Isometric strength testing. Recommendations based on a statistical analysis of the procedure.

Back injuries occurring during isometric strength testing motivated a statistical analysis to determine if a reduction in the number of exertions during the test was possible without profound influence upon the accuracy of the results. Strength measurements from more than 1,000 volunteers in an industrial back pain study were examined. It was concluded that one exertion in each test position for each subject provided a reasonably good indication of the subject's strength in that position, but strength in one position.