Moderate exercise after altitude exposure fails to induce decompression sickness.
BACKGROUND
The objective of this study was to determine the effect of exercise after altitude exposure (post-exposure exercise) on subsequent altitude decompression sickness (DCS) incidence. Existing USAF prohibition of exercise following altitude chamber training exposures and interest from operational personnel prompted our evaluation of post-exposure exercise as a DCS-inducing stressor.


METHODS
After a 1-h resting preoxygenation, 67 subjects were exposed to 30,000 ft for 2-h while performing mild, upper body exercise. The subjects were monitored for venous gas emboli (VGE) with an echo-imaging system and observed for signs and symptoms of DCS. Subjects without DCS (n = 31) or with DCS which resolved during recompression (n = 29) were randomly assigned to post-exposure rest (control, n = 29) or moderate exercise (50% of peak oxygen uptake, dual-cycle ergometry; n = 31) and both groups were monitored for delayed or recurring DCS.


RESULTS
The altitude exposure resulted in 48.3% DCS in the 60 volunteers serving as test or control subjects. Of 31 subjects assigned to the post-exposure exercise group, 15 had developed DCS which resolved during descent. No cases of DCS were observed or reported during or following post-exposure exercise.


CONCLUSIONS
The results show that moderate exercise after exposure did not result in either delayed-onset or recurring DCS.
Webb
James T
JT
Wyle Laboratories, Life Sciences, Systems, and Services, San Antonio, TX 78232, USA. james.webb@brooks.af.mil
Pilmanis
Andrew A
AA
Fischer
Michele D
MD
D000328:Adult; D003665:Decompression Sickness / Q000209:etiology*; D015444:Exercise; D006801:Humans; D008297:Male