The histidine-containing dipeptide carnosine (p-alanyl-L-histidine) exists widely in the skeletal muscle of vertebrates. The biological role of carnosine has not been well established, but it is believed to act as a cytosolic buffering agent. We prepared an extract of chicken breast meat that is an abundant source of carnosine and its related dipeptide anserine (β-alanyl-1-methyl-L-histidine). The purpose of this study was to examine the effects of extract (CBEX^<TM>) supplementation on high-intensity intermittent exercise performance. Eight male subjects performed two experimental trials (CBEX and placebo treatment). Each trial consisted of two intermittent cycle ergometer sprints separated by a 20-min recovery period. Intermittent exercise consisted often 5-s maximal sprints with 25-s of recovery between each sprint. The subjects were given 190 g of experimental soup containing either 40 g of CBEX or no CBEX 30 min before each trial. Anserine and its related amino acid in plasma were detectable 30 min after CBEX supplementation. However, plasma carnosine was not detectable. In the CBEX group, the subjects exhibited high power during the latter half of intermittent exercise compared with the placebo group. These results suggest that pre-exercise CBEX supplementation improves intermittent exercise performance, possibility by restraining the decrease of intracellular pH and thereby delaying the onset of fatigue.
