title: The Astronaut-Athlete: Optimizing Human Performance in Space.
abstract: It is well known that long-duration spaceflight results in deconditioning of neuromuscular and cardiovascular systems, leading to a decline in physical fitness. On reloading in gravitational environments, reduced fitness (e.g., aerobic capacity, muscular strength, and endurance) could impair human performance, mission success, and crew safety. The level of fitness necessary for the performance of routine and off-nominal terrestrial mission tasks remains an unanswered and pressing question for scientists and flight physicians. To mitigate fitness loss during spaceflight, resistance and aerobic exercise are the most effective countermeasure available to astronauts. Currently, 2.5 h·d, 6-7 d·wk is allotted in crew schedules for exercise to be performed on highly specialized hardware on the International Space Station (ISS). Exercise hardware provides up to 273 kg of loading capability for resistance exercise, treadmill speeds between 0.44 and 5.5 m·s, and cycle workloads from 0 and 350 W. Compared to ISS missions, future missions beyond low earth orbit will likely be accomplished with less vehicle volume and power allocated for exercise hardware. Concomitant factors, such as diet and age, will also affect the physiologic responses to exercise training (e.g., anabolic resistance) in the space environment. Research into the potential optimization of exercise countermeasures through use of dietary supplementation, and pharmaceuticals may assist in reducing physiological deconditioning during long-duration spaceflight and have the potential to enhance performance of occupationally related astronaut tasks (e.g., extravehicular activity, habitat construction, equipment repairs, planetary exploration, and emergency response).
authors.affiliation: 1Department of Health, Nutrition, and Exercise Science, North Dakota State University, Fargo, North Dakota; 2Exercise Physiology and Countermeasures Laboratory, Universities Space Research Association, Houston, Texas; 3National Aeronautics and Space Administration, Exercise Physiology and Countermeasures Laboratory, Houston, Texas; 4Exercise Physiology and Countermeasures Laboratory, JES Tech, Houston, Texas; and 5Department of Health and Human Performance, University of Houston, Houston, Texas.
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Hackney
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Scott
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Hanson
authors.forename: Kirk L
authors.initials: KL
authors.lastname: English
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Downs
authors.forename: Lori L
authors.initials: LL
authors.lastname: Ploutz-Snyder
mesh_terms: D018480:Astronauts; D056352:Athletes; D019587:Dietary Supplements; D015444:Exercise / Q000502:physiology*; D017079:Exercise Tolerance; D018478:Extravehicular Activity; D006801:Humans; D053580:Muscle Strength; D064797:Physical Conditioning, Human / Q000295:instrumentation / Q000502:physiology*; D010809:Physical Fitness; D013026:Space Flight; D013647:Task Performance and Analysis