Lie supine floor or mat with board (approximately 2 x 6 inch or 5 x 15 cm) under knees. Place arms down to sides.
Raise leg with knee completely extended and ankle dorsiflexed. Repeat on opposite leg.
Dowel or plumb line is placed next to inside ankle and allowed to dangle vertically between legs off floor. Position of dowel relative to lower leg is noted.
Opposite knee should remain in contact with board. Lower back and head should remain on floor.