In gyms everywhere, high-intensity interval training replaced hour-plus cardio sessions. The prevalence of these short, full-body circuits is most evident in the popularity of CrossFit's intense, minutes-long "workouts of the day." "Shorter workouts allow greater intensity," says Ryan Halvorson, senior editor of 'IdeaFitness Journal.' "That's why marathoners can be gaunt or plump, while avid CrossFitters tend to be lean and muscular."
Credit: Getty Images
Powered By ZergNet
Gear of the Year
102 of the Best Tools, Toys & Tech
Plus: The Woman Who Bails Out the NFL's Bad Boys
ON NEWSSTANDS NOW
The Woman Who Bails Out the NFL's Bad Boys
Jalen Rose: NBA's Inside Man
Sign up to receive the Men’s Journal newsletter and special offers from MJ and its marketing partners.