A force platform was utilized to provide a new and sensitive means to
measure postural steadiness and stability. Normal standards are presented
for the center of pressure of the vertical supportive force during standing
and sustained weight-shifting of normal men in three age groups. Two
distinguishing characteristics were seen for normal upright posture: (1) a
large area of stability over which weight can be safely shifted and
maintained, and (2) steadiness such that the center of pressure fluctuates
incessantly, traversing large total excursions, while remaining remarkably
close to the mean point. The youngest age group showed the greatest
steadiness and stability and the oldest group showed the least.