First, A Little Background

Before we get into the best ways to grow your forearms, we need to understand the muscles we need to train.

There are over 20 different muscles in your forearm, but they are split into two different categories. Flexors & Extensors.

Your Flexors are responsible for, well, flexing. Your Extensors are responsible for extending. Who saw that coming! For the most part, the Flexors in your wrists are on your palm side, and the Extensors are on the back of your forearm. If you put your hand around your forearm, around a third of the way up (just grab the thickest part), and pull your hand toward your forearm, you will be able to feel the Flexors activate, and when you try move your hand to touch the back to your forearm with the back of your hand, you should feel your Extensors activate.

Two other mentions here are your stabilizing muscles, your Pronating Muscles and your Supination Muscles. Your Pronating muscles control the movement that rotates your palm from facing the sky to the floor, and your Supinating muscles rotate your palm from the floor to the sky. It’s important to train these for a few reasons:

• Improves Wrist Stability
• Increases rotational strength & rotational grip strength
• Helps to prevent injuries to joints and the elbow by providing additional stability
• Can help prevent or lesson joint pains like tennis elbow

As part of any good forearm training routine, you should incorporate at least 4 different exercises in order to work all your muscles.

• One exercise for your Flexor Group that curls your wrist inwards (palm toward front of forearm).
• One exercise for your Extensor Group that curls wrist outwards (back of hand toward back of forearm).
• One exercise for your Brachioradialis (not to be confused with the Brachialis) and Supination Muscles that has a rotational curling motion from palms up to palms facing your body.
• And finally, one that targets your Pronating Muscles in a pronated (palm down only) curling motion.

Best Exercises For Each Muscle Group

Wrist Curls (Flexors): Sit and rest your forearms on your knees or a bench with palms facing up. Curl a barbell or dumbbells upward using only your wrists. This movement will directly target your Flexors.
Reverse Wrist Curls (Extensors): Perform the same setup as wrist curls, but keep your palms facing down to lift the weight upward. This movement will directly target your Extensors.
Rotating Hammer Curls (Brachioradialis & Supination Muscles): Do rotating dumbbell hammer curls (palms facing the your legs by your side, and rotating so they face the sky at the top of the curl, and rotate back to facing your legs at the bottom). The hammer curl motion will engage your Brachioradialis and the rotating motion engages both your Brachioradialis further and your Supination Muscles.
Reverse Bicep Curls (Pronating Muscles): Starting with your palms facing the floor, preform a curling motion maintaining this position and keeping your elbow in a fixed position. This targets the Pronating Muscles by making it act as a stabilizer during the movement,
Dead Hangs / Plate Pinches (Grip Strength): Either hang from the pull up bar or pinch weight plates with your fingers and thumb and hold them statically, this will build endurance within your forearms and improve grip strength.