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Skin surface cooling improves orthostatic tolerance following prolonged head-down bed rest
David M Keller1, David A Low, Scott L Davis
1Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, 7232 Greenville Ave., Dallas, TX 75231, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 2, 2011
Summary
Skin surface cooling may help preserve orthostatic tolerance after head-down bed rest (HDBR). This intervention improved tolerance post-HDBR, offering a potential countermeasure for microgravity or immobilization.
Area of Science:
- Human physiology
- Space medicine
- Cardiovascular research
Background:
- Prolonged microgravity or head-down bed rest (HDBR) impairs human orthostatic tolerance.
- Skin surface cooling is known to improve orthostatic tolerance, but its efficacy after HDBR is unstudied.
Purpose of the Study:
- To test if skin surface cooling can preserve orthostatic tolerance following prolonged HDBR.
Main Methods:
- Eight subjects underwent a 6° HDBR protocol.
- Orthostatic tolerance was assessed using lower-body negative pressure (LBNP) tests before and after HDBR.
- Thermal conditions included normothermia and skin surface cooling via a tube-lined suit.
Main Results:
- HDBR significantly reduced normothermic orthostatic tolerance (CSI decreased from 1037 to 574 mmHg·min).
- Post-HDBR, skin surface cooling significantly increased orthostatic tolerance (CSI to 797 mmHg·min) compared to normothermia.
- The improvement did not fully reverse the tolerance reduction from HDBR.
Conclusions:
- Skin surface cooling partially restores orthostatic tolerance after HDBR.
- This method shows promise as a countermeasure for spaceflight and prolonged immobilization.
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