Abstract
Objective: To clarify the kinetics of gait instability with aging on an uneven surface.
Design: Floor reaction forces were measured on floors with even and uneven surfaces.
Setting: A force plate with an uneven surface was set on the floor of the laboratory.
Subjects : Twenty-six men and 17 women (age, 20 to 81 years) with no gait disturbances volunteered to participate in the study. The subjects walked at their own desired speed and at 120 steps/minute (cadence 120) .
Interventions: The subjects' heels landed on an elevations, or in the depression between two elevations while walking.
Results: The floor reaction force while walking at the subjects' desired speed on the even surface decreased with age. The vertical component and the fore and aft component of the floor reaction force on the depressed surface between two elevations decreased significantly, but the lateral component of the floor reaction force did not. The floor reaction force on the even surface at 120 steps/minute increased more than that at the subjects' desired speed. In particular, the vertical and lateral components on the depressed surface increased significantly, but the fore and aft component did not.
Conclusions: The lateral component of the floor reaction force for landing with the ankle joint in a pronated position was not related with aging. Thus, elderly people can walk safely on an uneven surface by walking slowly with short steps and strides.
