Abstract
Breathing pattern in response to maximal exercise was examined in four subjects during a 7-day acclimatisation to a simulated altitude of 4247 m (barometric pressure, PB = 59.5 kPa). Graded exercise tests to exhaustion were performed during normoxia (day 0), and on days 2 and 7 of hypoxia, respectively. Ventilation was significantly augmented in the hypoxic environment, as were both the mean inspiratory flow (VT/TI) and inspiratory duty cycle (TI/TTOT) components of it. VI/TI was increased due to a significant increase in tidal volume (VT) and a corresponding decrease in inspiratory time duration (TI). Throughout a range of exercise ventilation, TI/TTOT was increased due to an apparently greater decrease in expiratory time duration (TE) with respect to TI. In all cases, the relation between VT and TI displayed a typical range 2 behaviour, with evidence of a range 3 occurring at very high ventilatory rates. There was essentially no difference observed in the VT-TI relation during exercise between the normoxic and hypoxic conditions. No significant changes were observed in the breathing pattern in response to exercise within the exposure period (from day 2 to day 7), although there was a discernible tendency to a higher stage 3 plateau by day 7 of altitude exposure.
Original language | English (US) |
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Pages (from-to) | 61-65 |
Number of pages | 5 |
Journal | European Journal of Applied Physiology and Occupational Physiology |
Volume | 62 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1 1991 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Physiology
- Public Health, Environmental and Occupational Health
Keywords
- Graded exercise
- Hypobaric hypoxia
- Mean inspiratory flow
- Regulation of breathing
- Respiratory phase durations