So far, the first two movements have focused primarily on working the long head of the bicep (seen best when looking at the arm from the side), when the arms are at the side of the body. The short head (shown on the image above, being the fatter, longer muscle of the bicep, and sitting just under the long head), is worked most when the elbow(s) are in front of the body, such as the preacher curl, which is demonstrated above using the back of an inclined bench.
This is a great exercise to perform as a single arm movement, (I personally think all workouts should include at least one unilateral movement), which allows you to focus solely on one side at a time. This can help squash any imbalances in strength and size before they become too visible. I’m also a big fan using the bench in an incline position as a preacher bench. Not all gyms have preacher benches, or they only have seated benches and not freestanding preacher benches). An inline bench allows you to really position yourself well whilst supporting the entire arm during the movement. This again makes it an especially strict movement, and therefore very effective for working a specific region of the bicep.
My tip here would simply be to ensure that the entire back of the arm (triceps) is rested on the bench, with the elbow and shoulder aligned. With your arm fully extended open, holding the weight with a standard underhand grip, your arm should be as straight as possible, which will force the bicep to do all the work to lift the weight up. This is one exercise where you should be looking for as greater range of motion as possible, from start to finish. So long as the elbow doesn’t lift off from the bench, you should find you can curl the dumbbell almost up the shoulder with full contraction in the bicep. I would also get used to opening the bicep up to it’s fullest length during this exercise, as the preacher curl is a great exercise that specifically targets the lowest region of the bicep, as well as the thicker, short head of the bicep – which is mostly seen in its fullest glory during a front bicep shot.
- External Rotation at the wrist during the curl. Think of turning your little finger outwards as you curl up (the opposite motion to pouring a jug of water), which will further pull in the short bicep head, giving a more intense contraction at the peak of the movement.
- Cable Concentration Curl. If the foot of the bench is positioned to a low-set cable pulley, you can modify so that instead of using a dumbbell to curl, you can hold a handle attached to the cable, and curl. The main difference here is that you’ll feel a constant level of tension on the bicep throughout the full range of motion.