You’ve been going to the gym, and you even bought some new workout clothes to wear there. Good for you for not being so literal. If you strip down the etymology of “gymnasium,” you’ll find that it comes from the Greek word gymnásion, which is related to the word gymnázesthai, meaning “to train in the nude.” (The Greek word gumnos means “naked.”)

Did you know that some of your favorite (or least favorite) forms of exercise are named after people? Pilates, an exercise system that aims to improve strength and flexibility, is named for Joseph Pilates, the German fitness instructor who created it.

And if you’ve ever had to do the squat thrust known as a “burpee,” you can blame American psychologist R.H. Burpee. He devised the “Burpee test” as a way to judge people’s physical fitness.

As challenging as some exercises can be, you should be able to breathe easy during your aerobics class. That’s because the word “aerobic” is formed from the Greek root aero, meaning “air” or “oxygen.” It’s no surprise, then, that aerobic exercises typically aim to improve heart and lung function. The word “aerobics” is likely a shortening of “aerobic exercises,” modeled on the word “calisthenics”—which itself is a form of aerobics.

“Calisthenics” comes from a Greek phrase meaning “beautiful strength,” combining the Greek word kalli- (“beautiful”) with sthenos (“strength”).

The “bell” in “dumbbell” doesn’t mean “beautiful”—it means… bell. The dumbbell is named for its resemblance to the implement used to ring church bells, with the word “dumb” likely intended to mean “silent.” “Dumbbell” served as the model for the similar “barbell,” in which weights are connected by a long bar.

No matter how much you can lift, your muscles are still little mice—at least etymologically. That’s right, “muscle” comes from the Latin word mūsculus, which is a diminutive of mūs—“mouse.” Apparently, ancient Romans thought that some muscles resembled little mice.

Good workout. Now go on and spot your friends with some heavy word facts.