The Incline DB Curl is to biceps what the incline DB Triceps extension is to triceps. The biceps are a partial supinator of the wrist, just as triceps are a partial pronator.
Beginning the exercise correctly requires starts with proper offset grip orientation. The thumb-side of the hand must rest against the DB – I refer to this as the neck of dumbbell, as opposed to the ankle, which we grasp when we perform triceps extension.
If the dumbbell has extra plates one side versus another, the thumb must be further away from the heavier of the two sides. The opposite rule applies for triceps grip orientation.
Once the DB’s are in proper position, sit on the bench and lay back. Flex the elbows so the DB’s are at the top position. This is contrary to most instructions on how to perform curls. Supinate the wrists fully, and then extend the shoulders so that the humerii are perpendicular to the floor.
As the timer reaches its 3-second countdown, normalize the lumbar and cervical spines, and allow the ribcage to slide downwards. Begin lowering the DB’s through the range of motion by performing only eccentric (lowering) elbow flexion.
Halfway through the movement, begin pronating the wrists across the remainder of the eccentric elbow flexion. As you reach the end of the range, attempt full pronation of the wrists as you attempt external rotation of the shoulders to maximize the rotational – counter-rotational effect of the primal rotational pattern. When this movement is complete, revers the pathway and return to the top position.
Do not flex the shoulders to do this – you are to flex the elbows and supinate the wrists. This results in the DB’s moving upward. Lifting the DB’s results in flexing the shoulders. This is efficient to lift the DB’s to a higher position but is inefficient to get the body to move correctly.