To estimate the subjective or physiological intensity of work, many index have been employed concerning the functional responses of oxygen transport system. In this study the validity of the index VO₂/VO₂max was discussed.
22 untrained healthy boys aged 16 were selected for the program, and the work was performed with a bicycle ergometer. Work load was increased progressively; 720 kpm/ min (2kp × 60rpm) for the first two minutes, and then increased 180 kpm/min (0.5 kp × 60 rpm) every successive minute to exhaustion. VO₂ and heart rate were measured at each step of load intensity. The expired air was collected in Douglas bag and was analyzed by Sholander apparatus for oxygen and carbon dioxyde.
There were some individual differences in correlation curves of VE to VO₂ and of FEO₂ to VO₂. The differences, however, were reduced and almost the similar curves were obtained when VE and FEO₂ were plotted against VO₂/VO₂ max instead of VO₂.
VO₂/VO₂ max and HR/HR max gave a very high correlation, 0.96. Though the correlation between VO₂ max and total work performed in exercise was 0.68, the correlation between VO₂/VO₂ max and total work was-0.89.
From these results, we should say that the index VO₂/VO₂ max and other functional index using their maximal values as denominator may be quite useful. And also we may assume that the work can be done with the highest efficiency when VO₂, heart rate, FEO₂, VE and probably some other physiological functions are at about 60% of their maximum. At least, we may say that there might occur some changes at this point in physiological conditions relating to the work capacity.