system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: In the olden days before gyms were a thing how did people gain large amounts of muscle mass?
gpt
Ever wonder where the term "Dumbbell" comes from? People noticed that bell-ringers were pretty ripped, an unusual thing back in the day. Lots of people were strong from manual labor, but the muscles would hardly be bulging. Bell ringers though, were *yoked*. 

Someone realized that yanking on ropes connected to a few tons of bell was a pretty sweet workout, but you know... kind of impractical for most people. Even if you had the money, pissing people off by ringing a bell all of the time wouldn't work. So... someone figured out that you could use a system of pulleys, ropes, and counterweights to imitate the workout, but without the sound; this would be a silent (dumb) bell. 

Over time the workout gear changed, and "dumbbell" came to refer to the weights we're familiar with today.