Lie face down on an exercise mat with your legs extended directly behind you and your palms placed on the floor either side of your face. Bring your left leg up to your left side until your knee is level with your hip and bent at 90 degrees. Position a foam roller parallel to your body and under the middle of your left thigh. This is your start position. Shifting your weight into your left thigh and applying pressure, gently roll back and forth on the foam roller, feeling for any particular areas of tension. Repeat for the recommended amount of time before changing to the other side.