Here’s an easy way to protect your lower back: People who walked backwards on a treadmill for 15 minutes three times a week reported less back pain, according to research from a well-known U.S. university. The link is unclear, but the researchers observed that facing away from the treadmill console tilts the hips up and engages the core, which strengthens the back. Give it a try at 2.0 M.P.H. with no incline.