Some factors affecting eccentric contraction strength

Properties of the force developed during eccentric contractions were investigated using a specially designed dynamometer. Elbow flexion was performed at the maximal voluntary contraction level. A force transducer was placed on the anterior surface of the wrist to measure elbow flexion force. Immediately after an isometric contraction of 2 seconds (ST1), the elbow joint was eccentrically stretched about 15° (ECC), and again put in an isometric state (ST2). Starting elbow angles were randomly assigned every 15° from 70° to 130° (full extension 180°) and stretch speeds ranged from 2.5 to 20 rpm. The muscle force during ECC was always greater than those during ST1 and ST2, and the difference between starting isometric force and eccentric peak force was greater at a higher speed.