The relative merits of the step test, bicycle ergometer, and treadmill in the assessment of cardio-respiratory fitness.

Abstract

1. Step, bicycle and treadmill tests for the prediction of aerobic work capacity have been compared in ten young men. 2. The efficiency of performance of a simple step test at a comfortable speed was independent of step height (over the range 9 to 18 inches). Efficiency was reduced at low and at high rates of stepping. On the bicycle ergometer efficiency was independent of load over the range 384 to 960 kg.m./min. Individuals with a large aerobic capacity were less efficient in the performance of both tasks; this was apparently attributable to unmeasured anaerobic components of metabolism. 3. The oxygen consumption at a given rate of external work decreased in step, bicycle, and treadmill tests, as each task was learnt. The oxygen consumption during the first definitive test of each type could be predicted from the work rate without systematic error. The variance of this prediction decreased with learning, but remained consistently greater for the treadmill than for step and bicycle tests. 4. Whether the ‘work’ or the oxygen consumption scale of the Astrand nomogram was used to predict aerobic work capacity, the variance of the discrepancy between predicted and directly measured values was marginally smaller for the step test than for the bicycle ergometer; it was also smaller than for the treadmill test. On grounds of reliability and convenience, the step test thus seems the method of choice for the prediction of aerobic work capacity. 5. With all three test procedures, the aerobic work capacity could be predicted with a much smaller coefficient of variation if the oxygen consumption used in this prediction was measured rather than estimated from the work rate.