Shoulder position influences elbow extension force in healthy individuals

The purpose of this study was to compare measurements of elbow extension force obtained with the shoulder in four different positions. The four positions in which 24 healthy subjects (13 men, 11 women, mean age = 29.9 years) were tested twice with a hand-held dynamometer were: 1) body supine, shoulder adducted and neutrally rotated; 2) body sitting, shoulder flexed and internally rotated; 3) body sitting, shoulder flexed and externally rotated; 4) body supine, shoulder abducted and externally rotated. Although repeated measurements in each position were reliable (intraclass correlation coefficients >/= 0.980), the magnitude of the elbow extension force was significantly different between positions (F = 13.435, p < 0.001). The lowest and highest forces were measured in positions one and four (above), respectively. If an individual is retested at a later time, the same positions as used previously should be employed if real changes in elbow extension strength are to be disclosed. The specific position used is probably best selected on the basis of patient, tester, and environmental factors. J Orthop Sports Phys Ther 1990;12(3):111-114.