Think working out has to be hard? Think again! HIIT workouts appear to do the impossible by helping you to burn more calories than a 40-minute run in a quarter of that time! Better yet, they also build muscle, improve athletic performance and give you more energy.Ready to get started with the most highly effective and efficient workouts on the planet?Along the way, we’ll discover that there’s a lot more to HIIT than just the basic alternating speeds; we’ll learn some advanced techniques like cardio acceleration, fartlek training, speed drills, concurrent training, metcon, tabata, finishers and more.