Carnosine concentration in the muscle of thoroughbred horses and its implications in exercise performance

The exercise performance of thoroughbred racing horses is affected by factors such as body weight, muscle type, and nutrition . Carnosine (β-alanyl histidine), a small and water-soluble dipeptide, in the muscle is a factor that contributes to the exercise performance of animals . This peptide and its analogues anserine (1-methyl-carnosine) are present in the skeletal muscles and nervous tissues of many vertebrates . The concentration of carnosine in the muscles is high. It is one of the most abundant small-molecule compounds in skeletal muscles, with concentrations similar to those of creatine and ATP. During high intensity exercise, muscle contractions lead to the production of lactic acid, and the resulting acidosis causes muscle contractile fatigue. Owing to the alkaline property of carnosine (pKa = 7.01), it is thought to play a significant role in intracellular buffering and maintaining the pH balance in muscle . In addition to pH buffering, carnosine reportedly has many beneficial characteristics such as anti-oxidant, anti-glycation, and anti-crosslink activities . Considering these characteristics, the concentration of muscle carnosine is thought to have a posit ive relationship with exercise performance 2, . Indeed, high concentrations of muscle carnosine have been found in