Q.Raju intends to train his biceps; while exercising using dumbbells, which joints should remain stationary and which should move?

Step 1. The biceps muscle runs across the front of the upper arm and produces flexion of the forearm at the elbow — it is a prime mover (agonist) for elbow flexion, acting like the effort in a Class III lever with the elbow as the fulcrum.

Step 2. For a dumbbell curl to train the biceps specifically, only the elbow joint should be allowed to move — flexing to bring the forearm up and extending to lower it back down. …

Identify which joint the target muscle (biceps) acts across, and note that isolating a muscle means keepi …

• Forgetting to keep the shoulder still, which lets stronger shoulder muscles take over the lift ('swinging' the weight). …