[1][2][3][4] The device is essentially two pieces of metal tube bent in a loop and connected with a hinge.
The simple mechanism allows exercising any suitable muscle where a small angle can be created to press it, for example the biceps (elbow flexion) or the hamstrings (knee flexion).
The infomercials featured people watching television and exercising with the ThighMaster at the same time.
[6][7][8] The ThighMaster was invented in Sweden by then-physical medicine intern (later "Dr.") Anne Marie Bennstrom (Prescott) as the "V-Bar" physical therapy device.
"[10] It achieved commercial success when marketed under the "ThighMaster" name by Joshua Reynolds (often erroneously credited as the inventor), who also made a great deal of money with his version of the Mood ring.