[Effect of aging on the aerobic capacity measured by a step-test]

The purpose of this study was to develop a step-test in order to evaluate age-related change in aerobic capacity. A total of 149 healthy men of age through 18 to 83 yrs ascended and descended a single step of 0.2 m height in time to a metronome. The step rate increased step-wise through three stages, each of 3 min duration; 15, 20 and 25 (step/min) for subjects aged 59 or less, and 10, 15, and 20 (step/min) for those age 60 and over. Using the linear relationship between load and heart rate, physical work capacity (PWC, watt/kg) was estimated as the work load with maximum heart rate predicted by age (220-age). In the elderly group (n = 34), heart rate at the end of the last stage was within 60-80% of the maximum heart rate for 25 subjects, and more than 80% for the other 9 subjects. No risky arrhythmia or significant ST change on ECG appeared in any subject. A retest of the step-test for 16 elderly subjects showed its repeatability and a linear relationship between heart rate and oxygen consumption. The results suggested that the step-test was applicable to the elderly in regard to appropriate work load and safety. The PWC significantly declined with aging (r = 0.52, p < 0.001). Relative aerobic capacity, taking that at age 20 as 100%, was 60% and 53% for subjects aged 60 and 70, respectively, which was in good agreement with available reports which measured oxygen consumption directly.