Influence of exercise on plasma and muscle free amino acids in trained rainbow trout

Variations in the concentration of free amino acids in the muscle and plasma of trout submitted to 5 minutes of intense exercise have been studied. The responses of untrained fish and those trained performing the same type of exercise twice daily for 28 days are compared. Total amino acid concentrations in muscle tend to diminish after intense exercise. Significant decreases are observed in muscle content of alanine, beta-alanine, isoleucine and ornithine. Plasma amino acids tend to increase after exercise with significant differences in glutamate, GABA, methionine and NH4+. The small variations due to intense exercise suggest that the amino acids are mobilised. Training led to a decrease in total amino acid concentration in plasma but not in muscle, where levels of aspartate and ornithine increased. This suggests a metabolic adaptation to exercise, with amino acid level retention in the muscle.