Instead of using traditional modes of cardio training, MetaCardio employs resistance training exercises to provide a muscle-building stimulus, which, in turn, enhances the overall fat-burning and metabolism-boosting potential of your workout. It’s the basis of my newest fitness program with Men’s Heath, METASHRED EXTREME. There are lots of ways you can do MetaCardio, but 20-10 intervals are among my favorites. This particular interval became world famous in 1994 when the Tabata study discovered that 4-minutes of 20-10 intervals delivered greater fat loss and fitness improvements than 60 minutes of long, slow, and boring cardio.