Extreme workouts part of a growing trend in gyms

... thanks to a seemingly never-ending techno beat of late-night commercials touting DVDs for such intense works outs as P90X and Insanity. P90X, which a promotional website describes as "sweat-inducing, muscle-pumping exercises designed to transform ...

http://medicalxpress.com/news/2013-08-extreme-workouts-trend-gyms.html