The concept behind HIIT is simple: Exercise as hard as you can for a few minutes, recover just long enough to stop sucking wind, and repeat. This spikes your metabolism and builds muscle quickly. And unlike those leisurely treadmill sessions, it burns calories both during a workout and (here’s the beautiful part) for up to 24 hours afterward. The regimen is brutal but quick. You’ll be done with the whole thing in thirty sweat-filled (and swear-filled) minutes.
As a guy who’s been on a HIIT kick, I can say that the hardest part is finding the motivation to volunteer for redline-speed wind sprints or set after set of jump squats. You can’t half-ass these exercises. I’ve learned that eating a banana and downing two glasses of water pre-workout—rather than just hydrating during—helps avoid wicked cramps and soreness. And man, the results are swift: Each session is mentally easier than the last, and I began waving good-bye to my love handles around week five.
At right are three HIIT-ified versions of common workouts. They’re flexible, and you can be, too. Replace one gym visit each week with a HIIT routine, or power through three a week. When you’re no longer gasping for oxygen after a set, you know your pain is paying off. This is your moment of triumph—and your signal to be even more ferocious next time out.