FORCE AND ELECTROMYOGRAPHIC (EMG) RELATIONSHIPS OF LEG EXTENSORS DURING ERGOMETER CONTRACTIONS

Abstract

'The purpose of this study was to examine the force/EMG relationship during dynamic muscle contractions. Three ergometers (isokinetic dynamometer, adapted leg-only ergometer, standard rowing ergometer) were modified with strain gauges and potentiometers to measure force and displacement. Surface electrodes were used to record EMG of rectus femoris (RF) and vastus lateralis (VL) muscles. Trained rowers (n=ll) performed leg extensions at randomly selected target forces under each condition. There was a strong positive linear correlation between force and EMG amplitude (RF, VL) under constant velocity conditions (r2=.866, .871). Although diminished in strength, this relationship was maintained under leg-only and standard ergometer conditions. The findings support the use of force/EMG analysis during rowing performance.