After-burn is the new buzz word in the fitness industry. Exercise after-burn is a term used to describe the phenomenon of excess post-exercise oxygen consumption or EPOC. It’s EPOC that keeps you burning extra fat long after you’ve slipped off your exercise shoes and settled down to more sedentary pursuits. The after-burn is your friend when it comes to burning calories and fat.
What is EPOC or Exercise After-Burn?
When you start out exercising, your body needs more energy in the form of ATP. Initially, anaerobic energy production supplies ATP to the muscles. The phosphocreatine and glycolytic energy systems are the systems used for ATP until oxygen consumption can be ramped up and the aerobic system, which burns fat as fuel, can gear up.
Anaerobic systems operate in the absence of oxygen. In doing so, they create an oxygen deficit that has to be paid back after exercise with increased oxygen consumption and a bump-up in metabolism. Phosphocreatine stores that were used during exercise also have to be replaced, which puts additional demands on the body and increases the body’s metabolic rate even after the workout is finished. Exercise, especially intense exercise raises core body temperature and increases levels of hormones such as norepinephrine and epinephrine, which contribute to the after-burn effect.
After a workout, the body has to work harder to restore muscle phosphocreatine levels muscles and oxygen to the muscles and blood that were depleted during the oxygen deficit. It also has to restore normal body temperature. If a workout was intense, lactic acid will have built up, and it will require more energy to convert it back into glucose by the liver. This increase in energy requirements gives your metabolism a boost after you stop your workout.
What Type of Exercise Gives You the Greatest Exercise After-Burn?
Two factors determine how large the after-burn is after exercise. One is exercise duration and the other is intensity. Of the two, intensity is the more important factor. EPOC is greatest during exercise sessions carried out at 75% of V02 max or greater. This isn’t surprising since exercise at higher intensity creates more of an oxygen deficit and causes a build-up of lactic acid. It also raises core body temperature more.
Duration of exercise plays a role in the degree of after-burn after exercise too. As long as you’re working out at a moderate intensity or greater exercising longer at the same intensity will increase after-burn more. A 60-minute workout will give more of an EPOC than a 20-minute one when the intensities of the two workouts are equal. Research also shows that short bursts of high-intensity exercise with periods of recovery, interval training style, boosts EPOC more than steady-state exercise at a moderate intensity.
What Effect Does Resistance Training Have on Exercise After-Burn?
Higher intensity weight training sessions using heavier weights causes more of an after-burn than less intense ones, and circuit resistance training boosts EPOC more than resting between sets. One more reason to lift heavier, and minimize the amount of rest between sets.
The Bottom Line?
If you want to increase exercise after-burn, ramp up the intensity, duration or both of your workouts. Of the two, increasing the intensity boosts after-burn more. If you can’t do high-intensity aerobics for prolonged periods, do interval training where you increase the intensity for short intervals and then recover. Short bouts of high-intensity exercise of ten minutes or less can boost your EPOC too. If you’re looking for a low impact high-intensity workout make sure to order my new AfterBurn video which has been designed by me to increase your EPOC in the comfort of your own home without any high impact moves.
When you train with weights, challenge your muscles with heavier weights until you can barely eke out the last rep, or do circuit training to increase the after-burn. These are ways to boost the amount of fat you burn for hours or even days after a workout. Who doesn’t want that?
References:
Exercise Physiology. Theory and Application to Fitness and Performance. Seventh edition. 2009.
Idea Health and Fitness Association. “Exercise After-Burn: A Research Update”
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