Most back pain is harmless – caused by sleeping in an awkward position, stretched muscles, overexertion, sitting down too long or falling on the ischial tuberosity (the bones of the butt that you sit on), or minor hip injuries caused by twisting a certain way during sports like volleyball. Many injuries arise simply from improper form during exercise, sports injuries, or strains.
With a roster of muscles ranging from the powerful glutes to the small and agile abductors, the hips control practically all your movements. Almost every endurance athlete overworks some hip muscles while underworking others, causing severe imbalances: Runners are infamous for having weak hip adductors—the muscles on the side of the hip that help you step laterally—while cyclists tend to have massive quads and tiny glutes.
A sedentary lifestyle can lead to having weak and tight hip flexors as they are always in the shortened position. Tight hip flexors can lead to a limited range of motion, poor posture, lower back and hip pain, and even injuries. These muscles need to get a workout when you are standing and doing movements such as raising your leg to climb stairs, run, or ride a bicycle.