ABSOLUTE AND RELATIVE WORK CAPACITY IN WOMEN AT 758, 586, AND 523 TORR BAROMETRIC-PRESSURE

  • 1 January 1980
    • journal article
    • research article
    • Vol. 51  (5) , 439-444
Abstract
Six young women performed an incremental bicycle work test at sea level barometric pressure (PB = 758 torr) and during acute exposure (1 h) to simulated altitudes of PB 586 and 523 torr. Submaximal O2 uptake (.hivin.VO2) for a given workload was independent of altitude but maximal O2 uptake (.ovrhdot.VO2 max) decreased 10 and 13%, respectively, at the higher altitudes. Although heart rate (fC) was consistently higher at altitude for a given .ovrhdot.VO2, the slope of fC vs. .ovrhdot.VO2 was independent for altitude and .ovrhdot.VO2 max. Exercise fC is apparently a function of the relative workload, i.e., .ovrhdot.VO2 as a percentage of .ovrhdot.VO2 max measured at each PB. CO2 elimination increased with altitude for a given .ovrhdot.VO2 but was a function of the relative workload. Pulmonary ventilation (BTPS) was consistently 10-15% higher at altitude when expressed as a percent of .ovrhdot.VO2 max, primarily due to an increase in respiratory rate. Compared to males, this increased ventilation may impart a slight advantage to women in maintaining arterial oxygenation, but ventilatory reserve may be decreased and limited at higher altitudes. At altitudes down to PB 523 torr, the control of fC responses and decrements in maximal O2 uptake in women were similar to males, but ventilatory control mechanisms differed.

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