Strengthening the BackTwo types of strength-training moves that may benefit the lower back are flexion and extension exercises. In flexion exercises, you bend forward to stretch the muscles of the back and hips. In extension exercises, you bend backward to develop the muscles that support the spine. One example is doing leg lifts while lying on your stomach. Depending on the cause of your back pain, there are some exercises you should not do. If you have back pain, make sure to talk to your doctor about what exercises are safe for you.