Tired. referring to the state of forearms in a desperate state, swollen and unresponsive.
The feeling of overworked muscles. Most climbers are familiar with the forearm pump: too much finger work causes the forearms to swell and the strength to disappear. With a serious forearm pump, even holding a glass of beer can become a serious challenge.
The feeling found in overworked muscles when climbing hard or hanging around on marginal holds trying to place protection.