Athlean-X (Jeff Cavaliere)

Jeff Cavaliere is one of the most credentialed fitness YouTubers on the platform — a physical therapist and former New York Mets strength coach whose channel has been correcting bad gym advice for well over a decade, building an audience of millions of subscribers. His science-based approach stood out in a landscape often dominated by influencers giving questionable advice. The "stop doing this exercise" series has identified movement flaws in popular exercises that many trainers now flag as well. If you only watch one fitness channel, this is it.