Lauren Casey was 15 and a tenor sax player in her Minnesota high school marching band when the pain in her hip and lower back became severe. It hurt when she walked and when she stood for hours at her ...

Joni Mitchell sang, “You don’t know what you’ve got till it’s gone.” The song wasn’t about the strength of the pelvic floor—the muscles and connective tissue slung beneath the torso—but it could have ...