Fig. 1.

Design of experiments 2–4. Each box represents a bout of eccentric contractions performed in vivo. In experiment 2, mice performed five repeated bouts separated by 10, 14, or 18 days. In experiment 3, the contractility of extensor digitorum longus (EDL) muscles from 5 bouts +3 and 1 bout +3 mice was tested 3 days after the final in vivo bout. An extra interval of recovery (14–18 days) was permitted before the contractility of EDL muscles from 5 bouts +full mice was tested. In experiment 4, wild-type mice were added to compare recovery times. Isometric torque was assessed 3 and 7 days postinjury after bouts 1 and 4 as well as immediately before and after each bout.