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.

If you have been on corticosteroids for more than a few weeks and your legs feel heavier climbing stairs, or standing up from a chair takes real effort, you have probably already heard the standard advice: "take vitamin D, do some light exercise, and mention it at your next appointment." That advice is not wrong.