Constant effort during static and dynamic muscular exercise

Ss maintained sense of effort constant over time for two tasks: static handgrip contractions held for 3 min., and dynamic exercise performed on a bicycle ergometer for 12 min. Initial force of handgrip ranged from 18-85% of maximum voluntary contraction, and initial power output for cycling ranged from a level that elicited 30% to a level that elicited 85% of maximum oxygen uptake. Except at the lowest levels of effort, constant-effort functions (force vs. time, power output vs. time) for the two tasks declined sharply at first, more slowly thereafter. Handgrip declined toward a steady state (asymptote) force near 15% of maximum voluntary contraction and functions for cycling toward a steady state power output that elicited oxygen uptakes equal to or less than approximately 50% of maximum. The two types of constant-effort functions reflect basic differences between static and dynamic tasks.