Assessment Of Leg Muscle Power Using A Stair-climbing Power Test In Community-dwelling Elderly People

Abstract

A stair-climbing power test (SCPT) is an inexpensive, practical test that is simple to perform. An individual's lower extremity power is a critical element regarding both mobility and the activities of daily living, while it is also a key determinant of independence for elderly people. PURPOSE: To determine the usefulness of the SCPT, a modification of the Margaria stair-climbing power test, by comparing the results obtained from the SCPT with those from a leg power test in community-dwelling elderly people. METHODS: The subjects of this study consisted of physically-independent elderly men (N=19, aged 75+/-6 yrs) and women (N=18, aged 77+/-6 yrs). The stair-climbing power was measured using ordinary stairs (17.5cm step height, 6-stair flights, 105 cm total height). The time spent in stair climbing was measured by a stopwatch. The subjects were instructed to ascend the stairs as fast as they could. The stair-climbing power was then calculated with the body mass, the time spent in stair climbing, the vertical height travelled, and the gravitational acceleration. The bilateral leg extensor power (LEP) was measured using an isotonic leg power system (Combi, Anaero Press 3500, Japan) in a sitting position. The isometric knee extension strength was measured on each side of the knee using a specially designed dynamometer (Yagami, Japan). RESULTS: The stair-climbing power was 297.6+/-60.3 watts (mean +/- SD) for men and 199.1 +/-60.6 watts for women. LEP was 768.2+/-324.6 watts for men and 361.6+/-152.8 watts for women. The knee extension strength was 39.4 +/-9.2 kg for men and 24.0 +/-6.8 kg for women. The stair-climbing power correlated closely with both the leg extensor power (r=0.557, p<0.05 in men and r=0.541, p<0.05 in women) and with the knee extension strength (r=0.566, p<0.05 in men and r=0.657, p<0.05 in women). CONCLUSIONS: From a practical viewpoint as a field test, the SCPT was found to be useful for assessing the functional leg power levels in physically-independent, ambulatory elderly people.