The purposes of this study were to observe physiological responses of the middle-aged to exercise by a tentative aerobic work capacity test and to elucidate physiological characteristics of a middle-aged marathoner.
　A tentative method of aerobic work capacity test was developed from the viewpoint of safety. The procedure was to exercise at two given submaximal loads (100W and 150W for four minutes, respectively) on a electric bicycle ergometer which could keep workloads constant even if pedalling rates changed. Three healthy middle-aged males (one marathoner, one jogger and one control) performed this exercise. During the exercise, oxygen and carbon dioxide concentration was continuously analyzed. Heart rate (HR) and brachial artery blood pressure were monitored every minute, and oxygen uptake (VO₂), pulmonary ventilation (VE), oxygen pulse, respiratory rate, tidal volume and oxygen removal were obtained. This tentative aerobic work capacity test followed Margaria's two-step load method. Estimation of VO₂ was based upon Balke's formula. VO₂max estimated from the HR and VO₂ values at the two workloads showed small standard error (5.74%) and a high correlation coefficient (r=0.957, p<0.001) was found between measured VO₂max and estimated VO₂max. Consequently, it could be concluded that this test method was reliable.
　There was little difference in performance time between Marathoner and Jogger, but differences were found in VO₂max, O₂ pulse and O₂ removal. particularly, Marathoner showed greater value of O₂ pulse at exhaustion, compared with Jogger and Control (18.4 vs. 15.5 and 11.6me/beat). These results indicated that Marathoner's great performance was based upon efficient oxygen transportation system.

DESCENTE SPORTS SCIENCE Vol.6/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE