Resumen de [beta]-Alanine Improves Sprint Performance in Endurance Cycling

Ruud van Thienen, Karen van Proeyen, Bart Vanden Eynde, Joke Puype, Thomas Lefere, Peter Hespel

• Purpose: Recent research has shown that chronic dietary [beta]-alanine ([beta]ALA) supplementation increases muscle carnosine content, which is associated with better performance in short (1-2 min) maximal exercise. Success in endurance competitions often depends on a final sprint. However, whether [beta]ALA can be ergogenic in sprint performance at the end of an endurance competition is at present unknown. Therefore, we investigated the effect of 8-wk [beta]ALA administration in moderately to well-trained cyclists on sprint performance at the end of a simulated endurance cycling race.

  Methods: A double-blind study was performed, which consisted of two experimental test sessions interspersed by an 8-wk [beta]ALA (2-4 g[middle dot]d-1; n = 9) or matched placebo (PL; n = 8) supplementation period. In the pretesting and the posttesting, subjects performed a 10-min time trial and a 30-s isokinetic sprint (100 rpm) after a 110-min simulated cycling race. Capillary blood samples were collected for determination of blood lactate concentration and pH.

  Results: Mean power output during the time trial was approximately 300 W and was similar between PL and [beta]ALA during either the pretesting or the posttesting. However, compared with PL, during the final sprint after the time trial, [beta]ALA on average increased peak power output by 11.4% (95% confidence interval = +7.8 to +14.9%, P = 0.0001), whereas mean power output increased by 5.0% (95% confidence interval = +2.0 to +8.1%, P = 0.005). Blood lactate and pH values were similar between groups at any time.

  Conclusion: Oral [beta]ALA supplementation can significantly enhance sprint performance at the end of an exhaustive endurance exercise bout.