Effect of alpha-tocopherol supplementation on plasma homocysteine and oxidative stress in highly trained athletes before and after exhaustive exercise

Micronutrients and athletic performance: A review

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

Management of Oxidative Stress: Crosstalk Between Brown/Beige Adipose Tissues and Skeletal Muscles

Exercise plays an important role in the physiology, often depending on its intensity, duration, and frequency. It increases the production of reactive oxygen species (ROS). Meanwhile, it also increases antioxidant enzymes involved in the oxidative damage defense. Prolonged, acute, or strenuous exercise often leads to an increased radical production and a subsequent oxidative stress in the skeletal muscles, while chronic regular or moderate exercise results in a decrease in oxidative stress. Notably, under pathological state, such as obesity, aging, etc., ROS levels could be elevated in humans, which could be attenuated by proper exercise. Significantly, exercise stimulates the development of beige adipose tissue and potentially influence the function of brown adipose tissue (BAT), which is known to be conducive to a metabolic balance through non-shivering thermogenesis (NST) and may protect from oxidative stress. Exercise-related balance of the ROS levels is associated with a healthy metabolism in humans. In this review, we summarize the integrated effects of exercise on oxidative metabolism, and especially focus on the role of brown and beige adipose tissues in this process, providing more evidence and knowledge for a better management of exercise-induced oxidative stress.

Effects of Vitamin E and Coenzyme Q10 Supplementation on Oxidative Stress Parameters in Untrained Leisure Horses Subjected to Acute Moderate Exercise

The effects of antioxidant supplements on exercise-induced oxidative stress have not been investigated in untrained leisure horses. We investigated the effects of 14-day supplementation with vitamin E (1.8 IU/kg/day), coenzyme Q₁₀ (CoQ₁₀; ubiquinone; 800 mg/day), and a combination of both (the same doses as in mono-supplementation) on the blood levels of CoQ₁₀, vitamin E, and oxidative stress parameters in untrained leisure horses subjected to acute moderate exercise. Correlations between lipid peroxidation and muscle enzyme leakage were also determined. Forty client-owned horses were included in the study, with 10 horses in each of the antioxidant and placebo (paraffin oil) groups. Blood parameters were measured before supplementation, before and immediately after exercise, and after 24 h of rest. The differences in individual parameters between blood collection times and groups were analysed with linear mixed models (p ˂ 0.05). None of the supplemented antioxidants affected vitamin E and CoQ₁₀ concentrations, oxidative stress parameters, or serum muscle enzymes. Lipid peroxidation occurred in horses supplemented with placebo and CoQ₁₀ but not in horses supplemented with vitamin E or the combination of both antioxidants. These results suggest that vitamin E alone or in combination with CoQ₁₀ prevented lipid peroxidation in untrained leisure horses subjected to acute moderate exercise.

Antioxidant supplements and endurance exercise: Current evidence and mechanistic insights

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

ameliorates exhaustive exercise-induced fatigue in mice by suppressing mitophagy in skeletal muscle

The aim of present study was to evaluate the potential effects of Rhodiola crenulata oral liquid (RCOL) on exhaustive exercise (EE)-induced fatigue in mice. Male Institute of Cancer Research mice from five treatment groups (n=10 per group) were orally administered with sterilized water for the Control and EE groups and/or RCOL at doses of 1.02, 3.03 and 6.06 ml/kg/day, once daily for 2 weeks. Anti-fatigue activity was subsequently evaluated by measuring the levels of creatine kinase (CK), lactic acid (LA), lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and total anti-oxidative capability (T-AOC). Histopathology was assessed using hematoxylin and eosin staining. Ultrastructures of mitochondria were observed by transmission electron microscopy. Energy supply capacity was assessed using citrate synthase (CS), succinate dehydrogenase (SDH), Na⁺-K⁺-ATPase, and liver and quadriceps glycogen content assays. Expression levels of mRNA and protein associated with mitophagy in the skeletal muscle were measured by reverse transcription-quantitative PCR and western blotting, respectively. RCOL was observed to markedly inhibit fatigue-induced oxidative stress by increasing the activities of SOD, CAT and T-AOC, whilst reducing the accumulation of LA, CK, LDH and MDA. Histological analysis of the quadriceps femoris tissue suggested increased numbers of muscle fibers in the RCOL groups compared with those in the EE group. RCOL administration was found to reverse EE-induced mitochondrial structural damage and alleviated defects inflicted onto the energy supply mechanism by increasing CS, SDH, Na⁺-K⁺-ATPase and glycogen levels. Additionally, RCOL reduced the protein expression of PTEN-induced kinase 1 (PINK1), Parkin, microtubule-associated proteins 1A/1B light chain 3, sequestosome 1 and ubiquitin, whilst lowering the gene expression of PINK1 and Parkin. Taken together, results from the present study clarified the anti-fatigue effect of RCOL, where the underlying mechanism may be associated with increased antioxidant activity, enhanced energy production and the inhibition of mitophagy by suppressing the PINK1/Parkin signaling pathway.

Total Dietary Antioxidant Intake Including Polyphenol Content: Is it Capable to Fight against Increased Oxidants within the Body of Ultra-Endurance Athletes?

The role of dietary antioxidants on exhaustive exercise-induced oxidative stress has been well investigated. However, the contribution of total dietary antioxidant capacity on exogenous antioxidant defense and exercise performance has commonly been disregarded. The aims of the present investigation were to examine (i) the effects of dietary total antioxidant intake on body antioxidant mechanisms, and (ii) an exhaustive exercise-induced oxidative damage in ultra-endurance athletes. The study included 24 ultra-marathon runners and long-distance triathletes (12 male and 12 female) who underwent an acute exhaustive exercise test (a cycle ergometer (45 min at 65% VO₂max) immediately followed by a treadmill test (75% VO₂max to exhaustion). Oxidative stress-related biomarkers (8-isoprostaglandin F2alpha (8-iso PGF2a), total oxidant status (TOS, total antioxidant status (TAS)) in plasma were collected before and after exercise. Oxidative stress index was calculated to assess the aspect of redox balance. Blood lactate concentrations and heart rate were measured at the 3rd and 6th min after exercise. Dietary antioxidant intake was calculated using the ferric reducing ability of plasma (FRAP) assay. Dietary total antioxidant intake of the subjects was negatively correlated with pre-exercise TOS concentrations (rs = -0.641 in male, and rs = -0.741 in females) and post- vs. pre- (∆) 8-iso PGF2a levels (rs = -0.702 in male; p = 0.016, and rs = -0.682 in females; p = 0.024), and positively correlated with ∆ TAS concentrations (rs = 0.893 in males; p = 0.001, and rs = 0.769 in females; p = 0.002) and post- exercise lactate concentrations (rs = 0.795 for males; p = 0.006, and rs = 0.642 for females; p = 0.024). A positive meaningful (p = 0.013) interaction was observed between time at exhaustion and dietary antioxidant intake (rs = 0.692) in males, but not in females. In conclusion, the determination of total dietary antioxidant intake in ultra-endurance athletes may be crucial for gaining a better perspective on body antioxidant defense against exhaustive exercise-induced oxidative stress. However, the effects of dietary antioxidant on exercise performance and recovery rate needs further investigation.

Effects of Dietary or Supplementary Micronutrients on Sex Hormones and IGF-1 in Middle and Older Age: A Systematic Review and Meta-Analysis

Observational research suggests that micronutrients may be protective for sarcopenia, a key health issue during ageing, potentially via effects on hormone synthesis and metabolism. We aimed to carry out a systematic review of RCTs investigating effects of increasing dietary or supplemental micronutrient intake on sex hormones and IGF-1 in individuals aged 45 years or older. We searched MEDLINE, EMBASE and Cochrane databases for RCTs reporting the effects of different micronutrients (vitamins A, C, D, or E; carotenoids; iron; copper; zinc; magnesium; selenium; and potassium) on sex hormones or IGF-1. Of the 26 RCTs identified, nine examined effects of vitamin D, nine of multi-nutrients, four of carotenoids, two of selenium, one of zinc, and one of vitamin E. For IGF-1 increasing vitamin D (MD: −0.53 nmol/L, 95% CI: −1.58, 0.52), multi-nutrients (MD: 0.60 nmol/L, 95% CI −1.12 to 2.33) and carotenoids (MD −1.32 nmol/L; 95% CI −2.76 to 0.11) had no significant effect on circulating concentrations. No significant effects on sex hormones of other micronutrients were found, but data were very limited. All trials had significant methodological limitations making effects of micronutrient supplementation on sex hormones unclear. Further high quality RCTs with physiological doses of micronutrients in people with low baseline intakes or circulating concentrations, using robust methodology, are required to assess effects of supplementation adequately.

Potential Role of Tocotrienols on Non-Communicable Diseases: A Review of Current Evidence

Tocotrienol (T3) is a subfamily of vitamin E known for its wide array of medicinal properties. This review aimed to summarize the health benefits of T3, particularly in prevention or treatment of non-communicable diseases (NCDs), including cardiovascular, musculoskeletal, metabolic, gastric, and skin disorders, as well as cancers. Studies showed that T3 could prevent various NCDs, by suppressing 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) in the mevalonate pathway, inflammatory response, oxidative stress, and alternating hormones. The efficacy of T3 in preventing/treating these NCDs is similar or greater compared to tocopherol (TF). TF may lower the efficacy of T3 because the efficacy of the combination of TF and T3 was lower than T3 alone in some studies. Data investigating the effects of T3 on osteoporosis, arthritis, and peptic ulcers in human are limited. The positive outcomes of T3 treatment obtained from the preclinical studies warrant further validation from clinical trials.

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.

Exogenous Plant-Based Nutraceutical Supplementation and Peripheral Cell Mononuclear DNA Damage Following High Intensity Exercise

Plant-based nutraceuticals are categorised as nutritional supplements which contain a high concentration of antioxidants with the intention of minimising the deleterious effect of an oxidative insult. The primary aim of this novel study was to determine the effect of exogenous barley-wheat grass juice (BWJ) on indices of exercise-induced oxidative stress. Ten (n = 10) apparently healthy, recreationally trained (V̇O_2max 55.9 ± 6 mL&middot;kg^&minus;1&middot;min^&minus;1), males (age 22 ± 2 years, height 181 ± 6 cm, weight 87 ± 8 kg, body mass index (BMI) 27 ± 1) volunteered to participant in the study. In a randomised, double-blinded, placebo-controlled crossover design, participants consumed either a placebo, a low dose (70 mL per day) of BWJ, or a high dose (140 mL per day) of BWJ for 7-days. Experimental exercise consisted of a standard maximal oxygen uptake test until volitional fatigue. DNA damage, as assessed by the single cell gel electrophoresis comet assay, increased following high intensity exercise across all groups (time &times; group; p < 0.05, Effect Size (ES) = 0.7), although there was no selective difference for intervention (p > 0.05). There was a main effect for time in lipid hydroperoxide concentration (pooled-group data, pre- vs. post-exercise, p < 0.05, ES = 0.2) demonstrating that exercise increased lipid peroxidation. Superoxide dismutase activity (SOD) increased by 44.7% following BWJ supplementation (pooled group data, pre- vs. post). The ascorbyl free radical (p < 0.05, ES = 0.26), &alpha;-tocopherol (p = 0.007, ES = 0.2), and xanthophyll (p = 0.000, ES = 0.5), increased between the pre- and post-exercise time points indicating a main effect of time. This study illustrates that a 7-day supplementation period of a novel plant-derived nutraceutical product is insufficient at attenuating exercise-induced oxidative damage. It is possible that with a larger sample size, and longer supplementation period, this novel plant-based nutraceutical could potentially offer effective prophylaxis against exercise-induced oxidative stress; as such, this justifies the need for further research.

Comparison of the effects of two antioxidant diets on oxidative stress markers in triathletes

Intense exercise generates an imbalance in the redox system. However, chronic exercise can yield antioxidant adaptations. A few studies with humans have investigated the effects of antioxidant diets on athletes. Therefore we compared the effects of two dietary interventions on oxidative stress in competitive triathletes. Thirteen male triathletes were selected and divided into 2 groups: one that had a regular antioxidant diet (RE-diet) and the other that had a high antioxidant diet (AO-diet). The diet period was 14 days and blood samples were collected before and after this period. The AO-diet provided twice the dietary reference intake (DRI) of α-tocopherol (30 mg), five times the DRI of ascorbic acid (450 mg), and twice the DRI of vitamin A (1800 g), while the RE-diet provided the DRI of α-tocopherol (15 mg), twice the DRI of ascorbic acid (180 mg) and the DRI of vitamin A (900 μg). The oxidative stress parameters evaluated were: thiobarbituric acid reactive substances (TBARS), total reactive antioxidant potential (TRAP), total sulfhydryl, carbonyl, superoxide dismutase (SOD) activity, hydrogen peroxide consumption and glutathione peroxidase (GPx) activity. We observed, after the diet period, an increase in sulfhydryl, TRAP, TBARS and SOD activity, and a decrease in carbonyl levels. However, no changes were found in hydrogen peroxide consumption or GPx activity. We concluded that antioxidant-enriched diets can improve the redox status of triathletes.

Effect of α-tocopherol megadoses on hematologic parameters and antioxidant capacity of rats in an ultraendurance probe

This study was aimed to analyze the effect of two different megadoses of α-tocopherol (vit E) in the antioxidant activity and red and white blood series of Wistar rats after a 180-min ultraendurance probe. Three groups of 10 rats were analyzed; VEAG: acute administration of a megadoses of 5,000 IU/kg of vit E the day before the probe; VECG: chronic administration of 1,000 IU/kg/day of vit E for 6 days before the probe; CG: placebo administration. VEAG presented white cells, red blood cells, hematocrit, hemoglobin values significantly higher than CG and VECG (p < 0.05). The mean corpuscular hemoglobin and lymphocytes concentrations were significantly higher in the VECG than in the other two groups (p < 0.05). Similarly, VEAG presented a significantly higher vit E blood concentration than VECG and CG (p < 0.05), and VECG than CG (p < 0.05). Finally, we found a significantly positive correlation between trolox equivalent antioxidant capacity (TEAC) and red blood cells concentration (r = 0.374) and a significantly inverse correlation between TEAC and blood lactate concentration (r = -0.365). Our findings suggest that acute vit E megadoses could protect against transitory sport anemia symptoms and increase the white blood cell count in comparison with the chronic dose and control groups after an ultraendurance probe.

Effect of exercise-induced dehydration on circulatory markers of oxidative damage and antioxidant capacity

Dehydration is a common event associated with exercise. However, few studies have examined the effects of dehydration on plasma redox status in humans. Eighty-two athletes were recruited and baseline anthropometrics and blood samples were obtained. Athletes then engaged in a dehydration protocol, training until 3% of preweight body mass was lost. Athletes returned to the lab and had postdehydration blood collected. Athletes then consumed an isotonic drink until pre-exercise body weight was reestablished. Blood was then recollected (1 h post full rehydration (PFR)). Samples were centrifuged and the plasma snap frozen in liquid nitrogen and stored at −80 °C. Lipid and protein oxidative stress was determined by measuring F2-isoprostanes and protein carbonyls (PC), respectively. Antioxidant capacity was determined by the ferric reducing ability of plasma (FRAP) and trolox equivalent antioxidant capacity (TEAC) assays. Plasma osmolality was determined using an osmometer. Statistical analysis utilized a 1-way ANOVA with posthoc testing. Values are reported as mean ± SD. Plasma osmolality was significantly elevated immediately postdehydration (p ≤ 0.001) but decreased to baseline at PFR. Plasma TEAC increased immediately postdehydration and at PFR (p ≤ 0.001). FRAP increased immediately postdehydration (p ≤ 0.001) and decreased to below baseline at PFR (p ≤ 0.05). Conversely, F2-isoprostanes declined significantly from baseline to immediately postdehydration and then significantly rose at PFR (p ≤ 0.001), whereas PC declined at PFR (p ≤ 0.01). This study indicates that dehydration and exercise cause a significant increase in plasma osmolality and antioxidant potential immediately postexercise. We propose dehydration significantly elevates antioxidant concentration which suppresses F2-isoprostanes and PC.

α-Tocopherol supplementation and the oxidative stress, homocysteine, and antioxidants in lead exposure

To investigate whether α-tocopherol supplementation in workers exposed to lead would reduce the oxidative stress intensity and decrease homocysteine level, the examined population was randomly divided into two groups. Workers in the first group (n = 49, reference group) were not administered any drugs. Workers in the second group (n = 34) were administered orally α-tocopherol, 200 mg per day for 12 weeks. The level of α-tocopherol significantly increased compared to the baseline and the reference group. The level of thiol groups significantly increased compared to the reference group. However, the levels of malondialdehyde and homocysteine did not significantly change. Animal studies suggest the ability of α-tocopherol administration to reverse adverse health effects of lead exposure, such as oxidative stress; however, the results of this study on humans do not confirm these protective effects.

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.

The Effects of Acute Exercise and Exercise Training on Plasma Homocysteine: A Meta-Analysis

Background

Although studies have demonstrated that physical exercise alters homocysteine levels in the blood, meta-analyses of the effects of acute exercise and exercise training on homocysteine blood concentration have not been performed, especially regarding the duration and intensity of exercise, which could affect homocysteine levels differently.

Objective

The aim of this meta-analysis was to ascertain the effects of acute exercise and exercise training on homocysteine levels in the blood.

Method

A review was conducted according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses using the online databases PubMed, SPORTDiscus, and SciELO to identify relevant studies published through June 2015. Review Manager was used to calculate the effect size of acute exercise and exercise training using the change in Hcy plasmaserum concentration from baseline to post-acute exercise and trained vs. sedentary control groups, respectively. Weighted mean differences were calculated using random effect models.

Results

Given the abundance of studies, acute exercise trials were divided into two subgroups according to exercise volume and intensity, whereas the effects of exercise training were analyzed together. Overall, 22 studies with a total of 520 participants indicated increased plasma homocysteine concentration after acute exercise (1.18 μmol/L, 95% CI: 0.71 to 1.65, p < .01). Results of a subgroup analysis indicated that either long-term exercise of low-to-moderate intensity (1.39 μmol/L, 95% CI: 0.9 to 1.89, p < .01) or short-term exercise of high intensity (0.83 μmol/L, 95% CI: 0.19 to 1.40, p < .01) elevated homocysteine levels in the blood. Increased homocysteine induced by exercise was significantly associated with volume of exercise, but not intensity. By contrast, resistance training reduced plasma homocysteine concentration (-1.53 μmol/L, 95% CI: -2.77 to -0.28, p = .02), though aerobic training did not. The cumulative results of the seven studies with a total of 230 participants in exercise training analysis did not demonstrate a significant impact on homocysteine levels in the blood (-0.56 μmol/L, 95% CI: -1.61 to 0.50, p = .23).

Conclusions

Current evidence demonstrates that acute exercise increases homocysteine levels in the blood independent of exercise duration and intensity. Resistance, but not aerobic training decreases plasma homocysteine levels.

Effectiveness of a superoxide dismutase supplement derived from melon extract as a recovery aid for horses following strenuous exercise

An antioxidant derived from a variety of melon purported to be high in superoxide dismutase was fed to horses and the effect on performance and recovery was measured following repeated daily bouts of intense exercise. In a cross-over design study, six unfit Standardbred mares were fed this antioxidant at a rate of 2.0 IU/kg body weight (BW)/d as part of the daily ration for 4 weeks before undergoing a simulated race test (SRT) repeated over a 3-day period. The SRT, designed to simulate the training of Standardbreds, consisted of a 2 min warm-up at 6 m/s followed by a high speed run to fatigue at 125% of the speed calculated to correspond to the horse’s maximal aerobic capacity (VO2max) as determined in a baseline incremental exercise test. Measurements included VO2 and the VO2 recovery time, VO2 at the point of recovery, run time, as well as plasma lactate, and plasma cortisol. Oxidative stress was measured by assessing malondialdehyde (MDA). The results from the study demonstrated that there were no differences (P>0.05) in mean values for the plasma concentrations of lactate, cortisol, or MDA. However, when supplemented with this antioxidant, there was an observable pattern with a small-to-medium effect size of an increase average run time of 14 s. Another important observation was that despite the longer run time, there was a moderate effect for a faster VO2 recovery time. The data suggest that supplementation with 2.0 IU/kg BW of this antioxidant had a modest but non-significant effect on performance and recovery time. Additionally, it did not negatively impact physiology in untrained Standardbred mares.

Effects of powdered Montmorency tart cherry supplementation on an acute bout of intense lower body strength exercise in resistance trained males

Background

The purpose of this study was to examine whether short-term ingestion of a powdered tart cherry supplement prior to and following intense resistance-exercise attenuates muscle soreness and recovery strength loss, while reducing markers of muscle damage, inflammation, and oxidative stress.

Methods

Twenty-three healthy, resistance-trained men (20.9 ± 2.6 yr, 14.2 ± 5.4 % body fat, 63.9 ± 8.6 kg FFM) were matched based on relative maximal back squat strength, age, body weight, and fat free mass. Subjects were randomly assigned to ingest, in a double blind manner, capsules containing a placebo (P, n = 12) or powdered tart cherries [CherryPURE^®] (TC, n = 11). Participants supplemented one time daily (480 mg/d) for 10-d including day of exercise up to 48-h post-exercise. Subjects performed ten sets of ten repetitions at 70 % of a 1-RM back squat exercise. Fasting blood samples, isokinetic MVCs, and quadriceps muscle soreness ratings were taken pre-lift, 60-min, 24-h, and 48-h post-lift and analyzed by MANOVA with repeated measures.

Results

Muscle soreness perception in the vastus medialis (¼) (p = 0.10) and the vastus lateralis (¼) (p = 0.024) was lower in TC over time compared to P. Compared to pre-lift, TC vastus medialis (¼) soreness was significantly attenuated up to 48-h post-lift with vastus lateralis (¼) soreness significantly lower at 24-h post-lift compared to P. TC changes in serum creatinine (p = 0.03, delta p = 0.024) and total protein (p = 0.018, delta p = 0.006) were lower over time and smaller from pre-lift levels over time compared to P Significant TC group reductions from pre-lift levels were found for AST and creatinine 48-h post-lift, bilirubin and ALT 60-min and 48-h post-lift. No significant supplementation effects were observed for serum inflammatory or anti-inflammatory markers. None of the free radical production, lipid peroxidation, or antioxidant capacity markers (NT, TBARS, TAS, SOD) demonstrated significant changes with supplementation. Changes in TC whole blood lymphocyte counts (p = 0.013) from pre-lift were greater compared to P, but TC lymphocyte counts returned to pre-lift values quicker than P.

Conclusion

Short-term supplementation of Montmorency powdered tart cherries surrounding a single bout of resistance exercise, appears to be an effective dietary supplement to attenuate muscle soreness, strength decrement during recovery, and markers of muscle catabolism in resistance trained individuals.

Palm tocotrienol-rich fraction inhibits methionine-induced cystathionine β-synthase in rat liver

Oxidative stress plays an important role in cardiovascular diseases. The study investigated the effects of dietary palm tocotrienol-rich fraction on homocysteine metabolism in rats fed a high-methionine diet. Forty-two male Wistar rats were randomly assigned to six groups. Five groups were fed with high-methionine diet (1%) for 10 weeks. Groups 2 to 5 were also given dietary folate (8 mg/kg) and three doses of palm tocotrienol-rich fraction (30, 60 and 150 mg/kg) from week 6 to week 10. The last group was only given basal rat chow. High-methionine diet increased plasma homocysteine after 10 weeks, which was prevented by the supplementations of folate and high-dose palm tocotrienol-rich fraction. Hepatic S-adenosyl methionine (SAM) content was unaffected in all groups but S-adenosyl homocysteine (SAH) content was reduced in the folate group. Folate supplementation increased the SAM/SAH ratio, while in the palm tocotrienol-rich fraction groups, the ratio was lower compared with the folate. Augmented activity of hepatic cystathionine β-synthase and lipid peroxidation content by high-methionine diet was inhibited by palm tocotrienol-rich fraction supplementations (moderate and high doses), but not by folate. The supplemented groups had lower hepatic lipid peroxidation than the high-methionine diet. In conclusion, palm tocotrienol-rich fraction reduced high-methionine-induced hyperhomocysteinaemia possibly by reducing hepatic oxidative stress in high-methionine-fed rats. It may also exert a direct inhibitory effect on hepatic cystathionine β-synthase.

Alterations in redox homeostasis in the elite endurance athlete

BACKGROUND

The production of reactive oxygen (ROS) and nitrogen species (RNS) is a fundamental feature of mammalian physiology, cellular respiration and cell signalling, and essential for muscle function and training adaptation. Aerobic and anaerobic exercise results in alterations in redox homeostasis (ARH) in untrained, trained and well trained athletes. Low to moderate doses of ROS and RNS play a role in muscle adaptation to endurance training, but an overwhelming increase in RNS and ROS may lead to increased cell apoptosis and immunosuppression, fatigued states and underperformance.

OBJECTIVES

The objectives of this systematic review are: (a) to test the hypotheses that ARH occur in elite endurance athletes; following an acute exercise bout, in an endurance race or competition; across a micro-, meso- or macro-training cycle; following a training taper; before, during and after altitude training; in females with amenorrhoea versus eumenorrhoea; and in non-functional over-reaching (NFOR) and overtraining states (OTS); (b) to report any relationship between ARH and training load and ARH and performance; and (c) to apply critical difference values for measures of oxidative stress/ARH to address whether there is any evidence of ARH being of physiological significance (not just statistical) and thus relevant to health and performance in the elite athlete.

METHODS

Electronic databases, Embase, MEDLINE, and SPORTDiscus were searched for relevant articles. Only studies that were observational articles of cross-sectional or longitudinal design, and included elite athletes competing at national or international level in endurance sports were included. Studies had to include biomarkers of ARH; oxidative damage, antioxidant enzymes, antioxidant capacity, and antioxidant vitamins and nutrients in urine, serum, plasma, whole blood, red blood cells (RBCs) and white blood cells (WBCs). A total of 3,057 articles were identified from the electronic searches. Twenty-eight articles met the inclusion criteria and were included in the review.

RESULTS

ARH occurs in elite endurance athletes, after acute exercise, a competition or race, across training phases, and with natural or simulated altitude. A reduction in ARH occurs across the season in elite athletes, with marked variation around intensified training phases, between individuals, and the greatest disturbances (of physiological significance) occurring with live-high-train-low techniques, and in athletes competing. A relationship with ARH and performance and illness exists in elite athletes. There was considerable heterogeneity across the studies for the biomarkers and assays used; the sport; the blood sampling time points; and the phase in the annual training cycle and thus baseline athlete fitness. In addition, there was a consistent lack of reporting of the analytical variability of the assays used to assess ARH.

CONCLUSIONS

The reported biochemical changes around ARH in elite athletes suggest that it may be of value to monitor biomarkers of ARH at rest, pre- and post-simulated performance tests, and before and after training micro- and meso-cycles, and altitude camps, to identify individual tolerance to training loads, potentially allowing the prevention of non-functionally over-reached states and optimisation of the individual training taper and training programme.

Long-term oral feeding of lutein-fortified milk increases voluntary running distance in rats

To evaluate the effects of lutein-fortified milk administration on running exercise, a voluntary wheel-running model was performed in rats. Four-week-old F344 rats were administered test milk (10 mL/kg) daily following a 4-h fasting period, and their running distances were measured each day for a 9-week period. Total weekly running distance significantly increased from the sixth week until the end of the test period in lutein-supplemented rats (lutein-fortified milk administered) compared with control rats (vehicle administered). This increase was not apparent in rats administered lutein alone. In the lutein-fortified-milk exercise group compared with the sedentary control group, carnitine palitroyltransferase 1 (CPT-1), total AMP-activated protein kinase (tAMPK), and phosphorylated AMP-activated protein kinase (pAMPK) contents were significantly increased in the gastrocnemius muscle, with a concomitant decrease in triglyceride and total cholesterol levels in the blood and liver. Furthermore, the lutein level in blood of lutein-administered rats significantly decreased with exercise. These results suggest that lutein-fortified milk may enhance the effect of exercise by effective utilization of lipids when combined with voluntary running.

Reductive stress after exercise: The issue of redox individuality

Exercise has been consistently used as an oxidant stimulus in redox biology studies. However, previous studies have focused on group differences and did not examine individual differences. As a result, it remains untested whether all individuals experience oxidative stress after acute exercise. Therefore, the main aim of the present study was to investigate whether some individuals exhibit unexpected responses after an acute eccentric (i.e., muscle-damaging) exercise session. Ninety eight (N = 98) young men performed an isokinetic eccentric exercise bout with the knee extensors. Plasma, erythrocytes and urine samples were collected immediately before and 2 days post-exercise. Three commonly used redox biomarkers (F₂-isoprostanes, protein carbonyls and glutathione) were assayed. As expected, the two oxidant biomarkers (F₂-isoprostanes and protein carbonyls) significantly increased 2 days after exercise (46% and 61%, respectively); whereas a significant decrease in glutathione levels (by −21%) was observed after exercise. A considerable number of the participants exhibited changes in the levels of biomarkers in the opposite, unexpected direction than the group average. More specifically, 13% of the participants exhibited a decrease in F₂-isoprostanes and protein carbonyls and 10% of the participants exhibited an increase in glutathione levels. Furthermore, more than 1 out of 3 individuals exhibited either unexpected or negligible (from 0% to ± 5%) responses to exercise in at least one redox biomarker. It was also observed that the initial values of redox biomarkers are important predictors of the responses to exercise. In conclusion, although exercise induces oxidative stress in the majority of individuals, it can induce reductive stress or negligible stress in a considerable number of people. The data presented herein emphasize that the mean response to a redox stimulus can be very misleading. We believe that the wide variability (including the cases of reductive stress) described is not limited to the oxidant stimulus used and the biomarkers selected.

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Exercise may induce reductive stress instead of the expected oxidative stress.

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The initial values of biomarkers are major predictors of the responses to exercise.

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The mean response of a group to a redox stimulus can be misleading.

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

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

Palm tocotrienol-rich fraction improves vascular proatherosclerotic changes in hyperhomocysteinemic rats

This study investigated the effects of palm tocotrienol-rich fraction (TRF) on aortic proatherosclerotic changes in rats fed with a high methionine diet. Forty-two male Wistar rats were divided into six groups. The first group was the control (fed with a basal diet). Another five groups were fed with 1% methionine diet for 10 weeks. From week 6 onward, folate (8 mg/kg diet) or palm TRF (30, 60, and 150 mg/kg diets) was added into the diet of the last four rat groups, respectively. The high methionine diet raised the plasma total homocysteine and aortic lipid peroxidation, which were reduced by the palm TRF and folate supplementations. Plasma nitric oxide was reduced in the high methionine group compared to the control (3.72 ± 0.57 versus 6.65 ± 0.53 μmol/L, P < 0.05), which reduction was reversed by the palm TRF (60 and 150 mg/kg) and folate supplementations. The increased aortic vascular cell adhesion molecule-1 expression in the methionine group (2.58 ± 0.29) was significantly reduced by the folate (1.38 ± 0.18) and palm TRF at 150 mg/kg (1.19 ± 0.23). Palm TRF was comparable to folate in reducing high methionine diet-induced plasma hyperhomocysteinemia, aortic oxidative stress, and inflammatory changes in rats.

The effects of resistance training on cardiovascular disease risk factors in postmenopausal women: a randomized-controlled trial

Our aim was to determine the effects of resistance training on cardiovascular risk factors in postmenopausal women. Forty-five women were included in the study. Resistance exercises were done with an intensity of 60% of 1-Repetition Maximum, for 12 weeks. Heart rate, blood pressure, estimated peak VO(2), lipid profiles, and homocysteine levels were evaluated. There were significant time and group interactions for body mass index (p = .02), heart rate (p = .04), systolic blood pressure (p = .03), estimated mean peak VO(2) (p = .00), and total cholesterol (p = .00), but there were no interactions with other evaluated parameters. Resistance training has beneficial effects on particular cardiovascular risk factors in postmenopausal women.

Redox biology of exercise: an integrative and comparative consideration of some overlooked issues

The central aim of this review is to address the highly multidisciplinary topic of redox biology as related to exercise using an integrative and comparative approach rather than focusing on blood, skeletal muscle or humans. An attempt is also made to re-define ‘oxidative stress’ as well as to introduce the term ‘alterations in redox homeostasis’ to describe changes in redox homeostasis indicating oxidative stress, reductive stress or both. The literature analysis shows that the effects of non-muscle-damaging exercise and muscle-damaging exercise on redox homeostasis are completely different. Non-muscle-damaging exercise induces alterations in redox homeostasis that last a few hours post exercise, whereas muscle-damaging exercise causes alterations in redox homeostasis that may persist for and/or appear several days post exercise. Both exhaustive maximal exercise lasting only 30 s and isometric exercise lasting 1–3 min (the latter activating in addition a small muscle mass) induce systemic oxidative stress. With the necessary modifications, exercise is capable of inducing redox homeostasis alterations in all fluids, cells, tissues and organs studied so far, irrespective of strains and species. More importantly, ‘exercise-induced oxidative stress’ is not an ‘oddity’ associated with a particular type of exercise, tissue or species. Rather, oxidative stress constitutes a ubiquitous fundamental biological response to the alteration of redox homeostasis imposed by exercise. The hormesis concept could provide an interpretative framework to reconcile differences that emerge among studies in the field of exercise redox biology. Integrative and comparative approaches can help determine the interactions of key redox responses at multiple levels of biological organization.

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.

Effect of blueberry ingestion on natural killer cell counts, oxidative stress, and inflammation prior to and after 2.5 h of running

Blueberries are rich in antioxidants known as anthocyanins, which may exhibit significant health benefits. Strenous exercise is known to acutely generate oxidative stress and an inflammatory state, and serves as an on-demand model to test antioxidant and anti-inflammatory compounds. The purpose of this study was to examine whether 250 g of blueberries per day for 6 weeks and 375 g given 1 h prior to 2.5 h of running at ∼72% maximal oxygen consumption counters oxidative stress, inflammation, and immune changes. Twenty-five well-trained subjects were recruited and randomized into blueberry (BB) (N = 13) or control (CON) (N = 12) groups. Blood, muscle, and urine samples were obtained pre-exercise and immediately postexercise, and blood and urine 1 h postexercise. Blood was examined for F2-isoprostanes for oxidative stress, cortisol, cytokines, homocysteine, leukocytes, T-cell function, natural killer (NK), and lymphocyte cell counts for inflammation and immune system activation, and ferric reducing ability of plasma for antioxidant capacity. Muscle biopsies were examined for glycogen and NFkB expression to evaluate stress and inflammation. Urine was tested for modification of DNA (8-OHDG) and RNA (5-OHMU) as markers of nucleic acid oxidation. A 2 (treatment) × 3 (time) repeated measures ANOVA was used for statistical analysis. Increases in F2-isoprostanes and 5-OHMU were significantly less in BB and plasma IL-10 and NK cell counts were significantly greater in BB vs. CON. Changes in all other markers did not differ. This study indicates that daily blueberry consumption for 6 weeks increases NK cell counts, and acute ingestion reduces oxidative stress and increases anti-inflammatory cytokines.

Assessment of oxidative stress in lymphocytes with exercise

This study investigated whether changes in the cellular composition of blood during exercise could partly account for observations of exercise-induced changes in lymphocyte oxidative stress markers. Markers of oxidative stress were assessed before and after 60 min of intense treadmill running. Samples were collected from 16 men (means ± SD: age 33 ± 13 yr; body mass index 23.8 ± 2.5 kg/m2; maximal oxygen uptake 59.7 ± 5.2 ml·kg−1·min−1). Peripheral blood lymphocytes were assayed for protein carbonyl concentration, and plasma was assessed for lipid peroxides and antioxidant capacity. In a separate study, intracellular thiol concentration was determined in lymphocyte subsets from eight characteristically similar men by flow cytometry, of which T-cell memory populations were further identified on the basis of CD27, CD28, and CD45RA expression. Total lymphocyte protein carbonyls were transiently increased with exercise and returned to baseline within 15 min ( P < 0.001). This change was accompanied by an increase in plasma lipid peroxides ( P < 0.05) and total antioxidant capacity ( P < 0.001). Correlation analyses showed that lymphocyte protein carbonyl content was not related to changes in the cellular composition of peripheral blood during exercise. Natural killer cells (CD3−CD56+) and late-differentiated/effector memory cells (CD4+/CD8+CD27−CD28−/CD45RA+), which mobilized most with exercise, showed high intracellular thiol content ( P < 0.001). High thiol content suggests a lower oxidative load carried by these lymphocytes. Thus vigorous exercise resulted in a transient increase in lymphocyte oxidative stress. Results suggest this was unrelated to the alterations in the cellular composition of peripheral blood.

No effect of antioxidant supplementation on muscle performance and blood redox status adaptations to eccentric training

BACKGROUND

It was recently reported that antioxidant supplementation decreases training efficiency and prevents cellular adaptations to chronic exercise.

OBJECTIVE

This study aimed to investigate the effects of vitamin C and vitamin E supplementation on muscle performance, blood and muscle redox status biomarkers, and hemolysis in trained and untrained men after acute and chronic exercise. A specific type of exercise was applied (eccentric) to produce long-lasting and extensive changes in redox status biomarkers and to examine more easily the potential effects of antioxidant supplementation.

DESIGN

In a double-blinded fashion, men received either a daily oral supplement of vitamin C and vitamin E (n = 14) or placebo (n = 14) for 11 wk (started 4 wk before the pretraining exercise testing and continued until the posttraining exercise testing). After baseline testing, the subjects performed an eccentric exercise session 2 times/wk for 4 wk. Before and after the chronic eccentric exercise, the subjects underwent one session of acute eccentric exercise, physiologic measurements were performed, and blood samples and muscle biopsy samples (from 4 men) were collected.

RESULTS

The results failed to support any effect of antioxidant supplementation. Eccentric exercise similarly modified muscle damage and performance, blood redox status biomarkers, and hemolysis in both the supplemented and nonsupplemented groups. This occurred despite the fact that eccentric exercise induced marked changes in muscle damage and performance and in redox status after exercise.

CONCLUSION

The complete lack of any effect on the physiologic and biochemical outcome measures used raises questions about the validity of using oral antioxidant supplementation as a redox modulator of muscle and redox status in healthy humans.

Effects of 6 weeks of n-3 fatty acids and antioxidant mixture on lipid peroxidation at rest and postexercise

The purpose of this randomized study was to measure the influence of 6 weeks of LCPUFA (600 mg EPA and 400 mg DHA per day) supplementation alone or in association with 30 mg vitamin E, 60 mg vitamin C and 6 mg β-carotene on resting and exercise-induced lipid peroxidation in judoists (n = 36). Blood samples were collected at rest before (T (1)) and after the supplementation period, in preexercise (T (2)) and postexercise (T (3)) conditions, for analysis of α-tocopherol, retinol, lag phase (Lp) before free radical-induced oxidation, maximum rate of oxidation (R (max)) during the propagating chain reaction, maximum amount of conjugated dienes (CD(max)) accumulated after the propagation phase, and nitric oxide, malondialdehyde and lipoperoxide (POOL) concentrations. Dietary data were collected using a 7-day diet record. There were no significant differences among treatment groups with respect to habitual intakes of energy from fat, carbohydrate, or protein. At T (1), there were no significant differences among treatment groups with respect to lipid peroxidation, lag phase, and levels of α-tocopherol or retinol. The consumption of an n-3 LC PUFA supplement increased oxidative stress at rest and did not attenuate the exercise-induced oxidative stress. The addition of antioxidants did not prevent the formation of oxidation products at rest. On the contrary, it seems that the combination of antioxidants added to the n-3 LCPUFA supplement led to a decrease in, CD(max), R (max), and POOL and MDA concentrations after a judo training session.

Oxidative stress and inflammatory parameters after an Ironman race

OBJECTIVE

The aim of the present study was to investigate oxidative stress markers and inflammatory response in triathletes after an Ironman race (IR).

DESIGN

Descriptive research.

PARTICIPANTS

Eighteen well-trained male triathletes (mean age, 34.7 +/- 2.15 years; weight, 69.3 +/- 1.9 kg; height, 1.81 +/- 0.58 cm) participated in the study.

SETTING

Ironman Triathlon (3.8-km swim, 180-km cycle, 42.2-km run). Mean environmental conditions ranged from 20 to 25 degrees C and from 79% to 85% relative humidity.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Before the race and up to 20 minutes after completing the full race, the weights and heights of volunteers were measured and a 10 mL blood sample was drawn from an antecubital vein. Aliquots of washed/lysed red blood cells and plasma/serum samples were stored at -80 degrees C. Lipid peroxidation, protein carbonylation, superoxide dismutase and catalase activities, and cytokines levels [tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-6, IL-10, and IL-1ra] were determined.

RESULTS

After the IR, the results showed a significant increase in TBARS levels (prerace = 1.15 +/- 0.11; postrace = 1.98 +/- 0.27), lipid hydroperoxide content (prerace = 0.75 +/- 0.03; postrace = 1.46 +/- 0.18), protein carbonylation (prerace = 0.67 +/- 0.12; postrace = 2 0.15 +/- 0.60), superoxide dismutase (prerace = 2.67 +/- 0.62; postrace = 3.97 +/- 1.48), and catalase (prerace = 1.48 +/- 0.18; postrace = 2.84 +/- 0.39). TNF-alpha, IL-6, and IL-10 were not detected at basal conditions, but all markers were significantly increased after the IR (TNF-alpha: prerace = ND and postrace = 67.47 +/- 10.34; IL-6: prerace = ND and postrace = 55.41 +/- 3.45; IL-10: prerace = ND and postrace = 122.53 +/- 9.69; IL-1ra: prerace = 127.79 +/- 25.65 and postrace = 259.51 +/- 32.9).

CONCLUSIONS

An Ironman race provokes significant alterations in oxidative stress and inflammatory parameters. Thus, more studies with other markers and different designs are needed to elucidate the cellular alterations induced by an IR.

Oxidative stress, obesity, and breast cancer risk: results from the Shanghai Women's Health Study

PURPOSE

Increased reactive oxygen species may exhaust the antioxidant capability of human defense systems, leading to oxidative stress and cancer development. Urinary F2-isoprostanes, secondary end products of lipid peroxidation, are more accurate markers of oxidative stress than other available biomarkers. No prospective study has investigated whether levels of 15-F(2t)-isoprostane (15-F(2t)-IsoP) and its metabolite 2,3-dinor-5,6-dihydro-15-F(2t)-IsoP (15-F(2t)-IsoPM) are related to breast cancer risk.

PATIENTS AND METHODS

We conducted a nested case-control study within the Shanghai Women's Health Study, a population-based cohort study of 74,942 Chinese women between 40 and 70 years of age. Prediagnostic urinary 15-F(2t)-IsoP and 15-F(2t)-IsoPM were measured by gas chromatography mass spectrometry for 436 breast cancer cases and 852 individually matched controls.

RESULTS

Urinary excretion of isoprostanes was not significantly different between cases and controls. However, among overweight women, levels of isoprostanes were positively associated with breast cancer risk, which became stronger with increasing body mass index (BMI). Among women with a BMI > or = 29, the odds ratio (OR) increased to 10.27 (95% CI, 2.41 to 43.80) for the highest compared with the lowest tertile of 15-F(2t)-IsoPM (P for trend = .003; P for interaction = .0004). In contrast, 15-F(2t)-IsoP and 15-F(2t)-IsoPM were inversely associated with breast cancer risk among nonoverweight women. Among women with a BMI < or = 23, breast cancer risk was reduced with increasing 15-F(2t)-IsoP levels in a dose-response manner (P for trend = .006), with an OR of 0.46 (95% CI, 0.26 to 0.80) for the highest tertile versus the lowest (P for interaction = .006).

CONCLUSION

Our results suggest that the role of oxidative stress in breast cancer development may depend on adiposity.

Efeito do exercício de ultrarresistência sobre parâmetros de estresse oxidativo

INTRODUÇÃO: Exercícios de longa duração podem levar ao desequilíbrio entre os sistemas pró e antioxidante, acarretando dano a lipídeos, proteínas e DNA. Entretanto, alguns estudos avaliando triatlo Ironman observaram proteção aos lipídeos. OBJETIVO: Avaliar parâmetros de estresse oxidativo após uma competição de meio Ironman. MÉTODOS: Participaram 11 sujeitos com idade de 31,1 ± 3,3 anos, massa corporal de 72,4 ± 5,4kg, estatura de 176,2 ± 4,8cm, gordura corporal de 9,8 ± 3,3 %, VO2máx na corrida de 60,7 ± 6,0mL/kg/min. Foram mensurados: dano a lipídeos através da quimiluminescência nos eritrócitos e TBARS no plasma, dano a proteínas através das carbonilas plasmáticas, ácido úrico e compostos fenólicos plasmáticos, assim como a atividade antioxidante enzimática da catalase, superóxido dismutase e glutationa peroxidase nos eritrócitos. RESULTADOS: Houve redução na atividade da enzima superóxido dismutase (23,24 ± 1,49 para 20,77 ± 2,69U SOD/mg proteína, p = 0,045), e aumento no ácido úrico (40,81 ± 10,68 para 60,33 ± 6,71mg/L, p < 0,001) logo após a competição. Não houve diferença estatisticamente significativa na atividade das enzimas antioxidantes catalase e glutationa peroxidase e nos compostos fenólicos totais, assim como não foi observado dano a lipídeos (TBARS e quimiluminescência) e proteínas (carbonilas). CONCLUSÃO: Esse grupo de atletas não sofreu estresse oxidativo, provavelmente devido à liberação de ácido úrico e outros antioxidantes no plasma.

Does physical exercise modify antioxidant requirements?

Physical training is known to induce a biochemical adaptive response which might require an increase in the ingestion and/or the absorption of micronutrients. A question that is still being raised is whether acute or chronic exercise modifies antioxidant requirements. First, the present review brings to light the most crucial studies on the topic. Second, it interprets the established relationships between antioxidant micronutrient intakes and the adaptive response of antioxidant systems. Finally, it exposes the major questions connected with antioxidant micronutrient requirements for athletes. To this effect, the training-load interaction with nutrition is taken into account. As oxidative stress cannot be avoided, the imbalance between oxidants and antioxidants can be alleviated to minimise oxidative damage and outcomes. There is growing evidence that one specific antioxidant cannot by itself prevent oxidative stress-induced damage, as direct adverse effects of supplementation are attributed to undesirable synergic effects. Other effects can be supposed that limit the endogenous adaptive effect of training. High doses of antioxidant supplements can minimise the effects of radical oxygen species themselves or generate pro-oxidant effects. Effects are only exhibited when nutritional status is deficient. There are no convincing effects of supplementation in well-trained athletes. Risk/benefit analysis emerges on evidence for an unknown risk of supranutritional intakes, a supposed impairment of adaptive effects and a still unknown long-term risk. Appropriate status can be achieved by a diversified and balanced diet, adapted to specific needs, by awareness of high-density food intakes (avoiding products containing a low density of micronutrients).

Acute exercise and oxidative stress: a 30 year history

The topic of exercise-induced oxidative stress has received considerable attention in recent years, with close to 300 original investigations published since the early work of Dillard and colleagues in 1978. Single bouts of aerobic and anaerobic exercise can induce an acute state of oxidative stress. This is indicated by an increased presence of oxidized molecules in a variety of tissues. Exercise mode, intensity, and duration, as well as the subject population tested, all can impact the extent of oxidation. Moreover, the use of antioxidant supplements can impact the findings. Although a single bout of exercise often leads to an acute oxidative stress, in accordance with the principle of hormesis, such an increase appears necessary to allow for an up-regulation in endogenous antioxidant defenses. This review presents a comprehensive summary of original investigations focused on exercise-induced oxidative stress. This should provide the reader with a well-documented account of the research done within this area of science over the past 30 years.

Effect of exercise on oxidative stress biomarkers

Acute bouts of aerobic and anaerobic exercise can induce a state of oxidative stress, as indicated by an increase in oxidized molecules in a variety of tissues and body fluids. The extent of oxidation is dependent on the exercise mode, intensity, and duration, and is specifically related to the degree of oxidant production. Findings of increased oxidative stress have been reported for both healthy and diseased subjects following single bouts of exercise. While acute exercise has the ability to induce an oxidative stress, this same exercise stimulus appears necessary to allow for an upregulation in endogenous antioxidant defenses. This chapter presents a summary of exercise-induced oxidative stress.

F2-isoprostanes in human health and diseases: from molecular mechanisms to clinical implications

Oxidative stress is implicated as one of the major underlying mechanisms behind many acute and chronic diseases, and involved in normal aging. However, the measurement of free radicals or their end products is complicated. Thus, proof of association of free radicals in pathologic conditions has been absent. Isoprostanes are prostaglandin-like bioactive compounds that are biosynthesized in vivo independent of cyclooxygenases, principally through free-radical catalyzation of arachidonic acid. Isoprostanes are now considered to be reliable biomarkers of oxidative stress, as evidenced by an autonomous study organized recently by the National Institutes of Health (NIH) in the United States. A number of these compounds have potent biologic activities such as vasoconstrictive and certain inflammatory properties. Isoprostanes are involved in many human diseases. Additionally, elevated levels of F(2)-isoprostanes have been seen in normal human pregnancy and after intake of some fatty acids, but their physiologic assignments have not yet been distinctive. This evidence indicates that measurement of bioactive F(2)-isoprostanes in body fluids offers a unique noninvasive analytic utensil to study the role of free radicals in physiology, oxidative stress-related diseases, experimental acute or chronic inflammatory conditions, and also in the assessment of various antioxidants, radical scavengers, and drugs.

Chronic quercetin ingestion and exercise-induced oxidative damage and inflammation

Quercetin is a flavonoid compound that has been demonstrated to be a potent antioxidant in vitro. The objective of this study was to evaluate if quercetin ingestion would increase plasma antioxidant measures and attenuate increases in exercise-induced oxidative damage. Forty athletes were recruited and randomized to quercetin or placebo. Subjects consumed 1000 mg quercetin or placebo each day for 6 weeks before and during 3 d of cycling at 57% work maximum for 3 h. Blood was collected before and immediately after exercise each day, and analyzed for F2-isoprostanes, nitrite, ferric-reducing ability of plasma, trolox equivalent antioxidant capacity, and C-reactive protein. Statistical analyses involved a 2 (treatment) × 6 (times) repeated measures analysis of variance to test main effects. F2-isoprostanes, nitrite, ferric-reducing ability of plasma, trolox equivalent antioxidant capacity, and C-reactive protein were significantly elevated as a result of exercise, but no group effects were found. Despite previous data demonstrating potent antioxidant actions of quercetin in vitro, this study indicates that this effect is absent in vivo and that chronic quercetin ingestion does not exert protection from exercise-induced oxidative stress and inflammation.