Researchers have long questioned why patients with Duchenne muscular dystrophy (DMD) tend to manage well through childhood and adolescence, yet succumb to their disease in early adulthood, or why elderly people who lose muscle strength following bed rest find it difficult or impossible to regain. Now, researchers at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), part of the National Institutes of Health, are beginning to find answers in a specialized population of cells called satellite cells. Their findings, reported in the journal Genes & Development, suggest a potential therapeutic target for conditions where muscle deterioration threatens life or quality of life.