Vitamin E supplementation decreases muscular and oxidative damage but not inflammatory response induced by eccentric contraction

Temporal tracking of cysteine 34 oxidation of plasma albumin as a biomarker of muscle damage following a bout of eccentric exercise

PURPOSE

Exercise-induced muscle damage (EIMD) results in the generation of reactive oxygen species (ROS), but little is known about the temporal profile of change in ROS post-EIMD and how ROS levels relate to the onset of and recovery from EIMD. Our primary aim was to examine the effect of EIMD on the pattern of change in the blood level of thiol-oxidised albumin, a marker of oxidative stress.

METHODS

Seven male participants were subjected on separate days to eccentric muscle contraction to cause EIMD or a no-exercise condition. After each session, the participants collected daily dried blood spots to measure thiol-oxidised albumin and returned to the laboratory every 2 days for the assessment of indirect markers of EIMD, namely maximal voluntary contraction (MVC), delayed onset muscle soreness (DOMS), creatine kinase (CK), and myoglobin.

RESULTS

Eccentric exercise resulted in a significant decrease in MVC and increase in DOMS, CK, myoglobin, and thiol-oxidised albumin with the latter reaching above baseline level within 24-48 h post-exercise. All the markers of EIMD returned to baseline level within 6 days post-exercise, but not the level of thiol-oxidised albumin which remained elevated for 10 days after exercise. There was a moderate correlation between changes in thiol-oxidised albumin and DOMS, but no significant relationship between any other markers of muscle damage.

CONCLUSION

The levels of thiol-oxidised albumin increase in response to EIMD and remain elevated for several days post-exercise. The temporal pattern of change in the level of thiol-oxidised albumin suggests that this may be a useful biomarker of muscle repair post-EIMD.

Effects of aerobic exercise during recovery from eccentric contraction on muscular performance, oxidative stress and inflammation

This study investigated the effects of aerobic exercise during recovery from eccentric contraction (EC) on muscular performance, oxidative stress, and inflammation. Nineteen male subjects between 18 and 29 years were divided into unexercised (control, n = 9) and exercised (n = 10) groups. Initially, the subjects performed EC as 3 sets until exhaustion with elbow flexion and extension on the Scott bench at 80% in 1RM, followed by four aerobic exercise sessions. The results obtained indicated (p > 0.05) that aerobic physical exercise during the recovery period does not improve muscle performance (isometric strength and muscular fatigue), oxidative stress parameters (lipid peroxidation, protein oxidation and antioxidant enzyme activity), and inflammatory cytokines (IL-1β, TNF-α, IL-10). In conclusion, the aerobic exercise during the recovery period does not alter the parameters of performance, oxidative stress and inflammation induced by the EC.

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.

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.

Can Low-Dose of Dietary Vitamin E Supplementation Reduce Exercise-Induced Muscle Damage and Oxidative Stress? A Meta-Analysis of Randomized Controlled Trials

Vitamin E plays an important role in attenuating muscle damage caused by oxidative stress and inflammation. Despites of beneficial effects from antioxidant supplementation, effects of antioxidants on exercise-induced muscle damage are still unclear. The aim of this meta-analysis was to investigate the effects of dietary vitamin E supplementation on exercise-induced muscle damage, oxidative stress, and inflammation in randomized controlled trials (RCTs). The literature search was conducted through PubMed, Medline, Science Direct, Scopus, SPORTDiscuss, EBSCO, Google Scholar database up to February 2022. A total of 44 RCTs were selected, quality was assessed according to the Cochrane collaboration risk of bias tool (CCRBT), and they were analyzed by Revman 5.3. Dietary vitamin E supplementation had a protective effect on muscle damage represented by creatine kinase (CK; SMD −1.00, 95% CI: −1.95, −0.06) and lactate dehydrogenase (SMD −1.80, 95% CI: −3.21, −0.39). Muscle damage was more reduced when CK was measured immediately after exercise (SMD −1.89, 95% CI: −3.39, −0.39) and subjects were athletes (SMD −5.15, 95% CI: −9.92, −0.39). Especially vitamin E supplementation lower than 500 IU had more beneficial effects on exercise-induced muscle damage as measured by CK (SMD −1.94, 95% CI: −2.99, −0.89). In conclusion, dietary vitamin E supplementation lower than 500 IU could prevent exercise-induced muscle damage and had greater impact on athletes

Effects of hydrogen-rich water and ascorbic acid treatment on spontaneously hypertensive rats

Hydrogen-rich water (HW) has been suggested to possess antioxidant properties of value in treatments of lifestyle diseases and for prevention of latent pathologies. To date, the potential benefits of HW against the deleterious effects of excessive salt intake and hypertension have not been investigated. Here, we first examined the effects of HW or HW supplemented with 0.1% ascorbic acid (HWA) on spontaneously hypertensive rats (SHR) that had been fed a normal diet. In comparison to control rats given distilled water (DW), we found that HW did not significantly influence systolic blood pressure (SBP) or diastolic blood pressure (DBP) in SHR; however, the increase in SBP and DBP were inhibited in the HWA group. Next, four groups of SHR were given DW, 0.1% ascorbic acid-added DW (DWA), HW, or HWA in combination with a 4% NaCl-added diet. SHR fed the 4% NaCl-added diet showed increased hypertension; HWA treatment resulted in a significant reduction in blood pressure. The HWA group tended to have lower plasma angiotensin II levels than the DW group. In addition, urinary volumes and urinary sodium levels were significantly lower in the HWA group than the DW group. Urinary isoprostane, an oxidative stress marker, was also significantly lower in the HWA group, suggesting that the inhibitory effect of HWA on blood pressure elevation was caused by a reduction in oxidative stress. These findings suggest a synergistic interaction between HW and ascorbic acid, and also suggest that HWA ingestion has potential for prevention of hypertension.

Key points for the development of antioxidant cocktails to prevent cellular stress and damage caused by reactive oxygen species (ROS) during manned space missions

Exposure to microgravity and ionizing radiation during spaceflight missions causes excessive reactive oxygen species (ROS) production that contributes to cellular stress and damage in astronauts. Average spaceflight mission time is expected to lengthen as humanity aims to visit other planets. However, longer missions or spaceflights will undoubtedly lead to an increment in microgravity, ionizing radiation and ROS production. Strategies to minimize ROS damage are necessary to maintain the health of astronauts, future space colonists, and tourists during and after spaceflight missions. An antioxidant cocktail formulated to prevent or mitigate ROS damage during space exploration could help maintain the health of space explorers. We propose key points to consider when developing an antioxidant cocktail. We discuss how ROS damages our body and organs, the genetic predisposition of astronauts to its damage, characteristics and evidence of the effectiveness of antioxidants to combat excess ROS, differences in drug metabolism when on Earth and in space that could modify antioxidant effects, and the characteristics and efficacy of common antioxidants. Based on this information we propose a workflow for assessing astronaut resistance to ROS damage, infight monitoring of ROS production, and an antioxidant cocktail. Developing an antioxidant cocktail represents a big challenge to translate current medical practices from an Earth setting to space. The key points presented in this review could promote the development of different antioxidant formulations to maintain space explorers' health in the future.

Effect of taurine associated gold nanoparticles on oxidative stress in muscle of mice exposed to overuse model

Muscle overuse and its consequent muscle damage has no cure. Therefore, the present study aimed to investigate the regulatory role of tau-AuNPs on muscle recovery of muscle overuse model. The animals (Male Swiss mice) were randomly divided into four groups: Control (Ctr; n=6); tau-AuNPs (n=6); overuse (n=6); and overuse plus tau-AuNPs (n=6). Exercise sessions were performed for 21 consecutive days, and one exercise model was applied daily in the following sequence: low intensity, moderate intensity, and high intensity. The mice were then sacrificed. The quadriceps muscles were surgically removed for subsequent biochemical analysis (oxidative stress parameters, DNA damage markers and muscle differentiation protein). The overuse group significantly increased the oxidative stress parameters and DNA damage markers, whereas tau-AuNPs significantly decreased the oxidative stress parameters in the overuse animal model. However, there were no significant differences observed between overuse group and overuse plus tau-AuNPs administrated group in relation to DNA damage markers including DNA damage frequency and index levels when compared to control and tau-AuNPs groups. Muscle differentiation protein Myf-5 was increased in the overuse plus tau-AuNPs administration group when compared to control group. In conclusion, tau-AuNPs had significant effect on reducing oxidative stress parameters and increasing myogenic regulatory protein Myf-5 in the overuse group. However, it did not have significant effect on reducing DNA damage.

The lack of association between dietary antioxidant quality score with handgrip strength and handgrip endurance amongst Tehranian adults: A cross-sectional study from a Middle East country

OBJECTIVE

The association between dietary antioxidant quality score (DAQS) and handgrip strength (HS) and handgrip endurance (HE) is still unclear. We aimed to investigate whether adherence to dietary antioxidant quality score (DAQS) is associated with handgrip strength (HS) and handgrip endurance (HE) amongst adults in Tehran.

METHODS

This cross-sectional study was conducted on 270 (43.7% males, mean age 37 years and 56.3% females, mean age 35 years) apparently healthy adult subjects (53.2% were married) selected from different parts of Tehran, Iran. Dietary intake was assessed using a 168-item validated food frequency questionnaire. DAQS was calculated using antioxidant-nutrient intake. Body composition was measured using a body composition analyser. Handgrip strength and endurance were measured by a digital handgrip dynamometer. Relative muscle strength was expressed as the ratio of handgrip strength by body mass index (BMI).

RESULTS

The results showed that DAQs had no significant association with HS (P = .67, adjusted R²  = .60) and HE (P = .19, adjusted R²  = .08) after adjusting for potential confounders. However, a significant positive association was found between selenium intake and HE even after adjusting for potential confounders (P = .01, adjusted R²  = .10). After controlling for potential confounders no differences in the mean of HS (P = .29) and also HE (P = .61) amongst tertiles of DAQS was found. Positive linear association was found between vitamin C (P = .02, adjusted R²  = .53) and vitamin E (P = .03, adjusted R²  = .55) intake with relative muscle strength.

CONCLUSION

Our results revealed that no significant association between DAQS and HE and HS. It was found that more intake of selenium was positively linked to HE. Dietary intake of vitamin C and vitamin E are associated with higher relative muscle strength. It is evident that more prospective studies are needed to confirm the veracity of our results.

Supplementation with Vitamins C and E and Exercise-Induced Delayed-Onset Muscle Soreness: A Systematic Review

Muscle damage induced by exercise may have several consequences such as delayed-onset muscle soreness, a side-effect of the release of free radicals during oxidative stress. To mitigate the oxidative stress cascade, the oral intake of antioxidants has been assessed by several research groups. This review examines whether supplementation with vitamin C and/or vitamin E is able to prevent or attenuate delayed-onset muscle soreness after eccentric exercise. The PubMed, Web of Science, Medline, and Embase databases were searched to identify studies meeting the inclusion criteria: primary randomized control trials, healthy male and female participants aged 16–80 years, and an intervention consisting of the intake of vitamin C and/or vitamin E without other supplements plus a controlled eccentric exercise regimen. Further requirements were the measurement of muscle soreness or markers of delayed-onset muscle soreness. All original full-text articles in English or translated into English published from January 2000 to June 2020 were considered for this review. Fourteen studies were finally identified, including 280 participants, 230 men, and 50 women aged 16–30 years. All participants were healthy individuals with different starting levels of physical activity. Supplementation was acute in two studies and chronic in 12, and its consisted of vitamin C in eight studies, vitamin E in two studies, and both in four studies. Only in 3 of the 14 studies was muscle soreness found to be significantly reduced in response to vitamin C and/or vitamin E supplementation at all time points when compared to the placebo group. Despite some studies showing the beneficial effects of chronic supplementation with these vitamins on muscle soreness manifesting 24–72 h after eccentric exercise, the evidence is so far insufficient to confirm that the intake of antioxidant vitamins is able to minimize delayed-onset muscle soreness in this context.

Antioxidants and Exercise Performance: With a Focus on Vitamin E and C Supplementation

Antioxidant supplementation, including vitamin E and C supplementation, has recently received recognition among athletes as a possible method for enhancing athletic performance. Increased oxidative stress during exercise results in the production of free radicals, which leads to muscle damage, fatigue, and impaired performance. Despite their negative effects on performance, free radicals may act as signaling molecules enhancing protection against greater physical stress. Current evidence suggests that antioxidant supplementation may impair these adaptations. Apart from athletes training at altitude and those looking for an immediate, short-term performance enhancement, supplementation with vitamin E does not appear to be beneficial. Moreover, the effectiveness of vitamin E and C alone and/or combined on muscle mass and strength have been inconsistent. Given that antioxidant supplements (e.g., vitamin E and C) tend to block anabolic signaling pathways, and thus, impair adaptations to resistance training, special caution should be taken with these supplements. It is recommended that athletes consume a diet rich in fruits and vegetables, which provides vitamins, minerals phytochemicals, and other bioactive compounds to meet the recommended intakes of vitamin E and C.

The effect of vitamin E supplementation on selected inflammatory biomarkers in adults: a systematic review and meta-analysis of randomized clinical trials

The previous meta-analysis of clinical trials revealed a beneficial effect of vitamin E supplementation on serum C-reactive protein (CRP) concentrations; however, it is unknown whether this vitamin has the same influence on other inflammatory biomarkers. Also, several clinical trials have been published since the release of earlier meta-analysis. Therefore, we aimed to conduct a comprehensive meta-analysis to summarize current evidence on the effects of vitamin E supplementation on inflammatory biomarkers in adults. We searched the online databases using relevant keywords up to November 2019. Randomized clinical trials (RCTs) investigating the effect of vitamin E, compared with the placebo, on serum concentrations of inflammatory cytokines were included. Overall, we included 33 trials with a total sample size of 2102 individuals, aged from 20 to 70 years. Based on 36 effect sizes from 26 RCTs on serum concentrations of CRP, we found a significant reduction following supplementation with vitamin E (− 0.52, 95% CI − 0.80, − 0.23 mg/L, P < 0.001). Although the overall effect of vitamin E supplementation on serum concentrations of interleukin-6 (IL-6) was not significant, a significant reduction in this cytokine was seen in studies that used α-tocopherol and those trials that included patients with disorders related to insulin resistance. Moreover, we found a significant reducing effect of vitamin E supplementation on tumor necrosis factor-α (TNF-α) concentrations at high dosages of vitamin E; such that based on dose–response analysis, serum TNF-α concentrations were reduced significantly at the dosages of ≥ 700 mg/day vitamin E (P_{non-linearity} = 0.001). Considering different chemical forms of vitamin E, α-tocopherol, unlike other forms, had a reducing effect on serum levels of CRP and IL-6. In conclusion, our findings revealed a beneficial effect of vitamin E supplementation, particularly in the form of α-tocopherol, on subclinical inflammation in adults. Future high-quality RCTs should be conducted to translate this anti-inflammatory effect of vitamin E to the clinical setting.

Vitamins C and E Associated With Cryotherapy in the Recovery of the Inflammatory Response After Resistance Exercise: A Randomized Clinical Trial

de Brito, E, Teixeira, AdO, Righi, NC, Paulitcth, FdS, da Silva, AMV, and Signori, LU. Vitamins C and E associated with cryotherapy in the recovery of the inflammatory response after resistance exercise: A randomized clinical trial. J Strength Cond Res XX(X): 000-000, 2019-The objective of this research was to compare the effects of cryotherapy associated with vitamins (C and E) on the recovery of the inflammatory response from the resistance exercise (RE) session of untrained volunteers. Fourteen subjects (26.2 ± 5 years old, 25.8 ± 3 kg·m) underwent 4 sessions of RE with different forms of recovery. The RE consisted of 4 sets of 10 maximal repetitions for each exercise (extensor bench, squat, and leg press). The recoveries were randomized and comprised the passive (control), with vitamins C (1 g) and E (800 UI) supplementation 40 minutes before exercise, with cryotherapy (immersion in water 15° C for 10 minutes), and the association (vitamins and cryotherapy). Hemogram, inflammatory markers (C-reactive protein and creatine kinase [CK]), and parameters of oxidative stress (lipid peroxidation [LPO] and antioxidant capacity against radical peroxyl) were evaluated before (baseline) and after (0, 30, and 120 minutes) the RE sessions. Muscle pain (primary outcome) was evaluated 24 hours after exercise. C-reactive protein (p = 0.010) and LPO (p < 0.001) increased (120 minutes) only in passive recovery. Recovery with cryotherapy (30 minutes), with vitamins and the association (0 and 30 minutes) delayed increases in CK (p < 0.001). Antioxidant capacity against radical peroxyl increased (30 minutes) only in recovery with the association (p < 0.011). The pain decreased in the recoveries with cryotherapy and association (p < 0.001). The association of vitamins (C and E) with cryotherapy attenuated the inflammatory response and pain, favoring recovery after an acute RE session.

EFFECT OF AQUATIC EXERCISE AFTER ECCENTRIC CONTRACTION-INDUCED MUSCLE INJURY

ABSTRACT Introduction: Muscle microlesions produced by eccentric contractions (EC) cause changes in strength, endurance, power and neuromuscular activity parameters for an extended period of time. Objectives: To investigate the effect of aquatic exercise after EC-induced muscle injury on strength, endurance, power and neuromuscular activity parameters. Methods: A cross-sectional experimental study with six subjects (age 25 ± 4 years, weight 77 ± 4kg and height of 162 ± 2 cm) with EC-induced muscle injury followed up during a recovery period (48h, 72h and 96h) without intervention (Group 1A) and involving aquatic exercises (Group 1B). Dynamic and isometric strength, muscular endurance, and vertical/horizontal power tests as well as vastus lateralis neuromuscular activity measurements were performed before, immediately after, and during the recovery period. Results: Our results indicate that the intervention in Group 1B, when compared to Group 1A, accelerated the recovery of dynamic (p <0.01) and isometric (p <0.03) strength at 48h and 72h, increased vertical power at 48h (p <0.05) and horizontal power at 48h and 72h (p <0.05), and reduced neuromuscular activity (p <0.05) at 48h and 72h after EC. Conclusions: According to our findings, performing aquatic exercises during the recovery period improves muscle efficiency and accelerates strength, power and neuromuscular activity recovery. Level of evidence l; Randomized clinical trial.

S-allyl cysteine: A potential compound against skeletal muscle atrophy

BACKGROUND

Oxidative stress is crucial player in skeletal muscle atrophy pathogenesis. S-allyl cysteine (SAC), an organosulfur compound of Allium sativum, possesses broad-spectrum properties including immuno- and redox-modulatory impact. Considering the role of SAC in regulating redox balance, we hypothesize that SAC may have a protective role in oxidative-stress induced atrophy.

METHODS

C2C12 myotubes were treated with H₂O₂ (100 μM) in the presence or absence of SAC (200 μM) to study morphology, redox status, inflammatory cytokines and proteolytic systems using fluorescence microscopy, biochemical analysis, real-time PCR and immunoblotting approaches. The anti-atrophic potential of SAC was confirmed in denervation-induced atrophy model.

RESULTS

SAC pre-incubation (4 h) could protect the myotube morphology (i.e. length/diameter/fusion index) from atrophic effects of H₂O₂. Lower levels of ROS, lipid peroxidation, oxidized glutathione and altered antioxidant enzymes were observed in H₂O₂-exposed cells upon pre-treatment with SAC. SAC supplementation also suppressed the rise in cytokines levels (TWEAK/IL6/myostatin) caused by H₂O₂. SAC treatment also moderated the degradation of muscle-specific proteins (MHCf) in the H₂O₂-treated myotubes supported by lower induction of diverse proteolytic systems (i.e. cathepsin, calpain, ubiquitin-proteasome E3-ligases, caspase-3, autophagy). Denervation-induced atrophy in mice illustrates that SAC administration alleviates the negative effects (i.e. mass loss, decreased cross-sectional area, up-regulation of proteolytic systems, and degradation of total/specific protein) of denervation on muscles.

CONCLUSIONS

SAC exerts significant anti-atrophic effects to protect myotubes from H₂O₂-induced protein loss and myofibers from denervation-induced muscle loss, due to the prevention of elevated proteolytic systems and inflammatory/oxidative molecules.

GENERAL SIGNIFICANCE

The results signify the potential of SAC against muscle atrophy.

Phytoplankton Supplementation Lowers Muscle Damage and Sustains Performance across Repeated Exercise Bouts in Humans and Improves Antioxidant Capacity in a Mechanistic Animal

The purpose of this study was to investigate the impact of antioxidant-rich marine phytoplankton supplementation (Oceanix, OCX) on performance and muscle damage following a cross-training event in endurance-trained subjects. Additionally, an animal model was carried out to assess the effects of varying dosages of OCX, with exercise, on intramuscular antioxidant capacity.

METHODS

In the human trial, endurance-trained subjects (average running distance = 29.5 ± 2.6 miles × week^-1) were randomly divided into placebo (PLA) and OCX (25 mg) conditions for 14 days. The subjects were pre-tested on a one-mile uphill run, maximal isometric strength, countermovement jump (CMJ) and squat jump (SJ) power, and for muscle damage (creatine kinase (CK)). On Day 12, the subjects underwent a strenuous cross-training event. Measures were reassessed on Day 13 and 14 (24 h and 48 h Post event). In the animal model, Wistar rats were divided into four groups (n = 7): (i) Control (no exercise and placebo (CON)), (ii) Exercise (E), (iii) Exercise + OCX 1 (Oceanix, 2.55 mg/day, (iv) Exercise + OCX 2 (5.1 mg/day). The rats performed treadmill exercise five days a week for 6 weeks. Intramuscular antioxidant capacity (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px)) and muscle damage (CK and myoglobin (MYOB) were collected. The data were analyzed using repeated measures ANOVA and t-test for select variables. The alpha value was set at p < 0.05.

RESULTS

For the human trial, SJ power lowered in PLA relative to OCX at 24 h Post (-15%, p < 0.05). Decrements in isometric strength from Pre to 48 h Post were greater in the PLA group (-12%, p < 0.05) than in the OCX. Serum CK levels were greater in the PLA compared to the OCX (+14%, p < 0.05). For the animal trial, the intramuscular antioxidant capacity was increased in a general dose-dependent manner (E + Oc2 > E + Oc1 > E > CON). Additionally, CK and MYOB were lower in supplemented compared to E alone.

CONCLUSIONS

Phytoplankton supplementation (Oceanix) sustains performance and lowers muscle damage across repeated exercise bouts. The ingredient appears to operate through an elevating oxidative capacity in skeletal muscle.

Nutritional strategies for maintaining muscle mass and strength from middle age to later life: A narrative review

Progressive age-related reductions in muscle mass and strength (sarcopenia) can cause substantial morbidity. This narrative review summarizes evidence of nutritional interventions for maintaining muscle mass and strength from midlife through old age. PubMed and Cochrane databases were searched to identify studies of dietary intake and nutritional interventions for sustaining muscle mass and strength. The benefits of progressive resistance training with and without dietary interventions are well documented. Protein and amino acid (particularly leucine) intake should be considered, and supplementation may be warranted for those not meeting recommended intakes. Vitamin D receptors are expressed in muscle tissue; meta-analyses have shown that vitamin D benefits muscle strength. Data suggest that milk and other dairy products containing different bioactive compounds (i.e. protein, leucine) can enhance muscle protein synthesis, particularly when combined with resistance exercise. Omega-3 s can improve muscle mass and strength by mediating cell signaling and inflammation-related oxidative damage; no studies were specifically conducted in sarcopenia. Low-dose antioxidants (e.g. vitamins C and E) can protect muscle tissue from oxidative damage, but relevant studies are limited. Magnesium is involved with muscle contraction processes, and data have shown benefits to muscle strength. Acidogenic diets increase muscle protein breakdown, which is exacerbated by aging. Alkalizing compounds (e.g. bicarbonates) can promote muscle strength. Small studies of probiotics and plant extracts have generated interest, but few large studies have been conducted. Based on available data, dietary and supplemental interventions may add to the benefits of exercise on muscle mass and strength; effects independent of exercise have not been consistently shown.

Effect of regional muscle damage and inflammation following eccentric exercise on electrical resistance and the body composition assessment using bioimpedance spectroscopy

We investigated the effect of muscle damage and inflammation on electrical resistance and the body composition assessment by using bioimpedance spectroscopy (BIS). Twenty-two subjects completed 30 repetitions of maximal eccentric contractions of the elbow flexors with one arm. Whole-body resistance of extracellular and intracellular components (Re and Ri, respectively) on the exercised and non-exercised sides were measured using BIS. Body composition was calculated from both sides of resistance at baseline and 96 h after exercise. Re decreased only on the exercised side at 96 h after exercise (P < 0.05). Fat-free and fat mass values estimated from resistance on the exercised side were altered by 3.1% and - 15.6%, respectively, at 96 h after exercise (P < 0.05); those estimated from the non-exercised side were unaltered. Eccentric exercise-induced muscle damage and inflammation reduce Re and induce non-negligible estimation error in the body composition assessment using BIS.

α-Tocopherol Protects the Heart, Muscles, and Testes from Lipid Peroxidation in Growing Male Rats Subjected to Physical Efforts

The effect of α-tocopherol supplementation on adaptation to training is still equivocal. The aim of the study was to determine the effect of training and α-tocopherol supplementation on α-tocopherol and thiobarbituric acid reactive substance (TBARS) concentration in the rat liver, heart, muscles, and testes. Male Wistar rats (n = 32) were divided into four groups (nonsupplemented, not trained—C; nonsupplemented, trained—CT; supplemented, not trained—E; supplemented and trained—ET). During the 14-day experimental period, 2 mg/d of vitamin E as α-tocopherol acetate was administered to the animals (groups E and ET). Rats in the training group (CT and ET) were subjected to 15 minutes of treadmill running each day. The α-tocopherol levels in rat tissues were assessed using high-performance liquid chromatography (HPLC). Lipid peroxides were determined by TBARS spectrophotometric method. α-Tocopherol had a significant impact on α-tocopherol concentration in all tissues. Training increased the α-tocopherol concentration in the heart and muscles but reduced it in the liver. Training also caused increased lipid peroxidation in the muscles, heart, and testes; but a higher α-tocopherol content in tissues reduced the TBARS level. The main finding of the study is that impaired α-tocopherol status and its adequate intake is needed to maintain optimal status to prevent damage to the skeletal and cardiac muscles as well as the testes in growing individuals.

Irreversible plasma and muscle protein oxidation and physical exercise

The imbalance between the reactive oxygen (ROS) and nitrogen (RNS) species production and their handling by the antioxidant machinery (low molecular weight antioxidant molecules and antioxidant enzymes), also known as oxidative stress, is a condition caused by physiological and pathological processes. Moreover, oxidative stress may be due to an overproduction of free radicals during physical exercise. Excess of radical species leads to the modification of molecules, such as proteins - the most susceptible to oxidative modification - lipids and DNA. With regard to the oxidation of proteins, carbonylation is an oxidative modification that has been widely described. Several studies have detected changes in the total amount of protein carbonyls following different types of physical exercise, but only few of these identified the specific amino acidic residues targets of such oxidation. In this respect, proteomic approaches allow to identify the proteins susceptible to carbonylation and in many cases, it is also possible to identify the specific protein carbonylation sites. This review focuses on the role of protein oxidation, and specifically carbonyl formation, for plasma and skeletal muscle proteins, following different types of physical exercise performed at different intensities. Furthermore, we focused on the proteomic strategies used to identify the specific protein targets of carbonylation. Overall, our analysis suggests that regular physical activity promotes a protection against protein carbonylation, due to the activation of the antioxidant defence or of the turnover of protein carbonyls. However, we can conclude that from the comprehensive bibliography analysed, there is no clearly defined specific physiological role about this post-translational modification of proteins.

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.

Modulatory effects of taurine on metabolic and oxidative stress parameters in a mice model of muscle overuse

OBJECTIVE

The aim of this study was to investigate the regulatory effects of taurine on the biochemical parameters of muscle injury by overuse.

METHODS

Male Swiss mice were divided into four groups: control (Ctrl), overuse (Ov), taurine (Tau), and overuse plus taurine (OvTau). High-intensity exercise sessions were administered for 21 d with concomitant subcutaneous injections of taurine (150 mg/kg). The mice were then sacrificed. The quadriceps muscles were surgically removed for subsequent histologic analysis and evaluation of mitochondrial function, oxidative stress parameters, tissue repair, and DNA damage markers.

RESULTS

The Ov group showed significant differences compared with the Ctrl group (all P <0.05). The fiber area decreased by 49.34%, whereas the centralized nuclei contents (Ctrl = 1.33%; Ov = 28.67%), membrane potential (Ctrl_suc = 179.05 arbitrary fluorescence units (AFUs), Ctrl_suc+ADP = 198.11 AFUs; Ov_suc = 482.95 AFUs, Ov_suc+ADP = 461.6 AFUs), complex I activity (Ctrl = 20.45 nmol ⋅ min ⋅ mg protein, Ov = 45.25 nmol ⋅ min ⋅ mg protein), hydrogen peroxide (Ctrl_suc = 1.08 relative fluorescence unit (RFU) ⋅ sec ⋅ mg protein, Ctrl_suc+ADP = 0.23 RFU ⋅ sec ⋅ mg protein; Ov_suc = 5.02 RFU ⋅ sec ⋅ mg protein, Ov_suc+ADP = 0.26 RFU ⋅ sec ⋅ mg protein) and malondialdehyde (Ctrl = 0.03 nmol ⋅ mg ⋅ protein, Ov = 0.06 nmol ⋅ mg ⋅ protein) levels, and DNA damage (Ctrl_freq = 7.17%, Ov_freq = 31.17%; Ctrl_index = 4.17, Ov_index = 72.5) were increased. Taurine administration reduced the number of centralized nuclei (OvTau = 5%), hydrogen peroxide levels (OvTau_suc = 2.81 RFU ⋅ sec ⋅ mg protein, OvTaus_suc+ADP = 1.54 RFU ⋅ sec ⋅ mg protein), membrane potential (OvTau_suc = 220.18 AFUs, OvTaus_suc+ADP = 235.28 AFUs), lipid peroxidation (OvTau = 0.02 nmol/mg protein), and DNA damage (OvTau_freq = 21.33%, OvTau_index = 47.83) and increased the fiber area by 54% (all P <0.05).

CONCLUSION

Taken together, these data suggest that taurine supplementation modulates various cellular remodeling parameters after overuse-induced muscle damage, and that these positive effects may be related to its antioxidant capacity.

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.

Different training responses to eccentric endurance exercise at low and moderate altitudes in pre-diabetic men: a pilot study

This pilot study aimed (a) to evaluate the effects of eccentric exercise training at low and moderate altitudes on physical fitness in pre-diabetic men and (b) to establish whether or not oxidative stress levels and antioxidant status were associated with performance improvements. In this crossover trial, five pre-diabetic men conducted nine downhill walking sessions (3 days/week, 3 consecutive weeks) at low altitude (from 1360 to 850 m) and one year later at moderate altitude (from 2447 to 2000 m). Exercise testing and the determination of parameters of oxidative stress and antioxidant capacity were performed pre- and post-training. The biological antioxidant activity of plasma (BAP) increased after eccentric training at moderate altitude (p < 0.001), whereas diacron reactive oxygen metabolites (dROMs) remained unchanged. Also, the BAP/dROMs ratio increased only after training at moderate-altitude training (p = 0.009). Maximum power output improved after training at low altitude and the changes were significantly related to baseline BAP/dROMs ratio (r = 0.90). No decrease was seen for fasting plasma glucose. Eccentric exercise training in pre-diabetic men improved performance only when performed at low altitude and this improvement was positively related to the baseline BAP/dROMs ratio. In contrast, 3 weeks of eccentric exercise training increased BAP levels and the BAP/dROMs ratio only at moderate altitude without improving the performance. Thus, one might speculate that the BAP/dROMs ratio has to increase before performance improvements occur at moderate altitude.

Redox Mechanism of Reactive Oxygen Species in Exercise

It is well known that regular exercise can benefit health by enhancing antioxidant defenses in the body. However, unaccustomed and/or exhaustive exercise can generate excessive reactive oxygen species (ROS), leading to oxidative stress-related tissue damages and impaired muscle contractility. ROS are produced in both aerobic and anaerobic exercise. Mitochondria, NADPH oxidases and xanthine oxidases have all been identified as potential contributors to ROS production, yet the exact redox mechanisms underlying exercise-induced oxidative stress remain elusive. Interestingly, moderate exposure to ROS is necessary to induce body's adaptive responses such as the activation of antioxidant defense mechanisms. Dietary antioxidant manipulation can also reduce ROS levels and muscle fatigue, as well as enhance exercise recovery. To elucidate the complex role of ROS in exercise, this review updates on new findings of ROS origins within skeletal muscles associated with various types of exercises such as endurance, sprint and mountain climbing. In addition, we will examine the corresponding antioxidant defense systems as well as dietary manipulation against damages caused by ROS.

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

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

The antioxidant requirement for plasma membrane repair in skeletal muscle

Vitamin E (VE) deficiency results in pronounced muscle weakness and atrophy but the cell biological mechanism of the pathology is unknown. We previously showed that VE supplementation promotes membrane repair in cultured cells and that oxidants potently inhibit repair. Here we provide three independent lines of evidence that VE is required for skeletal muscle myocyte plasma membrane repair in vivo. We also show that when another lipid-directed antioxidant, glutathione peroxidase 4 (Gpx4), is genetically deleted in mouse embryonic fibroblasts, repair fails catastrophically, unless cells are supplemented with VE. We conclude that lipid-directed antioxidant activity provided by VE, and possibly also Gpx4, is an essential component of the membrane repair mechanism in skeletal muscle. This work explains why VE is essential to muscle health and identifies VE as a requisite component of the plasma membrane repair mechanism in vivo.

Assessment of eccentric exercise-induced oxidative stress using oxidation-reduction potential markers

The aim of the present study was to investigate the use of static (sORP) and capacity ORP (cORP) oxidation-reduction potential markers as measured by the RedoxSYS Diagnostic System in plasma, for assessing eccentric exercise-induced oxidative stress. Nineteen volunteers performed eccentric exercise with the knee extensors. Blood was collected before, immediately after exercise, and 24, 48, and 72 h after exercise. Moreover, common redox biomarkers were measured, which were protein carbonyls, thiobarbituric acid-reactive substances, total antioxidant capacity in plasma, and catalase activity and glutathione levels in erythrocytes. When the participants were examined as one group, there were not significant differences in any marker after exercise. However, in 11 participants there was a high increase in cORP after exercise, while in 8 participants there was a high decrease. Thus, the participants were divided in low cORP group exhibiting significant decrease in cORP after exercise and in high cORP group exhibiting significant increase. Moreover, only in the low cORP group there was a significant increase in lipid peroxidation after exercise suggesting induction of oxidative stress. The results suggested that high decreases in cORP values after exercise may indicate induction of oxidative stress by eccentric exercise, while high increases in cORP values after exercise may indicate no existence of oxidative stress.

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.

Scratch wound closure of myoblasts and myotubes is reduced by inflammatory mediators

Complex interactions exist between muscle repair processes and acute inflammatory responses that are initiated by exercise-induced muscle damage. The purpose of this study was to examine whether inflammatory mediators secreted by activated macrophages affect the migration of myogenic cells to the injury site. Migration was measured using a scratch wound closure assay in C2 C12 -derived myogenic cells incubated in activated macrophage-conditioned medium. Both myoblast and myotube migrations were significantly reduced in activated macrophage-conditioned medium compared with control medium. Furthermore, we demonstrated that the inhibitory effect on myoblast and myotube migrations was mediated, at least in part, by the two major cytokines secreted by activated macrophages, tumour necrosis factor (TNF)-α and interleukin (IL)-6. These findings suggest that the migration rate of myogenic cells may be reduced by inflammatory mediators. It may provide useful insights for future researches on the role of macrophages in the process of muscle repair and regeneration.

Effects of anatabine and unilateral maximal eccentric isokinetic muscle actions on serum markers of muscle damage and inflammation

The purpose of this study was to examine the effects of anatabine supplementation in conjunction with unilateral, maximal eccentric isokinetic muscle actions on serum markers of muscle damage and pro-inflammatory cytokines in humans. Seventeen men (mean ± S.D. age = 22.4 ± 3.2 yrs) participated in this double-blinded, placebo-controlled, crossover study. Participants were randomly assigned to two 10-day conditions (anatabine and placebo) separated by a 2-4 week washout period. After seven days of supplementation, blood was sampled immediately prior to PRE, immediately following POST, and 24, 48, and 72 h after 6 sets of 10 repetitions of unilateral, maximal eccentric isokinetic forearm flexion exercise. Concentrations of serum creatine kinase, lactate dehydrogenase, myoglobin, high sensitivity c-reactive protein, and TNF-α were measured. Creatine kinase, myoglobin, and lactate dehydrogenase increased (P<0.05), while high sensitivity c-reactive protein and TNF-α did not change (P>0.05) after the eccentric exercise during both conditions. Lactate dehydrogenase was higher (P<0.05) during the anatabine condition. The primary findings of this study were two-fold: (a) anatabine had no beneficial effects on traditional markers of muscle damage (creatine kinase, lactate dehydrogenase, and myoglobin) compared to placebo after the eccentric exercise protocol, and (b) the eccentric exercise protocol did not elicit increase in the pro-inflammatory cytokines (c-reactive protein and TNF-α). Future studies are needed to examine the effects of anatabine on naturally-occurring inflammation that is common with aging or obesity. Furthermore, additional research is needed to examine the relationship between muscle damage and inflammation after eccentric exercises of different modes, durations, and intensities.

Strength gain through eccentric isotonic training without changes in clinical signs or blood markers

Background

Localized exercises are widely used in rehabilitation processes. The predominant options are exercises with an emphasis on either concentric or eccentric contractions. Eccentric exercises promote greater strength gains compared to classical concentric stimuli, but can cause muscle damage. The aim of present study was to compare strength training composed of 10 sessions with progressive loads between groups with a predominance of concentric versus eccentric contraction through an analysis of isotonic strength, pressure pain threshold, creatine kinase, tumor necrosis factor-alpha and cortisol.

Methods

One hundred twenty male subjects were divided into four groups: C1 and E1 – single session of maximum strength with emphasis on concentric and eccentric contraction, respectively; C10 and E10 – 10 sessions with progressive loads from 80% to maximum strength with emphasis on concentric and eccentric contraction, respectively.

Results

Isotonic strength increased by 10% in E10 following the ten training sessions. C1 and E1 exhibited a lower pressure pain threshold 48 hours after the sessions in comparison to C10 and E10, respectively. Creatine kinase was increased in C1 in comparison to baseline, with significant differences (p ≤ 0.05) in comparison to E1 at 48 and 96 hours as well as C10 at 48, 72 and 96 hours. No significant differences were found in TNF-α or cortisol among the groups or evaluation times.

Conclusion

Eccentric contraction training promotes functional adaptation. Moreover, both concentric and eccentric contraction training have a protective effect on the muscle in relation to a single session of maximum strength exercise.

Trial registration

RBR-75scwh

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.

Anti-inflammatory interventions and skeletal muscle injury: benefit or detriment?

Exercise, eccentric contractions, acute trauma, and disease are all causal mechanisms of skeletal muscle injury. After skeletal muscle is injured, it undergoes sequential phases of degeneration, inflammation, regeneration, and fibrosis. Events that occur in response to inflammation trigger regenerative processes. However, since inflammation causes pain, decreases skeletal muscle function, has a negative effect on performance, and contributes to fibrosis, which is one of the leading causes of delayed regeneration, the general practice has been to reduce inflammation. The problem with this approach is that preventing inflammation may hinder recovery. Current treatment options for inflammation are not necessarily effective and, in some cases, they may be unsafe. This review focuses on the question of whether the most beneficial course of treatment should be to block inflammation or if it is sensible to allow inflammatory processes to progress naturally. If blocking inflammation is perceived as a beneficial approach, it is not yet known at what time point during the inflammatory response it is most sensible to interfere. To address these issues, this review evaluates the effects of various anti-inflammatory agents on recovery processes in response to exercise-induced, traumatic, and disease-associated models of skeletal muscle injury. A collective analysis such as this should lay the foundation for future work that systematically manipulates the inflammatory response to most effectively promote regeneration and functional recovery in injured skeletal muscle, while reducing the negative effects of inflammatory processes such as pain and fibrosis.

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.

Creatine supplementation does not decrease oxidative stress and inflammation in skeletal muscle after eccentric exercise

Thirty-six male rats were used; divided into 6 groups (n = 6): saline; creatine (Cr); eccentric exercise (EE) plus saline 24 h (saline + 24 h); eccentric exercise plus Cr 24 h (Cr + 24 h); eccentric exercise plus saline 48 h (saline + 48 h); and eccentric exercise plus Cr 48 h (Cr + 48 h). Cr supplementation was administered as a solution of 300 mg · kg body weight(-1) · day(-1) in 1 mL water, for two weeks, before the eccentric exercise. The animals were submitted to one downhill run session at 1.0 km · h(-1) until exhaustion. Twenty-four and forty-eight hours after the exercise, the animals were killed, and the quadriceps were removed. Creatine kinase levels, superoxide production, thiobarbituric acid reactive substances (TBARS) level, carbonyl content, total thiol content, superoxide dismutase, catalase, glutathione peroxidase, interleukin-1b (IL-1β), nuclear factor kappa B (NF-kb), and tumour necrosis factor (TNF) were analysed. Cr supplementation neither decreases Cr kinase, superoxide production, lipoperoxidation, carbonylation, total thiol, IL-1β, NF-kb, or TNF nor alters the enzyme activity of superoxide dismutase, catalase, and glutathione peroxides in relation to the saline group, respectively (P < 0.05). There are positive correlations between Cr kinase and TBARS and TNF-α 48 hours after eccentric exercise. The present study suggests that Cr supplementation does not decrease oxidative stress and inflammation after eccentric contraction.

Effects of therapeutic pulsed ultrasound and dimethylsulfoxide phonophoresis on oxidative stress parameters after injury induced by eccentric exercise

INTRODUCTION

The aim of the study was to evaluate the effects of TPU together with DMSO on oxidative stress parameters after eccentric exercise.

METHODS

Thirty and six animals were divided in control; eccentric exercise (EE); EE+saline gel 0.9%; EE+TPU 0.8 W/cm(2); EE+DMSO gel; EE+TPU+DMSO gel and submitted to one 90-min downhill run (1.0 km h(-1)). TPU was used 2, 12, 24, 46 h after exercise session and 48 h after the animals were killed and the gastrocnemius muscles were surgically removed. Production of superoxide anion, creatine kinase (CK) levels, lipoperoxidation, carbonylation, and antioxidants enzymes were analyzed.

RESULTS

Showed that TPU and gel-DMSO improved muscle healing. Moreover, superoxide anion production, TBARS level and protein carbonyls levels, superoxide dismutase and catalase activity were all decreased in the group TPU plus gel-DMSO.

DISCUSSION

Our results show that DMSO is effective in the reduction of the muscular lesion and in the oxidative stress after eccentric exercise only when used with TPU.

Pulsed ultrasound associated with gold nanoparticle gel reduces oxidative stress parameters and expression of pro-inflammatory molecules in an animal model of muscle injury

Background

Nanogold has been investigated in a wide variety of biomedical applications because of the anti-inflammatory properties. The purpose of this study was to evaluate the effects of TPU (Therapeutic Pulsed Ultrasound) with gold nanoparticles (GNP) on oxidative stress parameters and the expression of pro-inflammatory molecules after traumatic muscle injury.

Materials and methods

Animals were divided in nine groups: sham (uninjured muscle); muscle injury without treatment; muscle injury + DMSO; muscle injury + GNP; muscle injury + DMSO + GNP; muscle injury + TPU; muscle injury + TPU + DMSO; muscle injury + TPU + GNP; muscle injury + TPU + DMSO + GNP. The ROS production was determined by concentration of superoxide anion, modulation of antioxidant defenses was determined by the activity of superoxide dismutase, catalase and glutathione peroxidase enzymes, oxidative damage determined by formation of thiobarbituric acid-reactive substance and protein carbonyls. The levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were measured as inflammatory parameters.

Results

Compared to muscle injury without treatment group, the muscle injury + TPU + DMSO + GNP gel group promoted a significant decrease in superoxide anion production and lipid peroxidation levels (p < 0.050). It also showed a significant decrease in TNF-α and IL-1β levels (p < 0.050) when compared to muscle injury without treatment group.

Conclusions

Our results suggest that TPU + DMSO + GNP gel presents beneficial effects on the muscular healing process, inducing a reduction in the production of ROS and also the expression of pro-inflammatory molecules.

Antioxidant supplementation during exercise training: beneficial or detrimental?

High levels of reactive oxygen species (ROS) produced in skeletal muscle during exercise have been associated with muscle damage and impaired muscle function. Supporting endogenous defence systems with additional oral doses of antioxidants has received much attention as a noninvasive strategy to prevent or reduce oxidative stress, decrease muscle damage and improve exercise performance. Over 150 articles have been published on this topic, with almost all of these being small-scale, low-quality studies. The consistent finding is that antioxidant supplementation attenuates exercise-induced oxidative stress. However, any physiological implications of this have yet to be consistently demonstrated, with most studies reporting no effects on exercise-induced muscle damage and performance. Moreover, a growing body of evidence indicates detrimental effects of antioxidant supplementation on the health and performance benefits of exercise training. Indeed, although ROS are associated with harmful biological events, they are also essential to the development and optimal function of every cell. The aim of this review is to present and discuss 23 studies that have shown that antioxidant supplementation interferes with exercise training-induced adaptations. The main findings of these studies are that, in certain situations, loading the cell with high doses of antioxidants leads to a blunting of the positive effects of exercise training and interferes with important ROS-mediated physiological processes, such as vasodilation and insulin signalling. More research is needed to produce evidence-based guidelines regarding the use of antioxidant supplementation during exercise training. We recommend that an adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain the optimal antioxidant status in exercising individuals.

Energy expenditure during 2-day trail walking in the mountains (2,857 m) and the effects of amino acid supplementation in older men and women

We compared relative exercise intensity and active energy expenditure (AEE) on trail walking in the mountains, with those of daily exercise training, and whether branched-chain amino acid (BCAA) and arginine supplementation attenuated the release of markers indicating muscle damage and declines in physical performance. Twenty-one subjects (~63 years) were divided into two groups: amino acid (AA, 51 g of amino acids and 40 g of carbohydrate, male/female = 6/4) or placebo (PL, 91 g of carbohydrate, male/female = 6/5) supplementation during 2 days of trail walking in the mountains. We measured heart rate (HR), AEE, fatigue sensation, water and food intake, and sweat loss during walking. In addition, we measured peak aerobic capacity [Formula: see text] and heart rate (HR(peak)) with graded-intensity walking, vertical jumping height (VJ) before and after walking. We found that average HR and AEE during uphill walking were ~100% HR(peak) and ~60% [Formula: see text], while they were ~80 and ~20% during downhill walking, respectively. Moreover, average total AEE per day was sevenfold that of their daily walking training. VJ after walking remained unchanged compared with the baseline in AA (P > 0.2), while it was reduced by ~10% in PL (P < 0.01), although with no significant difference in the reduction between the groups (P > 0.4). The responses of other variables were not significantly different between groups (all, P > 0.2). Thus, trail walking in the mountains required a high-intensity effort for older people, while the effects of BCAA and arginine supplementation were modest in this condition.

Redox homeostasis, oxidative stress and disuse muscle atrophy

A pivotal role has been ascribed to oxidative stress in determining the imbalance between protein synthesis and degradation leading to muscle atrophy in many pathological conditions and in disuse. However, a large variability in disuse-induced alteration of redox homeostasis through muscles, models and species emerges from the literature. Whereas the causal role of oxidative stress appears well established in the mechanical ventilation model, findings are less compelling in the hindlimb unloaded mice and very limited in humans. The mere coexistence of muscle atrophy, indirect indexes of increased reactive oxygen species (ROS) production and impairment of antioxidant defence systems, in fact, does not unequivocally support a causal role of oxidative stress in the phenomenon. We hypothesise that in some muscles, models and species only, due to a large redox imbalance, the leading phenomena are activation of proteolysis and massive oxidation of proteins, which would become more susceptible to degradation. In other conditions, due to a lower extent and variable time course of ROS production, different ROS-dependent, but also -independent intracellular pathways might dominate determining the variable extent of atrophy and even dispensable protein oxidation. The ROS production and removal are complex and finely tuned phenomena. They are indeed important intracellular signals and redox balance maintains normal muscle homeostasis and can underlie either positive or negative adaptations to exercise. A precise approach to determine the levels of ROS in living cells in various conditions appears to be of paramount importance to define and support such hypotheses.