The brachialis is a key muscle for maximum arm development. If you compare the current champions to the older superstars, you’ll realize that the hypertrophy of the brachialis is much more pronounced nowadays than it was in the past. The brachialis represents at least three-fourths the size of the modern champ’s biceps. In fact, in some the brachialis actually appears larger than the biceps.
Unfortunately, most average bodybuilders neglect their brachialis and focus exclusively on biceps and triceps. By following a specialized routine targeting an underdeveloped brachialis, though, you can easily gain an inch on your arms.
A well-built brachialis is aesthetically a very important muscle. Jean-Claude Van Damme’s arms are a good example. They’re not big, yet they look impressive onscreen because of his well-developed brachialis. That’s important if you’re wearing a T-shirt that reveals only the lower parts of your upper arms.
When you curl with your thumbs up, your biceps are placed in a weaker position than with regular curls. Bodybuilding folklore claims that to compensate for that weakness, the brachialis takes over. Research using electromyographic (EMG) analysis supports that belief.1
Even if the brachialis works more during hammer curls than regular curls, it’s not a guarantee that your brachialis recruitment will be significant enough to trigger hypertrophy. I assumed mine was until I tried spider curls. After a few reps I felt my brachialis muscles blow up like balloons, a sensation I’d never had with any other exercise. That’s when I understood that I’d never really recruited my brachialis before. I believe that’s true of most natural bodybuilders, judging by the appearance of their arms.
The brachialis is one of the trickiest muscles for natural bodybuilders to develop (the upper-chest and rear-shoulder muscle groups are also a challenge). Unless you’re naturally gifted, it’s very difficult to recruit the brachialis, in part because of highly variable levels of neuronal innervation among individuals.2 What’s more, your left and right brachialis are unlikely to respond equally to curls. For example, my right brachialis is preferentially recruited by spider curls. Conversely, my left brachialis needs to be much closer to my head to produce a significant contraction.
As I look at the pros’ brachialis muscles, I realize I’m not the only one with that problem. Most of them have very uneven brachialis development, which is most obvious during a back double-biceps pose. People wrongly assume that uneven biceps hypertrophy causes the imbalance.
An imbalance of development between the brachialis and the biceps can result in pain in the elbow area that can prove a significant obstacle when working your biceps.
The brachialis is also recruited during basic back exercises. By working it, you will become stronger in those back movements, indirectly resulting in a better back. After a few workouts of brachialis specialization my performance on back exercises improved significantly. I noticed that for the first time my brachialis muscles were sore after a back workout, which showed I was starting to learn how to recruit the muscle.
There are four major brachialis exercises. Two play on wrist placement: hammer curls and reverse curls. You can do both with free weights or cables. Don’t forget to experiment with various degrees of wrist rotation. The other two’spider curls and overhead cable curls’use the biceps position as the main stimulus. The closer to the head the biceps is, the more the brachialis will come into play.
My brachialis muscles are much more sensitive to my biceps placement than to my wrist position. The pump induced makes it easy to tell when you work the brachialis properly. Most bodybuilders will need to learn how to contract their brachialis. To speed up that learning process, I recommend you work one arm at a time rather than both arms simultaneously.
Illustration by Fr’d’ric Delavier
Editor’s note: Fr’d’ric Delavier is an accomplished powerlifter and the author of the worldwide best-seller Strength Training Anatomy, available from Home Gym Warehouse, 1-800-447-0008, or at www.home-gym.com.
References 1 Naito, A., et al. (1995). Electromyographic (EMG) study of the elbow flexors during supination and pronation of the forearm. Tohoku J Exp Med. 175:285. 2 Mahakkanukrauh P., and Somsarp, V. (2002). Dual innervation of the brachialis muscle. Clin Anat. 15:206-9.