β-alanine supplementation improves isometric endurance of the knee extensor muscles

Background: we examined the effect of four weeks of β-alanine supplementation on isometric endurance of the knee extensors at 45% maximal voluntary isometric contraction (mvic).methods: thirteen males (age 23 ± 6 y; height 1.80 ± 0.05 m; body mass 81.0 ± 10.5 kg),matched for pre-supplementation isometric endurance,were allocated to either a placebo (n = 6) or β-alanine (n = 7; 6.4 g·d -1 over 4 weeks) supplementation group. participants completed an isometric knee extension test (iket) to fatigue,at an intensity of 45% mvic,before and after supplementation. in addition,two habituation tests were completed in the week prior to the pre-supplementation test and a further practice test was completed in the week prior to the post-supplementation test. mvic force,iket hold-time,and impulse generated were recorded.results: iket hold-time increased by 9.7 ± 9.4 s (13.2%) and impulse by 3.7 ± 1.3 kn·s -1 (13.9%) following β-alanine supplementation. these changes were significantly greater than those in the placebo group (iket: t (11) = 2.9,p ≤0.05; impulse: t (11) = 3.1,p ≤ 0.05). there were no significant changes in mvic force in either group.conclusion: four weeks of β-alanine supplementation at 6.4 g·d -1 improved endurance capacity of the knee extensors at 45% mvic,which most likely results from improved ph regulation within the muscle cell as a result of elevated muscle carnosine levels. © 2012 sale et al.; licensee biomed central ltd.