Limb-girdle muscular dystrophy is not a single disease. It is a family of more than 30 genetically distinct conditions that share one outcome: progressive weakness of the shoulder and hip muscles that, over years or decades, erodes independence.

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.