The level of physical activity and the growth hormone (GH) response to acute physical exercise.

There is no clear evidence about the influence of programmed physical activity (training) on growth hormone (GH) response to acute physical exercise. The aim of this study was to estimate the relationship between the level of physical activity and the serum growth hormone concentration in response to acute physical exercise. The study was performed on 20, healthy male subjects. Based on the level of their physical activities they were divided in two groups of equal size: group 1, trained, and group 2, untrained subjects. All subjects performed one boot of exercise on cycle ergometer, lasting 30 minutes. Work intensity was approx. 65% of VO2 max, and the rate of cycling was 60/min. Serum GH concentrations were measured by IRMA (immunoradiometric assays) method in blood samples obtained in the period of rest, during exercise and in the recovery period. There were marked differences in the dynamics of changes in the serum GH concentrations during exercise period between the groups of various level of physical activity despite the lack of the significant differences in basal level and maximal level of serum GH concentration at the end of exercise. Untrained subjects showed faster increase in serum GH concentration than trained subjects, but in trained subjects the restoration of the basal values in the recovery period was faster. These results indicate that the level of physical activities in young, healthy male subjects has no influence on GH response to acute physical exercise.