Get Good at Pull-ups and Chin-ups
Just like sprinters are known for having well-developed glutes and legs, gymnasts have some of the most enviable biceps in sports. Why? In short, pull-ups and chins are great for upper arm development. Under the superficial biceps muscles lays a smaller muscle called the brachialis. The most effective way to train this muscle is by pulling it from above. The development of the brachialis will push the "peak" of the biceps up much higher and add to overall thickness of the upper arm in the process. It's something the curls just can't reach.
Try this: At the end of your workouts that don't involve chins, try a descending ladder.
- Do 10 pull ups, then rest 1 minute.
- Then do 8, and rest for 1 minute.
- Then 6, then 4, and finally, 2.
- The next day, do the same finisher, but change the exercise to palms-in chin ups. The cumulative volume will make your biceps grow.