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What is the Afterburn Effect and how can I keep burning longer?

Did you know you could get a greater return on your workout investment?  The work you put into each exercise bout can lead to a larger payout than you thought.  After your exercise bouts, you can sit back and smile as your body burns more body fat while you rest!  This exercise afterburn, or the Afterburn effect, is scientifically referred to as EPOC, or excess post-exercise oxygen consumption. After an exercise bout, the amount of oxygen consumed can be measured. For a period of time, oxygen uptake remains elevated about resting levels during exercise recovery.  This increase in oxygen consumption comes at an energy cost. How does your body pay that cost? With your stored body fat!

“I want to invest in that,” you say? Well, with any investment, one wants to know how do I reap the greatest rewards?

What factors affect EPOC and lead to a greater post-exercise caloric expenditure?
Looking at the charts below, you can see a comparison of Light, low intensity exercise vs Heavy, high intensity exercise.

light exercise heavy exercise

The blue portion of each chart indicates the oxygen consumption that occurs during the exercise session. The orange portion of the chart indicates the oxygen consumption that continues during the post-exercise recovery. You can see that both light and heavy exercise elicit an EPOC response. However, notice the larger magnitude and longer duration of the EPOC response following the heavy exercise session. You can also see that the heavy exercise session elicited greater oxygen consumption during the session. So, not only did the subject expend more energy during the session, they also expended more energy after the exercise session.

What contributes to EPOC and why is EPOC greater following higher intensity exercise?
Oxygen consumption remains elevated post-exercise as the body replenishes depleted energy sources, restores muscle and blood O2 levels, converts lactic acid to glucose, and provides the energy for an elevated heart rate, breathing rate, elevated body temperature, and increased metabolic rate. Higher intensity exercise magnifies all of these things. Higher intensity exercise leads to:
  • Higher body temperature
  • Greater amount of energy and oxygen depletion
  • Greater amounts of circulating epinephrine and norepinephrine which increase metabolic rate
  • Greater amounts of lactic acid
  • Higher heart rates and breathing rates
The intensity of the exercise bout has the greatest effect on EPOC.
Bahr and Sejersted (1991) found that exercise at 75% VO2max for 80 minutes resulted in the largest post-exercise calorie expenditure at 150.5 calories. It also resulted in the longest duration of EPOC at 10.5 hours when compared to exercise at 29% VO2max (18 minutes of Afterburn) and 50% VO2max (3 hours and 18 minutes of Afterburn). 150 additional calories is equivalent to cookies, a soda, a Vanilla Latte at Starbucks, a bag of chips, or ½ cup of mozzarella cheese.  It may not seem like a lot of calories but if we consumed an extra 150 calories of food each day, it would lead to an extra 15 pounds of weight gain per year!

You can see that it pays to put more work into your workouts. With higher intensity work, you will increase the rate at which you burn fat after you complete a workout.

Intensity is one factor that leads to an increase in the number of calories expended after an exercise bout. Research shows that it takes anywhere from 15 minutes to 48 hours to fully recover to a resting state.  That’s a long time to burn excess body fat!

The magnitude and duration of EPOC depends on the duration of exercise as well as the intensity.
Increasing exercise duration significantly increases EPOC. Chad and Wenger (1988) investigated the effect of exercise duration on EPOC (30, 45, and 60 minutes at 70% VO2max). They found that EPOC was greatest with the longer duration.
  • 30 minute duration elicited 33 calories over 2 hours and 8 minutes
  • 45 minute duration elicited 74.5 calories over 3 hours and 24 minutes
  • 60 minute duration elicited 165 calories over 7 hours and 35 minutes
Interval training yields a larger Afterburn effect than continuous exercise and heavy resistance training can also result in a significant amount of exercise Afterburn.

The fact is that any additional caloric expenditure following exercise can add up over time and may contribute to long-term weight management.

So what does my Afterburn Investment portfolio look like?

  • Focus on improving your training status so you are able to perform higher-intensity exercise for periods of 30 minutes or more.
  • Regularly incorporate interval training workouts, as this type of training positively enhances EPOC.
  • Add Resistance training to your workout program twice a week. This should be high intensity or circuit resistance training.
Which Cycleup classes will help me achieve a larger Afterburn?
  • Monday and Wednesday 8:30am Watts Up with Robert
    • 30 minutes of high intensity interval training that will have you burning for hours afterwards.
  • Tuesday and Thursday 9:30am Ride and Ripped with Heather
    • 30 minutes of high intensity cycling followed by 30 minutes of high intensity circuit resistance training for a double bang EPOC effect!
  • All standard Cycleup classes offer 45 minutes of high intensity tempo training, continuous interval training, and supramaximal interval training focused on improving your training status and increasing your fitness to handle higher workloads.
So the next time you are sitting in the lobby at Cycleup after your killer fun class, smile and thank your instructor (and yourself) for pushing you so hard because now you can burn baby burn without even working!

Heather Flebbe, M.S., ACSM holds her Master's Degree in Exercise Physiology and is a lecturer at California State University, Los Angeles as well as College of the Canyons. Heather also presents for the American College of Sports Medicine certification workshops. She may be reached at fastbikermom@gmail.com.