The patho-physiology of disuse and the problem of prolonged weightlessness: A review.

Abstract : The physiological implications of zero-G as encountered in space flight are discussed and the available research concerning the physiolog ical effects of weightlessness is reviewed. The purpose of this review is to proceed from the present state of knowledge of normal human physi ological systems, particularly as their structure and function are affected by gravity, to a con sideration of the possible physiological conse quences of prolonged human exposure to zero-G. Methods used to produce and to simulate zero-G are briefly reviewed. The data suggesting that prolonged weightlessness will be a deconditioning environment is presented. This data is considered for possible untoward effects of prolonged expo sure to weightlessness, and for methods of pre vention of undesired effects. The problem of artificial gravity by rotation of a space vehicle is briefly considered. Areas of needed future investigation are suggested.