Effects of oral supplementation with a mixture of amino acids on immune function in athletes at a summer training camp for track and field and long-distance runners.

Athletes become increasingly susceptible to infection with intense exercise, which has an immunosuppressive effect. Sixteen long-distance runners participated in the present study. The clinical indexes, mainly related to the immune state, of 8 subjects in the amino acid intake group and 8 subjects in the placebo intake group were measured before and after a 7-day training camp. Significant increases in levels of myoglobin (Mb) and growth hormone (GH), and significant decreases in natural killer cell activity (NK) and Fisher's ratio were observed after as compared to before the training camp in the placebo group. However, these changes were not observed in the amino acid supplementation group. These findings suggest that amino acid supplementation during a training camp may have a stress-reducing effect by inhibition of muscle protein degradation, as well as by inhibiting the reduction of immunological functions, and may also contribute to protection against infectious diseases. [ABSTRACT FROM AUTHOR]