Figure 2.
Absolute power (Watts, A) and specific power (normalized to anterior mid-thigh muscle cross sectional area) (Watts per cm2, B) plotted against movement velocity in middle-aged healthy (mean ± SD age: 47.2 ± 5 yrs), older healthy (74 ± 4 yrs) and older mobility-limited participants (78.1 ± 5 yrs). Testing was conducted using a Cybex-II dynamometer. Five consecutive maximal isokinetic (constant velocity) knee extensions were performed at 60, 90, 180, and 240 degrees second, with participants instructed to kick out as fast and hard as possible. Each testing condition was separated by at least 1 minute of rest. A significant group × velocity interaction was indicated for both power variables with all groups significantly different. Post hoc testing revealed: *older mobility-limited was less than middle-aged healthy adults and older healthy adults; †power has increased from the previous (slower) velocity in middle-aged healthy and older healthy but not in older mobility- limited; and ‡power has increased from the previous (slower) velocity in middle-aged healthy but not in older healthy or older mobility-limited. Older mobility-limited showed no difference is absolute or specific power between contraction velocities (60–90, or between 90, 180 and 240 degrees per second) indicating a plateau in the ability to produce power at faster speeds. (Reprinted from (13).Copyright © 2010 Oxford University Press. Used with permission.)