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.

Effect of training load on simulated team sport match performance.

This study examined the effect of training load on running performance and plasma markers of anaerobic metabolism, muscle damage, and inflammation during a simulated team sport match performance. Seven team sport athletes (maximal oxygen uptake, 47.6 ± 4.2 mL·kg(-1)·min(-1)) completed a 60-min simulated team sport match before and after either 4 days of HIGH or LOW training loads. Venous blood samples were taken pre-match, immediately post-match, and 2 h post-match for interlukin-6, monocyte chemoattractant protein-1 (MCP-1), creatine kinase (CK), lactate dehydrogenase, C-reactive protein, xanthine oxidase (XO), and hypoxanthine. Following HIGH training load, sprint velocity decreased (p < 0.001) and total distance covered was reduced (HIGH 5495 ± 670 m, LOW 5608 ± 674 m, p = 0.02) was observed during the simulated match protocol compared with the LOW match simulation. Decreased performance capacity was accompanied by a significant increase in serum CK concentration (HIGH 290 ± 62 U·L(-1), LOW 199 ± 33 U·L(-1), p = 0.005). The HIGH training also resulted in a decreased post-match hypoxanthine and MCP-1 and an increase in XO concentration 2 h post-match. Four days of increased training load reduced running performance during the match simulation and altered the metabolic and inflammatory response to high-intensity intermittent exercise.