9.stretch to do after run: Happy Baby also stretche to Relieve Lower Back Pain and Open Tight Hips -Begin lying flat on your back. Bend both knees and hold onto the outside edges of your flexed feet with your hands. Keep your arms on the outsides of your legs. Gently use your upper body strength to equally press both knees to the floor below your armpits. Try not to tense your shoulders or chest, but keep everything relaxed.