Abstract

To assess the change in plasma level of 22 and 20 kDa GH isoforms following acute aerobic exercise and chronic aerobic training, 30 male athletes in two pubertal and pre-pubertal groups were studied. Acute aerobic exercise consisted of 30 min running at 65% Vo2max on the treadmill. Plasma was sampled 30 min before and immediately after the aerobic exercise and assayed for total concentrations. These measurements were repeated at the end of six weeks of aerobic training (30 min running on the treadmill, three times weekly, at 70-80% Vo2max). In both groups, acute aerobic exercise was followed by increased 22 kDa and decreased 20 kDa concentration. These changes were larger in the pre-pubertal group. Chronic aerobic training was associated with decreased 22 kDa and increased 20 kDa response to acute aerobic exercise in both groups. There was no significant change in the rest levels of 22 and 20 kDa concentration in either groups following chronic aerobic training.