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Oxygen consumption and carbon dioxide elimination during normal and hyperventilated breathing at progressive work rates Loewen, Henry Rudolf

Abstract

This study was undertaken to determine and compare the rates of oxygen consumption and carbon dioxide elimination during normal and hyperventilated breathing at progressive work rates. Three subjects stepped at 18, 24, 30, 36 and 40 steps per minute on an eighteen inch bench for a duration of ten minutes or until exhaustion. All exercises were performed inside a 6,900 liter closed circuit respirometer. The volume of each subject obtained from hydrostatic weighings was subtracted from the chamber volume as was the volume of the bench. Net volume was corrected to STPD. The respirometer was equipped with Beckman oxygen and carbon dioxide analyzers, an internal cooling system as well as wet and dry thermocouples on three sides . Oxygen and carbon dioxide concentrations were continuously analyzed and automatically recorded against time. A resting metabolic rate was established prior to each work task. Completion of the exercise was followed by a fifteen minute recovery period. Curves of cumulative oxygen consumption (VO₂) and carbon dioxide elimination (VCO₂) were plotted against time. By determining the gradients of these curves at different points it was possible to plot the corresponding velocity curves [formula omitted]. The acceleration curves [formula omitted] were derived from the velocity curves. An IBM computer program was used to determine the velocity and acceleration values. When compared to normal breathing, hyperventilating at the higher work loads increases the VO₂ and VCO₂ during the early phase of exercise. This is generally followed by decreased VO₂ during the recovery period. There are well defined differences in the derivative curves between normal and hyperventilated breathing. Implications for athletic performance are indicated. Derivative curves of oxygen consumption and carbon dioxide elimination appear to be highly individual. Their use as a fitness criterion is indicated.

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