More than 30 years after they were published, pictures of Arnold Schwarzenegger’s infamous bicep peaks continue to motivate gym-goers. You can walk into just about any gym in the country and see people performing Arnold’s signature bicep move — “ the Dumbbell Concentration Curl ” — as they envision their biceps growing taller and taller with every repetition. Though the Concentration Curl is a great exercise for developing the two main heads of the bicep, there is an unsung hero here that seldom gets the respect it deserves: the brachialis.
The brachialis muscle, which is hidden under the larger muscles of the biceps near the elbow, is a very strong flexer of the elbow joint. In fact, studies show that this muscle generates 70 percent of the total arm flexion force! The anatomy of the brachialis prevents it from being fully activated during supination (palms up) exercises such as the standard bicep curl.
Most people utilize a palms-up, supinated grip when performing biceps movements. This is too bad. A well-trained brachialis leads to a strong grip, stronger flexion force potential, and a thicker lower bicep. Also, the brachialis’ position under the bicep can make the biceps appear even larger when fully developed. Not to mention, it is the brachialis muscle that gives your upper arms that dense, athletic look! To fully activate the brachialis, you must perform a movement with the palms facing inward.
How to train the brachialis
The Cable Hammer Curl is one of the most effective ways to train the brachialis. Perform 3-4 sets of this exercise before beginning your arm routine. Slower is better — more time under tension equates to more muscle growth. Also, be sure to extend your arms fully at the bottom of the repetition to ensure a full stretch that activates every muscle fiber in your brachialis. The cable version of this exercise works the muscles in a different manner than traditional barbells or dumbbells. While performing this exercise with a cable machine, you will keep constant tension on the muscle group, and ensure a full stretch at the bottom of each repetition.

1) Using a standard cable pulley machine, attach a braided rope to the bottom anchor and select a weight that will allow you to complete 12 repetitions with perfect form.
2) Grasp the rope with palms facing inward, and step away from the machine to create tension in your upper arms and forearms.
3) Slowly curl your forearms toward your chin without moving any part of your body except the elbow joint. Shoulders and upper arms will remain completely stationary.
4) Pause briefly at the top of the repetition with your palms facing one another to contract the brachialis, and return to the starting position.
Tempo: 5/1/3 — To create more time under tension and stress the muscle significantly, focus on slow repetitions. The eccentric phase of the lift (lowering the weight) should take 5 seconds.
Nutrition Tips for Bigger Biceps
Get enough calories – If you are striving to build bigger biceps, it is important that you provide your body with enough calories to fuel workouts and recover optimally.
Supplement smart – To give your biceps the raw materials they need to perform and recover, use the following supplements:
- BCAAs (Branched Chain Amino Acids): Consume 5 grams of BCAAs prior to training your biceps
- Whey Protein: Consume 20-30 grams of whey protein within 45 minutes of training
Don’t be afraid of fat – Consume moderate amounts of health fats from healthy sources such as almonds, nut butters, coconut oil, and olive oil.