Abstract
Carnosine is a cytoplasmic dipeptide found in high concentrations in the skeletal muscle of both vertebrates and non-vertebrates, and is associated with muscle buffering, sensitivity of calcium release channels and/or calcium sensitivity of the contractile apparatus and scavenging of reactive oxygen species. It has been shown that the elevation of muscle carnosine concentrations through the dietary intake of carnosine or supplementation with ²-alanine can lead to improved high-intensity exercise performance and capacity, although the mechanism underpinning these improvements remains to be elucidated. Furthermore, whilst there is some suggestion that prolonged high-intensity exercise training can result in increased muscle buffering capacity, it is unknown whether this is due to increased muscle carnosine content. Several important questions relating to carnosine and ²-alanine supplementation remain. Firstly, the upper limit to carnosine concentration in muscle, and concomitant exercise benefits, are currently unknown. Prolonged supplementation with ²-alanine will allow us to provide some answers to these questions, whilst also providing information on the effects of long term supplementation on carnosine related genes. Secondly, the mechanisms contributing to the performance effects of increased muscle carnosine are currently debated within the literature; providing an analysis of the carnosine content of various compartments within the muscle cell (e.g., mitochondria, cytosol, nucleus) would provide evidence to suggest the most likely mechanism contributing to increased exercise performance and capacity. Thirdly, no studies have examined the effects of long-term high-intensity exercise training on increases in muscle carnosine and muscle buffering capacity. As such, we propose here a comprehensive programme of work, comprising three experimental investigations, aimed at gaining some insight into these vitally important questions. Study 1 will investigate the effect of long-term ²-alanine supplementation on peak muscle carnosine concentrations, as well as the associated changes in exercise capacity, carnosine related genes and any potential side effects. The effects of prolonged high-intensity training on muscle buffering capacity and muscle carnosine concentrations, both in whole muscle and single muscle fibres, will be determined in study 2. Study 3 will utilise a comparative physiology design in order to examine the muscle carnosine content of the humming bird, pheasant and human, and will also determine the compartmentalisation of carnosine in the cell. (AU)
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