After my email yesterday about the value of working out for 20 seconds, I received an email from a subscriber. Here’s what Rhonda, a personal trainer wrote me:“Thank you. Thank you. Thank you. It is about time somone had the guts to call out all the trainers who jump on the interval bandwagon. I can’t believe a trainer would have their clients do all out sprinting for 60 seconds!! That is insanity…”

20 Seconds Revisited