A calf strain rarely announces itself with drama the first time. It shows up as a sudden pull mid-sprint, a sharp pinch during a tennis serve, or a tight, bruised feeling behind the knee that takes weeks longer to settle than anyone expected.

A strain in the lateral head of the gastrocnemius, the muscle that gives the calf its diamond shape, is a strange injury to live with. It rarely announces itself with the drama of a full rupture. There is often just a sudden pull, a bruise that shows up two days later on the outside of the calf, and then weeks of a leg that feels almost normal until you push off hard, jump, or sprint.