Erector spime muscle fatigue: an electromyographic study

Abstract

The erector spinae muscles are important antigravity muscles, responsible for the physical and functional integrity of the spine. The study of these muscles fatigue is justified by its association to low-back pain. This study aimed at verifying the occurrence and behaviour of muscle fatigue by analysing electromyographic signs from the erector spinae muscles in an isometric test. Nine male volunteers aged in average 20,4±1,3 years old were submitted to a test of isometric contractions of the erector spinae muscles against loads of 5%, 10%, 15% and 20% of the maximum load. In order to record electromyographic signs a module was used for acquisition of biological signs with four channels, an analogic-digital circuit board and surface electrodes positioned bilaterally on the iliocostalis and multifidus muscles. Muscle fatigue was identified by the increase in electromyographic sign amplitude. The protocol here used proved effective in verifying the occurrence of fatigue in isometric contraction to exhaustion. Findings are that the iliocostalis showed predominantly more fatigue than the multifidus muscle. Bilateral comparison shows that right side erector spinae muscles evidenced predominantly more fatigue than the left side ones.