Bioelectric activity of selected muscle groups in people with impingement syndrome

The aim of this study was to assess the changes of the bioelectric activity of the selected muscles and their impact on the functioning of the shoulder joint in people with impingement syndrome. The study covered 58 subjects aged between 24 and 85, who were treated for impingement syndrome in the years 2004-2006. The average duration of the disease was 40 months. The following muscles were tested for bioelectric activity using surface myography: deltoid, supraspinatus, infraspinatus, latissimus dorsi, greater pectoral and biceps brachii on the healthy and the diseased sides. A significant drop in activity of the deltoid and the infraspinatus muscles on the diseased side was observed. The following muscles showed comparable activity on both sides: the supraspinatus, latissimus dorsi and the greater pectoral muscle. The activity of the biceps brachii muscles grew during resisted movements. The drop in the activity of the deltoid and the infraspinatus muscles on the affected side is an important factor responsible for changes of the active mobility of the shoulder and for the development of instability of the shoulder joint. A similar activity of the latissimus dorsi, greater pectoral and biceps brachii muscles on both sides indicates a development of the compensatory mechanisms and the role of those muscles in the dynamic stabilisation of the shoulder joint.