise performance and recovery; exercise-induced muscle damage, oxidative stress, inflammation; and cardiovascular function in healthy adults and (ii) to outline the experimental conditions in which POM supplementation is more or less likely to benefit exercise performance and/or recovery. Multiple electronic databases were used to search for studies examining the effects of POM intake on physiological responses during and/or following exercise in healthy adult. Articles were included in the review if they investigated the effects of an acute or chronic POM supplementation on exercise performance, recovery and/or physiological responses during or following exercise. The existing evidence suggests that POM supplementation has the potential to confer antioxidant and anti-inflammatory effects during and following exercise, to improve cardiovascular responses during exercise, and to enhance endurance and strength performance and post-exercise recovery. However, the beneficial effects of POM supplementation appeared to be less likely when (i) unilateral eccentric exercise was employed, (ii) the POM administered was not rich in polyphenols (<1·69 g/l) and (iii) insufficient time was provided between POM-ingestion and the assessment of physiological responses/performance (≤1 h). The review indicates that POM has the potential to enhance exercise performance and to expedite recovery from intensive exercise. The findings and recommendations from this review may help to optimise POM-supplementation practice in athletes and coaches to potentially improve exercise-performance and post-exercise recovery.

Antioxidants for preventing and reducing muscle soreness after exercise: a Cochrane systematic review

OBJECTIVE

To determine whether antioxidant supplements and antioxidant-enriched foods can prevent or reduce delayed-onset muscle soreness after exercise.

METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, SPORTDiscus, trial registers, reference lists of articles and conference proceedings up to February 2017.

RESULTS

In total, 50 studies were included in this review which included a total of 1089 participants (961 were male and 128 were female) with an age range of 16-55 years. All studies used an antioxidant dosage higher than the recommended daily amount. The majority of trials (47) had design features that carried a high risk of bias due to selective reporting and poorly described allocation concealment, potentially limiting the reliability of their findings. We rescaled to a 0-10 cm scale in order to quantify the actual difference between groups and we found that the 95% CIs for all five follow-up times were all well below the minimal important difference of 1.4 cm: up to 6 hours (MD -0.52, 95% CI -0.95 to -0.08); at 24 hours (MD -0.17, 95% CI -0.42 to 0.07); at 48 hours (mean difference (MD) -0.41, 95% CI -0.69 to -0.12); at 72 hours (MD -0.29, 95% CI -0.59 to 0.02); and at 96 hours (MD -0.03, 95% CI -0.43 to 0.37). Thus, the effect sizes suggesting less muscle soreness with antioxidant supplementation were very unlikely to equate to meaningful or important differences in practice.

CONCLUSIONS

There is moderate to low-quality evidence that high-dose antioxidant supplementation does not result in a clinically relevant reduction of muscle soreness after exercise of up to 6 hours or at 24, 48, 72 and 96 hours after exercise. There is no evidence available on subjective recovery and only limited evidence on the adverse effects of taking antioxidant supplements.

The effects of different passive static stretching intensities on recovery from unaccustomed eccentric exercise - a randomized controlled trial

Effects of passive static stretching intensity on recovery from unaccustomed eccentric exercise of right knee extensors was investigated in 30 recreationally active males randomly allocated into 3 groups: high-intensity (70%-80% maximum perceived stretch), low-intensity (30%-40% maximum perceived stretch), and control. Both stretching groups performed 3 sets of passive static stretching exercises of 60 s each for hamstrings, hip flexors, and quadriceps, over 3 consecutive days, post-unaccustomed eccentric exercise. Muscle function (eccentric and isometric peak torque) and blood biomarkers (creatine kinase and C-reactive protein) were measured before (baseline) and after (24, 48, and 72 h) unaccustomed eccentric exercise. Perceived muscle soreness scores were collected immediately (time 0), and after 24, 48, and 72 h postexercise. Statistical time × condition interactions observed only for eccentric peak torque (p = 0.008). Magnitude-based inference analyses revealed low-intensity stretching had most likely, very likely, or likely beneficial effects on perceived muscle soreness (48-72 h and 0-72 h) and eccentric peak torque (baseline-24 h and baseline-72 h), compared with high-intensity stretching. Compared with control, low-intensity stretching had very likely or likely beneficial effects on perceived muscle soreness (0-24 h and 0-72 h), eccentric peak torque (baseline-48 h and baseline-72 h), and isometric peak torque (baseline-72 h). High-intensity stretching had likely beneficial effects on eccentric peak torque (baseline-48 h), but likely had harmful effects on eccentric peak torque (baseline-24 h) and creatine kinase (baseline-48 h and baseline-72 h), compared with control. Therefore, low-intensity stretching is likely to result in small-to-moderate beneficial effects on perceived muscle soreness and recovery of muscle function post-unaccustomed eccentric exercise, but not markers of muscle damage and inflammation, compared with high-intensity or no stretching.

Antioxidants for preventing and reducing muscle soreness after exercise

BACKGROUND

Muscle soreness typically occurs after intense exercise, unaccustomed exercise or actions that involve eccentric contractions where the muscle lengthens while under tension. It peaks between 24 and 72 hours after the initial bout of exercise. Many people take antioxidant supplements or antioxidant-enriched foods before and after exercise in the belief that these will prevent or reduce muscle soreness after exercise.

OBJECTIVES

To assess the effects (benefits and harms) of antioxidant supplements and antioxidant-enriched foods for preventing and reducing the severity and duration of delayed onset muscle soreness following exercise.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, SPORTDiscus, trial registers, reference lists of articles and conference proceedings up to February 2017.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials investigating the effects of all forms of antioxidant supplementation including specific antioxidant supplements (e.g. tablets, powders, concentrates) and antioxidant-enriched foods or diets on preventing or reducing delayed onset muscle soreness (DOMS). We excluded studies where antioxidant supplementation was combined with another supplement.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results, assessed risk of bias and extracted data from included trials using a pre-piloted form. Where appropriate, we pooled results of comparable trials, generally using the random-effects model. The outcomes selected for presentation in the 'Summary of findings' table were muscle soreness, collected at times up to 6 hours, 24, 48, 72 and 96 hours post-exercise, subjective recovery and adverse effects. We assessed the quality of the evidence using GRADE.

MAIN RESULTS

Fifty randomised, placebo-controlled trials were included, 12 of which used a cross-over design. Of the 1089 participants, 961 (88.2%) were male and 128 (11.8%) were female. The age range for participants was between 16 and 55 years and training status varied from sedentary to moderately trained. The trials were heterogeneous, including the timing (pre-exercise or post-exercise), frequency, dose, duration and type of antioxidant supplementation, and the type of preceding exercise. All studies used an antioxidant dosage higher than the recommended daily amount. The majority of trials (47) had design features that carried a high risk of bias due to selective reporting and poorly described allocation concealment, potentially limiting the reliability of their findings.We tested only one comparison: antioxidant supplements versus control (placebo). No studies compared high-dose versus low-dose, where the low-dose supplementation was within normal or recommended levels for the antioxidant involved.Pooled results for muscle soreness indicated a small difference in favour of antioxidant supplementation after DOMS-inducing exercise at all main follow-ups: up to 6 hours (standardised mean difference (SMD) -0.30, 95% confidence interval (CI) -0.56 to -0.04; 525 participants, 21 studies; low-quality evidence); at 24 hours (SMD -0.13, 95% CI -0.27 to 0.00; 936 participants, 41 studies; moderate-quality evidence); at 48 hours (SMD -0.24, 95% CI -0.42 to -0.07; 1047 participants, 45 studies; low-quality evidence); at 72 hours (SMD -0.19, 95% CI -0.38 to -0.00; 657 participants, 28 studies; moderate-quality evidence), and little difference at 96 hours (SMD -0.05, 95% CI -0.29 to 0.19; 436 participants, 17 studies; low-quality evidence). When we rescaled to a 0 to 10 cm scale in order to quantify the actual difference between groups, we found that the 95% CIs for all five follow-up times were all well below the minimal important difference of 1.4 cm: up to 6 hours (MD -0.52, 95% CI -0.95 to -0.08); at 24 hours (MD -0.17, 95% CI -0.42 to 0.07); at 48 hours (MD -0.41, 95% CI -0.69 to -0.12); at 72 hours (MD -0.29, 95% CI -0.59 to 0.02); and at 96 hours (MD -0.03, 95% CI -0.43 to 0.37). Thus, the effect sizes suggesting less muscle soreness with antioxidant supplementation were very unlikely to equate to meaningful or important differences in practice. Neither of our subgroup analyses to examine for differences in effect according to type of DOMS-inducing exercise (mechanical versus whole body aerobic) or according to funding source confirmed subgroup differences. Sensitivity analyses excluding cross-over trials showed that their inclusion had no important impact on results.None of the 50 included trials measured subjective recovery (return to previous activities without signs or symptoms).There is very little evidence regarding the potential adverse effects of taking antioxidant supplements as this outcome was reported in only nine trials (216 participants). From the studies that did report adverse effects, two of the nine trials found adverse effects. All six participants in the antioxidant group of one trial had diarrhoea and four of these also had mild indigestion; these are well-known side effects of the particular antioxidant used in this trial. One of 26 participants in a second trial had mild gastrointestinal distress.

AUTHORS' CONCLUSIONS

There is moderate to low-quality evidence that high dose antioxidant supplementation does not result in a clinically relevant reduction of muscle soreness after exercise at up to 6 hours or at 24, 48, 72 and 96 hours after exercise. There is no evidence available on subjective recovery and only limited evidence on the adverse effects of taking antioxidant supplements. The findings of, and messages from, this review provide an opportunity for researchers and other stakeholders to come together and consider what are the priorities, and underlying justifications, for future research in this area.

Nutrition and Supplementation in Soccer

Contemporary elite soccer features increased physical demands during match-play, as well as a larger number of matches per season. Now more than ever, aspects related to performance optimization are highly regarded by both players and soccer coaches. Here, nutrition takes a special role as most elite teams try to provide an adequate diet to guarantee maximum performance while ensuring a faster recovery from matches and training exertions. It is currently known that manipulation and periodization of macronutrients, as well as sound hydration practices, have the potential to interfere with training adaptation and recovery. A careful monitoring of micronutrient status is also relevant to prevent undue fatigue and immune impairment secondary to a deficiency status. Furthermore, the sensible use of evidence-based dietary supplements may also play a role in soccer performance optimization. In this sense, several nutritional recommendations have been issued. This detailed and comprehensive review addresses the most relevant and up-to-date nutritional recommendations for elite soccer players, covering from macro and micronutrients to hydration and selected supplements in different contexts (daily requirements, pre, peri and post training/match and competition).

Vitamin A Oral Supplementation Induces Oxidative Stress and Suppresses IL-10 and HSP70 in Skeletal Muscle of Trained Rats

Exercise training intensity is the major variant that influences the relationship between exercise, redox balance, and immune response. Supplement intake is a common practice for oxidative stress prevention; the effects of vitamin A (VA) on exercise training are not yet described, even though this molecule exhibits antioxidant properties. We investigated the role of VA supplementation on redox and immune responses of adult Wistar rats subjected to swimming training. Animals were divided into four groups: sedentary, sedentary + VA, exercise training, and exercise training + VA. Over eight weeks, animals were submitted to intense swimming 5 times/week and a VA daily intake of 450 retinol equivalents/day. VA impaired the total serum antioxidant capacity acquired by exercise, with no change in interleukin-1β and tumor necrosis factor-α levels. In skeletal muscle, VA caused lipid peroxidation and protein damage without differences in antioxidant enzyme activities; however, Western blot analysis showed that expression of superoxide dismutase-1 was downregulated, and upregulation of superoxide dismutase-2 induced by exercise was blunted by VA. Furthermore, VA supplementation decreased anti-inflammatory interleukin-10 and heat shock protein 70 expression, important factors for positive exercise adaptations and tissue damage prevention. Our data showed that VA supplementation did not confer any antioxidative and/or protective effects, attenuating exercise-acquired benefits in the skeletal muscle.

Pomegranate Supplementation Accelerates Recovery of Muscle Damage and Soreness and Inflammatory Markers after a Weightlifting Training Session

Purpose

The aim of this study was to investigate the effect of natural Pomegranate juice supplementation on performance and acute and delayed responses of muscle soreness and biomarkers of muscle damage after a weightlifting training session.

Methods

Nine elite weightlifters (21±0.5 years) performed two Olympic-Weightlifting-sessions after either placebo (PLA) or natural pomegranate juice (POMj) supplementations. Heart rate, blood pressure and blood samples (hematological parameters, muscle damage and C-reactive protein (CRP)) were collected at rest, 3min and 48h after each session. Weightlifting performance, RPE, and DOMS were also assessed after each training session.

Results

T-test showed higher performance (+8.30%) and lower RPE values (-4.37%) using POMj supplementation (p<0.05) in comparison with PLA. For the DOMS values, a significant improvement (13.4%) was shown only for the knee extensors (p<0.01) using the POMj. Compared to PLA condition, POMj attenuated the acute (i.e., 3min) increase of systolic blood pressure (SBP), HR, CK and LDH (p<0.05; -4.46%, -1.81%, -8.75%, -1.64%, respectively) and blunted the significant increase of ASAT, PAL and CRP (p>0.05). Additionally, during the 48h following the training session, POMj improved the recovery kinetic of SBP (p<0.01, 7.97%), CK (p<0.001, 11.34%), LDH (p<0.05, 7.30%) and ASAT (p<0.05, 6.77%). Indeed, the present study showed that 48h of recovery associated to natural POMj supplementation was sufficient to reach the resting values of the selected muscle damage markers after intensive training session.

Conclusion

Natural POMj seems to ameliorate the capacity to adhere to an intensive training program. Therefore, elite weightlifters are advised to use natural POMj during intensive training program and competition to accelerate muscle recovery.

Trial Registration

ClinicalTrials.gov NCT02697903

Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage

KEY POINTS

Skeletal muscle hypertrophy is one of the main outcomes from resistance training (RT), but how it is modulated throughout training is still unknown. We show that changes in myofibrillar protein synthesis (MyoPS) after an initial resistance exercise (RE) bout in the first week of RT (T1) were greater than those seen post-RE at the third (T2) and tenth week (T3) of RT, with values being similar at T2 and T3. Muscle damage (Z-band streaming) was the highest during post-RE recovery at T1, lower at T2 and minimal at T3. When muscle damage was the highest, so was the integrated MyoPS (at T1), but neither were related to hypertrophy; however, integrated MyoPS at T2 and T3 were correlated with hypertrophy. We conclude that muscle hypertrophy is the result of accumulated intermittent increases in MyoPS mainly after a progressive attenuation of muscle damage.

ABSTRACT

Skeletal muscle hypertrophy is one of the main outcomes of resistance training (RT), but how hypertrophy is modulated and the mechanisms regulating it are still unknown. To investigate how muscle hypertrophy is modulated through RT, we measured day-to-day integrated myofibrillar protein synthesis (MyoPS) using deuterium oxide and assessed muscle damage at the beginning (T1), at 3 weeks (T2) and at 10 weeks of RT (T3). Ten young men (27 (1) years, mean (SEM)) had muscle biopsies (vastus lateralis) taken to measure integrated MyoPS and muscle damage (Z-band streaming and indirect parameters) before, and 24 h and 48 h post resistance exercise (post-RE) at T1, T2 and T3. Fibre cross-sectional area (fCSA) was evaluated using biopsies at T1, T2 and T3. Increases in fCSA were observed only at T3 (P = 0.017). Changes in MyoPS post-RE at T1, T2 and T3 were greater at T1 (P < 0.03) than at T2 and T3 (similar values between T2 and T3). Muscle damage was the highest during post-RE recovery at T1, attenuated at T2 and further attenuated at T3. The change in MyoPS post-RE at both T2 and T3, but not at T1, was strongly correlated (r ≈ 0.9, P < 0.04) with muscle hypertrophy. Initial MyoPS response post-RE in an RT programme is not directed to support muscle hypertrophy, coinciding with the greatest muscle damage. However, integrated MyoPS is quickly 'refined' by 3 weeks of RT, and is related to muscle hypertrophy. We conclude that muscle hypertrophy is the result of accumulated intermittent changes in MyoPS post-RE in RT, which coincides with progressive attenuation of muscle damage.

Effects of powdered Montmorency tart cherry supplementation on acute endurance exercise performance in aerobically trained individuals

BACKGROUND

The purpose of this study was to determine whether short-term supplementation of a powdered tart cherry supplement prior to and following stressful endurance exercise would affect markers of muscle damage, inflammation, oxidative stress, and/or muscle soreness.

METHODS

27 endurance-trained runners or triathlete (21.8 ± 3.9 years, 15.0 ± 6.0 % body fat, 67.4 ± 11.8 kg) men (n = 18) and women (n = 9) were matched based on average reported race pace, age, body mass, and fat free mass. Subjects were randomly assigned to ingest, in a double-blind manner, capsules containing 480 mg of a rice flour placebo (P, n = 16) or powdered tart cherries [CherryPURE®] (TC, n = 11). Subjects supplemented one time daily (480 mg/day) for 10-d, including race day, up to 48-hr post-run. Subjects completed a half-marathon run (21.1 km) under 2-hr (111.98 ± 11.9 min). Fasting blood samples and quadriceps muscle soreness ratings using an algometer with a graphic pain rating scale were taken pre-run, 60-min, 24 and 48-h post-run and analyzed by MANOVA with repeated measures.

RESULTS

Subjects in the TC group averaged 13 % faster half-marathon race finish times (p = 0.001) and tended to have smaller deviations from predicted race pace (p = 0.091) compared to P. Attenuations in TC muscle catabolic markers were reported over time for creatinine (p = 0.047), urea/blood urea nitrogen (p = 0.048), total protein (p = 0.081), and cortisol (p = 0.016) compared to P. Despite lower antioxidant activity pre-run in TC compared to P, changes from pre-run levels revealed a linear increase in antioxidant activity at 24 and 48-h of recovery in TC that was statistically different (16-39 %) from P and pre-run levels. Inflammatory markers were 47 % lower in TC compared to P over time (p = 0.053) coupled with a significant difference between groups (p = 0.017). Soreness perception between the groups was different over time in the medial quadriceps (p = 0.035) with 34 % lower pre-run soreness in TC compared to P. Over the 48-h recovery period, P changes in medial quadriceps soreness from pre-run measures were smaller compared to TC.

CONCLUSION

Results revealed that short-term supplementation of Montmorency powdered tart cherries surrounding an endurance challenge attenuated markers of muscle catabolism, reduced immune and inflammatory stress, better maintained redox balance, and increased performance in aerobically trained individuals.

Falls, physical limitations, confusion and memory problems in people with type II diabetes, undiagnosed diabetes and prediabetes, and the influence of vitamins A, D and E

AIMS

To examine the association between type II diabetes, prediabetes and undiagnosed diabetes with falls, physical limitations, confusion and memory problems, and to evaluate the effects of vitamins A, D and E levels on the associations.

METHODS

Data from 37,973 participants of the National Health and Nutrition Examination Survey was analyzed.

RESULTS

The participants' mean age was 46±17years, 20% had diabetes of which 17% were unaware of their condition (undiagnosed diabetes), and 21% had prediabetes. Diabetes was significantly associated with falls, difficulties in stooping, crouching, kneeling, completing house chores, getting in and out bed, standing and sitting for long periods, reaching over head, grasping, holding objects, and attending social events. The association between diabetes and confusion or memory problems was stronger for those diagnosed before age 40. Memory problems were reported only by people with diabetes with lower vitamin D levels. Vitamin A and E levels did not modify the association between diabetes and falls or any of the physical functions, confusion or memory problems. Prediabetes was only associated with difficulty standing for long periods.

CONCLUSIONS

Diabetes was associated with falls, difficulties in physical functioning and attending social events. Vitamin D levels modified the effects on confusion and memory problems.

Desensitized morphological and cytokine response after stretch-shortening muscle contractions as a feature of aging in rats

Recovery from contraction-induced injury is impaired with aging. At a young age, the secondary response several days following contraction-induced injury consists of edema, inflammatory cell infiltration, and segmental muscle fiber degeneration to aid in the clearance of damaged tissue and repair. This morphological response has not been wholly established at advanced age. Our aim was to characterize muscle fiber morphology 3 and 10 days following stretch-shortening contractions (SSCs) varying in repetition number (i.e. 0, 30, 80, and 150) for young and old rats. For muscles of young rats, muscle fiber degeneration was overt at 3 days exclusively after 80 or 150 SSCs and returned significantly closer to control values by 10 days. For muscles of old rats, no such responses were observed. Transcriptional microarray analysis at 3 days demonstrated that muscles of young rats differentially expressed up to 2144 genes while muscles of old rats differentially expressed 47 genes. Bioinformatic analysis indicated that cellular movement was a major biological process over-represented with genes that were significantly altered by SSCs especially for young rats. Protein levels in muscle for various cytokines and chemokines, key inflammatory factors for cell movement, increased 3- to 50-fold following high-repetition SSCs for young rats with no change for old rats. This age-related differential response was insightful given that for control (i.e. 0 SSCs) conditions, protein levels of circulatory cytokines/chemokines were increased with age. The results demonstrate ongoing systemic low-grade inflammatory signaling and subsequent desensitization of the cytokine/chemokine and morphological response to contraction-induced injury with aging - features which accompany age-related impairment in muscle recovery.

The effect of pulsating electrostatic field application on the development of delayed onset of muscle soreness (DOMS) symptoms after eccentric exercise

[Purpose] The aim of the study was to establish whether pulsating electrostatic field application, shown to increase blood flow and metabolic activity and to function as an ion pump, is able to reduce muscle pain after exercise-induced muscle damage. [Subjects and Methods] Seven participants (4 males, 3 females) performed two sessions of downhill running separated by at least 4 weeks. After the running sessions, participants were either treated for 45 min with a pulsating electrostatic field (field intensity, 9000 V; current, <9 mA; frequency, 50 Hz) or a sham treatment. The order of the intervention was random, and the condition was blinded for the participants. Muscle soreness score, creatine kinase, and jump ability were assessed before and up to 48 hours after running. [Results] Twenty-four and 48 hours after the downhill running, the muscle soreness score tended to be less increased after pulsating electrostatic field administration when compared with the sham setting (changes in muscle soreness score: 3.7±1.6 vs. 5.7±2.2 after 24 h and 3.1±2.0 vs. 5.4±3.2 after 48 h, respectively). No further differences were detected. [Conclusion] The outcomes show that a pulsating electrostatic field might be a promising treatment to reduce muscle soreness after exercise-induced muscle damage. However, further studies are needed to confirm the present outcomes and to establish the mechanism by which a pulsating electrostatic field may reduce muscle pain.

The effect of milk on the attenuation of exercise-induced muscle damage in males and females

PURPOSE

The consumption of 500 ml milk following muscle damaging exercise can attenuate decreases in muscle functional capacity and increases in markers of muscle damage and soreness in males. There has been no similar research in female participants. Therefore, the aim of this study was to investigate the effects of milk consumption on exercise-induced muscle damage (EIMD) in males and females.

METHODS

Thirty-two team sport players (male n = 16; female n = 16) were randomly, but equally divided into four groups: male milk, male carbohydrate, female milk, and female carbohydrate. Immediately following muscle damaging exercise, participants consumed either 500 ml of milk or 500 ml of an energy-matched carbohydrate solution. Skeletal troponin I (sTnI), creatine kinase (CK), peak torque, counter movement jump height, 20 m sprint performance and passive and active soreness were recorded prior to and 24, 48 and 72 h post-EIMD.

RESULTS

For females, milk had a likely/very likely beneficial effect on attenuating losses in peak torque at 60°/s from baseline to 24, 48 and 72 h, and a likely beneficial effect in minimising decrements in sprint performance and soreness over 72 h. Milk was unlikely to have a negative effect on serum markers of damage from baseline to 48 and 72 h. For males, milk had an unclear effect on muscle function variables. Milk had a most likely/likely beneficial effect on limiting muscle soreness from baseline to 72 h, and a possible beneficial effect on attenuating increases in CK. The effect on sTnI was unlikely to be negative from baseline-72 h. Overall gender comparisons provided many unclear outcomes. However, female participants demonstrated smaller increases in sprint time, passive soreness, active soreness (non-dominant leg) and sTnI values.

CONCLUSION

Consumption of 500 ml of milk post-EIMD can limit decrements in muscle function in females, and limit increases in soreness and serum markers of muscle damage in females and males.

Vitamin C and E supplementation alters protein signalling after a strength training session, but not muscle growth during 10 weeks of training

This study investigated the effects of vitamin C and E supplementation on acute responses and adaptations to strength training. Thirty-two recreationally strength-trained men and women were randomly allocated to receive a vitamin C and E supplement (1000 mg day(-1) and 235 mg day(-1), respectively), or a placebo, for 10 weeks. During this period the participants' training involved heavy-load resistance exercise four times per week. Muscle biopsies from m. vastus lateralis were collected, and 1 repetition maximum (1RM) and maximal isometric voluntary contraction force, body composition (dual-energy X-ray absorptiometry), and muscle cross-sectional area (magnetic resonance imaging) were measured before and after the intervention. Furthermore, the cellular responses to a single exercise session were assessed midway in the training period by measurements of muscle protein fractional synthetic rate and phosphorylation of several hypertrophic signalling proteins. Muscle biopsies were obtained from m. vastus lateralis twice before, and 100 and 150 min after, the exercise session (4 × 8RM, leg press and knee-extension). The supplementation did not affect the increase in muscle mass or the acute change in protein synthesis, but it hampered certain strength increases (biceps curl). Moreover, increased phosphorylation of p38 mitogen-activated protein kinase, Extracellular signal-regulated protein kinases 1 and 2 and p70S6 kinase after the exercise session was blunted by vitamin C and E supplementation. The total ubiquitination levels after the exercise session, however, were lower with vitamin C and E than placebo. We concluded that vitamin C and E supplementation interfered with the acute cellular response to heavy-load resistance exercise and demonstrated tentative long-term negative effects on adaptation to strength training.

Effects of Differing Dosages of Pomegranate Juice Supplementation after Eccentric Exercise

Dietary supplementation with pomegranate juice improves isometric strength recovery after unaccustomed eccentric exercise. The purpose of this study was to determine if there is a dose response effect of pomegranate juice supplementation after eccentric exercise isometric strength recovery. Forty-five nonresistance trained, recreationally active men were assigned once-daily pomegranate juice, twice-daily pomegranate juice, or placebo supplementation. On day four of supplementation, 20 min of downhill running and 40 maximal eccentric elbow flexion repetitions were performed. Isometric knee extensor and elbow flexor strength, muscular soreness, and serum myoglobin concentrations were measured prior to exercise and 2, 24, 48, 72, and 96 h after exercise. Throughout the postexercise time period, while isometric knee extensor and elbow flexor strength were similar between once-daily and twice-daily pomegranate juice supplementation groups, isometric strength was significantly higher in pomegranate juice groups than placebo. Knee extensor soreness, elbow flexor soreness, and myoglobin increased in response to exercise but were similar between groups. It is apparent that pomegranate juice supplementation improves strength recovery in leg and arm muscles following eccentric exercise; however, no dose response effect was present. We conclude that once-daily pomegranate juice supplementation is not different from twice-daily supplementation in regards to strength recovery after eccentric exercise.

Effects of vitamin E supplementation on exercise-induced oxidative stress: a meta-analysis

Tocopherols (commonly referred to as “vitamin E”) are frequently studied antioxidants in exercise research. However, the studies are highly heterogeneous, which has resulted in contradicting opinions. The aim of this review is to identify similar studies investigating the effects of tocopherol supplementation on exercise performance and oxidative stress and to perform minimally biased qualitative comparisons and meta-analysis. The literature search and study selection were performed according to Cochrane guidelines. A 2-dimensional study execution process was developed to enable selection of similar and comparable studies. Twenty relevant studies were identified. The high variability of study designs resulted in final selection of 6 maximally relevant studies. Markers of lipid peroxidation (malondialdehyde) and muscle damage (creatine kinase) were the 2 most frequently and similarly measured variables. Meta comparison showed that tocopherol supplementation did not result in significant protection against either exercise-induced lipid peroxidation or muscle damage. The complex antioxidant nature of tocopherols and low accumulation rates in muscle tissues could underlie an absence of protective effects.

Black Currant Nectar Reduces Muscle Damage and Inflammation Following a Bout of High-Intensity Eccentric Contractions

This investigation determined the efficacy of black currant nectar (BCN) in reducing symptoms of exercise-induced muscle damage (EIMD). Sixteen college students were randomly assigned to drink either 16 oz of BCN or a placebo (PLA) twice a day for eight consecutive days. A bout of eccentric knee extensions (3 × 10 sets @ 115% of 1RM) was performed on the fourth day. Outcome measures included muscle soreness (subjective scale from 0 to 10) and blood markers of muscle damage (creatine kinase, CK), inflammation (interleukin-6, IL-6), and oxygen radical absorbance capacity (ORAC). Although there were no differences in reported soreness between groups, consumption of BCN reduced CK levels at both 48 (PLA = 82.13% vs. BCN = -6.71%, p = .042) and 96 h post exercise (PLA = 74.96% vs. BCN = -12.11%, p = .030). The change in IL-6 was higher in the PLA group (PLA = 8.84% vs. BCN = -6.54%, p = .023) at 24 h post exercise. The change in ORAC levels was higher in the treatment group (BCN = 2.68% vs. PLA = -6.02%, p = .039) at 48 h post exercise. Our results demonstrate that consumption of BCN prior to and after a bout of eccentric exercise attenuates muscle damage and inflammation.

Vitamin E in sarcopenia: current evidences on its role in prevention and treatment

Sarcopenia is a geriatric syndrome that is characterized by gradual loss of muscle mass and strength with increasing age. Although the underlying mechanism is still unknown, the contribution of increased oxidative stress in advanced age has been recognized as one of the risk factors of sarcopenia. Thus, eliminating reactive oxygen species (ROS) can be a strategy to combat sarcopenia. In this review, we discuss the potential role of vitamin E in the prevention and treatment of sarcopenia. Vitamin E is a lipid soluble vitamin, with potent antioxidant properties and current evidence suggesting a role in the modulation of signaling pathways. Previous studies have shown its possible beneficial effects on aging and age-related diseases. Although there are evidences suggesting an association between vitamin E and muscle health, they are still inconclusive compared to other more extensively studied chronic diseases such as neurodegenerative diseases and cardiovascular diseases. Therefore, we reviewed the role of vitamin E and its potential protective mechanisms on muscle health based on previous and current in vitro and in vivo studies.

Dietary strategies to recover from exercise-induced muscle damage

Exhaustive or unaccustomed intense exercise can cause exercise-induced muscle damage (EIMD) and its undesirable consequences may decrease the ability to exercise and to adhere to a training programme. This review briefly summarises the muscle damage process, focusing predominantly on oxidative stress and inflammation as contributing factors, and describes how nutrition may be positively used to recover from EIMD. The combined intake of carbohydrates and proteins and the use of antioxidants and/or anti-inflammatory nutrients within physiological ranges are interventions that may assist the recovery process. Although the works studying food instead of nutritional supplements are very scarce, their results seem to indicate that food might be a favourable option as a recovery strategy. To date, the only tested foods were milk, cherries, blueberries and pomegranate with promising results. Other potential solutions are foods rich in protein, carbohydrates, antioxidants and/or anti-inflammatory nutrients.

Increased platelet oxidative metabolism, blood oxidative stress and neopterin levels after ultra-endurance exercise

The purpose of the present investigation was to identify muscle damage, inflammatory response and oxidative stress blood markers in athletes undertaking the ultra-endurance MultiSport Brazil race. Eleven well-trained male athletes (34.3 ± 3.1 years, 74.0 ± 7.6 kg; 172.2 ± 5.1 cm) participated in the study and performed the race, which consisted of about 90 km of alternating off-road running, mountain biking and kayaking. Twelve hours before and up to 15 minutes after the race a 10 mL blood sample was drawn in order to measure the following parameters: lactate dehydrogenase and creatine kinase activities, lipid peroxidation, catalase activity, protein carbonylation, respiratory chain complexes I, II and IV activities, oxygen consumption and neopterin concentrations. After the race, plasma lactate dehydrogenase and creatine kinase activities were significantly increased. Erythrocyte TBA-RS levels and plasma protein carbonylation were markedly augmented in post-race samples. Additionally, mitochondrial complex II activity and oxygen consumption in post-race platelet-rich plasma were also increased. These altered biochemical parameters were accompanied by increased plasma neopterin levels. The ultra-endurance event provoked systemic inflammation (increased neopterin) accompanied by marked oxidative stress, likely by increasing oxidative metabolism (increased oxidative mitochondrial function). This might be advantageous during prolonged exercise, mainly for efficient substrate oxidation at the mitochondrial level, even when tissue damage is induced.

Chronic alcohol ingestion delays skeletal muscle regeneration following injury

Background

Chronic alcohol ingestion may cause severe biochemical and pathophysiological derangements to skeletal muscle. Unfortunately, these alcohol-induced events may also prime skeletal muscle for worsened, delayed, or possibly incomplete repair following acute injury. As alcoholics may be at increased risk for skeletal muscle injury, our goals were to identify the effects of chronic alcohol ingestion on components of skeletal muscle regeneration. To accomplish this, age- and gender-matched C57Bl/6 mice were provided normal drinking water or water that contained 20% alcohol (v/v) for 18–20 wk. Subgroups of mice were injected with a 1.2% barium chloride (BaCl₂) solution into the tibialis anterior (TA) muscle to initiate degeneration and regeneration processes. Body weights and voluntary wheel running distances were recorded during the course of recovery. Muscles were harvested at 2, 7 or 14 days post-injection and assessed for markers of inflammation and oxidant stress, fiber cross-sectional areas, levels of growth and fibrotic factors, and fibrosis.

Results

Body weights of injured, alcohol-fed mice were reduced during the first week of recovery. These mice also ran significantly shorter distances over the two weeks following injury compared to uninjured, alcoholics. Injured TA muscles from alcohol-fed mice had increased TNFα and IL6 gene levels compared to controls 2 days after injury. Total protein oxidant stress and alterations to glutathione homeostasis were also evident at 7 and 14 days after injury. Ciliary neurotrophic factor (CNTF) induction was delayed in injured muscles from alcohol-fed mice which may explain, in part, why fiber cross-sectional area failed to normalize 14 days following injury. Gene levels of TGFβ₁ were induced early following injury before normalizing in muscle from alcohol-fed mice compared to controls. However, TGFβ₁ protein content was consistently elevated in injured muscle regardless of diet. Fibrosis was increased in injured, muscle from alcohol-fed mice at 7 and 14 days of recovery compared to injured controls.

Conclusions

Chronic alcohol ingestion appears to delay the normal regenerative response following significant skeletal muscle injury. This is evidenced by reduced cross-sectional areas of regenerated fibers, increased fibrosis, and altered temporal expression of well-described growth and fibrotic factors.

Polyphenols in exercise performance and prevention of exercise-induced muscle damage

Although moderate physical exercise is considered an essential component of a healthy lifestyle that leads the organism to adapt itself to different stresses, exercise, especially when exhaustive, is also known to induce oxidative stress, inflammation, and muscle damage. Many efforts have been carried out to identify dietary strategies or micronutrients able to prevent or at least attenuate the exercise-induced muscle damage and stress. Unfortunately most studies have failed to show protection, and at the present time data supporting the protective effect of micronutrients, as antioxidant vitamins, are weak and trivial. This review focuses on those polyphenols, present in the plant kingdom, that have been recently suggested to exert some positive effects on exercise-induced muscle damage and oxidative stress. In the last decade flavonoids as quercetin, catechins, and other polyphenols as resveratrol have caught the scientists attention. However, at the present time drawing a clear and definitive conclusion seems to be untimely.

Effects of taurine supplementation following eccentric exercise in young adults

The purpose of the present study was to investigate the effects of taurine supplementation on muscle performance, oxidative stress, and inflammation response after eccentric exercise (EE) in males. Twenty-one participants (mean age, 21 ± 6 years; weight, 78.2 ± 5 kg; height, 176 ± 7 cm) were selected and randomly divided into two groups: placebo (n = 10) and taurine (n = 11). Fourteen days after starting supplementation, subjects performed EE (3 sets until exhaustion, with EE of the elbow flexors on the Scott bench, 80% 1 repetition maximum (RM)). Blood samples were collected and muscle performance was measured on days 1, 14, 16, 18, and 21 after starting the supplements. Then, performance, muscle damage, oxidative stress, and inflammatory markers were analyzed. The taurine supplementation resulted in increased strength levels and thiol total content and decreased muscle soreness, lactate dehydrogenase level, creatine kinase activity, and oxidative damage (xylenol and protein carbonyl). Antioxidant enzymes (superoxide dismutase, catalase, and gluthatione peroxidase) and inflammatory markers (tumor necrosis factor, interleukin-1β (IL-1β), and interleukin-10 (IL-10)) were not altered during the recovery period compared with the placebo group. The results suggest that taurine supplementation represents an important factor in improving performance and decreasing muscle damage and oxidative stress but does not decrease the inflammatory response after EE.

Eccentric exercise increases satellite cell content in type II muscle fibers

INTRODUCTION

Satellite cells (SCs) are of key importance in skeletal muscle tissue growth, repair, and regeneration. A single bout of high-force eccentric exercise has been demonstrated to increase mixed muscle SC content after 1-7 d of postexercise recovery. However, little is known about fiber type-specific changes in SC content and their activation status within 24 h of postexercise recovery.

METHODS

Nine recreationally active young men (23 ± 1 yr) performed 300 eccentric actions of the knee extensors on an isokinetic dynamometer. Skeletal muscle biopsies from the vastus lateralis were collected preexercise and 24 h postexercise. Muscle fiber type-specific SC content and the number of activated SCs were determined by immunohistochemical analyses.

RESULTS

There was no difference between Type I and Type II muscle fiber SC content before exercise. SC content significantly increased 24 h postexercise in Type II muscle fibers (from 0.085 ± 0.012 to 0.133 ± 0.016 SCs per fiber, respectively; P < 0.05), whereas there was no change in Type I fibers. In accordance, activation status increased from preexercise to 24 h postexercise as demonstrated by the increase in the number of DLK1+ SCs in Type II muscle fibers (from 0.027 ± 0.008 to 0.070 ± 0.017 SCs per muscle fiber P < 0.05). Although no significant changes were observed in the number of Ki-67+ SCs, we did observe an increase in the number of proliferating cell nuclear antigen-positive SCs after 24 h of postexercise recovery.

CONCLUSION

A single bout of high-force eccentric exercise increases muscle fiber SC content and activation status in Type II but not Type I muscle fibers.

Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damage

Background

Exercise-induced muscle damage (EIMD) is accompanied by localized oxidative stress / inflammation which, in the short-term at least, is associated with impaired muscular performance. Dietary antioxidants have been shown to reduce excessive oxidative stress; however, their effectiveness in facilitating recovery following EIMD is not clear. Blueberries demonstrate antioxidant and anti-inflammatory properties. In this study we examine the effect of New Zealand blueberries on EIMD after strenuous eccentric exercise.

Methods

In a randomized cross-over design, 10 females consumed a blueberry smoothie or placebo of a similar antioxidant capacity 5 and 10 hours prior to and then immediately, 12 and 36 hours after EIMD induced by 300 strenuous eccentric contractions of the quadriceps. Absolute peak and average peak torque across the knee, during concentric, isometric, and eccentric actions were measured. Blood biomarkers of oxidative stress, antioxidant capacity, and inflammation were assessed at 12, 36 and 60 hours post exercise. Data were analyzed using a two-way ANOVA.

Results

A significant (p < 0.001) decrease in isometric, concentric and eccentric torque was observed 12 hours following exercise in both treatment groups. During the 60 hour recovery period, a significant (p = 0.047) interaction effect was seen for peak isometric tension suggesting a faster rate of recovery in the blueberry intervention group. A similar trend was observed for concentric and eccentric strength. An increase in oxidative stress and inflammatory biomarkers was also observed in both treatment groups following EIMD. Although a faster rate of decrease in oxidative stress was observed in the blueberry group, it was not significant (p < 0.05) until 36 hours post-exercise and interestingly coincided with a gradual increase in plasma antioxidant capacity, whereas biomarkers for inflammation were still elevated after 60 hours recovery.

Conclusions

This study demonstrates that the ingestion of a blueberry smoothie prior to and after EIMD accelerates recovery of muscle peak isometric strength. This effect, although independent of the beverage’s inherent antioxidant capacity, appears to involve an up-regulation of adaptive processes, i.e. endogenous antioxidant processes, activated by the combined actions of the eccentric exercise and blueberry consumption. These findings may benefit the sporting community who should consider dietary interventions that specifically target health and performance adaptation.

Low-frequency fatigue as an indicator of eccentric exercise-induced muscle injury: the role of vitamin E

This study investigates whether vitamin E can attenuate eccentric exercise-induced soleus muscle injury as indicated by the amelioration of in situ isometric force decline following a low-frequency fatigue protocol (stimulation at 4 Hz for 5 min) and the ability of the muscle to recover 3 min after the termination of the fatigue protocol. Adult male Wistar rats were divided into vitamin E-supplemented or placebo-supplemented groups studied at rest, immediately post-exercise or 48 h post-exercise. Daily dl-α-tocopheryl acetate intraperitoneal injections of 100 mg/kg body mass for 5 consecutive days prior to exercise doubled its plasma levels. Fatigue index and recovery index expressed as a percentage of the initial tension. FI at 0 h post- and 48 h post-exercise respectively was 88% ± 4.2% and 89% ± 6.8% in the vitamin E groups versus 76% ± 3% and 80% ± 11% in the placebo groups. RI was 99% ± 3.4% and 100% ± 6% in the vitamin E groups versus 82% ± 3.1% and 84% ± 5.9% in the placebo groups. Complementally to the traditionally recorded maximal force, low-frequency fatigue measures may be beneficial for assessing injury-induced decrease in muscle functionality.

Inhibition of caspase mediated apoptosis restores muscle function after crush injury in rat skeletal muscle

Although muscle regeneration after injury is accompanied by apoptotic cell death, prolonged apoptosis inhibits muscle restoration. The goal of our study was to provide evidence that inhibition of apoptosis improves muscle function following blunt skeletal muscle injury. Therefore, 24 rats were used for induction of injury to the left soleus muscle using an instrumented clamp. All animals received either 3.3 mg/kg i.p. of the pan-caspase inhibitor Z-valinyl-alanyl-DL: -aspartyl-fluoromethylketone (z-VAD.fmk) (n = 12 animals) or equivalent volumes of the vehicle solution DMSO (n = 12 animals) at 0 and 48 h after trauma. After assessment of the fast twitch and tetanic contraction capacity of the muscle at days 4 and 14 post injury, sampling of muscle tissue served for analysis of cell apoptosis (cleaved caspase 3 immunohistochemistry), cell proliferation (BrdU immunohistochemistry) as well as of muscle tissue area and myofiber diameter (HE planimetric analysis). Muscle strength analysis after 14 days in the z-VAD.fmk treated group revealed a significant increase in relative muscle strength when compared to the DMSO treated group. In contrast to the DMSO treated injured muscle, showing a transient switch towards a fast-twitching muscle phenotype (significant increase of the twitch-to-tetanic force ratio), z-VAD.fmk treated animals showed an enhanced healing process with a faster restoration of the twitch-to-tetanic force ratio towards the physiological slow-twitching muscle phenotype. This enhancement of muscle function was accompanied by a significant decrease of cell apoptosis and cell proliferation at day 4 as well as by a significant increase of muscle tissue area at day 4. At day 14 after injury z-VAD.fmk treated animals presented with a significant increase of myofiber diameter compared to the DMSO treated animals. Thus, z-VAD.fmk could provide a promising option in the anti-apoptotic therapy of muscle injury.

Exercise-induced muscle damage and inflammation: re-evaluation by proteomics

Using proteomics combined with immunohistochemistry (IHC), we re-evaluated our previous hypothesis that voluntary eccentric exercise does not result in inflammation or necrosis while it does lead to muscular adaptation/remodeling through Z-band related proteins. Muscle biopsies from m. vastus lateralis were taken from five control and five exercised subjects 48 h after 45 min of downhill running. General muscle morphology was examined using histology and histochemistry. Proteomics was used to reveal protein profiles and novel proteins. IHC with specific antibody against three Z-band related proteins identified by proteomics was also performed. General morphology showed no muscle degeneration or inflammation in any exercised biopsy. Proteomics revealed that out of 612 individual protein spots, the exercised biopsy presented three proteins with significant (p < 0.05) higher expression ratio and four proteins of lower ratio compared to controls. Four of the proteins desmin, actin, Rab-35 and LDB3 are Z-band related; the former two have long been the focus of interest and were found to be up-regulated in the study; the latter two are Z-band assembly/stabilization protein and were for the first time observed to be down-regulated in exercised muscles. The other three proteins are related with either cellular metabolism or calcium homeostasis and none is related with muscle necrosis or inflammation. IHC observations that both desmin and actin were increased whereas LDB3 was completely absent in some focal areas are consistent with proteomic results and with our previous observations. The results of the study confirmed our previous findings and therefore strengthened the hypothesis that voluntary eccentric exercise does not cause human muscle necrosis or inflammation; instead, muscular remodeling occurs specifically through Z-band related proteins.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Our systematic review has demonstrated that antioxidant supplements may increase mortality. We have now updated this review.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements for prevention of mortality in adults.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to February 2011. We scanned bibliographies of relevant publications and asked pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Random-effects and fixed-effect model meta-analyses were conducted. Risk of bias was considered in order to minimise the risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors. Random-effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Seventy-eight randomised trials with 296,707 participants were included. Fifty-six trials including 244,056 participants had low risk of bias. Twenty-six trials included 215,900 healthy participants. Fifty-two trials included 80,807 participants with various diseases in a stable phase. The mean age was 63 years (range 18 to 103 years). The mean proportion of women was 46%. Of the 78 trials, 46 used the parallel-group design, 30 the factorial design, and 2 the cross-over design. All antioxidants were administered orally, either alone or in combination with vitamins, minerals, or other interventions. The duration of supplementation varied from 28 days to 12 years (mean duration 3 years; median duration 2 years). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects model meta-analysis (21,484 dead/183,749 (11.7%) versus 11,479 dead/112,958 (10.2%); 78 trials, relative risk (RR) 1.02, 95% confidence interval (CI) 0.98 to 1.05) but significantly increased mortality in a fixed-effect model (RR 1.03, 95% CI 1.01 to 1.05). Heterogeneity was low with an I(2)- of 12%. In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. Meta-regression analysis did not find a significant difference in the estimated intervention effect in the primary prevention and the secondary prevention trials. In the 56 trials with a low risk of bias, the antioxidant supplements significantly increased mortality (18,833 dead/146,320 (12.9%) versus 10,320 dead/97,736 (10.6%); RR 1.04, 95% CI 1.01 to 1.07). This effect was confirmed by trial sequential analysis. Excluding factorial trials with potential confounding showed that 38 trials with low risk of bias demonstrated a significant increase in mortality (2822 dead/26,903 (10.5%) versus 2473 dead/26,052 (9.5%); RR 1.10, 95% CI 1.05 to 1.15). In trials with low risk of bias, beta-carotene (13,202 dead/96,003 (13.8%) versus 8556 dead/77,003 (11.1%); 26 trials, RR 1.05, 95% CI 1.01 to 1.09) and vitamin E (11,689 dead/97,523 (12.0%) versus 7561 dead/73,721 (10.3%); 46 trials, RR 1.03, 95% CI 1.00 to 1.05) significantly increased mortality, whereas vitamin A (3444 dead/24,596 (14.0%) versus 2249 dead/16,548 (13.6%); 12 trials, RR 1.07, 95% CI 0.97 to 1.18), vitamin C (3637 dead/36,659 (9.9%) versus 2717 dead/29,283 (9.3%); 29 trials, RR 1.02, 95% CI 0.98 to 1.07), and selenium (2670 dead/39,779 (6.7%) versus 1468 dead/22,961 (6.4%); 17 trials, RR 0.97, 95% CI 0.91 to 1.03) did not significantly affect mortality. In univariate meta-regression analysis, the dose of vitamin A was significantly associated with increased mortality (RR 1.0006, 95% CI 1.0002 to 1.001, P = 0.002).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.