The prediction of neck extensor force using surface electromyography

Abstract

BACKGROUND:

The relationship between muscular force and electromyography (EMG) has been investigated by numerous researchers. EMG has not previously been used as a means of estimating force in the cervical erector spinae (CES).

OBJECTIVE:

Use EMG of the CES musculature to indirectly predict neck extension force.

METHODS:

Isometric contractions of the CES muscles were studied at increasing levels of contractile force across all participants (n= 12) to produce an individualised force-EMG relationship. The method of least squares was used to determine the linear regression trend line for the force-EMG relationship. The validity of these individual `correlation curves' was demonstrated through further, blinded, investigation.

RESULTS:

A linear relationship was identified for the individualised correlation curves that gained in strength for < 50% maximum voluntary contraction(MVC; R²> 0.8 for 80% of trials). The prediction of muscle force from the correlation curves was found to be statistically similar to the equivalent experimental data (p> 0.05). Given the tendency of EMG to slightly overestimate force in most cases, an adjustment coefficient was calculated to reduce the error in the predicted force data.

CONCLUSIONS:

This study reports a validated method using EMG to indirectly acquire CES muscular force, which has application for clinicians and research scientists working in fields including sport and rehabilitation.