Gayle Parseghian, a 55-year-old ballet teacher from Toledo, Ohio, goes through stretching exercises at the Rehabilitation Institute of Chicago. She’s participating in a a four-week, intensive “boot camp” program to relieve her chronic back pain. Before starting the program, Parseghian tried herbal patches, vitamins, injections, prescription narcotics and a battery-operated device that sends electrical impulses to the body to block pain. She said nothing worked. (M. Spencer Green/Associated Press)