[Work capacity evaluation and orthostatic tolerance in experiments with long-term isolation]

Orthostatic tolerance (OT) and physical performance were tested against the ground simulation of several spaceflight factors. Before and after prolonged isolation and confinement three human subjects were tested by tilting, LBNP, and graded incremental aerobic exercise in the sitting position. Results suggested good OT in all the subjects. However, the pattern of orthostatic reaction was modified depending on the initial functional state of each subject. This was especially distinct in subjects 002 and 003 whose OT was slightly reduced by the experimental conditions. Orthostatic reactions in subject 004 showed greater stability in the baseline data collection period and was not much affected by isolation and confinement. HR variations at rest carried an individual character. On the whole, HR tended downward, particularly in 002. Indices of AP and, to a higher degree, its systolic constituent wandered outside the region of baseline values and even the norm limits in 002 and 004. Maximum variations were documented at the end of the second (003 and 004) and the third (002) months in experiment. ECG parameters in all the operators displayed different patterns of the norm. Diffusive repolarization, especially in the left chest leads, was noted to decline in the experiment. Tolerance of LBNP was qualified as good. Meanwhile, subject 003 developed symptoms of strained functioning of compensatory/adaptive mechanisms responsible for the OT maintenance. Repeated testing by LBNP was found to raise HR. Hence, prolonged simulation of space flight causes some reduction of orthostatic and LBNP tolerance, and degradation of physical performance.