Effects of Chronic Beta-Alanine Supplementation with and without Acute Sodium Bicarbonate Ingestion on Peak Muscle Carnosine Concentration, Washout and High-Intensity Exercise Performance

Abstract

Carnosine (beta-alanyl-L-histidine) is a cytoplasmic dipeptide found in high concentrations in the skeletal muscle of both vertebrates and non-vertebrates, as well as in the central nervous system. It has been shown that the elevation of muscle carnosine concentrations through the dietary intake of carnosine or supplementation with beta-alanine provides a method of increasing intracellular buffering capacity during exercise. Additionally, one study to date has indicated that sodium bicarbonate may have a synergistic effect on performance when co-supplemented with beta-alanine. Thus, the aim of this study is to examine the effects of beta-alanine supplementation with and without acute sodium bicarbonate supplementation on: a) peak muscle carnosine concentration; b) muscle carnosine washout and c) high-intensity exercise performance. Forty-five physically active male volunteers (aged between 18-30 years) will be recruited to this study. Subjects will be randomly allocated to one of three supplementation groups: 1) beta-alanine group receiving 6.4 g/d for 16 weeks followed by a maltodextrin placebo for 16 weeks; 2) beta-alanine supplementation group receiving 3.2 g/d for 32 weeks; 3) Placebo group receiving a maltodextrin placebo for 32 weeks. At weeks 0, 8, 16, 24 and 32, muscle carnosine content will be assessed in vivo by 1H-MRS and high-intensity exercise capacity will be determined using the CCT110% test. One of the tests will be performed following the acute ingestion of 0.3 g/kg sodium bicarbonate taken over the preceding 4 h and the other will be following the acute ingestion of a matched placebo (maltodextrin). Blood samples will be analysed for lactate, blood gases, haemoglobin and pH. After the normality and homogeneity of the variance are confirmed, the dependent variables will be compared using a mixed model. The significance level will be set at p < 0.05.