A STUDY OF RESPONSES TO WORK ON A BICYCLE ERGOMETER

Abstract

A linear relationship between the amount of O absorbed and the load of work was maintained by all subjects during moderate exertion. In 4 of 6 cases, the linear relationship was broken soon after the crest-load was passed. The pulse frequency also, like O absorption, augments roughly in a linear relationship to the increase in work up to a certain load, which is found to vary from man to man. The O-pulse rises steadily with an increasing load of physical work, and gives a plotted curve with the concavity towards the abscissa, except for the heaviest loads. The minute-volume of breathing for the 4 subjects who reacted well maintained a linear relationship to the load of work up to the crest-load. For larger loads the increase in lung ventilation becomes excessive and diverges upward from the normal line of augmentation. There is a tendency for the frequency and depth of breathing to increase proportionately with the load up to or just above the crest-load. With overloads of work the frequency of breathing augments inordinately. The limit of voluntary physical effort in 2 cases seemed to be due primarily to failure of the heart to augment proportionately to the increased demands of the tissues for O. Another limiting factor was indicated in the failure of the O-pulse to augment in the usual degree. This is interpreted to be due to an inability to adequately increase the coefficient of utilization of 0.