Barbell Lying Preacher Curl

Sit on a preacher bench with your chest against the pad and your arms extended over the edge, holding a barbell with an underhand grip.

Keeping your upper arms stationary, exhale and curl the weights while contracting your biceps.

Continue to raise the bar until your biceps are fully contracted and the bar is at shoulder level.

Hold the contracted position for a brief pause as you squeeze your biceps.

Inhale and slowly begin to lower the barbell back to the starting position.

Repeat for the desired number of repetitions.

Recruiting larger muscle groups to "help" move the weight instead of isolating Biceps — swinging momentum or shifting the torso takes tension off the muscle this exercise is meant to train.

Rounding the upper back or shrugging the shoulders up toward the ears at the start of the pull instead of initiating with the target muscle.

Using an asymmetric grip or uneven bar path, which can quietly overload one side of the body over repeated sets.

Skipping a warm-up set at lighter load/intensity — even "beginner" exercises benefit from a rehearsal set to groove the movement pattern before working sets.