最大に至る負荷漸増作業に対する呼吸循環機能の対応

概要

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Cardiac output by the impedance cardiography method, oxygen uptake, and ventilation were measured during work to determine possible factors influencing maximal aerobic working capacity. Four male subjects, two were distance runners, and the other two were jumpers, performed a graded exercise to maximum on an ergometer. In all subjects cardiac output was the first measurement to reach its maximum and, thereafter, it decreased slightly. This decline of cardiac output resulted from a decrease in stroke volume. Heart rate continued to increase after cardiac output had leveled off. A further increase in O_2 uptake was seen after heart rate reached maximal level. Ventilation increased linearly with increasing workload up to the point requiring minute ventilation of 60-70 L per min. but thereafter, it increased disproportionately. Thus, circulatory factors are dominant in limiting the capacity. Distance runners showed greater stroke volume (and hence lower heart rate) for a given oxygen consumption than that of jumpers, suggesting effects of aerobic work on a circulatory efficiency. Furthermore, a high cardiac output per kg of body weight in runners was accompanied with a high maximal oxygen uptake per kg of body weight. No obvious difference was obtained in ventilatory responses between distance runners and jumpers.
中京大学の論文
1979-02-01