One of the main muscles indoor rock climbing works is the latissimus dorsi, aka the “lats” of the mid-back, Mace says. This “pull” muscle helps you hang onto the wall and pull yourself up to the next hold.
The more often you rock climb, the faster you’ll improve the grip strength in your hands. Mainly, climbing works the small “digital flexors” that curl your fingers, says Penner, which you use to pinch those smaller holds on the wall.
“As you grip it causes the forearms to contract,” Mace says, which is why your arms get a good workout — and often feel so sore after a climb.
It’s also why climbers typically have strong forearm muscles, Penner adds.