Studies of the maximum capacity of men for physical effort

Summary

Physiologists working on exercise physiology are concerned not only with the maximum oxygen intake of individuals, but also with the ability of an individual to work for prolonged periods.Wyndham and colleagues have found this maximum level to be at about 60% of an individual's maximum oxygen intake.

Gross body weight is highly correlated with maximum oxygen intake and for the purpose of comparison it is more meaningful to express oxygen intake in terms of ml/min/kg of body weight. This expression also permits for the mean oxygen intake in ml/min/kg of one group to be compared with that of any other group.

80 young South African Caucasian males were tested to determine their oxygen intake in terms of their body weights. The figure obtained was 47.7±3.79 ml/min/kg. This figure compares favourably with the figure for U.S. Army recruits (48.3±0.94ml/min/kg), with the figure for U.S. White sharecroppers (49.6±0.52 ml/min/kg) and the figure for the Arctic Indians (49.1 ml/min/kg). When a correction factor for the high altitude of Johannesburg is employed then the figure for the S. A. Caucasian is 55 ml/min/kg. This would indicate that the active, young S. A. Caucasians are, in fact, fitter than their counter parts in other advanced Western countries.

If the effort involved in any task and the oxygen intake in ml/min/kg are known quantities, it is possible for the physiologist to assess whether or not the individual or the group of individuals will be able to perform the task concerned. Judged on the criteria of oxygen intake in ml/min/kg and the 50% level required for prolonged effort, it was found that all S. A. Caucasians were capable of moderate work, but that 24% were incapable of hard work.