Intrarater and Interrater Reliability of Scapulothoracic and Glenohumeral Strength Measurements by the Belt-Stabilized Handheld Dynamometer in Individuals With Subacromial Pain Syndrome.

OBJECTIVE

The purpose of this study was to evaluate the intrarater and interrater reliability of glenohumeral and scapulothoracic muscle strength measured in individuals with chronic, unilateral subacromial pain syndrome.

METHODS

Fifty individuals with shoulder pain were evaluated in 2 sessions using a belt-stabilized handheld dynamometer (HHD) for maximum isometric strength of the glenohumeral flexion, extension, abduction, lateral and medial rotation, and elevation, protraction, retraction, and retraction with scapular depression. Reliability was determined using the intraclass correlation coefficient (ICC2,3) with the standard error of measurement (SEM), the minimal detectable change (MDC), and a percentage of average strength (%SEM and %MDC).

RESULTS

The values of intraclass correlation coefficient, SEM, and %SEM for glenohumeral muscles ranged from 0.93 to 0.98, 1 kg, and 7% to 14%, respectively, and for scapulothoracic muscles from 0.90 to 0.98, 2 to 4 kg, and 10% to 17%, respectively. The MDC and %MDC values ranged from 2 to 4 kg and 19% to 38% for glenohumeral muscles and 4 to 11 kg and 27% to 47% for scapulothoracic muscles, respectively.

CONCLUSION

Belt-stabilized handheld dynamometer demonstrated excellent reliability to measure scapulothoracic and glenohumeral muscle strength in patients with chronic, unilateral subacromial pain syndrome. Guidelines for correct positioning and measurement of the strength of the shoulder complex along with their clinical viability are presented.