Low chemoresponsiveness and inadequate hyperventilation contribute
to exercise induced hypoxemia.
Harms, Craig A., and Joel M. Stager.
Human Performance Laboratory, Department of Kinesiology, Indiana
University, Bloomington, Indiana 47405
APStracts 2:0154A, 1995.
Is inadequate hyperventilation a cause of the exercise induced
hypoxemia (EIH) observed in some athletes during intense exercise? If
so, is this related to low chemoresponsiveness? To test the
hypothesis that EIH, inadequate hyperventilation, and
chemoresponsiveness are related, 36 non-smoking healthy men were
divided into hypoxemic (HYP;n=13) or normoxemic (NOR;n=15) groups
based on arterial oxygen saturation (SaO2)(HYP <90%; NOR >92%)
observed during O2max. Men with intermediate SaO2 values (n=8) were
only included in correlation analysis. Ventilatory parameters were
collected at rest, during a treadmill O2max test, and during a five
min run at 90% O2max. Chemoresponsiveness at rest was assessed via
hypoxic ventilatory response (HVR) and hypercapnic ventilatory
response (HCVR). O2max was not significantly different between NOR
and HYP. SaO2 was 93.8+/-0.9% (NOR) and 87.7+/-2.0% (HYP) at VO2max.
PETO2 and VE/VO2 were lower while PETCO2 was higher for HYP
(p<.01). PETO2, PETCO2, and VE/VO2 correlated (p<.05) to SaO2
(r=.84, r=-.70, r=.72, resp) suggesting that differences in
oxygenation were due to differences in ventilation. HVR and HCVR were
significantly lower for HYP. HVR was related to VE/VO2 (r=.43) and
HCVR was related to VE/VCO2 at O2max (r=.61). In summary, the results
suggest that inadequate hyperventilation, related to low hypoxic and
hypercapnic drive is a significant mechanism in the hypoxemia
experienced by some athletes during intense exercise.
Received 14 July 1994; accepted in final form 6 April 1995.
APS Manuscript Number A712-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 19 April 1995.