Planning strategies for development of effective exercise and nutrition countermeasures for long-duration space flight

Abstract

Exercise and nutrition represent primary countermeasures used during space flight to maintain or restore maximal aerobic capacity, musculoskeletal structure, and orthostatic function. However, no single exercise, dietary regimen, or combination of prescriptions has proven entirely effective in maintaining or restoring cardiovascular and musculoskeletal functions to preflight levels after prolonged space flight. As human space flight exposures increase in duration, identification, assessment, and development of various effective exercise-and nutrition-based protective procedures will become paramount. The application of adequate dietary intake in combination with effective exercise prescription will be based on identification of basic physiologic stimuli that maintain normal function in terrestrial gravity, and understanding how specific combinations of exercise characteristics (e.g., duration, frequency, intensity, and mode) can be combined with minimal nutritional requirements that mimic the stimuli normally produced by living in Earth's gravity environment. This can be accomplished only with greater emphasis of research on ground-based experiments targeted at understanding the interactions between caloric intake and expenditure during space flight. Future strategies for application of nutrition and exercise countermeasures for long-duration space missions must be directed to minimizing crew time and the impact on life-support resources. Nutrition 2002;18:880 -888.

Large-scale mRNA analysis of female skeletal muscles during 60 days of bed rest with and without exercise or dietary protein supplementation as countermeasures

“…In this context, it appears particularly important to define the impact of countermeasures at the cellular and molecular levels. Skylab space missions were the first to include a countermeasure program involving astronaut exercises ranging from 30 to 90 min/day with a clear emphasis on aerobic metabolism (25). Both space and ground experiments have already demonstrated that maximal resistance exercise is effective in preserving muscle structure and function (3,79,80) and that nutritional aid is key in the maintenance of the muscle mass, well-being and performance of the astronauts (70,72).…”

Exercise within lower body negative pressure partially counteracts lumbar spine deconditioning associated with 28-day bed rest

“…However, these devices are uncomfortable or lack sufficient loads to maintain preflight musculoskeletal mass. The optimal protocol and equipment for exercise in space are still unresolved (5). Over the past 10 yr, we have developed a lower body negative pressure (LBNP) treadmill exercise system that provides both cardiovascular and musculoskeletal responses equivalent to upright exercise in gravity (3,9,21,31).…”

Does Chronic Experimental Head-Down Tilt Alter Intramural Innervation Density of Limb Blood Vessels?

“…A single bout of maximal exercise increased the responsiveness of the arterial baroreflexes after acute exposure to microgravity. Therefore the development of effective exercise and nutrition countermeasures designed to maintain baroreflex functions could prove instrumental in ameliorating the deleterious effects of microgravity on cardio-vascular mechanisms [30]. Although the baroreflexes and the vestibulosympathetic reflex do not appear to interact centrally to modify sympathetic outflow during an orthostatic challenge, they complement each other [31,32].…”