| Summary: | Exercise induced arterial hypoxaemia (EIAH) is reported to occur in ~ 50% of
highly trained male aerobic athletes. EIAH can have detrimental effects on athletic
performance. Reversal of EIAH has been reported to increase maximal oxygen
consumption (VO₂max) and endurance performance time in some subjects during heavy
exercise. The number of investigations involving EIAH and females are small, and the
results thus far are controversial. It has been reported that some females experience
EIAH at a relatively lower fitness level compared to males, while other studies report that
the prevalence in females is no different from that of males. Anatomical differences may
predispose females to certain EIAH mechanisms, which may increase the prevalence of
EIAH in this population. Expiratory flow limitation has been correlated to EIAH in
women and may contribute to inspiratory muscle fatigue. Inspiratory muscle fatigue is
reported to occur in males following heavy bouts of exercise, however, the relationship
between EIAH and inspiratory muscle fatigue in women, had not been determined. The
purpose of this investigation was to determine the prevalence of EIAH in females and
observe any relationship between EIAH and inspiratory muscle fatigue. The prevalence
of EIAH in women was determined in a large sample of females (n = 52, mean = 26.5
years) (VO₂max range: 28.0 - 61.3 ml/kg/min). It was hypothesized that EIAH would
occur with a greater prevalence and relatively lower % VO₂max than previously reported
in males. Prior to and following exercise, subjects performed a maximal inspiratory
pressure (MIP) maneuver of the mouth, and handgrip strength test. The exercise test
consisted of an incremental test (50 watts/2.5 min) to exhaustion (VO₂max) on an
electronically braked cycle ergometer. End tidal CO₂ (PETCO₂) was recorded at each
stage of the test. In this study, the prevalence of EIAH in women was slightly greater than
that previously reported for males (67 %, n = 35). Hypoxaemic participants were
grouped according to their degree of desaturation: mild EIAH SaO₂ = 94-92 % (n = 19),
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