Often, low back pain is caused — or aggravated — by strains (torn muscle or tendon) and sprains (tears in the ligaments), which are caused by overstretching, lifting something incorrectly, or tight hips (though stiffness throughout the body can be a trigger, because after all, the hip bone's connected to the leg bone, and so on). To help improve muscle flexibility (and potentially help prevent that dreaded lower back ache), try these five stretches two to three times daily.