The brachialis muscle is responsible for bending at the elbow. It starts under the biceps muscles and extends from the upper arm bone, the humerus, along the forearm bone, the ulna, to just past the bend of the arm. It bends by contracting and pulling on the forearm bone. Every time you pick up an item or hold a phone to your ear, the brachialis muscle activates in tandem with the biceps. (ref. 1) Brachialis muscle stretches improve the flexibility of the biceps whether or not the biceps are flexed.
Stretch the biceps and stretch the brachialis. Face your back to a wall while you stand. Do not place your back against the wall.
Lift your arms up over your head and extend them backward until your palms are touching the wall. Make sure all 10 of your fingers are pointing upward, toward the ceiling or sky. This may feel awkward at first, but your arms will naturally bend at the elbow, activating the brachialis muscle.
Keep your palms on the wall and lean forward a bit. Do not lean so far out that you experience pain in your arms or shoulders.
Squat. Your squat will be limited and you may find that your knees will not bend to 90 degrees while keeping your palms on the wall. That is okay and adequately stretches the brachialis and biceps muscles with every knee flex.
Hold your squatted position for 10 to 30 seconds before rising and repeating Step 4.
Wrist Flexor Stretch
Stretch the wrist flexor and stretch the brachialis muscle. The key is arm pronation, or holding the palm downward.
Stand and face a wall. Extend your arm toward the wall with your palm in an upward position. Resist the urge to touch the wall.
Never bend your arm at the elbow. Rotate the wrist counterclockwise to turn the palm downward. This pronates the arm. Touch just your fingertips to the wall.
Stretch the wrist flexor and brachialis muscle by slowly placing your palm flat against the wall. You should not experience discomfort from this stretch. If your palm cannot become flush with the wall, move a bit closer to it.
Hold this stretch for 10 to 30 seconds.