Abating Heat Accrual During Exercise in Microgravity and Implications for Future Long-Term Missions

INTRODUCTION: Space agencies will embark on manned journeys to Mars on smaller vehicles than those used previously. In-flight exercise on those flights must abate the adverse effects microgravity (μG) has on humans. Due to space constraints on these vehicles, a single exercise device must address multiple fitness needs. Exercise and μG individually cause body heat accrual. During in-flight exercise they conspire to exacerbate heat gain. Given the duration of Mars missions and volume of exercise they entail, excess heat accrual must be addressed.

METHODS: This review presents data on μG, thermoregulation, and exercise. Since their relationships are impacted by other variables, energy balance, body water, and cerebral and vascular physiology are discussed. Data are integrated to acknowledge the challenges long-term missions, and the in-flight exercise that accompanies them, impose on thermoregulation. Strategies to limit heat accrual are discussed.

RESULTS: Current in-flight exercise and hardware will not address heat accrual mitigation or operational performance needs for Mars missions.

DISCUSSION: This review suggests for future missions, crewmembers: 1) consume beverages with high sodium contents; 2) employ palm cooling for conductive heat transfer; and 3) perform plyometric exercise on gravity-independent hardware. Research should continue to evaluate these treatments to abate heat gain in μG.

Maguire K, Wydotis M, Bollinger L, Caruso J. Abating heat accrual during exercise in microgravity and implications for future long-term missions. Aerosp Med Hum Perform. 2025; 96(1):53–61.