What do the forearm muscles do?
The forearm holds more than a dozen small muscles. They bend and straighten the wrist and fingers, and they turn the hand over. Together they decide how hard you can grip, which matters every time you carry shopping, open a jar or hold on to a bar.
How do you train your forearms?
Holding something heavy for time is the simplest way: carries and dead hangs build grip directly. Rows, pull-ups and deadlifts also work the forearms, because you have to hold on. Wrist curls let you target the muscles on their own.