Effects of antagonist pre-load on knee extensor isokinetic muscle performance

The aim of this study was to evaluate and compare acute effects of a reciprocal action protocol and a super-set protocol on knee extensor performance during concentric isokinetic exercise. Fourteen men aged 29.4±6.1 years were tested on three different protocols, with 1 min of rest between sets: control (3 sets of 10 isokinetic knee extension repetitions), reciprocal action protocol (3 sets of 10 repetitions of reciprocal isokinetic concentric knee flexion and knee extension repetitions), and super-set protocol (3 sets of a combination of 10 repetitions of knee flexion immediately followed by 10 repetitions of knee extension repetitions). Tests were performed at 60° · s^-1 and 180° · s^-1, randomized across 3 days and separated by at least 72 h. There were no significant differences between protocols for peak torque at 60° · s71 or 180° · s^-1. Total work was significantly higher during the reciprocal action protocol compared with the super-set protocol at 608 · s^-1. There was a significant decline in peak torque (from 240.6 to 212.9 N · m) and total work (from 2294 to 1899 J) for the control condition at 60° · s^-1. Also, total work declined significantly across sets for the super-set protocol at 60° · s^-1 (from 2157 to 1707 J). Results indicate that a reciprocal action protocol provides torque maintenance during multiple sets of isokinetic training, both at slow and high velocities.