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Body temperature and thermoregulation during submaximal exercise after 115-day spaceflight
S M Fortney1, V Mikhaylov, S M Lee
1NASA Johnson Space Center, Houston, TX 77058, USA.
Aviation, Space, and Environmental Medicine
|March 10, 1998
Summary
Spaceflight reduces the body's ability to lose heat during exercise. This preliminary study found decreased skin blood flow and sweating sensitivity after long-duration spaceflight, leading to a faster core temperature rise.
Area of Science:
- Human physiology
- Space medicine
- Thermoregulation
Background:
- Altered thermoregulation is known from spaceflight simulations.
- Previous studies have not examined thermoregulation after actual spaceflight.
Purpose of the Study:
- To test if body temperatures and heat loss responses during exercise are similar before and after spaceflight.
- To investigate the effects of long-duration spaceflight on human thermoregulation.
Main Methods:
- Two astronauts performed supine submaximal cycle exercise before and after a 115-day mission on Mir.
- Core temperature, skin blood flow, and sweating rate were measured during exercise.
Main Results:
- Astronauts could not complete the postflight exercise protocol due to elevated core temperature.
- Postflight, the sensitivity of skin blood flow and sweating responses to core temperature was reduced.
- The thresholds for initiating sweating and skin blood flow did not change significantly.
Conclusions:
- Long-duration spaceflight significantly reduces the sensitivity of heat loss responses.
- This diminished thermoregulatory capacity results in a more rapid increase in core body temperature postflight.
- Further research is needed to understand the implications for astronaut health and performance.