Be very gentle when stretching prior to a run. The muscles will have warmed up and be better prepared to be stretched. My version stretches one leg at a time. Stand with the rear foot approximately two to three feet from the wall. The rear leg should be straight, the front leg is bent and your hands touch the wall.
Feet point straight ahead, heels are on the ground.
Hold for 10 seconds, switch legs, repeat 10 times. Straighten one leg, place it, with the knee locked, on a foot stool. Bend your body and bring your head towards the leg. Hold this position for 10 seconds. Switch sides, repeat 10 times.