Effect of acute hypoxia on maximal exercise in trained and sedentary women.
OBJECTIVE
The purpose of this study was to determine the physiological responses of sedentary and endurance-trained female subjects during maximal exercise at different levels of acute hypoxia.


METHODS
Fourteen women who were sea level residents were divided into two groups according to their level of fitness: 1) endurance-trained women (TW) (N = 7), VO(2max) = 56.3 +/- 4.7 mL.kg(-1).min(-1); and 2) sedentary women (SW) (N = 7), VO(2max) = 34.8 +/- 5.6 mL.kg(-1).min(-1). Subjects performed four maximal cycle ergometer tests in normoxia and under hypoxic conditions (F(I)O(2) = 0.187, 0.154, and 0.117, corresponding to altitudes of 1000, 2500, and 4500 m, respectively).


RESULTS
VO(2max) decreased significantly by 3.6 +/- 2.1, 14 +/- 2.5, and 27.4 +/- 3.6% in TW, and by 5 +/- 4, 9.4 +/- 6.4, and 18.7 +/- 7% in SW at 1000, 2500, and 4500 m, respectively. The drop of VO(2max) (DeltaVO(2max)) was greater in TW at and above 2500 m. Arterial O2 saturation (SpO(2)) at maximal exercise was lower in TW at every altitude (1000 m: 90.9 +/- 1.9 vs 94.6 +/- 1.4%; 2500 m: 82.8 +/- 2.8 vs 90.0 +/- 2.1%; 4500 m: 65.0 +/- 4.7 vs 73.6 +/- 4.5%). Maximal heart rate decreased significantly from 1000 m in the two groups. SpO(2) was correlated to DeltaVO(2max) at 4500 m (r = -0.81, P < 0.01) and 2500 m (r = -0.81, P < 0.01), but not below. Furthermore, we noted a relationship between SpO(2) and O2 pulse (VO(2)/HR) at every F(I)O(2).


CONCLUSIONS
These results demonstrate that endurance-trained women show a greater decrement in VO(2max) at high altitudes. This could be explained mainly by a higher arterial desaturation, which is largely caused, according to our results, by diffusion limitation.
Woorons
Xavier
X
Laboratory of Functional and Cellular Responses to Hypoxia, UFR-SMBH Universite Paris, 74 rue Marcel Cachin, 93017 Bobigny Cedex, France. xwoorons@laposte.net
Mollard
Pascal
P
Lamberto
Christine
C
Letournel
Muriel
M
Richalet
Jean-Paul
JP
D000328:Adult; D000531:Altitude; D001784:Blood Gas Analysis; D016552:Ergometry; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption
D010100:Oxygen