Determinants for stair climbing by elderly from muscle morphology.

The relationship between muscle cross-sectional area (CSA) of the hip joint and lower extremities and speed of stair ascent/descent was investigated in a sample of 127 elderly women (ages: 60-70 years old). The participants performed ascent and descent of stairs with 12 steps for which the speeds for ascent and descent separately from video film were calculated. The ascent speed significantly correlated with CSAs of knee extensor (r=.21, p<.05) and psoas major muscle (r=.25, p<.01), which were assessed by magnetic resonance imaging. The descent speed also correlated with CSAs of the same muscle groups (with knee extensor: r=.20, p<.05, with m. psoas major: r=.18, p<.05). The rest of the muscle groups were not related to the ascent/descent speeds of the step. These results suggested that the muscle mass of the knee extensor muscle group and also the psoas major muscle could be a factor in potential capacity in stair ascent/descent by humans.