Age-related differences in postural control in humans in response to a sudden deceleration generated by postural disturbance.

Age-related differences in postural control in response to a relatively large deceleration resulting from postural disturbance were investigated in eight normal elderly men (age range 67-72 years) and eight young men as controls (age range 19-22 years) using a moving platform. Data were obtained for the hip, knee and ankle angles, position of the centre of foot pressure (CFP), head acceleration, and muscle activity of the leg muscles. The elderly subjects had slower and larger ankle and hip joint movements, and CFP displacement in response to the disturbance compared to the young controls. The elderly subjects also had a delayed occurrence, and greater magnitude of peak acceleration of head rotation than did the young subjects. For the elderly subjects, the CFP was closely related to angular changes in the hip joint movement, but not to those of the ankle and knee joint movements. For the young subjects, on the other hand, the CFP was significantly correlated with angular change in the ankle joint. Cocontraction of the tibialis anterior and gastrocnemius muscles was observed in the elderly subjects. The results indicated that a movement pattern for postural correction in the elderly adults was different from that of the young adults. The elderly relied more on hip movements while the young controls relied on ankle movements to control postural stability.