The effect of submaximal arm, leg, and“arm+leg”exercise on oxygen uptake (VO₂), heart rate (HR), and pulmonary ventilation (V_E) was studied in three male subjects. The“arm+leg”exercise was performed in ten different ways with different arm load ranging from 14 to 60% of the total work load. VO₂ and V_E were found higher in the arm exercise than in the other types of exercise at submaximal work. At a given work load, the lowest HR was observed in the“arm+leg”exrcise when the arm was loaded with 14 to 33% of the total work load. And the highest HR was obtained in the arm exercise. The higher HR during the arm exercise as compared to the legor“arm + leg”exercise may be accounted for by the fact that an exercise with small muscle group appears to elicit lower stroke volume and more pronounced rise in sympathetic tone. In the“arm + leg”exercise, HR at a given work load or VO₂ varied with the proportion of arm load. However V_E, whcih might be affected by stroke volume, was unaffected by the rate of arm to the total work load at a given work load or VO₂. This indicates that the sympathetic tone may be affected by the proportion of work load distribution on the active msucle groups in the“arm + leg”exercise.

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.