Underpronation, often known as supination, is the inverse. When you run or walk, your feet turn disproportionately outward due to underpronation. This can cause your spine and hips to go out of alignment, resulting in lower back discomfort. A lack of proper pronation can also lead to foot problems such as hammer toes and flat feet. If you suffer from lower back pain, it's important to identify the underlying cause. You may want to consider adding support for your feet with shoe inserts if they are found to be underpronating. In addition, changing your running style to avoid pushing off too high could help reduce the risk of injury. For example, if you push off of the ground when running, you're putting extra pressure on your knees and causing them to act as levers rather than springs. Instead, try using a mid-foot strike approach where you hit the ground with your heel first for more natural springing action from your legs. Lower back pain can be caused by many factors, some physical and some not. If you aren't able to find the source of your pain using these suggestions, see a doctor.