Where is the resistance applied during Forearm Supination in anti-gravity testing?

• A. At the elbow
• B. At the forearm midline
• C. At the shoulder
• D. To the wrist just proximal to the joint line into pronation

Answer: (D)

The test aims to isolate the forearm's supinators (supinator and biceps brachii) by creating resistance at the most effective lever arm for forearm rotation. Applying resistance at the wrist, just proximal to the joint line, directs the force to oppose the motion of supination and requires the forearm muscles to work against gravity in that plane. This location minimizes involvement from proximal muscles around the elbow or shoulder and reduces substitutions, providing a cleaner measure of forearm supination strength. If resistance were placed at the elbow or shoulder, other muscles (like elbow flexors or shoulder rotators) would contribute and muddy the assessment. Applying resistance at the forearm midline is less effective for producing a clear pronation force, whereas near the wrist you get the proper torque to test the intended movement. So, resisting at the wrist just proximal to the joint line in the direction of pronation best tests forearm supination.