Like so many dubious health claims, stretching before exercise has its roots in yoga culture. Maria Konnikova explains that stretching is exercise in-and-of itself and shouldn’t be treated like a warm-up. Then why do so many trainers and health nuts preach stretching as gospel? Konnikova is a regular guest on The Gist, a New Yorker staff writer, and the author of The Confidence Game. In the Spiel, Rachel Maddow’s report on President Donald Trump’s taxes was fine news but bad showmanship. Today’s sponsors:Control GX gray-reducing shampoo. It is the first shampoo that gradually reduces gray. Green Mountain Coffee is passionate about making a smoother tasting cup. Try it today with $4 off when you buy two boxes of most Green Mountain Coffee K-Cup pods at keurig.com with code TRYGMC.