Long before it became a go-to for burning calories, the treadmill was a tool of punishment. In 1818, British engineer Sir William Cubitt invented the “tread-wheel” to reform idle prisoners. Inmates would step for hours on a massive rotating cylinder or climb never-ending stairs—often doing the equivalent of thousands of vertical feet a day. 

The devices powered mills or pumped water, but the goal wasn’t efficiency—it was discipline through exhaustion. Even Oscar Wilde, sentenced to hard labor, described the experience as spiritually crushing. It took over a century for the treadmill to shed its punitive past and rebrand as a symbol of health and self-improvement.