Electromyographic and force analysis of the deltoid muscle in subjects with shoulder impingement syndrome

Abstract

This study aimed at comparing electromyographic activity of the pars clavicularis, acromialis, and spinalis of the deltoideus muscle, as well as the force exerted during abduction, in healthy individuals and in those with shoulder impingement. Fifteen subjects with impingement syndrome (44.1±8.6 years old) with Neer degrees I and II took part in the study; 15 healthy subjects (43.6±8.1 years old) were paired to those of the first group. Electromyographic signals were collected in isometric contraction during traction of a force transducer, while the shoulder remained at 80° abduction, and normalized according to the maximum reference isometric contraction. Mann Whitney’s parametric test was used at a significance level of p<0.05 to compare mean electromyography of the deltoideus muscle pars, as well as the force, between the two groups. The study concluded that there was no difference in electromyographic activity of the deltoideus muscle or in the force exerted during abduction of the upper limb between healthy controls and individuals with shoulder impingement. It may thus be suggested that deltoideus muscle strengthening should not be the main focus during the rehabilitation process.