Apparently the people who rang early church bells all day were really buff. The clappers, which they had to rhythmically swing back and forth all day, increased proportionally with the size of the bell and could often be hundreds of pounds. Some people caught on to the great form of exercising, and, wanting to get bigger muscles themselves but not actually ring the bells, invented a device which mimicked the feel of swinging the clapper but did not make any noise. This was referred to as a dumb-bell, "dumb" in this context meaning "silent", and it eventually evolved into the dumbbells we know today. But what of barbells, which are just bigger versions of dumbbells? Well, it's kind of obvious if you think about it. If they're like dumbbells but with bars you can lift with, why not combine the words and call them barbells? The same logic followed for naming kettlebells, which looked like kettles but acted like dumbbells. And there you have it: the reason why three types of weights are named after a musical instrument!
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.