The rate of torque development: A unique, non-invasive indicator of eccentric-induced muscle damage?

This study examined the time courses of recovery for isometric peak torque and rate of torque development (RTD) after eccentric-induced muscle damage. 18 men completed 6 sets of 10 maximal eccentric isokinetic muscle actions at 30°-·-s^-1. Peak torque, peak RTD and RTD at 10 (RTD10), 50 (RTD50), 100 (RTD100) and 200-ms (RTD200), serum creatine kinase and lactate dehydrogenase were measured before (PRE), immediately after (POST), 24, 48 and 72-h after eccentric exercise. Creatine kinase and lactate dehydrogenase increased from 139 to 6-457 and from 116 to 199-IU-·-L^-1 from PRE to 72-h, respectively. Peak torque and all RTDs decreased at POST. Peak torque and RTD200 remained lower than PRE through 72-h. Peak RTD remained lower than PRE through 48-h, but was not different from PRE at 72-h. RTD10 and RTD100 were lower than PRE through 24-h, but were not different from PRE at 48 and 72-h. RTD50 decreased at POST, but was not different from PRE at 24-h. Early phase RTDs recovered more quickly than PT and RTD200. Early phase RTDs may reflect neural mechanisms underlying eccentric-induced force decrements, while late RTDs may describe the same physiological mechanisms as PT.