GLUTAMATE-ARGININE SALTS AND HORMONAL RESPONSES TO EXERCISE

Hormonal changes during exercise is of growing interest because of the ir robe in adaptation, and performance. The production Of amino acids (AA) due to the degradation of muscle protein increases during exercis e and some AA may be utilized for energy expenditure or as hormonal se cretagogues. Thus, one can propose a strategy to reduce muscle protein breakdown and regulate hormones involved in energy metabolism by diet ary AA supplementation. We assessed the effects of glutamate-arginine salt (AGs) ingestion on exercise-induced hormonal alterations in highl y trained cyclists (age 18-22 yrs). Using an indwelling catheter, we c ollected multiple blood samples at rest, during warm up, during and af ter an intense exercise session. Plasma growth hormone (hGH), insulin and cortisol were measured by radioimmunoassay. As reported in previou s studies, we observed a marked increase in plasma hGH and cortisol le vels during and after exercise in the placebo (Pl) condition as well a s a slight decrease in insulin concentration. In addition, we found th at the ingestion of AGs had significant effects on some dynamic hormon al changes. AGs had no effect on resting plasma levels of hGH, insulin or cortisol. However, the marked elevation in cortisol and hGH during and after exercise in the placebo condition, was greatly diminished w hen subjects ingested AGs. Our results show that AGs can modify exerci se-induced hormonal changes and raise the possibility that it may be u sed to alter energy metabolism during endurance exercise.