By Carey Rossi

If burning fat and getting lean are on your to-do list, try one of these heart-pumping routines that are scientifically proven to boost your metabolism even after you finish training

Want to boost your metabolism and burn fat faster? Amp up your intensity to increase your EPOC, or excess postexercise oxygen consumption. EPOC represents the energy required to recover from exercise, says Chris Scott, PhD, exercise physiologist at the University of Southern Maine Human Performance Laboratory (Portland).

"When exercise ends, it takes time and energy for muscle cells to return to resting levels. Recovery can also be expensive: Depleted glucose and fat stores need to be refilled, accumulated cell products need to be removed and protein levels need to be built back up. All this requires energy."

And the more rebuilding to be done, the greater the rate of EPOC, which in turn means more calories (using fatty tissue as fuel) are being burned after your workout. While the primary factor in determining EPOC is exercise intensity, says Scott, so is duration—just not to the same extent. Numerous studies support this idea, such as a Journal of Strength and Conditioning Research study done by Cedarville University (Ohio) researchers. When women performed either a weight-training or a cardio session, both of which burned the same amount of calories and were similar in intensity, the subjects experienced similar EPOC responses.

It's well known that lower-intensity aerobic exercise burns fat, but that doesn't mean your workouts should be a walk in the park.

"Intense exercise is associated with a tremendous amount of fat breakdown," says Scott. "The higher the exercise intensity, the greater the amount of carbohydrate burned. But the energy requirements of recovery, especially an active recovery, need to be considered. To be sure, muscle uses mostly carbs during weight training, but all the fat that's broken down during exercise is subsequently used to fuel recovery. EPOC primarily depends on fat and lactic acid as fuel. In fact, the recovery from EPOC is almost all aerobic and a terrific oxidizer of fat."

That said, the programs featured here vary in level of intensity and duration but all have a high EPOC. Whatever your preference, there's a workout geared to you.