Evaluation of the postural stability in man: movement and posture interaction.

The stability of upright posture was evaluated in 13 young and 13 elderly subjects by measuring the amplitude of centre of foot pressure (COFP) excursion in the anteroposterior and mediolateral directions while performing voluntary motor tasks requiring precise center of gravity control i.e., circular and forward-backward sways, squatting and rising on toes. The elderly subjects exhibited a significantly smaller COFP excursion than the young in the circular and forward-backward sways and a nonsignificant reduction in the COFP progression in the rise on toes and squatting tasks. The data document significant reorganization of the motor program execution due to decline in the postural stability in old adults.