Back pain is often characterized by discomfort in the upper, middle, or lower part of the back. The pain may come with muscle stiffness, making movement difficult or uncomfortable. In many cases, the pain increases when sitting for long periods, bending, or lifting heavy objects. Some people may experience pain that radiates to the hips, buttocks, or legs, especially if nerves are involved. Back pain can also limit flexibility, making it harder to twist, stand upright, or bend.