Abstract:The purpose of the present study was to investigate the effects of taurine supplementation on muscle performance, oxidative stress, and inflammation response after eccentric exercise (EE) in males. Twenty-one participants (mean age, 21 ± 6 years; weight, 78.2 ± 5 kg; height, 176 ± 7 cm) were selected and randomly divided into two groups: placebo (n = 10) and taurine (n = 11). Fourteen days after starting supplementation, subjects performed EE (3 sets until exhaustion, with EE of the elbow flexors on the Scott bench, 80% 1 repetition maximum (RM)). Blood samples were collected and muscle performance was measured on days 1, 14, 16, 18, and 21 after starting the supplements. Then, performance, muscle damage, oxidative stress, and inflammatory markers were analyzed. The taurine supplementation resulted in increased strength levels and thiol total content and decreased muscle soreness, lactate dehydrogenase level, creatine kinase activity, and oxidative damage (xylenol and protein carbonyl). Antioxidant enzymes (superoxide dismutase, catalase, and gluthatione peroxidase) and inflammatory markers (tumor necrosis factor, interleukin-1␤ (IL-1␤), and interleukin-10 (IL-10)) were not altered during the recovery period compared with the placebo group. The results suggest that taurine supplementation represents an important factor in improving performance and decreasing muscle damage and oxidative stress but does not decrease the inflammatory response after EE.Key words: taurine, eccentric exercise, physical performance, oxidative stress, inflammation, supplementation.Résumé : Cette étude se propose d'examiner les effets de la supplémentation en taurine sur la performance musculaire, le stress oxydatif et la réponse inflammatoire à la suite d'un exercice pliométrique chez des hommes. On répartit aléatoirement une sélection de 21 hommes (21 ± 6 ans, 78,2 ± 5 kg, 176 ± 7 cm) dans deux groupes : placebo (n = 10) et taurine (n = 11). Quatorze jours après le début de la supplémentation, les sujets effectuent sur un banc Scott trois séries d'exercices pliométriques des fléchisseurs du coude (80 % 1 RM) jusqu'à épuisement. On prélève des échantillons sanguins et on évalue la performance musculaire aux jours 1, 14, 16, 18 et 21 suivant le début de la supplémentation. Puis on analyse la performance, les lésions musculaires, le stress oxydatif et les marqueurs de l'inflammation. La supplémentation en taurine suscite une augmentation de la force et du contenu total en thiol ainsi qu'une diminution de la douleur musculaire, de la concentration de lactate déshy-drogénase, de l'activité de la créatine kinase et des lésions oxydatives (xylénol et protéine carbonylée). Pendant la période de récupération, on n'observe dans les groupes supplémentés aucune modification de l'activité des enzymes antioxydantes (superoxyde dismutase, catalase et glutathion peroxydase) et des marqueurs de l'inflammation (facteur de nécrose tumorale, interleukine-1␤ (IL-1␤) et interleukine-10 (IL-10)) comparativement au groupe placebo. D'après ces observa...

This study analyzes oxidative stress in skeletal muscle using different resisted training protocols. We hypothesize that different types of training produce different specifics. To test our hypothesis, we defined 3 resistance training protocols and investigated the respective biochemical responses in muscle. Twenty-four male Wistar rats were distributed in 4 groups: untrained (UT), muscular resistance training (RT), hypertrophy training (HT), and strength training (ST). After 12 weeks of training on alternate days, the red portion of the brachioradialis was removed and the following parameters were assessed: lactate and glycogen content, superoxide production, antioxidant enzyme content, and activities (superoxide dismutase, SOD; catalase, CAT; GPx, glutathione peroxidase). Thiobarbituric acid-reactive substances (TBARS), carbonyl, and thiol groups were also measured. Results showed increased superoxide production (UT = 5.348 ± 0.889; RT = 5.117 ± 0,651; HT = 8.412 ± 0.431; ST = 6.354 ± 0.552), SOD (UT = 0.078 ± 0.0163; RT = 0.101 ± 0.013; HT = 0.533 ± 0.109; ST = 0.388 ± 0.058), GPx (UT = 0.290 ± 0.023; RT = 0.348 ± 0.014; HT = 0.529 ± 0.049; ST = 0.384 ± 0.038) activities, and content of GPx (HT = 3.8 times; ST = 3.0 times) compared with the UT group. CAT activity was lower (UT = 3.966 ± 0.670; RT = 3.474 ± 0.583; HT = 2.276 ± 0.302; ST = 2.028 ± 0.471) in HT and ST groups. Oxidative damage was observed in the HT group (TBARS = 0.082 ± 0.009; carbonyl = 0.73 ± 0.053; thiol = 12.78 ± 0.917) compared with the UT group. These findings indicate that HT causes an imbalance in oxidative parameters in favor of pro-oxidants, causing oxidative stress in skeletal muscle.

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

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The objective of the present study was to investigate the effects of eccentric training on the activity of mitochondrial respiratory chain enzymes, oxidative stress, muscle damage, and inflammation of skeletal muscle. Eighteen male mice (CF1) weighing 30-35 g were randomly divided into 3 groups (N = 6): untrained, trained eccentric running (16°; TER), and trained running (0°) (TR), and were submitted to an 8-week training program. TER increased muscle oxidative capacity (succinate dehydrogenase and complexes I and II) in a manner similar to TR, and TER did not decrease oxidative damage (xylenol and creatine phosphate) but increased antioxidant enzyme activity (superoxide dismutase and catalase) similar to TR. Muscle damage (creatine kinase) and inflammation (myeloperoxidase) were not reduced by TER. In conclusion, we suggest that TER improves mitochondrial function but does not reduce oxidative stress, muscle damage, or inflammation induced by eccentric contractions.

Exercise increases both the consumption of oxygen and the production of reactive species in biological tissues, and this is counterbalanced by antioxidant adaptations to regular physical training. When the intensity of exercise fluctuates between mild and moderate, it improves the status of reduction-oxidation balance in the brain and induces neuroplasticity. However, intense exercise can oxidize the brain and impair neurological function. The effect of the frequency of exercise, which is an important factor in physical training, is still unknown. The effect of periodic exercise on biomarkers of oxidative stress in the hippocampus of mice was evaluated in this study. Mice were made to run on a treadmill for 8 weeks, two, three, or five times per week, and their hippocampi and quadriceps femoris muscles were then dissected. Biomarkers of oxidative damage were negatively correlated with the frequency of exercise and mitochondrial muscular activity, while the sulfhydryl contents were positively correlated with exercise frequency. A logistic analysis revealed a dose-dependent effect of exercise on these biomarkers. In summary, these results suggested that manipulating the frequency of physical exercise could induce antioxidant-related adaptations in the hippocampi of adult mice.

Age-associated decline in skeletal muscle mass and strength is associated with oxidative stress and Ca(2+) homeostasis disturbance. Exercise should be considered a viable modality to combat aging of skeletal muscle. This study aimed to investigate whether continuous and fractionated training could be useful tools to attenuate oxidative damage and retain calcium-handling proteins. We conducted the study using 24-month-old male Wistar rats, divided into control, continuous, and fractionated groups. Animals ran at 13 m min(-1) for five consecutive days (except weekends) for 6 weeks, for a total period of 42 days. Each session comprised 45 min of exercise, either continuous or divided into three daily sessions of 15 min each. Metabolic and oxidative stress markers, protein levels of mitochondrial transcription factors, and calcium-handling proteins were analyzed. Continuous exercise resulted in reduced ROS production as well as showed a decrease in TBARS levels and carbonyl content. On the other hand, fractionated training increased the antioxidant enzyme activities. The ryanodine receptor and phospholamban protein were regulated by continuous training while sodium calcium exchange protein was increased by the fractionated training. These data suggest that intracellular Ca(2+) can be modulated by various training stimuli. In addition, the modulation of oxidative stress by continuous and fractionated training may play an important regulatory role in the muscular contraction mechanism of aged rats, due to changes in calcium metabolism.