Physiological Variables Related to the Selection of Work Effort on a Treadmill and Bicycle.

Abstract Ten female subjects were asked to run on a treadmill at a speed selected previously to tire them in 15 minutes. They later were asked to try to repeat the same work effort on a bicycle. Heart rate increased 60% from either a slow walking base level or a nonloaded bicycle ride at 60 rpm, and RQ rose to .90 when the subjects felt work effort on a treadmill and bicycle were equivalent. The absolute value of oxygen uptake, ventilation, and heart rate did not indicate to the subject that the physiological strain was similar, since all these measurements were lower on the bicycle during the selected work effort. The oxygen debt was not related to physiological strain, since the treadmill O2 debt was double that of the bicycle exercise, though the subjects felt they were exercising at the same work level.