At this moment, as many as 30 percent of those reading this issue are suffering from backache. Eventually, 80 percent of Americans will experience low back pain. You can be a statistic or you can do something to keep your back healthy for life. The place to begin a back-building program is by stretching and strengthening your core muscles, says Nicole ODonnell, PT, ATC/L, a Cleveland Clinic physical therapist and athletic trainer. Core muscles in the abdomen, back, hips, and pelvic floor help support the spine and prevent back injury, and they allow for the kind of posture that decreases stress on the spine.