Vitamin C and e supplementation effects in professional soccer players under regular training

Influence of N-Acetylcysteine Supplementation on Physical Performance and Laboratory Biomarkers in Adult Males: A Systematic Review of Controlled Trials

N-acetylcysteine (NAC) is used as a sports supplement for its ability to modulate exercise-induced oxidative damage through its antioxidant actions and maintenance of glutathione homeostasis, positioning NAC as a strategy to improve physical performance. We aimed to evaluate the current evidence on the benefits of NAC supplementation on physical performance and laboratory biomarkers in adult men. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we systematically reviewed studies indexed in the Web of Science, Scopus, and PubMed to assess the effects of NAC on physical performance, laboratory biomarkers, and adverse effects in adult men. Original articles published up to 30 April 2023 with a controlled trial design comparing NAC supplementation with a control group were included. The modified McMaster Critical Review Form for Quantitative Studies was used as an assessment tool and the Cochrane Risk of Bias was applied. Of the 777 records identified in the search, 16 studies met the inclusion and exclusion criteria. Overall, most of the trials reported beneficial effects of NAC supplementation and no serious adverse events were reported. Participants supplemented with NAC showed significant improvements in exercise performance, antioxidant capacity, and glutathione homeostasis. However, there was no clear evidence of beneficial effects of NAC supplementation on haematological markers, inflammatory response, and muscle behaviour. NAC supplementation appears to be safe and may regulate glutathione homeostasis, have antioxidant effects, and improve exercise performance. However, further studies are needed to clarify the relevance of its use.

Differences in the Pro/Antioxidative Status and Cellular Stress Response in Elderly Women after 6 Weeks of Exercise Training Supported by 1000 mg of Vitamin C Supplementation

Vitamin C supplementation and exercise influence pro/antioxidative status and the cellular stress response. We tested the effects of exercise training for 6 weeks, supported by 1000 mg of vitamin C supplementation in elderly women. Thirty-six women were divided into two groups: a control group (CON) (n = 18, age 69.4 ± 6.4 years, 70.4 ±10.4 kg body mass) and a supplemented group (SUPP) (n = 18, aged 67.7 ± 5.6 years, body mass 71.46 ± 5.39 kg). Blood samples were taken twice (at baseline and 24 h after the whole period of training), in order to determine vitamin C concentration, the total oxidative status/capacity (TOS/TOC), total antioxidant status/capacity (TAS/TAC), and gene expression associated with cellular stress response: encoding heat shock factor (HSF1), heat shock protein 70 (HSPA1A), heat shock protein 27 (HSPB1), and tumor necrosis factor alpha (TNF-α). We observed a significant increase in TOS/TOC, TAS/TAC, and prooxidant/antioxidant balance in the SUPP group. There was a significant decrease in HSPA1A in the CON group and a different tendency in the expression of HSF1 and TNF-α between groups. In conclusion, vitamin C supplementation enhanced the pro-oxidation in elderly women with a normal plasma vitamin C concentration and influenced minor changes in training adaptation gene expression.

The soccer season: performance variations and evolutionary trends

The physiological demands of soccer challenge the entire spectrum of the response capacity of the biological systems and fitness requirements of the players. In this review we examined variations and evolutionary trends in body composition, neuromuscular and endurance-related parameters, as well as in game-related physical parameters of professional players. Further, we explore aspects relevant for training monitoring and we reference how different training stimulus and situational variables (e.g., competition exposure) affect the physiological and performance parameters of players. Generally, improvements of small magnitude in non- (non-CMJ) and countermovement-based jumps (CMJBased) and in the sprint acceleration (ACCPhase) and maximal velocity phase (MVPhase) are observed from start of preparation phase (PPS) to beginning of competition phase (BCP). A greater magnitude of increases is observed in physiological and endurance performance measures within this period; moderate magnitude in sub-maximal intensity exercise (velocity at fixed blood lactate concentrations; V2-4mmol/l) and large magnitude in VO2max, maximal aerobic speed (MAS) and intense intermittent exercise performance (IE). In the middle of competition phase (MCP), small (CMJBased and ACCPhase), moderate (non-CMJ; MVPhase; VO2max; sub-maximal exercise) and large (MAS and IE) improvements were observed compared to PPS. In the end of competition period (ECP), CMJBased and MVPhase improve to a small extent with non-CMJ, and ACCPhase, VO2max, MAS, sub-maximal intensity exercise and IE revealing moderate increments compared to PPS. Although less investigated, there are generally observed alterations of trivial magnitude in neuromuscular and endurance-related parameters between in-season assessments; only substantial alterations are examined for IE and sub-maximal exercise performance (decrease and increase of small magnitude, respectively) from BCP to MCP and in VO2max and IE (decrements of small magnitude) from MCP to ECP. Match performance may vary during the season. Although, the variability between studies is clear for TD, VHSR and sprint, all the studies observed substantial increments in HSR between MCP and ECP. Finally, studies examining evolutionary trends by means of exercise and competition performance measures suggests of a heightened importance of neuromuscular factors. In conclusion, during the preseason players "recover" body composition profile and neuromuscular and endurance competitive capacity. Within in-season, and more robustly towards ECP, alterations in neuromuscular performance seem to be force-velocity dependent, and in some cases, physiological determinants and endurance performance may be compromised when considering other in-season moments. Importantly, there is a substantial variability in team responses that can be observed during in-season. Consequently, this informs on the need to both provide a regular training stimulus and adequate monitorization throughout the season.

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.

The potential of Curcuma extract to alleviate muscle damage in amateur soccer players

Compounds with high bioactive are commonly used as a nutritional approach for accelerating muscle damage recovery after strenuous exercise. There are still inconsistent results of post-exercise antioxidant supplementation on the circulating muscle damage biomarker. This study aimed to examine the effect of post-exercise Curcuma extract supplementation in ice cream on muscle damage and inflammatory markers in amateur soccer players. Male amateur soccer athletes (aged 14 – 18 years) participated in a randomized double-blind placebo-controlled study under two conditions: control group (n = 10) and treatment group (n = 10). The treatment group was treated with Curcuma extract ice cream (250 mg/100 g) for 21 days. Blood samples were drawn before training, considered baseline, and 3 h after training on day 21. The level of creatine kinase, IL-6, haemoglobin (Hb), and lactic acid were quantified. There was a significant decrease in creatine kinase change in the treatment group compared to the control group (p <0.05). No change in IL-6 and Hb levels in the treatment group. Lactic acid decreased by 16.3% from baseline in the treatment group (p <0.05). Curcuma extract ice cream potentiates to ameliorate exercise-induced muscle damage.

An Overview of Physical Exercise and Antioxidant Supplementation Influences on Skeletal Muscle Oxidative Stress

One of the essential injuries caused by moderate to high-intensity and short-duration physical activities is the overproduction of reactive oxygen species (ROS), damaging various body tissues such as skeletal muscle (SM). However, ROS is easily controlled by antioxidant defense systems during low to moderate intensity and long-term exercises. In stressful situations, antioxidant supplements are recommended to prevent ROS damage. We examined the response of SM to ROS generation during exercise using an antioxidant supplement treatment strategy in this study. The findings of this review research are paradoxical due to variances in antioxidant supplements dose and duration, intensity, length, frequency, types of exercise activities, and, in general, the lack of a regular exercise and nutrition strategy. As such, further research in this area is still being felt.

Effect of a Shock Micro-Cycle on Biochemical Markers in University Soccer Players

This study aimed to examine various biochemical biomarkers changes during a shock micro-cycle in soccer players from a university team. The study had 22 players (age: 22 ± 3 years; body mass: 68.6 ± 7.1 kg; height: 1.73 ± 0.07 m). The study measured total cholesterol (TC), triglycerides (TG), cholesterol linked to high-density lipoproteins (HDL), low-density lipoproteins (LDL), very low density lipoproteins (VLDL), arterial index (AI), creatine kinase (CK), glutamate-oxalacetate-transaminase (GOT), glutamate-pyruvate-transaminase (GPT), creatinine (Cr), catalase (CAT), superoxide dismutase (SOD), cytokines IL6 and TNFα, total antioxidant capacity (Cap antiox tot), hemolysis percentage and glomerular filtration rate (GFR); measurements were conducted during a shock micro-cycle. The lipid profile variables had no statistical significance when compared on day 1 with day 14. Except for TNFα, the other biomarkers compared with day one had progressive increments until day seven, with a subsequent reduction on day 14; however, none of the biomarkers returned to baseline values despite this decrease. The data shown herein suggest the need to research these biomarkers in distinct types of mesocycles, exercise, intensity, load, and duration to diminish fatigue and improve athlete performance.

The Role of Vitamin C in Two Distinct Physiological States: Physical Activity and Sleep

This paper is a literature overview of the complex relationship between vitamin C and two opposing physiological states, physical activity and sleep. The evidence suggests a clinically important bidirectional association between these two phenomena mediated by different physiological mechanisms. With this in mind, and knowing that both states share a connection with oxidative stress, we discuss the existing body of evidence to answer the question of whether vitamin C supplementation can be beneficial in the context of sleep health and key aspects of physical activity, such as performance, metabolic changes, and antioxidant function. We analyze the effect of ascorbic acid on the main sleep components, sleep duration and quality, focusing on the most common disorders: insomnia, obstructive sleep apnea, and restless legs syndrome. Deeper understanding of those interactions has implications for both public health and clinical practice.

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.

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.

Redox homeostasis in sport: do athletes really need antioxidant support?

Supplementation with antioxidants received interest as suitable tool for preventing or reducing exercise-related oxidative stress possibly leading to improvement of sport performance in athletes. To date, it is difficult to reach a conclusion on the relevance of antioxidants supplementation in athletes and/or well-trained people. The general picture that emerges from the available data indicates that antioxidants requirement can be covered by dosage equal or close to the recommended dietary allowance (RDA) provided by consumption of a balanced, well-diversified diet. Nevertheless, it remains open the possibility that in specific context, such as in sports characterized by high intensity and/or exhaustive regimes, supplementation with antioxidants could be appropriated to avoid or reduce the damaging effect of these type of exercise. This review will discuss the findings of a number of key studies on the advantages and/or disadvantages for athletes of using antioxidants supplementation, either individually or in combination.

Protective Role of Vitamin C Intake on Muscle Damage in Male Adolescents Performing Strenuous Physical Activity

BACKGROUND:

Strenuous non-regular exercise increases reactive oxygen species ROS level leading to an impaired balance between the endogenous antioxidant defence system and the free radicals production. Antioxidants intake can detoxify the peroxides produced during exercise, attenuating the inflammatory responses and therefore may prevent exercise-induced muscle damage.

AIM:

The purpose of this study was to determine the role of vitamin C intake in attenuating markers of muscle damage, oxidative stress and inflammatory responses in male adolescents performing the non-regular strenuous exercise.

MATERIAL AND METHODS:

Twenty recreationally active male adolescents were assigned to participate in the study. Eligible subjects performed strenuous recreational exercise (2-3 times per week) were randomly divided into two groups: The vitamin C (VC) group that consumed 500 mg of capsulated vitamin C after breakfast for a period of 90 days and the placebo (PL) group that consumed identical capsules in form and aspect that contained 500 mg of maltodextrin for the same period. Aspartate aminotransferase (AST), creatine kinase (CK), lactate dehydrogenase (LDH) were assessed for muscle damage. Malondialdehyde (MDA) was evaluated as a marker of lipid peroxidation. Plasma creatinine, uric acid and urea were determined to monitor kidney function. C-reactive protein, a marker of systemic inflammation was also measured.

RESULTS:

In comparison between PL and VC groups, the plasma concentrations of muscle damage markers, oxidative stress markers, kidney function and inflammatory markers showed no significant difference in their baseline values (P > 0.05). The plasma concentrations of CK, LDH, MDA, urea, uric acid and CRP were significantly decreased in the VC group (P < 0.05) as compared to their values before the intake of vitamin C.

CONCLUSION:

The present results support the intake of vitamin C as an antioxidant for attenuating exercise-induced muscle damage, oxidative stress and inflammatory markers in male adolescents performing the strenuous physical activity.

Role of Water Soluble Vitamins in the Reduction Diet of an Amateur Sportsman

This study is aimed at determining the content of water soluble vitamins in amateur sportsmen before and after the use of reduction diet. Twenty adult male amateur sportsmen aged between 20 and 43 qualified for this study. The participants adhered to individually adjusted reduction diets for 3 months. Diet supplements were excluded from the diet during that time. Vitamins were analyzed before and after the reduction diet using HPLC. The following vitamins were analyzed: B1, B2, B3, PP, B5, B6, B7, B9, B12 and vitamin C. Statistically significant increase of riboflavin in blood plasma (p=0.0254) and statistically significant (p=0.048) decrease in the concentration of niacin was found when compared to the period before the diet. Appropriate level of riboflavin can be obtained by the consumption of proper amount of diary in the diet. Supplementation with PP is advised and, in case of improper diet, the supplementation of B1, B7 and B12 may also be considered.

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.

Exercise performance and physiological responses: the potential role of redox imbalance

Increases in oxidative stress or decreases in antioxidant capacity, or redox imbalance, are known to alter physiological function and has been suggested to influence performance. To date, no study has sought to manipulate this balance in the same participants and observe the impact on physiological function and performance. Using a single‐blind, placebo‐controlled, and counterbalanced design, this study examined the effects of increasing free radicals, via hyperoxic exposure (F_iO₂ = 1.0), and/or increasing antioxidant capacity, through consuming an antioxidant cocktail (AOC; vitamin‐C, vitamin‐E, α‐lipoic acid), on 5‐kilometer (km) cycling time‐trial performance, and the physiological and fatigue responses in healthy college‐aged males. Hyperoxic exposure prior to the 5 km TT had no effect on performance, fatigue, or the physiological responses to exercise. The AOC significantly reduced average power output (222 ± 11 vs. 214 ± 12 W), increased 5 km time (516 ± 17 vs. 533 ± 18 sec), suppressed ventilation (V_E; 116 ± 5 vs. 109 ± 13 L/min), despite similar oxygen consumption (VO₂; 43.1 ± 0.8 vs. 44.9 ± 0.2 mL/kg per min), decreased V_E/VO₂ (35.9 ± 2.0 vs. 32.3 ± 1.5 L/min), reduced economy (VO₂/W; 0.20 ± 0.01 vs. 0.22 ± 0.01), increased blood lactate (10 ± 0.7 vs. 11 ± 0.7 mmol), and perception of fatigue (RPE; 7.39 ± 0.4 vs. 7.60 ± 0.3) at the end of the TT, as compared to placebo (main effect, placebo vs. AOC, respectively). Our data demonstrate that prior to exercise, ingesting an AOC, but not exposure to hyperoxia, likely disrupts the delicate balance between pro‐ and antioxidant forces, which negatively impacts ventilation, blood lactate, economy, perception of fatigue, and performance (power output and 5 km time) in young healthy males. Thus, caution is warranted in athletes taking excess exogenous antioxidants.

Chronic Eccentric Exercise and Antioxidant Supplementation: Effects on Lipid Profile and Insulin Sensitivity

Eccentric exercise has been shown to exert beneficial effects in both lipid profile and insulin sensitivity. Antioxidant supplementation during chronic exercise is controversial as it may prevent the physiological training-induced adaptations. The aim of this study was to investigate: 1) the minimum duration of the eccentric exercise training required before changes on metabolic parameters are observed and 2) whether antioxidant supplementation during training would interfere with these adaptations. Sixteen young healthy men were randomized into the Vit group (1 g of vitamin C and 400 IU vitamin E daily) and the placebo (PL) group. Subjects received the supplementation for 9 weeks. During weeks 5-9 all participants went through an eccentric exercise training protocol consisting of two exercise sessions (5 sets of 15 eccentric maximal voluntary contractions) per week. Plasma triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), apolipoproteins (Apo A1, Apo B and Lpa) and insulin sensitivity (HOMA) were assessed before the supplementation (week 0), at weeks 5, 6, 7, 8 and 9. TG, TC and LDL were significantly lower compared to pre supplementation at both weeks 8 and 9 (P<0.05) in both groups. HDL was significantly elevated after 4 weeks of training (p < 0.005) in both groups. There was no effect of the antioxidant supplementation in any of the variables. There was no effect of either the training or the supplementation protocol in apolipoproteins levels and insulin sensitivity. A minimum duration of 3 weeks of eccentric exercise training is required before beneficial effects in lipid profile can be observed in healthy young men. Concomitant antioxidant supplementation does not interfere with the training-induced adaptations.

Cameroonian professional soccer players and risk of atherosclerosis

Background

Elevated titers of antibodies against oxidized low-density lipoproteins-cholesterol (ox-LDL-Ab) have been reported among professional athletes, paradoxically reflecting an increased risk of developing atherogenic and/or cardiovascular events. This study aimed to determine titers of ox-LDL-Ab in a group of Cameroonian professional soccer players, and evaluate their evolution during part of a competition season as well as the plasmatic antioxidant status to find out if this latter correlates with ox-LDL-Ab .

Methods

We conducted a descriptive cohort study in 2012 including 18 healthy male soccer players. Three samplings were performed in March (T1), May (T2), and July 2012 (T3) to assess the lipid profile, titers of ox-LDL-Ab, and plasmatic concentrations of four antioxidants: the ferric reducing antioxidant power (FRAP), reduced glutathione (GSH), superoxide dismutase (SOD), and uric acid.

Results

Ages ranged from 16 to 28 years with a median (interquartile range) of 19.5 (19–23) years. Total cholesterol, high-density lipoproteins-cholesterol (HDL-C), low-density lipoproteins-cholesterol (LDL-C) and triglycerides varied within normal ranges throughout the three samplings. While total cholesterol and LDL-C titers increased significantly (p = 0.003 and p = 0.006, respectively), triglycerides and HDL-C values varied non-significantly throughout the measurements (p = 0.061 and p = 0.192, respectively). The median ox-LDL-Ab titers were respectively: 653.3 (468.2–838.8) mIU/ml at T1, 777.7 (553.7–1150.7) mIU/ml at T2, and 1037.7 (901.7–1481.5) mIU/ml at T3. Overall, ox-LDL-Ab titers increased significantly from T1 to T3 (p = 0.006). Concomitantly, uric acid and FRAP concentrations decreased significantly (p = 0.001 and p = 0.003, respectively); on the contrary, GSH and SOD values increased, but insignificantly (p = 0.115 and p = 0.110, respectively). There was a positive and significant correlation between ox-LDL-Ab and HDL-C (ρ = 0.519, p = 0.027), and between ox-LDL-Ab and SOD (ρ = 0.504, p = 0.033) at T2. Ox-LDL-Ab values were expected to increase with each new visit (β = 201.1; p = 0.041) and each IU/ml of SOD titers (β = 23.6; p = 0.019).

Conclusion

These Cameroonian professional soccer players exhibited high levels of ox-LDL-Ab reflecting elevated levels of oxidatively-modified LDL-C particles with an increment over time, this being insufficiently counterbalanced by the antioxidant defense mechanisms. As a consequence, they may be at increased atherogenic and cardiovascular risks.

Control of antioxidant supplementation through interview is not appropriate in oxidative-stress sport studies: Analytical confirmation should be required

OBJECTIVE

Controlling antioxidant supplementation in athletes involved in studies related to oxidative stress and muscle damage is the key to ensure results. The aim of this study was to confirm through high-performance liquid chromatography (HPLC) analysis whether well-trained individuals lied during a personal interview when asked if they were taking supplements with antioxidants, and how this could affect oxidative stress, muscle damage, and antioxidant response.

METHODS

A total of 94 men, well trained in endurance sports, volunteered in this study. They denied taking any antioxidant supplementation at initial interview. After a HPLC analysis, abnormal α-tocopherol concentrations were detected, probably due to a hidden antioxidant supplementation. Participants were classified into two groups: no evidence of antioxidant supplementation (NS group = α-tocopherol values <80 nmol/mL; n = 75) and evidence of antioxidant supplementation (S group = α-tocopherol values >80 nmol/mL; n = 19). Lipid peroxidation, muscle damage, antioxidant enzyme activity, and nonenzymatic antioxidant content were analyzed according to this classification. Statistical comparisons were performed using Student's t test.

RESULTS

The α-tocopherol concentrations were significantly higher in the S group than in the NS group (MD = 725.01 ± 39.01 nmol/mL; P = 0.001). The S group showed a trend toward lower hydroperoxides than the NS group (MD = 1.19 ± 0.72 nmol/mL; P = 0.071). The S group showed significantly lower catalase activity than the NS group (MD = 0.10 ± 0.02-seg-1 mg-1; P < 0.01). Skeletal muscle damage markers did not differ between experimental groups.

CONCLUSIONS

Data from the present study reveal that 20% of participants lied in the exclusion criteria of antioxidant supplementation in a personal interview, as they showed high plasmatic α-tocopherol concentrations after HPLC verification. Catalase activity seems to be affected by high α-tocopherol plasma levels. Therefore, we strongly recommend the HPLC analysis as a necessary tool to verify the antioxidant intake and preserve results in studies linking oxidative stress and sport.

Vitamin C and E supplementation prevents some of the cellular adaptations to endurance-training in humans

BACKGROUND

It is clear that reactive oxygen species (ROS) produced during skeletal muscle contraction have a regulatory role in skeletal muscle adaptation to endurance exercise. However, there is much controversy in the literature regarding whether attenuation of ROS by antioxidant supplementation can prevent these cellular adaptations. Therefore, the aim of this study was to determine whether vitamin C and E supplementation attenuates performance and cellular adaptations following acute endurance exercise and endurance training.

METHODS

A double-blinded, placebo-controlled randomized control trial was conducted in eleven healthy young males. Participants were matched for peak oxygen consumption (VO 2peak) and randomly allocated to placebo or antioxidant (vitamin C (2 × 500 mg/day) and E (400 IU/day)) groups. Following a four-week supplement loading period, participants completed acute exercise (10 × 4 min cycling at 90% VO 2peak, 2 min active recovery). Vastus lateralis muscle samples were collected pre-, immediately-post- and 3h-post-exercise. Participants then completed four weeks of training (3 days/week) using the aforementioned exercise protocol while continuing supplementation. Following exercise training, participants again completed an acute exercise bout with muscle biopsies.

RESULTS

Acute exercise tended to increase skeletal muscle oxidative stress as measured by oxidized glutathione (GSSG) (P=0.058) and F2-isoprostanes (P=0.056), with no significant effect of supplementation. Acute exercise significantly increased mRNA levels of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), mitochondrial transcription factor A (TFAM) and PGC related coactivator (PRC), with no effect of supplementation. Following endurance training, supplementation did not prevent significantly increased VO 2peak, skeletal muscle levels of citrate synthase activity or mRNA or protein abundance of cytochrome oxidase subunit 4 (COX IV) (P<0.05). However, following training, vitamin C and E supplementation significantly attenuated increased skeletal muscle superoxide dismutase (SOD) activity and protein abundance of SOD2 and TFAM.

CONCLUSION

Following acute exercise, supplementation with vitamin C and E did not attenuate skeletal muscle oxidative stress or increased gene expression of mitochondrial biogenesis markers. However, supplementation attenuated some (SOD, TFAM) of the increased skeletal muscle adaptations following training in healthy young men.

Effect of N-acetylcysteine on cycling performance after intensified training

PURPOSE

This investigation examined the ergogenic effect of short-term oral N-acetylcysteine (NAC) supplementation and the associated changes in redox balance and inflammation during intense training.

METHODS

A double-blind randomized placebo-controlled crossover design was used to assess 9 d of oral NAC supplementation (1200 mg·d) in 10 well-trained triathletes. For each supplement trial (NAC and placebo), baseline venous blood and urine samples were taken, and a presupplementation cycle ergometer race simulation was performed. After the loading period, further samples were collected preexercise, postexercise, and 2 and 24 h after the postsupplementation cycle ergometer race simulation. Changes in total antioxidant capacity, ferric reducing ability of plasma, reduced glutathione, oxidized glutathione, thiobarbituric acid-reactive substances, interleukin 6, xanthine oxidase, hypoxanthine, monocyte chemotactic protein 1, nuclear factor κB, and urinary 15-isoprostane F2t concentration were assessed. The experimental procedure was repeated with the remaining supplement after a 3-wk washout. Eight participants completed both supplementation trials.

RESULTS

NAC improved sprint performance during the cycle ergometer race simulation (P < 0.001, ηp = 0.03). Supplementation with NAC also augmented postexercise plasma total antioxidant capacity (P = 0.005, ηp = 0.19), reduced exercise-induced oxidative damage (plasma thiobarbituric acid-reactive substances, P = 0.002, ηp = 0.22; urinary 15-isoprostane F2t concentration, P = 0.010, ηp = 0.431), attenuated inflammation (plasma interleukin 6, P = 0.002, ηp = 0.22; monocyte chemotactic protein 1, P = 0.012, ηp = 0.17), and increased postexercise nuclear factor κB activity (P < 0.001, ηp = 0.21).

CONCLUSION

Oral NAC supplementation improved cycling performance via an improved redox balance and promoted adaptive processes in well-trained athletes undergoing strenuous physical training.

Can supplementation with vitamin C and E alter physiological adaptations to strength training?

Background

Antioxidant supplementation has recently been demonstrated to be a double-edged sword, because small to moderate doses of exogenous antioxidants are essential or beneficial, while high doses may have adverse effects. The adverse effects can be manifested in attenuated effects of exercise and training, as the antioxidants may shut down some redox-sensitive signaling in the exercised muscle fibers. However, conditions such as age may potentially modulate the need for antioxidant intake. Therefore, this paper describes experiments for testing the hypothesis that high dosages of vitamin C (1000 mg/day) and E (235 mg/day) have negative effects on adaptation to resistance exercise and training in young volunteers, but positive effects in older men.

Methods/design

We recruited a total of 73 volunteers. The participants were randomly assigned to receiving either vitamin C and E supplementation or a placebo. The study design was double-blinded, and the participants followed an intensive training program for 10–12 weeks. Tests and measurements aimed at assessing changes in physical performance (maximal strength) and physiological characteristics (muscle mass), as well as biochemical and cellular systems and structures (e.g., cell signaling and morphology).

Discussion

Dietary supplements, such as vitamin C and E, are used by many people, especially athletes. The users often believe that high dosages of supplements improve health (resistance to illness and disease) and physical performance. These assumptions are, however, generally not supported in the scientific literature. On the contrary, some studies have indicated that high dosages of antioxidant supplements have negative effects on exercise-induced adaptation processes. Since this issue concerns many people and few randomized controlled trials have been conducted in humans, further studies are highly warranted.

Trial registration

ACTRN12614000065695

Alteration in basal redox state of young male soccer players after a six-month training programme

Despite worldwide popularity of soccer, there are still insufficient data about the effects of training process on oxidative stress-induced damage, which may occur during chronic exercise. The present study aimed to determine the effects of a six-month training programme on basal redox status of young male soccer players. The study included 26 male soccer players, aged 12-13, who participated in a six-month training programme, and 26 age-matched non-athletes who were not implemented in the training process. Blood samples were collected (before and after six-month training programme) in order to measure the following oxidative stress markers: index of lipid peroxidation (measured as TBARS), nitrites (NO2-), superoxide anion radical (O2-), hydrogen peroxide (H2O2), superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH) level. After six months, the levels of TBARS and NO2- were significantly increased, while the O2- and H2O2 remained unchanged. On the other hand, SOD and CAT activity increased, while GSH decreased. A carefully prepared training programme could strengthen most components of antioxidant defence systems and, except lipid peroxidation, does not promote oxidative stress in response to regular physical activity. These findings could help in the improvement of training programmes for young athletes.

Effect of antioxidant supplementation on exercise-induced cardiac troponin release in cyclists: a randomized trial

Background

Cardiac troponin is the biochemical gold standard to diagnose acute myocardial infarction. Interestingly however, elevated cardiac troponin concentrations are also frequently observed during and after endurance-type exercise. Oxidative stress associated with prolonged exercise has been proposed to contribute to cardiac troponin release. Therefore, the aim of this study was to assess the effect of 4 week astaxanthin supplementation (a potent cartenoid antioxidant) on antioxidant capacity and exercise-induced cardiac troponin release in cyclists.

Methods

Thirty-two well-trained male cyclists (age 25±5, weight 73±7 kg, maximum O₂ uptake 60±5 mL·kg⁻¹·min⁻¹, W_max 5.4±0.5 W·kg⁻¹; mean ± SD) were repeatedly subjected to a laboratory based standardized exercise protocol before and after 4 weeks of astaxanthin (20 mg/day), or placebo supplementation in a double-blind randomized manner. Blood samples were obtained at baseline, at 60 min of cycling and immediately post-exercise (≈ 120 min).

Results

The pre-supplementation cycling trial induced a significant rise of median cardiac troponin T concentrations from 3.2 (IQR 3.0–4.2) to 4.7 ng/L (IQR 3.7–6.7), immediately post-exercise (p<0.001). Four weeks of astaxanthin supplementation significantly increased mean basal plasma astaxanthin concentrations from non-detectable values to 175±86 µg·kg⁻¹. However, daily astaxanthin supplementation had no effect on exercise-induced cardiac troponin T release (p = 0.24), as measured by the incremental area under the curve. Furthermore, the elevation in basal plasma astaxanthin concentrations was not reflected in changes in antioxidant capacity markers (trolox equivalent antioxidant capacity, uric acid, and malondialdehyde). Markers of inflammation (high-sensitivity C-reactive protein) and exercise-induced skeletal muscle damage (creatine kinase) were equally unaffected by astaxanthin supplementation.

Conclusion

Despite substantial increases in plasma astaxanthin concentrations, astaxanthin supplementation did not improve antioxidant capacity in well-trained cyclists. Accordingly, exercise-induced cardiac troponin T concentrations were not affected by astaxanthin supplementation.

Trial registration

ClinicalTrials.gov NCT01241877

Effect of astaxanthin supplementation on paraoxonase 1 activities and oxidative stress status in young soccer players

The purpose of the study was to examine the effects of astaxanthin (Asx) on paraoxonase (PON1) activities and oxidative stress status in soccer players. Forty soccer players were randomly assigned in a double-blind fashion to Asx and placebo (P) group. Blood samples were obtained before, 45 and 90 days after supplementation. PON1 activity was assessed by using two substrates: paraoxon and diazoxon. The oxidative stress biomarkers were also examined: total sulphydryl group content (-SH groups), thiobarbituric acid-reactive substances (TBARS), advanced oxidation protein products and redox balance. The significant interaction effect of supplementation and training (p < 0.05) on PON1 activity toward paraoxon was observed. The PON1 activity toward diazoxon increased in Asx group after 90 days (p < 0.01), while there was no significant difference in P group. SH groups content rose from pre- to post-supplementation period only in Asx group (supplementation and training, p < 0.05; training, p < 0.01). TBARS levels decreased after 45 days and increased after 90 days of regular soccer training in both groups (training, p < 0.001). Redox balance decreased significantly in response to the regular training, regardless of treatment group (training, p < 0.001). Asx supplementation might increase total SH groups content and improve PON1 activity through protection of free thiol groups against oxidative modification.

Acute effects of resistance exercise and intermittent intense aerobic exercise on blood cell count and oxidative stress in trained middle-aged women

The aim of this study was to compare the effect of an intermittent intense aerobic exercise session and a resistance exercise session on blood cell counts and oxidative stress parameters in middle-aged women. Thirty-four women were selected and divided into three groups: RE group (performing 60 min of resistance exercises, N = 12), spinning group (performing 60 min of spinning, N = 12), and control group (not exercising regularly, N = 10). In both exercise groups, lymphocytes and monocytes decreased after 1-h recuperation (post-exercise) compared to immediately after exercise (P < 0.05). Immediately after exercise, in both exercised groups, a significant increase in TBARS (from 16.5 ± 2 to 25 ± 2 for the spinning group and from 18.6 ± 1 to 28.2 ± 3 nmol MDA/mL serum for the RE group) and protein carbonyl (from 1.0 ± 0.3 to 1.6 ± 0.2 for the spinning group and from 0.9 ± 0.2 to 1.5 ± 0.2 nmol/mg protein for the RE group) was observed (P < 0.05). A decrease in antioxidant activities (non-protein sulfhydryl, superoxide dismutase, catalase) was also demonstrated with a negative correlation between damage markers and antioxidant body defenses (P < 0.05). These results indicate that an acute bout of intermittent or anaerobic exercise induces immune suppression and increases the production of reactive oxygen species, causing oxidative stress in middle-aged and trained women. Furthermore, we demonstrated that trained women show improved antioxidant capacity and lower oxidative damage than sedentary ones, demonstrating the benefits of chronic regular physical activity.

Influence of nutrient intake on antioxidant capacity, muscle damage and white blood cell count in female soccer players

Background

Soccer is a form of exercise that induces inflammatory response, as well as an increase in free radicals potentially leading to muscle injury. Balanced nutritional intake provides important antioxidant vitamins, including vitamins A, C and E, which may assist in preventing exercise-related muscle damage. The purpose of the present study was to determine the effect of macro/micronutrient intake on markers of oxidative stress, muscle damage, inflammatory and immune response in female soccer players.

Methods

Twenty-eight female players belonging to two soccer teams of the same professional soccer club participated in this study after being informed about the aims and procedures and after delivering written consent. Each team completed an 8-day dietary record and played one competition match the same week. Participants were divided into two groups: the REC group (who complied with recommended intakes) and the NO-REC group (who were not compliant). Laboratory blood tests were carried out to determine hematological, electrolytic and hormonal variables, as well as to monitor markers of cell damage and oxidative stress. Blood samples were obtained 24 h before, immediately after and 18 h after official soccer matches. Student t-test or Mann–Whitney U-test was used to compare both groups throughout the match.

Results

At rest, we observed that the REC group had higher levels of total antioxidant status (TAS), glutathione peroxidase (GPx), and lower levels of creatine kinase (CK) and lactate dehydrogenase (LDH) in comparison to the NO-REC group. Immediately after the match, levels of TAS, GPx, superoxide dismutase (SOD), LDH and % lymphocytes were higher and the % of neutrophils were lower in the REC group compared to the NO-REC group. These differences were also maintained 18 h post-match, only for TAS and GPx.

Conclusions

Our data reveal an association between nutritional intake and muscle damage, oxidative stress, immunity and inflammation markers. The benefit of the intake of specific nutrients may contribute to preventing the undesirable physiological effects provoked by soccer matches.

Iron and vitamin status biomarkers and its association with physical fitness in adolescents: the HELENA study

There is a lack of studies that analyze the association between micronutrient-related biomarker status and physical fitness in adolescents. In the present study, biochemical parameters for iron and vitamin status were studied, along with objective measures of physical fitness in healthy male and female European adolescents. One thousand eighty-nine adolescents (580 girls, 12.5-17.5 yr) from the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) cross-sectional study were included. Hierarchical linear models were performed to determine the associations between micronutrient biomarkers and physical fitness. Age, seasonality, latitude, body mass index, menarche (in girls), and physical activity were used as covariates. For cardiorespiratory fitness, concentrations of hemoglobin, retinol, and vitamin C in male adolescents and β-carotene and 25(OH)D in female adolescents were associated with maximal oxygen consumption. For muscular fitness, concentrations of hemoglobin, β-carotene, retinol, and α-tocopherol in male adolescents and β-carotene and 25(OH)D in female adolescents were associated with better performance of the standing long jump test. In summary, concentrations of hemoglobin and most antioxidant vitamins in male adolescents and β-carotene and 25(OH)D in female adolescents were positively associated with cardiorespiratory and muscular fitness, after controlling for relevant confounders. The associations between physical fitness and iron or vitamin status observed in this cross-sectional study in adolescents should be followed up by a study specifically designed to evaluate causal relationships.

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.

Antioxidant supplementation does not alter endurance training adaptation

BACKGROUND

There is a considerable commercial market, especially within the sports community, claiming the need for antioxidant supplementation. One argument for antioxidant supplementation in sports is that physical exercise is associated with increased reactive oxygen and nitrogen species (RONS) production, which may cause cell damage. However, RONS production may also activate redox-sensitive signaling pathways and transcription factors, which subsequently, may promote training adaptation.

PURPOSE

Our aim was to investigate the effects of combined vitamin C and E supplementation to healthy individuals on different measures of exercise performance after endurance training.

METHODS

Using a double-blinded placebo-controlled design, moderately trained young men received either oral supplementation with vitamins C and E (n = 11) or placebo (n = 10) before and during 12 wk of supervised, strenuous bicycle exercise training of a frequency of 5 d x wk(-1). Muscle biopsies were obtained before and after training.

RESULTS

After the training period, maximal oxygen consumption, maximal power output, and workload at lactate threshold increased markedly (P < 0.01) in both groups. Also, glycogen concentration, citrate synthase, and beta-hydroxyacyl-CoA dehydrogenase activity in the muscle were significantly higher in response to training (P < 0.01) in both groups. However, there were no differences between the two groups concerning any of the physiological and metabolic variables measured.

CONCLUSIONS

Our results suggest that administration of vitamins C and E to individuals with no previous vitamin deficiencies has no effect on physical adaptations to strenuous endurance training.

Effect of beta-alanine supplementation on the onset of blood lactate accumulation (OBLA) during treadmill running: Pre/post 2 treatment experimental design

Background

β-Alanine (βA) has been shown to improve performance during cycling. This study was the first to examine the effects of βA supplementation on the onset of blood lactate accumulation (OBLA) during incremental treadmill running.

Methods

Seventeen recreationally-active men (mean ± SE 24.9 ± 4.7 yrs, 180.6 ± 8.9 cm, 79.25 ± 9.0 kg) participated in this randomized, double-blind, placebo-controlled pre/post test 2-treatment experimental design. Subjects participated in two incremental treadmill tests before and after 28 days of supplementation with either βA (6.0 g·d^-1)(βA, n = 8) or an equivalent dose of Maltodextrin as the Placebo (PL, n = 9). Heart rate, percent heart rate maximum (%HRmax), %VO_2max@OBLA (4.0 mmol.L^-1 blood lactate concentration) and VO_2max (L.min^-1) were determined for each treadmill test. Friedman test was used to determine within group differences; and Mann-Whitney was used to determine between group differences for pre and post values (p < 0.05).

Results

The βA group experienced a significant rightward shift in HR@OBLA beats.min^-1 (p < 0.01) pre/post (161.6 ± 19.2 to 173.6 ± 9.9) but remained unchanged in the PL group (166.8 ± 15.8 to 169.6 ± 16.1). The %HRmax@OBLA increased (p < 0.05) pre/post in the βA group (83.0% ± 9.7 to 88.6% ± 3.7) versus no change in the PL group (86.3 ± % 4.8 to 87.9% ± 7.2). The %VO_2max@OBLA increased (p < 0.05) in the βA group pre/post (69.1 ± 11.0 to 75.6 ± 10.7) but remained unchanged in the PL group (73.3 ± 7.3 to 74.3 ± 7.3). VO_2max (L.min^-1) decreased (p < 0.01) in the βA group pre/post (4.57 ± 0.8 to 4.31 ± 0.8) versus no change in the PL group (4.04 ± 0.7 to 4.18 ± 0.8). Body mass kg increased (p < 0.05) in the βA group pre/post (77.9 ± 9.0 to 78.3 ± 9.3) while the PL group was unchanged (80.6 ± 9.1 to 80.4 ± 9.0).

Conclusions

βA supplementation for 28 days enhanced sub-maximal endurance performance by delaying OBLA. However, βA supplemented individuals had a reduced aerobic capacity as evidenced by the decrease in VO_2max values post supplementation.

Oxidative stress in the hippocampus during experimental seizures can be ameliorated with the antioxidant ascorbic acid

Ascorbic acid has many nonenzymatic actions and is a powerful water-soluble antioxidant. It protects low density lipoproteins from oxidation and reduces harmful oxidants in the central nervous system. Pilocarpine-induced seizures have been suggested to be mediated by increases in oxidative stress. Current studies have suggested that antioxidant compounds may afford some level of neuroprotection against the neurotoxicity of seizures. The objective of the present study was to evaluate the neuroprotective effects of ascorbic acid (AA) in rats, against the observed oxidative stress during seizures induced by pilocarpine. Wistar rats were treated with 0.9% saline (i.p., control group), ascorbic acid (500 mg/kg, i.p., AA group), pilocarpine (400 mg/kg, i.p., pilocarpine group), and the association of ascorbic acid (500 mg/kg, i.p.) plus pilocarpine (400 mg/kg, i.p.), 30 min before of administration of ascorbic acid (AA plus pilocarpine group). After the treatments all groups were observed for 6h. The enzyme activities as well as the lipid peroxidation and nitrite concentrations were measured using spectrophotometric methods and the results compared to values obtained from saline and pilocarpine-treated animals. Protective effects of ascorbic acid were also evaluated on the same parameters. In pilocarpine group there was a significant increase in lipid peroxidation and nitrite level. However, no alteration was observed in superoxide dismutase and catalase activities. Antioxidant treatment significantly reduced the lipid peroxidation level and nitrite content as well as increased the superoxide dismutase and catalase activities in hippocampus of adult rats after seizures induced by pilocarpine. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, proving that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, and also imply that a strong protective effect could be achieved using ascorbic acid.

Effects of tocotrienol-rich fraction on exercise endurance capacity and oxidative stress in forced swimming rats

The present study aimed to examine the effects of tocotrienol-rich fraction (TRF) on exercise endurance and oxidative stress in forced swimming rats. Rats fed on isocaloric diet were orally given 25 (TRF-25) and 50 (TRF-50) mg/kg of TRF, or 25 mg/kg D-alpha-tocopherol (T-25) whilst the control group received only the vehicle for 28 days, followed by being forced to undergo swimming endurance tests, with measurements taken of various biochemical parameters, including blood glucose, lactate and urea nitrogen, glycogen, total antioxidant capacity, antioxidant enzymes, thiobarbituric acid-reactive substances (TBARS), and protein carbonyl. Results showed that the TRF-treated animals (268.0 +/- 24.1 min for TRF-25 and 332.5 +/- 24.3 min for TRF-50) swam significantly longer than the control (135.5 +/- 32.9 min) and T-25-treated (154.1 +/- 36.4 min) animals, whereas there was no difference in the performance between the T-25 and control groups. The TRF-treated rats also showed significantly higher concentrations of liver glycogen, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as of muscle glycogen and SOD than the control and the T-25-treated animals, but lower levels in blood lactate, plasma and liver TBARS, and liver and muscle protein carbonyl. Taken together, these results suggest that TRF is able to improve the physiological condition and reduce the exercise-induced oxidative stress in forced swimming rats.

Níveis comparativos de estresse oxidativo em camundongos em duas situações do limite orgânico: overreaching induzido por treinamento de natação e câncer

O objetivo deste trabalho foi comparar concentrações de estresse oxidativo em camundongos da linhagem Balb-C submetidos a duas condições severas de alterações orgânicas: treinamento exaustivo de natação (overreaching - grupo OVER; n = 10) e inoculação por tumor ascítico de Ehrlich (grupo TAE; n = 10). A proposta foi analisar como as duas situações comprometiam o equilíbrio entre os sistemas oxidantes e antioxidantes. Foram investigados alguns marcadores de estresse oxidativo, tais como as substâncias reativas ao ácido tiobarbitúrico (TBARS) e concentrações da atividade da enzima antioxidante catalase (CAT) no hemolisado. Como marcadores de lesão celular, quantificaram-se concentrações plasmáticas das enzimas creatina quinase (CK) e aspartato transferase (AST); complementado; também se observaram padrões de alterações fisiológicas por meio da quantificação plasmática de creatinina e uréia. Como resultados mais importantes, pôde-se observar que, nas duas situações de limite orgânico, seja por exercício exaustivo (OVER) ou pela inoculação de TAE, houve queda abrupta na concentração da enzima CAT (decréscimos de 30%; p < 0,01 e 72%; p < 0,001, respectivamente, comparando-se com o grupo treinado - T). Quanto à concentração de peroxidação lipídica (TBARS), detectaram-se aumentos significativos para os grupos OVER e TAE em relação ao grupo T (52%, p < 0,01; 90%, p < 0,001, respectivamente). Níveis liberados de CK foram mais proeminentes no grupo OVER, enquanto que a quantidade de AST no plasma foi mais elevada no grupo TAE. Chegou-se à conclusão de que os organismos estudados possuem um mesmo perfil de estresse oxidativo em situações limites que envolvem exercício físico e doença. Tais resultados permitirão profissionais envolvidos com elaboração das cargas de treinamento físico a se preocuparem com os períodos recuperativos, o que impede a instalação do quadro de overreaching, o qual se mostrou tão severo, em termos de estresse oxidativo, quanto o de uma situação patológica.