A lot of people experience lower back pain during and after they walk/run.  This problem can be caused by inflexibility of the hips (specifically the inability of the leg to travel behind the body correctly). In this short video, Justin Price (creator of The BioMechanics Method) teaches you a quick self-assessment and some easy exercises you can do to identify whether your hips are causing the problem and what you can do to alleviate your lower back pain.