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AbstractFifteen previously sedentary men (38–55 years old) participated in an endurance training program which consisted of running for 2–3 half-hours a week for 8–10 weeks. Maximal oxygen uptake increased in all subjects, mean increase from 2.68 to 3.06 l/min, i.e. 14 per cent. This increase was brought about by a 13 per cent increase in maximal cardiac output, from 18.7 to 21.1 l/min. Heart rate was 8–17 beats/min lower during submaximal exercise. The maximal heart rate decreased by 6 (from 182 to 176) beats/min. Thus stroke volume was increased 7–17 ml at submaximal and 17 ml (16 per cent) at maximal exercise. Heart volume determined from X-rays did not change. After the training, mean arterial blood pressure was on the average 5 mm Hg lower at a given submaximal oxygen uptake; no change was observed at maximal exercise.Key Words: A-a oxygen gradient during exercisearterial blood pressurearterial PCO2arterial pHarterial PO2a-v oxygen differenceheart ratemaximal cardiac outputstroke volume
Hartley et al. (Wed,) studied this question.