Short or long forearms: wrist size, insertions and why some forearms pop

Forearms are a giveaway of natural genetics, because most people never train them directly yet some still have thick ones. It comes down to insertions and wrist size.

What decides forearm size

Two things:

• Insertion: how low the forearm muscle belly runs toward the wrist. Low bellies fill the arm and look full; high bellies leave a gap and look thin.
• Wrist and frame size: thicker wrists are part of a bigger frame and make the forearm look more solid. Thin wrists make the same muscle look smaller.

How to tell

Hold your arm out and look at the lower forearm:

• Muscle runs low, thick wrist → strong forearm genetics.
• Muscle stops high, thin wrist, clear gap → harder genetics.

Your wrist circumference is also a quick read of your overall frame size.

How to train forearms that lag

• Train them directly and often. Forearms recover fast, so 2 to 4 short sessions a week works.
• High reps and grip work: wrist curls, reverse curls, and heavy holds or carries.
• Full range and a hard squeeze. Control the stretch and the contraction.
• Be patient. Thin-wristed forearms grow slowly but they do grow with volume.

Read it from a photo

Phyziq reads your forearm insertion and frame size from a scan, so you know whether forearms are an easy or stubborn area and how much direct work to give them.

FAQ

Do thin wrists mean small forearms forever? They make the forearm look smaller and the build slower, but volume still adds size.

Can I make my wrists bigger? The bone does not change, but the muscle and tendon around it thicken with heavy grip work.

Why are my forearms thin even with heavy lifting? Grip work during big lifts is not always enough. Add direct, high-volume forearm work.