Cardiorespiratory responses to graded exercise at increased ambient air pressure

Autor: L. Fagraeus, Dag Linnarsson, C. M. Hesser
Rok vydání: 1974
Předmět:
Zdroj: Acta physiologica Scandinavica. 91(2)
ISSN: 0001-6772
Popis: The separate and combined effects of increased inspired oxygen and nitrogen pressures on cardiorespiratory and metabolic responses to graded exercise (50, 100, and 150 W) were assessed by comparing data from identical work experiments performed under three different ambient conditions, viz. with the subjects breathing (A) air at 1.0 ATA, (5) oxygen at 1.0 ATA, and (C) air at 4.5 ATA (same inspired Po3 as in B). In general, the physiological responses to the various work loads were qualitatively similar in the three conditions, but for a given load quantitative differences were observed. By comparing Condition C with A it was found that a rise in both the O2 and N2 pressures resulted in the following changes at the highest work load: significant increments in Vos, Vco2, end-tidal and mixed expired Pco2, and oxygen pulse (Vo2 per heart beat), significant reductions in heart rate, VD, VD/VT, and ventilatory equivalents for oxygen (vI/vCO2) and carbon dioxide (vI/vCO2), and no consistent changes in Vi and respiratory exchange ratio. When related to vO2, i.e. to the metabolic rather than the ergometric load, Vi was lower in C than in A. By comparing Condition B with A, and C with B, evidence was obtained that the above changes in Vi, Pco2, ventilatory equivalents, oxygen pulse, and heart rate were caused in part by the rise in O2 pressure, and in part by factors related to the rise in N2 pressure, whereas the changes in VD and VD/VT were due mainly to the raised O2 pressure, and the changes in Vo2 and Vco2 to the raised Ns pressvire.
Databáze: OpenAIRE
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