Limitations to prediction of maximal oxygen intake

The predictability of maximal O2 intake (max Vo2) was studied in four groups of normal men, 18–24 years of age. Prediction of max Vo2 was made from pulse rate and Vo2 at a single submaximal workload at an ambient temperature of 78 F by use of the nomogram of Åstrand and Ryhming (1954) and underestimated actual max Vo2 by 27 ± 7% and 14 ± 7% in a sedentary group, before and after 2frac12–3 months of physical training, and by 5.6 ȁ 4% in a group of ten endurance athletes. Accuracy of prediction in all groups varied with approximation of pulse rate to 128 beats/min at 50% of max Vo2. Nonspecific stresses increased predictive errors in all groups. Constants b (slope) and A (intercept) in the regression equation Vo2 = bP – A (where P is pulse rate), were determined from Vo2 and pulse measured at four submaximal workloads requiring 13–28 ml O2/kg min. Prediction of max Vo2 by extrapolation of the slope to maximal pulse rate resulted in underestimation of 700–800 ml O2/min. Removal of 14% of circulating hemoglobin decreased max Vo2 by 4% but there was no change in pulse rates or predicted max Vo2. The relationship of RQ to V22 during work provided no reliable basis for prediction of max Vo2.

exercise pulse rate, oxygen intake, relationship; pulse rate, oxygen intake relationship in exercise; metabolic rate, maximal aerobic prediction of; aerobic metabolic rate, maximal, prediction of; phlebotomy, effect on maximal oxygen intake, pulse rate; blood loss, effect on maximal oxygen intake, pulse rate; training, effect on maximal oxygen intake, pulse rates; physical conditioning, effect on maximal oxygen intake, pulse rates

Submitted on October 4, 1963

Saturation of arterial blood with oxygen during maximal exercise

The per cent saturation of the arterial blood with oxygen was examined in four men before and during the last 15 sec of a 3-min run of sufficient intensity to elicit a maximal oxygen intake. The measurements were repeated after a 3-month period of intensive conditioning for middle distance running and in a group of four athletes in good physical condition. The per cent saturation in the sedentary group was 95.8 at rest and 93.4 during exhausting exercise; after conditioning the similar figures were 95.4 and 91.4 and, finally, the athletes showed a per cent saturation of 85.2 during the heavy work. The arterial oxygen content during exhausting work was found to be 20.12 ml/100 ml blood in the sedentary group before training, 19.02 after conditioning, and 18.18 in the group of athletes. It is concluded that, in athletes who are well conditioned and pushing themselves close to the limit of their capacity, arterial desaturation can take place.

athletic conditioning and arterial oxygen saturation; arterial desaturation in athletes; ventilation and arterial desaturation; oxygen intake and arterial oxygen saturation

Submitted on August 5, 1963