This specific combo is a legs and lungs killer: The fast-and-explosive switch lunges will dial up your heart rate and get your quads burning, helping to build explosive power and torch calories; the one- to two-second pause at the bottom of the sumo squat demands the muscles in your lower half produce the necessary force to get you back up to standing—with no help from momentum—which builds strength. (Tone up, beat stress, and feel great with Rodale’s new With Yoga DVD.)
Add this bodyweight superset to the end of any workout to boost its muscle-building, fat-blasting potential. (In a pinch, you can also complete it on it’s own for a quickie workout that will get your legs fired up and score you a few cardio points.) Because this circuit only lasts a few minutes, the goal here is all-out intensity—as many reps as you possibly can, and no rest breaks. I like to try to keep tabs on how many reps I did during each round: It’s a great way to see progress week over week (as you get fitter and stronger, you’ll be able to get more overall reps, especially in the final round or two of the circuit).