After a workout session, many changes occur in our body. We have a rise in blood pressure and body temperature, our respiratory rate increases, our heart rate elevates and there is also a release of stress hormones in our body. To bring the body back to the pre-exercising state or homeostasis, is added work for the body in the post-workout period. For this added work our body consumes oxygen at an elevated rate signifying energy expended for this added work. The calories expended (above resting values) after a workout session, is referred to as ‘Excess Post-exercise Oxygen Consumption’ or EPOC. EPOC was originally referred to as an oxygen debt.
This post-exercise state was first examined by A.V. Hill and H. Lupton in 1922. EPOC is closely related to the concept of after-burn but is a bit more exacting and measurable representation of an increase in BMR (basal metabolic rate). The following occurs during EPOC.
• Replenishment of the energy resources
• Deoxygenation of blood and restoration of circulatory hormones
• Decrease in body temperature
• Return to normal ventilation and heart rate
Weight training and endurance training or for that matter any physical activity, gives rise to EPOC. But, weight training contributes greatly to EPOC. Since there is very little to no damage or micro trauma while doing cardiorespiratory exercises like running or walking on the treadmill, there is very negligible EPOC and hence no impact on the Basal Metabolic Rate (BMR).
BMR is the rate at which, the body burns calories while at rest or while doing no physical work. Any activity that doesn’t significantly impact BMR and only concentrates on the amount of calories burnt during exercise can never be considered the best option for fat loss. Whereas, weight training has a very significant EPOC and thus impacts BMR, thus forcing the body to burn calories at an accelerated rate even after a workout session throughout the day to provide fuel for the repair work, of the micro-trauma caused by weight training.
Within the gamut of weight training exercises, all exercises are not equal, when it comes to their individual contributions to BMR. Which exercises are best for creating a significant EPOC is then hugely dependant on the surface area of damage caused by the Exercise.
For example, a squat will cause wear and tear in the quadriceps, gluteal group, hamstrings, lumbar and abdominals, thus causing a great deal of repair work leading to a substantial increase in BMR. Whereas, an isolation movement such as leg extensions will cause wear and tear only in the quadriceps group.
Hence K11 always advocates structural, unsupported power and compound movements which involve the entire body in the movement and hence produce a large surface area of damage and result in greater fat loss.
EPOC will also depend on the intensity of your workouts. A 6 rep max set will cause more wear and tear in your muscles as compared to a 15 rep max set, thus requiring more repair work and hence more calories required in the after burn