First, 7 days after PBS injection, rats were forced to run 15 km over 21 days. Synovium was evaluated in rats before and after 15 km running (Fig. 5a). Second, 7 days after MIA injection, rats were forced to run 15 km over 21 days. Synovium was evaluated in rats before, after 15 km running, and after 21 days without running (Fig. 5d).