Grip strength: relationship to shoulder position in normal subjects.

Abstract

The objective of this study was to evaluate the effect of shoulder position on grip strength. A Jamar dynamometer was used to measure the grip strength of 160 subjects (80 males and 80 females), stratified on both sex and age, in the four testing positions. For each of the tests of grip strength, the subject stood with the shoulder adducted and neutrally rotated while the forearm and wrist were held in the neutral position. The four hand strength tests consisted of three positions in which the elbow was maintained in full extension combined with varying degrees of shoulder flexion (i.e., 0 degree, 90 degrees, and 180 degrees) and of one position in which the elbow was flexed at 90 degrees with the shoulder in 0 degree of flexion. Only the dominant hand was tested. The results showed that the highest mean grip strength measurement was recorded when the shoulder was positioned at 180 degrees of flexion with elbow in full extension; whereas the position of 90 degrees elbow flexion with shoulder in 0 degree of flexion had the lowest grip strength score. In addition, the grip strength measured with the elbow in extension, regardless of shoulder position (i.e., 0 degree, 90 degrees, and 180 degrees of flexion), was significantly higher than when the elbow was flexed at 90 degrees with the shoulder positioned at 0 degree of flexion. Finally, grip strength differed significantly for both sexes and for each age group. The findings are valuable in the evaluation and rehabilitation training of hand injured patients.