The biceps are made up of two heads:
The inner biceps and the outer biceps.
The outer head makes up the bulk of the biceps and is best hit with basic mass building exercises, such as alternate dumbbell curls, standing barbell curls and EZ bar curls. However, the inner head makes more of a peak. To develop it, try isolating the biceps individually through exercises such as concentration curls.
The most basic way to do them is by sitting on a bench and using one arm to curl a dumbbell. I like to do this exercise as heavy as possible in a 6-8 rep range for 4 sets to really fatigue the muscle.
Concentration curls were a key part of Arnold Schwarzenegger’s routine for building those large peaks on his biceps. When doing them, take your time and really squeeze the biceps at the top of the movement and then slowly lower on the negative.
When Arnold did this exercise, he actually visualised his biceps as mountain peaks, which helped develop the mind-muscle connection. Concentration curl variations I use include: single-arm on an incline bench, which makes it more challenging and allows for a greater range of motion; single-arm cable curls, which provide constant tension. Preacher curls are another favourite exercise for building peaks. You can either do them using an EZ bar and a bench or as a machine curl.
As with concentration curls, I like to go heavy for 8-12 reps and focus on taking my time to really squeeze at the top of the movement and then slowly lowering the weight. A final exercise I find great for building peaks is seated hammer curls.
After doing heavy exercises, I often choose a moderately heavy weight and go as high as 12-15 reps for this one to really focus on form and force as much blood as possible into the muscle.