2005 Volume 1 Issue 2 Pages 45-50
Exercise is a potent stimulus to GH secretion. However it is unclear if exercise-induced GH release differs between different muscle groups, i.e., arm and leg exercise, when performed at equivalent exercise intensity. The purpose of this study was to compare the GH responses to an acute resistance exercise, combined with restriction of muscular venous blood flow (KAATSU), in muscle groups of the arm and leg. Five young male subjects performed two types of exercise tests, arm and leg exercise, on separate days. The intensity of exercise was 20% of 1-RM, which was measured at least 1 week before the experiment. The external restriction pressure during the KAATSU exercise was selected 50% higher than each measured-arm and estimated-leg systolic blood pressure. Venous blood samples were obtained prior to the start of exercise, immediately post exercise, and 15- and 60-min after exercise, and blood lactate (LA), growth hormone (GH), noradrenaline (NA), hematocrit, albumin and Na/K concentrations were measured. Significant elevations were apparent immediately post and 15-min after exercise for LA and at immediately post, 15- and 60-min after exercise for GH in both arm and leg exercise. Significant elevation was also observed after exercise for NA in both arm and leg, but leg exercise resulted in a greater increase in NA than arm at immediately post exercise. Change in plasma volume after exercise was not different between two exercises. These results suggest that GH secretory responses to exercise may be similar between the arm and leg when performed at equivalent exercise intensity and restriction stimulus.