INTENSIVE EXERCISE TRAINING DURING BED REST ATTENUATES DECONDITIONING

A 30-d 6 degrees head-down bed rest project was conducted to evaluate variable high-intensity, short-duration, isotonic cycle ergometer exer cise (ITE) training and high-intensity intermittent resistive isokinet ic exercise (IKE) training regimens designed to maintain peak VO2 and muscle mass, strength, and endurance at ambulatory control levels thro ughout prolonged bed rest. Other elements of the deconditioning (adapt ive) syndrome, such as proprioception, psychological performance, hypo volemia, water balance, body composition, and orthostatic tolerance, w ere also measured. Major findings are summarized in this paper. Compar ed with response during bed rest of the no exercise (NOE) control grou p: the ITE training regimen (a) maintained work capacity (peak VO2), ( b) maintained plasma and red cell volumes, (c) induced positive body w ater balance, (d) decreased quality of sleep and mental concentration, and (e) had no effect on the decrease in orthostatic tolerance; the I KE training regimen (f) attenuated the decrease in peak VO2 by 50%, (g ) attenuated loss of red cell volume by 40% but had no effect on loss of plasma volume, (h) induced positive body water balance, (i) had no adverse effect on quality of sleep or concentration, and (i) had no ef fect on the decrease in orthostatic tolerance. These findings suggest that various elements of the deconditioning syndrome can be manipulate d by duration and intensity of ITE or IKE training regimens and that s everal different training protocols will be required to maintain or re store physiological and psychological performance of individuals confi ned to prolonged bed rest.