Sit on floor facing suspension trainer loops in low position. Grasp bottom of loops, then lay supine. Raise legs and place heels in loops with soles contacting handles. Lie down supine on mat so knees and hips are bent with suspension straps hanging vertical. Place arms off to sides.
Raise hips up by extending hips until fully extended. Lower hips until hips and back make contact with mat. Repeat.
This exercise can be performed on TRXⓇ style suspension trainer. See Suspended Supine Feet Mount/Dismount. Hamstring enters active insufficiency as hip is raised since knee is flexed and hip does not flex beyond 90 degrees. However, it is used more to stabilize knees in fixed flexed position.
Dorsal flexion of ankle reduces active insufficiency of Gastrocnemius, allowing it to assist Hamstrings in maintaining fixed knee flexion. See Knee flexion abduction force vector diagram. Adductor Magnus does not assist since hip extension does not occur in fully flexed position.
Movement can be made easier by lying closer under anchor of suspension trainer.
Movement can be made more challenging by lying further back, away horizontally from anchor of suspension trainer.