What Is EPOC? (And Why It Matters)

Do you want a bigger bang for your exercise buck? Excess post-exercise oxygen consumption (EPOC) is one way to get it.

EPOC, often called the “afterburn effect,” is the increased use of oxygen and calories after you stop exercising. It’s the energy your body uses to return to a resting state — a gift that keeps on giving.

What is EPOC?

Sports medicine physician Michael Dakkak, DO, compares EPOC to the heat of a car’s engine.

“After you turn off your car, the engine stays warm,” he illustrates. “Your response to exercise is similar. When you finish a workout, your body continues to burn energy as part of recovery.”

Experts aren’t sure how long EPOC lasts, though estimates range from 15 minutes to 48 hours.

Can you measure EPOC?

Researchers use high-tech laboratory equipment to measure oxygen consumption during and after exercise. Some advanced fitness trackers also predict EPOC using data collected during your workout. But most people don’t have access to real-time, personal EPOC.

You can estimate EPOC using information from research studies. According to one study, the EPOC effect produces a 6% to 15% increase in overall calorie consumption. So, if you use 300 calories during a workout, you may burn up to 45 bonus calories from EPOC.

This may not seem significant, considering you naturally burn 1,300 to 2,000 calories a day. But EPOC calories add up.

“Over weeks, months and years, burning these additional calories translates to losing extra pounds — just from the afterburn,” Dr. Dakkak says. “EPOC can be one of many strategies for successful weight loss.”

What’s the function of increased oxygen consumption after exercise?

The EPOC effect is related to how your body stores and uses energy (metabolism). The main fuel for your cells is called adenosine triphosphate (ATP), which your body produces by breaking down the sugar glucose. ATP production can occur with oxygen (aerobic) or without (anaerobic).

Exercise, which increases your demand for ATP, can also be aerobic or anaerobic:

• Aerobic exercise includes activities you maintain at a continuous rate, like walking, jogging, cycling and swimming. During aerobic exercise, your cells use the oxygen you breathe to make ATP.
• Anaerobic exercise involves short bouts of strenuous activity, including sprinting, weight lifting and high-intensity interval training (HIIT). These exercises quickly use up the oxygen in your cells, creating an oxygen debt. They can also create small tears in your muscle fibers that, when repaired, lead to stronger muscles.

The EPOC effect is greatest after anaerobic exercise, Dr. Dakkak says. Increased oxygen consumption refuels and repairs your body as it:

• Cools down your body’s core temperature.
• Removes excess lactic acid that builds up during anaerobic ATP production.
• Repairs damaged muscle tissue.
• Replenishes cellular oxygen and ATP levels.

What’s the best EPOC workout?

The benefit you receive from EPOC depends on several factors, including your weight, age, baseline fitness, level of effort and duration of exercise. The main factor driving EPOC seems to be exercise intensity. In research studies, higher-intensity workouts typically show higher levels of EPOC than steady-state aerobic exercise.

One study compared EPOC in three exercise groups:

• Group 1 cycled for 40 minutes at a steady state of 80% of their maximum heart rate.
• Group 2 did circuit weight training of four sets of eight exercises. Each exercise included 15 repetitions at 50% of their maximum weight level.
• Group 3 performed three sets of eight heavy-resistance exercises at 80% to 90% of their maximum weight level until exhaustion.

EPOC was greatest in groups 2 and 3, while group 1 had a lower but still measurable EPOC.

Applying results from research studies to the real world can be tricky, but Dr. Dakkak says that the takeaway from this is that to boost EPOC, it’s best to rev up the intensity of your workouts. High-intensity workouts include:

• Resistance exercises: These use traditional weights or your body weight, like pushups, lunges and burpees.
• Interval training: Interval training is something you can do no matter your fitness level. Try alternating high levels of activity with steady-state exercise, like by incorporating sprints into your running or cycling routine. Or if walking is more your vibe, try short periods of speed-walking or light jogging.

How much should you exercise?

The U.S. Department of Health and Human Services’ current Physical Activity Guidelines for Americans recommends:

• 150 to 300 minutes of moderate-intensity or 75 to 150 minutes of vigorous-intensity activity per week.
• Moderate- or higher-intensity strength training of all major muscle groups at least two days per week.

Before starting or changing an exercise routine, talk to your healthcare provider to be sure it’s safe for you. And start slowly to let your body get used to the exercise and avoid injuries.

You can tailor exercise to your fitness level, time, resources and personal preferences. Whatever workout you choose, Dr. Dakkak recommends incorporating HIIT workouts two to three times per week.

“If you only have 30 minutes to exercise, do part of that workout at your maximum level of effort,” he advises. “For more demanding workouts, incorporate a 24- to 48-hour rest period to help you recover properly.”

Including some intensity intervals in your exercise routine can help you reap the benefits of EPOC. It can also provide an added boost to your strength, endurance and health.