抄録
To investigate cardiovascular adjustments to combined stress of gravity and exercise during dynamic exercise prolonged over 60 mlnutes in upright positlon, the three experiments were carried out. In Experirnent I, as performing moderate upright bicycling (66% VO2max) until exhaustion (average 86 minutes) in 4 trained men, changing manners of cardiovascular adjustments were shown in three phases, which were (1) regulating set-point body teperature, (2) making to maintain suitable blood pressure, and (3) failing to control the blood pressure. In Experiment II, as performing moderate supine cycling (55% VO2max) for 50 minutes under several LBNP conditions In 5 sedentary women, there were correspondingly similar changing manners of the cardiovascular adjustments to each of the phases given in Experiment I. In Experiment 111, as examining tolerance of orthostatic circulatory regulation, the tolerance was significantly correlated to VO2max and lean body mass (LBM) (both p<0.05) in 8 sedentary women. When a moderate upright exercise is performed over 60 minutes in upright position, the performance should be influenced by total muscle mass indicated by LBM as well as by VO2max, because the muscle mass could play a valuable role in the tolerance of orthostatic circulatory regulation vs. gravity.
