Indirect estimation of maximal oxygen uptake for study of working populations

Abstract

A total of 345 shipyeard workers (aged 23 to 47) volunteered to perform progressive exercise on a cycle ergometer (15 W/min increments) up to the symptom limited maximum. The results were used to obtain maximal oxygen uptake (ṅO2max), the oxygen uptake at a respiratory exchange ratio of unity (ṅO2 at R10), and cardiac frequency at an oxygen uptake of 45 mmol/min (fC45). In this group 156 men (45% of initial population) attained ṅO2 max as defined, 108 (31%) withdrew or did not exercise maximally, and 49 (14%) had transient electrocardiographic abnormalities. For the 156 men extrapolation of the relation of cardiac frequency on oxygen uptake to the predicted maximal cardiac frequency resulted in overestimation of ṅO2 max by 9.6%. ṅO2 Max per kg body mass was negatively correlated with body mass. ṅO2 Max (mean value 130.6 mmol/min) was described in terms of age, fat free mass, smoking (yes or no), and level of habitual activity (rated 1 to 4): the standard error of the estimate (SEE) was 17.3 mmol/min (R2 0.42); the equation was suitable for reference values. For estimating the ṅO2 max of individual men an empirical relation based on ṅO2 at R1-0, fC45, fat free mass, and % body fat had an SEE of 12.1 mmol/min (R2 0.67). Seventy six per cent of men (88% of those who exercised) attained ṅO2 at R1-0 (oxygen uptake approximately 73% of maximum). Thus the ṅO2 max could be estimated in a higher proportion of men than could achieve ṅO2 max. The estimate is appropriate for assessing exercise capacity in relation to employment. For investigating the determinants of exercise capacity in groups of subjects the submaximal index, ṅO2 at R1-0 is more informative.