Exercise represents the primary countermeasure used during spaceflight to maintain or restore maximal aerobic capacity (˙VO2max), musculoskeletal structure, and orthostatic function. However, no single exercise or combination of prescriptions has proven entirely effective in restoring cardiovascular and musculoskeletal functions to preflight levels following prolonged spaceflight. As human spaceflight exposures increase in duration, assessment and development of various effective exercise-based protective procedures become paramount. This must involve improvement in specific countermeasure prescription as well as development of additional approaches that will allow space travelers greater flexibility and medical safety during long flights. Effective exercise prescription will be based on identification of basic physiological stimuli that maintain normal function in terrestrial gravity and understanding of how specific combinations of exercise characteristics (e.g., duration, frequency, intensity, mode) can mimic these stimuli and affect the overall process of adaptation to microgravity. This can be accomplished only with greater emphasis of research on ground-based experiments. Future attention must also be directed to improving exercise compliance while minimizing both crew time and the impact of the exercise on life-support resources.
Physiology Research Branch, Clinical Sciences Division, Brooks AFB, TX 78235
Submitted for publication February 1995.
Accepted for publication December 1995.
The author thanks Dr. John E. Greenleaf and Dr. Peter Norsk for their valuable editorial comments. This manuscript was supported in part by a NASA grant administered under contracts NAS9-611 and NAS10-10285.
Address for correspondence: Victor A. Convertino, Ph.D., Physiology Research Branch, Clinical Sciences Division, AL/AOCY, 2507 Kennedy Circle, Brooks Air Force Base, TX 78235-5117.