The Effect of Bedrest on Various Parameters of Physiological Function. Xii. the Effect of Bedrest on Bone Mass and Calcium Balance. Nasa Cr-182.

THE EFFECT OF BEDREST ON VARIOUS PARAMETERS OF PHYSIOLOGICAL FUNCTION PART Vll l . THE EFFECT ON THE CARDIOVASCULAR TOLERANCE TO PASSIVE TILT By C. Vallbona, M.D., D. Cardus, M.D., F. B. Vogt, M.D. , and W. A. Spencer, M. D. 2 1 1 5 s . . This study was carried out to evaluate the effect of short term (3 days) and long term (14 days) bedrest on the cardiac tolerance to passive t i l t . It showed that there was a deterioration of the subjects' abi l i ty to tolerate passive ti l t. The deterioration was demonstrated by the negative slopes of the regressional line of blood pressure vs. time and the positive slopes of heart rate vs. time observed during t i l t procedures at the end of the period of bedrest. The intolerance to t i l t was more evident after bedrest for 14 days. This study showed also that isometric exercises performed while on bedrest improved the subiects' tolerance to passive t i It, as evidenced in the slopes of blood pressure, which although negative were less steep.