Hammer curls mainly target the brachialis and brachioradialis , with the biceps also working as a secondary muscle group. They’re great for building thicker upper arms and improving forearm and grip strength.

What they work

  • Brachialis: the main muscle under the biceps that adds upper-arm thickness.
  • Brachioradialis: a major forearm muscle that helps with arm strength and grip.
  • Biceps brachii: still involved, but usually less emphasized than in a standard curl.

Why people use them

Hammer curls are popular because they build arm size , support grip strength , and are often a bit joint-friendly thanks to the neutral grip position.

If you want, I can also explain hammer curls vs regular bicep curls in a quick table.