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The aim of the study was to compare effects of three-day N-acetylcysteine, alpha-lipoic acid or taurine administration on plasma antioxidant status and oxidative damage markers in healthy men after performing muscle-damaging exercise. Fifty-five healthy and trained men were randomly assigned to N-acetylcysteine (NAC, 1.8 g/day, 3 days), alpha-lipoic acid (ALA, 1.2 g/day, 3 days), taurine (TAU, 3 g/day, 3 days) and control group (CON), and exposed to intense resistance exercise. The resistance exercise induced the muscle damage which was observed by significant increase in total creatine kinase (CK) activity at 24 h rest. The administration of NAC and ALA significantly elevated the resting or/and postexercise plasma total antioxidant status (TAS) and total thiols (TT). Uric acid (UA) concentration was decreased by NAC, ALA and TAU at 24 h rest compared with CON. The plasma lipid peroxidation (TBARS) and protein carbonylation (PC) were considerably reduced by NAC and ALA administration at rest and after exercise. TAU did not have any influence on TAS, TT, TBARS and PC levels. Our study has shown that three-day oral N-acetylcysteine and alpha-lipoic acid administration enhanced plasma total antioxidant status and attenuated oxidative damage whereas taurine did not demonstrate any antioxidant action in healthy men after performing a single muscle-damaging exercise.

The aim of this study was to follow up whether the modification of pro-antioxidant status by oral thiol administration such as N-acetylcysteine and alpha-lipoic acid affects the hematological response. Twenty-eight healthy men participated in two independent experiments. Subjects were randomly assigned to one of four groups: controls (C(NAC) and C(ALA)), N-acetylcysteine (NAC) and alpha-lipoic acid (ALA). 1200 mg of N-acetylcysteine, 600 mg of alpha-lipoic acid or placebo were administered for 8 days in two doses. NAC or ALA administration significantly elevated plasma total antioxidant status (TAS) and reduced protein carbonylation (PC) and lipid peroxidation (TBARS) by more than 30 %. The reduced glutathione (GSH) and hematological parameters changed only in response to NAC administration. NAC significantly elevated the level of GSH (+33%), EPO (+26%), Hb (+9%) and Hct (+9%) compared with C(NAC). The mean corpuscular volume (MCV) and the mean corpuscular hemoglobin (MCH) also increased by more than 12% after NAC. The numerous negative or positive correlations between the measures of TAS, PC, TBARS and hematological parameters were found, which suggest the NAC-induced interaction between pro-antioxidant and hematological values. Our study has shown that both N-acetylcysteine and alpha-lipoic acid intake reveal an antioxidant action, but only N-acetylcysteine improves the haematological response.

The purpose of this study was to compare the pro-antioxidant status in healthy men exposed to muscle-damaging resistance exercise, and to investigate the practical application of Loverro's coefficient (P/A ratio) to evaluate the presence of oxidative stress. Twenty-eight healthy men were assigned to two groups performed multi-joint (M) or single-joint (S) resistance exercise. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) as well as the concentration of lipid peroxidation products (TBARS) in blood were evaluated. The P/A ratio was calculated from the mean values of erythrocyte TBARS, SOD, CAT and GPx. Creatine kinase (CK) activity was used as a marker of muscle damage. The applied resistance exercises triggered off the changes in pro-antioxidant ratio towards peroxidation which was proved by significant increase in erythrocyte TBARS concentration in M (+25%) and S (+27%) groups. Plasma TBARS increased only after multi-joint resistance exercise and correlated with erythrocyte P/A ratio (r = 0.536, P < 0.01). The multi-joint exercise caused decrease in SOD activity by 28% whereas the single-joint resistance exercise elevated enzyme activity by 20%. Activities of the other antioxidant enzymes changed simultaneously i.e. CAT activity increased by 14%-16% immediately after exercise, and GPx activity declined by 18%-34% during recovery in M and S groups. Even though, all erythrocyte parameters significantly changed following multi-joint and single-joint resistance exercises, the assessment of pro-antioxidant ratio showed the considerable increase in P/A only in M group. In summary, an analysis of pro- and antioxidant parameters showed significant changes in response to muscle-damaging exercise and demonstrated the practical application of P/A ratio to evaluate the risk of oxidative stress in athletes.

The aim of this study was to ascertain the influence of cysteine derivatives on pro-antioxidant equilibrium and to compare the antioxidant effectiveness of N-acetylcysteine, alpha-lipoic acid, and taurine by using Loverro's coefficient (pro-antioxidant ratio) in healthy men exposed to intensity-resistance exercise. Fifty-five men were randomly assigned to one of four groups: control (CON, placebo), N-acetylcysteine (NAC 1.8 g.day(-1), 3 days), alpha-lipoic acid (LIP 1.2 g.day(-1), 3 days), or taurine (TAU 3 g.day(-1), 3 days). The erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities, lipid peroxidation products (TBARS), and plasma protein thiol concentrations were evaluated. The P/A ratio was determined from the mean values of TBARS, SOD, GPx, and CAT. The applied exercise at maximal intensity induced the significant changes in pro-antioxidant equilibrium toward peroxidation, which was proved by a 25% increase in TBARS concentration in the CON group. The peroxidation was significantly diminished by NAC (-14%) and LIP (-16%), whereas TAU had no effect on the TBARS concentration. Cysteine derivatives administration prevented exercise-induced decline in SOD activity and increased in GPx activity during exercise. CAT activity changed only in the LIP group. The estimation of P/A ratio showed the lowest level of pro-antioxidant equilibrium after LIP administration. In the CON group, P/A ratio was directly correlated with the protein thiols level (r = 0.495, p < 0.001). These data confirm the antioxidant action of tested cysteine derivatives, particularly lipoic acid, and demonstrate the practical application of P/A ratio to evaluate the effectiveness of antioxidants in athletes.