A close-up view of the foot of Scientist-Astronaut William E. Thornton as he demonstrates the use of a treadmill-like exercise device which was developed for maintaining the leg and back muscles of the Skylab 4 crewman. Thornton is in the Skylab Orbital Workshop simulator in Building 5 at the Johnson Space Center. The Skylab 2 and Skylab 3 astronauts had no exercise device onboard capable of adequately maintaining their leg and back muscles. The treadmill device consists of a Teflon-coated aluminum plate or sheet bolted to the floor of the Skylab Orbital Workshop. The crewmen will wear the bicycle Ergometer harness while exercising. Bungee cords attached to the floor and to the harness will supply the downward pressure or force for the back and leg muscles. The astronauts feet will slide over the Teflon-coated plate as he marches in place.
