Set a cable machine pulley to the lowest attachment point with a handle attached.
Feet positioned in an athletic stance slightly outside shoulder-width.
Your knees are slightly bent and toes pointed straight ahead.
The core is braced and engaged. Shoulders are pinned back with your chest up.
Grab the handle with an underhand grip. Your elbows kept close to the torso.
While maintaining fixed upper arms, begin by curling the attachment up using your biceps until it is at shoulder level. The movement is initiated and controlled by the bicep.
Take a quick pause to hold the contraction at the top.
Lower slowly to starting stance, maintaining tension on the muscle throughout the range-of-motion.
The eccentric portion is just as important as the concentric with arm development.
*Tips*
Your upper arms and body should remain fixed for the whole exercise.
Only your forearms should move.
Keep the attachment along the same bar path from start to finish.
The muscle used first will be used the most. Momentum will negate the movement.