Stand up right, next to a door frame or a piece of equipment such as seen in the picture above. Notice how I’m leaning forward, in a straight line with my body. My left leg is positioned about a foot and a half behind the right foot. Once in this position lean further forward but continue keeping your entire foot on the floor, do not let the heel rise on the leg that you are stretching.
Do not hyper extend at the knee joint.
You will feel a nice stretch in the calf muscles of the leg.