Exercise is good for you. That's not a surprise to read, I hope. The benefits of cardiovascular workouts are robust (take the Mayo Clinic's word for it, not mine) and the downsides are minimal -- in many cases, it's limited to the experience of the workout itself. For many, the idea of getting on the exercise bike, going for a run outside, or even doing a few jumping jacks is akin to torture. But it's not. It's just exercise.

Unless you're using a treadmill. In that case, good news: it really is torture. Or, at least, it was originally.

The word "treadmill" first entered the English language in 1822, according to the Online Etymology Dictionary, and reinforced by a Google Ngram Viewer search result (embedded at that link). Most exercise equipment -- think "bike" or "weights" or "jump rope" -- describes either how to use the equipment or what makes the item useful for a workout. The word "treadmill" has the "tread" part -- signaling that it's used for walking -- but it also has a "mill" part, which suggests that it's used for grinding something down. And while exercise can definitely be a grind, that saying wasn't one back in the early 1800s. The early treadmills were a lot like sawmills or windmills or millstones, and less like your Nordic Track or Peloton. Here's a picture of an early one, via the PBS show, Nova:

In 1818, an English civil engineer named Sir William Cubitt devised a machine called the “tread-wheel” to reform stubborn and idle convicts.

Prisoners would step on the 24 spokes of a large paddle wheel, climbing it like a modern StairMaster. As the spokes turned, the gears were used to pump water or crush grain. (Hence the eventual name treadmill.) In grueling eight-hour shifts, prisoners would climb the equivalent of 7,200 feet.