Subjectivity of forces associated with manual-muscle test grades of 3+, 4-, and 4.

This study examined the subjectivity of forces applied by 10 testers during simulated manual-muscle testing. Individual testers were able to modify appropriately the forces they applied for muscle test grades of 3+, 4-, and 4, that is, the forces rose concomitantly with the grades. Testers were consistent between trials in the forces they applied for each grade while testing each specific action. They varied, however, in the forces they applied for each grade during the testing of the two different muscle actions. Moreover, testers differed significantly from one another in the forces they applied for each manual muscle test grade (3+, 4-, and 4). If an individual's strength is to be monitored using manual-muscle testing, grades obtained by a single tester are recommended.