The link between body heat accrual and cognition: future considerations for in-flight exercise

NASA's Human Research Program identified Roadmap gaps that acknowledge the importance of thermoregulation to preserve crewmember cognition. Although a resting core body temperature on Earth is 37°C, 2.5 mo in microgravity sees that same measure rise to 38°C. Of greater concern is an internal body temperature of ∼38.5°C may initiate cognitive decline, and an in-flight core body temperature may exceed 40°C during submaximal exercise. Such increases are anticipated to be a bigger concern on the upcoming Artemis (Moon) and Orion (Mars) campaigns, as crewmembers will experience longer periods of microgravity, yet the cognitive and operational demands placed upon them will remain high and unwavering throughout each mission. This review examines the potential impact between body heat accrual and cognition. Treatments that may abate body heat accrual's impact on cognition will be discussed. Due to the in-flight exercise's impact on body temperatures, countermeasures to address this concern are also described, as well as exercise recommendations for future long-term manned space missions.