Test: This range of motion test will be very familiar to anyone who has ever performed the butterfly stretch. To begin, sit on the floor, bend your knees and press your heels together. Let gravity pull your knees down at the sides. Grasp your feet with both hands and gently pull them towards your body. Measure the distance between your heels and your groin.
Movement: Remove any footwear, sit on the floor and gently bend your knees. Bring the soles of your feet together and let your knees drop to the sides. Without excessively bending in the lower back, clasp your feet together with your hands and pull your heels as close to your body as you comfortably can.
Instructions and effects for the Seated Groin Stretch exercise 
Movement in Frontal Plane