Influence of β-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity

Abstract

Muscle carnosine synthesis is limited by the availability of beta-alanine. Thirteen male subjects were supplemented with beta-alanine (CarnoSyn) for 4 wks, 8 of these for 10 wks. A biopsy of the vastus lateralis was obtained from 6 of the 8 at 0, 4 and 10 wks. Subjects undertook a cycle capacity test to determine total work done (TWD) at 110% (CCT(110%)) of their maximum power (Wmax). Twelve matched subjects received a placebo. Eleven of these completed the CCT(110%) at 0 and 4 wks, and 8, 10 wks. Muscle biopsies were obtained from 5 of the 8 and one additional subject. Muscle carnosine was significantly increased by +58.8% and +80.1% after 4 and 10 wks beta-alanine supplementation. Carnosine, initially 1.71 times higher in type IIa fibres, increased equally in both type I and IIa fibres. No increase was seen in control subjects. Taurine was unchanged by 10 wks of supplementation. 4 wks beta-alanine supplementation resulted in a significant increase in TWD (+13.0%); with a further +3.2% increase at 10 wks. TWD was unchanged at 4 and 10 wks in the control subjects. The increase in TWD with supplementation followed the increase in muscle carnosine.

Effect of β-alanine supplementation on 20 km cycling time trial performance

“…e cycling capacity test at 110% of powermax used by both of these studies is one of the few tests to be independently repeated with β-alanine supplementation. e increase in cycling capacity reported following 4 weeks of supplementation was similar in both studies; H et al 11 reported an increase of 13% and S et al 12 an increase of 15% using a slightly higher total intake of β-alanine. e fact that reductions in intracellular pH are unlikely to be limiting to 20 km time trial performance might thus help to explain the lack of a signi cant e ect in the present study.…”

“…As such, we cannot con rm in the present study that muscle carnosine contents were signi cantly increased and, if so, what the magnitude of this increase was. However, supplementation with β-alanine at this level has consistently been shown to increase muscle carnosine concentrations by over 60% 8,11 , with others reporting no non-responders to β-alanine supplementation 11,21,31 . Indeed, only one participant from the series of muscle studies to-date has failed to respond to β-alanine supplementation with an increase in muscle carnosine 8 .…”

“…Taking the existing evidence as a whole, the most likely mechanism for an e ect of increased muscle carnosine on exercise performance and capacity remains the e ect it has on intracellular pH bu ering. Lending support to this assertion, studies have examined the e ects of β-alanine on exercise capacity, using tests designed to induce large increases in intramuscular hydrogen cation levels and reductions in pH [11][12]30 , and have shown signi cant increases in exercise capacity. In relation to cycling, studies have shown signi cant e ects of β-alanine supplementation on high-intensity cycling capacity, as determined by increases in total work done [11][12] .…”

“…Lending support to this assertion, studies have examined the e ects of β-alanine on exercise capacity, using tests designed to induce large increases in intramuscular hydrogen cation levels and reductions in pH [11][12]30 , and have shown signi cant increases in exercise capacity. In relation to cycling, studies have shown signi cant e ects of β-alanine supplementation on high-intensity cycling capacity, as determined by increases in total work done [11][12] . e cycling capacity test at 110% of powermax used by both of these studies is one of the few tests to be independently repeated with β-alanine supplementation.…”

“…In particular, several studies have focussed on the effects of β-alanine supplementation on high intensity cycling capacity and have shown significant increases following supplementation [11][12][13] . The effects of β-alanine supplementation on cycling performance are more equivocal, with some showing no e ect 14 and others a signi cant improvement 15 .…”