Anatomia Trikonasana: Apply this technique to correct hyperextension of the knee. Begin by isolating the hamstrings. The cue for this is to slightly bend the knee and attempt to "scrub," or drag, the front foot toward the back, as shown. The mat will prevent the foot from moving, but the hamstrings will engage. The hamstrings are knee flexors and contracting them prevents hyperextension. Then, maintaining tension in these muscles, engage the quadriceps to straighten the knee.