Muscles worked
The concentration curl trains your biceps, helped by the brachialis underneath the biceps and the brachioradialis in your forearm. Because you are seated with your upper arm braced against your thigh, it is hard to get help from the rest of your body. The biceps both bends the elbow and turns the palm up, so many people turn their little finger slightly upwards at the top to let the muscle do both jobs. Training one arm at a time also shows you quickly if one side is weaker.
Common mistakes
- Your upper body helps out. When it gets heavy, many people lean back to get the dumbbell moving. Lean slightly forward from your hips and keep your upper body still, so only your forearm moves.
- The movement gets too short. Reversing long before your arm is almost straight means your biceps only work through half the movement. Lower until your arm is almost straight on every rep, even if that means a lighter dumbbell.
- The strong arm sets the pace. If you start with your stronger arm, it is easy to do more reps with it. Start with the weaker arm, then match the number of reps with the other.
Variations and alternatives
- The dumbbell curl is done standing with both arms and often allows a heavier weight.
- The preacher curl also keeps your upper arms still against a pad, but with a bar and both arms at once.
- The hammer curl is done with your palm facing in and puts more of the work on the brachialis and forearm.
- The band curl works at home when you have no dumbbell.
Sets and reps
The concentration curl is a pure isolation exercise and suits building muscle and endurance. 8 to 12 reps per arm over 2 to 3 sets is a good starting point, and 12 to 20 works late in the session. Heavy sets of 3 to 6 reps almost never add anything here. The guide to sets and reps explains how to choose.
The arm that is not lifting rests while the other works, so you can go straight from one arm to the other and rest once both are done. The jump to the next dumbbell is often large for a single arm. Add reps first and move up once you reach the top of your range on every set, with 1 to 2 reps in reserve. That is progressive overload, even in a small exercise.