An athlete performing a concentric isokinetic elbow flexion and extension exercise. Which type(s) of lever occur(s) at the elbow during this exercise?

An athlete performing a concentric isokinetic elbow flexion and extension exercise. Which type(s) of lever occur(s) at the elbow during this exercise?

• A. First class
• B. Second class
• C. First class and Third class
• D. Second class and Third class

Answer: (C)

At the elbow, the joint itself is the fulcrum and the lever type depends on where the load sits relative to that fulcrum and where the muscle force (effort) acts. For elbow flexion with the hand or forearm bearing the load, the muscle (biceps) attaches close to the elbow and the load is far away on the forearm. The fulcrum is between the lever’s segments, with the effort on one side and the load on the other, and the effort is applied closer to the joint than the load. That setup is a third-class lever, which is typical for most arm flexion movements. During elbow extension in an isokinetic setup, the resistance can be applied in a way that places the load on the opposite side of the fulcrum relative to the muscle force, so the fulcrum lies between the load and the effort. That configuration is a first-class lever. Because an isokinetic elbow action can involve both arrangements depending on how the resistance is applied and which segment bears the load, both first-class and third-class lever types can occur at the elbow.

At the elbow, the joint itself is the fulcrum and the lever type depends on where the load sits relative to that fulcrum and where the muscle force (effort) acts.

For elbow flexion with the hand or forearm bearing the load, the muscle (biceps) attaches close to the elbow and the load is far away on the forearm. The fulcrum is between the lever’s segments, with the effort on one side and the load on the other, and the effort is applied closer to the joint than the load. That setup is a third-class lever, which is typical for most arm flexion movements.

During elbow extension in an isokinetic setup, the resistance can be applied in a way that places the load on the opposite side of the fulcrum relative to the muscle force, so the fulcrum lies between the load and the effort. That configuration is a first-class lever.

Because an isokinetic elbow action can involve both arrangements depending on how the resistance is applied and which segment bears the load, both first-class and third-class lever types can occur at the elbow.