Abstract
BackgroundInvestigations 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.MethodsThirteen competitive swimmers underwent a 6-week, double-blind placebo-controlled study, ingesting 4.8 g.day− 1 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 (∆[La−]), 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 (BFincl).ResultsNo 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; BFincl: 25.02); absolute AnLa (p: 0.002; BFincl: 12.61), fatigue index (p > 0.001; BFincl: 63.25) and total anaerobic participation (p: 0.008; BFincl: 4.89).ConclusionsThus, 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.
Highlights
Effort in 400-m swimming is highly intense (i.e. 83.2% aerobic, 10.2% anaerobic lactic, 5.8% anaerobic alactic) [1]
Beta-alanine (β-alanine) supplementation has been widely used as an ergogenic strategy by competitive athletes from different sports [5, 6, 8] and seems capable to increase (~ 65% after 4 weeks) intramuscular carnosine content (β-alanyl-L-histidine), a cytoplasmic dipeptide found in human skeletal muscle [9, 10]
Repeated measures between-subjects ANOVA showed no significant differences for the variables
Summary
Effort in 400-m swimming is highly intense (i.e. 83.2% aerobic, 10.2% anaerobic lactic, 5.8% anaerobic alactic) [1]. A high demand of glycolytic energy is required and athletes must tolerate high blood lactate concentrations ([La−]) (i.e., 8.5 ± 3.2 mmol/L [2]) for approximately 4 min, estimated time at which maximum hydrogen ions (H+) accumulation and low intramuscular pH are reported [3]. In this sense, nutritional supplementation seems to be a good strategy to delay fatigue [4, 5]. 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
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