BACKGROUND:Investigations of β-alanine supplementation shows effects on metabolic (aerobic and anaerobic) participation and performance on swimming by a possible blood acidosis buffering. Considering this background, the objective of the present study was to analyze the effects of β-alanine supplementation on metabolic contribution and performance during 400-m swim.METHODS:Thirteen competitive swimmers underwent a 6-week, double-blind placebo-controlled study, ingesting 4.8?g.daysup-?1/sup of β-alanine or placebo. Before and after the supplementation period, the total anaerobic contribution (TAn) and 30-s all-out tethered swimming effort (30TS) were assessed. Anaerobic alactic (AnAl) and lactic energy (AnLa) was assumed as the fast component of excess post-exercise oxygen consumption and net blood lactate accumulation during exercise (?[Lasup-/sup]), respectively. Aerobic contribution (Aer) was determined by the difference between total energy demand and TAn. In addition to conventional statistical analysis (Repeated measures ANOVA; p??0.05), a Bayesian repeated measures ANOVA was used to evidence the effect probability (BFsubincl/sub).RESULTS:No differences and effects were found between groups, indicating no supplementation effects. Repeated measures ANOVA, with confirmation of effect, was indicate reduce in ?Lactate (p: 0.001; BFsubincl/sub: 25.02); absolute AnLa (p: 0.002; BFsubincl/sub: 12.61), fatigue index (p??0.001; BFsubincl/sub: 63.25) and total anaerobic participation (p: 0.008; BFsubincl/sub: 4.89).CONCLUSIONS:Thus, the results demonstrated that all changes presented were evidenced as a result of exposure to the training period and β-alanine supplementation doesn't affect metabolic contribution and performance during 400-m freestyle.
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