It’s supposedly Michelle Obama’s favorite fitness class. If that’s not enough to sell you, consider that this athletic, full-body workout—which takes place primarily on a souped-up resistance-based machine and taps into slow-twitch muscle fibers—is always challenging, never boring, and wholly unrelenting (there’s no rest or recovery during the 50-minute session). Great music, low lights, and coaches who know their stuff (and never allow awkward silences) make this a uniquely difficult, effective, and rewarding fitness experience. solidcore.co
This article originally appeared in our December 2017 issue.