Burn calories and torch fat all day long, even when you aren't working out! If you think this sounds like a cheesy tagline for a scary diet pill, then you've probably never heard of excess post-exercise oxygen consumption (try saying that three times fast!). Also known as EPOC, it's the scientific term for the afterburn effect, which can help you burn more calories long after you've left the gym. Read on to learn how EPOC can earn you more effective workouts—no gimmicks required.
A Better Burn
When a person works out at an intensity they can't sustain for a long period of time, two things happen: their muscles begin to burn and they start feeling out of breath. Why? Upon exertion, muscles start to fill up with lactic acid (the chemical responsible for that burning feeling) and the body's oxygen stores become depleted, says DailyBurn's LA-based fitness expert and trainer Kelly Gonzalez, MS, NASM CPT.
These high-intensity training sessions force the body to work harder to build its oxygen stores back up—for a period of 16 to 24 hours post-workout, research suggests. The result: more calories burned than if you'd exercised at a lower intensity for the same (or longer) period of time. Think about it like maxing out your credit card: During rest, your body has to work hard to clear away the lactic acid and pay back its oxygen debt. Exactly how much you can burn after exercising directly correlates to the duration and intensity of your workout, says DailyBurn trainer Anja Garcia, RN, MSN.
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Studies show strenuous resistance exercise results in greater post-exercise oxygen consumption compared to steady-state endurance exercise that burns the same number of calories. So while you might burn the same calories during an hour-long jog, shorter, more intense workouts give you more bang for your buck.
Over time high-intensity workouts can increase your VO2 max, or your body's ability to use oxygen for energy, Gonzalez says. That means better endurance, which leads to more energy and the ability to sustain more work for a longer period of time.
"You will find that when you do go back to slower, steady state cardio, you'll be able to maintain that longer with more ease," Gonzalez says.
For endurance athletes, adding one or two EPOC-enhancing workouts to your weekly routine can also provide a boost at the finish line. The reason: Working different aerobic systems improves endurance while building stronger fast-twitch muscle fibers, which can help deliver that final kick needed to finish strong.
HIIT and Run
Working out at 70 percent to 80 percent of your maximum heart rate will deliver the greatest EPOC effect, says Gonzalez, and high-intensity interval training (HIIT) is one of the best ways to get your heart beating. HIIT alternates between short, intense anaerobic exercises, such as sprints, with less-intense recovery periods. A 2:1 work-to-rest ratio has been found to create the best results, with workouts ranging from four to 30 minutes.
"In today's busy world, not a lot of people have 60 to 120 minutes to work out at a steady, slow pace," says Gonzalez. But these quick, efficient workouts make it easy to fit in a workout.
When time is of the essence, Tabata workouts can get the job done in just four minutes flat. Pick an exercise (running, biking, jumping rope, box jumps, mountain climbers, pushups, you name it) and alternate between 20 seconds of all-out work and 10 seconds of rest, repeating for eight rounds. A recent study out of the University of Wisconsin-La Crosse found Tabata-style workouts can burn a whopping 15 calories per minute, and the workout meets or exceeds fitness industry guidelines for improving cardio fitness and modifying body composition.
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As an alternative to interval training, circuit training (moving from one exercise to the next with no rest in between) will give you a similar effect, Gonzalez says.
It's important to note that your body will take longer to recover from super high-intensity workouts, so you shouldn't do this kind of training daily. Yoga, stretching, foam rolling, light cardio or any other activity that increases blood flow and aids in circulation will help aid recovery (that means vegging out in front of the TV doesn't count).
"We only get stronger when we recover," Gonzalez says, and it can take 24 to 48 hours to fully recover from a high intensity workout.