It is never, ever, my goal to make a client vomit during a workout. Never. Not my style at all.
That said, I did have a client once who ran to the bathroom and threw up. His mother-in-law is my long-term client and she brought her daughter and son-in-law to my small-group workout. He’d bragged about how he does _____ and _____ (2 popular apocalyptic-style workouts). I don’t know whether he was trying to impress me or his motherinlaw more, but he overworked and had to run to the rest-room. Came back very pale.
His mother-in-law and my other clients got through the workout just fine.