When you exercise, your cardiovascular, respiratory, circulatory and metabolic systems all work at higher levels than they do when you are at rest. When you stop exercising, your body needs time to return to its pre-exercise state. During this post-exercise period, your body requires additional oxygen to complete the recovery process. This afterburn effect of exercise, known as excess post-exercise oxygen consumption, or EPOC, contributes to the total calorie cost of your workout. You can influence your EPOC to augment weight loss or improve body composition. Your afterburn will be as high as your awareness of the factors that optimize it.
Features
EPOC is an estimated 15 percent of the total calories used during your workout, according to Dr. Len Kravitz, exercise science program coordinator and researcher at the University of New Mexico. Kravitz' research has identified several factors that enhance calorie burning for body-composition improvements. If you increase the calories burned during a workout, you also maximize the amount of energy that your body spends in its passive recovery -- up to 24 to 48 hours after you exercise.
Factors
The magnitude and duration of EPOC are directly related to the intensity and the duration of your exercise. Based on those two variables, recovery can take 15 minutes to 48 hours. Your sex and fitness level also affect your EPOC. After high-intensity cardiovascular exercise, EPOC is much greater than it would be for low-intensity exercise. Kravitz reported a study that compared two workouts of different intensities, each of which burned 500 calories; the two workouts reflected a large difference in EPOC. A long, slow walking workout can burn 500 calories; a faster, more intense workout will burn the same 500 calories, but the afterburn will be higher. Duration also affects EPOC. If you exercise at the same intensity for workouts of 20, 40 and 60 minutes, your EPOC will be highest for the 60-minute session.
Additional Considerations
Resistance training elicits a post-exercise oxygen consumption that burns additional calories. High-intensity strength training promotes greater EPOC than lower-intensity training -- a result consistent with different-intensity cardiovascular exercise workouts. Your training status can affect EPOC, but the balance is often similar. A higher training status yields a higher intensity that you are able to sustain during exercise. Your EPOC will decline as you become fitter and your body is better able to recover. Though EPOC contribution to total calories burned will be lower, there is a balance, due to energy expenditure.
Limitations
Because you are unable to obtain an exact measurement of post-exercise oxygen consumption, knowledge is limited to estimations. Kravitz recommends the Calories Per Hour website to accurately estimates total caloric expenditure based on age, sex, exercise duration and intensity level. It accounts for EPOC in its calculations. The consensus points to working as long and hard as you are able to reap the rewards of post-workout calorie burning.
References
- Dr. Len Kravitz; University of New Mexico; Albuquerque, New Mexico
- Dr. Len Kravitz Website: Exercise After-Burn Research Update
- "IDEA Fitness Journal"; Calorie Burning: It's Time to Think Outside the Box; Len Kravitz; April 2009
- "Physiology of Sport and Exercise"; Jack Wilmore et al.; 2008
Member Comments