Short and Stout - Maximizing Thickness With the Short Head
Grip Theory (This is what I base my workouts on)
According to this theory, to effectively target your short bicep when using dumbbells or any type of single arm cable curl or other exercise, use a supinated grip (palms up) and focus on keeping your hands as flat as possible or the pinky side of the hand held as high as the rest of the hand or higher, not allowing your hands to angle in towards a neutral or a hammer grip. This will put the maximum stress on the short head of the bicep. If you are doing any type of curl that involves a straight bar or an EZ bar, make sure your grip is at least slightly wider than shoulder width. This will cause the same effect as keeping your palms as flat as possible on the dumbbell grip. Without even using a dumbbell or bar, just take your hand with your palm completely facing up, make a fist, and contract your bicep in a curling motion. You should feel the short head bicep muscle more so than the long head.
The other theory about targeting the short head specifically is that you will effectively hit the short head more so when your elbows are in front of your body, such as the position used in preacher curls. Classic curls are even said to be better for short head growth because the elbow is slightly in front of the body. Although I use the grip theory and can actively feel the difference when I change my grip, I also happen to do a lot of exercises for my short head where my elbows are in front of my body. There is one major exercise that I do for the short head though that a lot of experts say is more beneficial for the long head - the incline dumbbell curl. The way I perform this curl though, is that I keep my hands extremely supinated to the point that the dumbbells can rest flat against the side of my stomach at the peak of the contraction, as you can see in the video to the right. I do agree though that this exercise would be great for the long head with a more natural grip in between supinated and neutral.
Conclusion on Targeting the Short Head
As you can see, it is easy to get carried away with the different theories or philosophies on what targets which head, so I invite you to try each theory or a combination of both and see what works best for you, since you are the important factor in this equation, not somebody else.
Here are my top 3 favorite bicep exercises to target the short head using either theory...