It's one of those basic ideas you hear scientists repeating all the time: correlation does not imply causation.
Just because two things happened together doesn't mean one caused the other.
Well, back in the 1920s, they ignored their own advice.
And the result was a major misconception that's still around today.
Because, despite what you probably were taught in high school, lactic acid does not make your muscles hurt when you exercise.
In fact, it might actually help.
It all started around 1920, with a German biochemist named Otto Meyerhof.
He helped figure out many of the steps of glycolysis, which is the series of chemical reactions that cells use to make energy from glucose — aka sugar.
He also kind of fit the "mad scientist" stereotype.
If you've ever seen a scientist in a movie electrifying disembodied frog legs, well, Meyerhof did that in real life.
