The Effect of a "wind-up" on Forearm Rotational Velocity

Subjects performed supination and pronation of the forearm against an inertial load with maximal voluntary effort, from either rest or when arresting the opposite motion of the load (a wind-up). The angular velocities produced at the mid-range of forearm movement were significantly greater with wind-up than without. The angle from which the movement began was significantly increased by wind-up. Isometric contractions produced torques which varied a great deal through the range of motion. While it was not possible to identify the physiology effects of wind-up, consideration was given to techniques which would achieve this aim. Wind-up was discussed in the context of skilled activity where sustained maximal contractions are unlikely throughout the activity.