Abstract: A person's leg muscles can be strengthened with a leg-support cross piece adapted to underlie the person's knee joint while the person lies with his back on a floor surface. The lower portion of the leg is swung up and down around the supported knee joint to exercise the leg muscles. An elastic strap type resistance unit may be extended from the framework that supports the cross piece for partial encirclement of the person's ankle, to increase the effort involved in swinging the leg.