High-intensity workouts: trainer's tips on how to do them safely

... College of Sports Medicine , these types of workouts will dominate in 2014. This includes workouts like Insanity, P90X, and CrossFit. They're all workouts that fitness professionals call "high-intensity interval training." People like them because ...

http://www.kfvs.com/story/24025492/high-intensity-workouts-trainers-tips-on-how-to-do-them-safely