After a long workday at your desk or hours in a car, it’s normal to feel a little stiff. It may just be that your hip flexors and lower back are tight. But you could also be experiencing a potentially debilitating condition called gluteal amnesia, or dead butt syndrome. “The name sounds silly, but the side effects are serious,” said Jane Konidis, a specialist in physical medicine and rehabilitation at the Mayo Clinic in Rochester, Minnesota. “The gluteus maximus is one of the strongest muscles i