Fat Burning Zone - Exposing the Myth Part 2
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Fat Burning Zone - Exposing the Myth Part 2
During part one of Exposing the Myth we explored the validity of the ‘fat burning zone’ and the reality behind the largely misunderstood concept. We came to an understanding that exercising at lower intensities was an ineffective style of training for the pursuit of expending energy, burning fat and ultimately losing weight.
A detailed discussion on the ‘fat burning zone’ can be read in Exposing the Myth: Part 1 for those of you who have only stumbled across Part 2 of this article. During the conclusion of my precursory article I alluded to another vital component of the fat burning equation that we must consider; excess post-exercise oxygen consumption, otherwise known as EPOC.
After a sustained period of exercise the body continues requiring oxygen at an elevated rate compared to resting (pre-exercise) levels. This ‘oxygen debt’ theory, hypothesised as early as the 1920s states that the body must replace the oxygen consumed by the muscles during mild to intense exercise. More specifically we now know that the increase in oxygen consumption post-exercise serves a variety of functions as the body attempts to restore itself to homeostasis and adapt to the stimulus (exercise) provided. Some of these functions include the replenishment of fuel stores, cellular repair, anabolism (creation of new cellular material e.g. proteins, cells, tissues) and the restoration of appropriate hormone balance. Central to this article is the fact that elevated levels of oxygen consumption are also accompanied by elevated levels of fuel (carbohydrates, protein & fat) consumption which forms the basis of using EPOC to our advantage on the quest to burn fat.
We know that the body continues to expend energy after exercise, so we must now investigate an important question… what type of exercise has the greatest effect on EPOC? Evidence has shown high intensity, interval style training has the most pronounced effect on EPOC1 and additional research also shows that resistance training produces greater EPOC responses than aerobic exercise2. The majority of this research leads to the conclusion that high intensity resistance exercise and to a slightly lesser extent, anaerobic cardiovascular exercise disturbs the body’s homeostasis to a greater degree than aerobic exercise. The result is a larger energy requirement after exercise to restore the body’s systems to normal2. Whilst we can see that resistance training (an anaerobic style of training) is the king when it comes to increasing EPOC the focus of these articles has been on cardiovascular training, so I’ll leave the fantastic benefits of resistance training to another day!
Elevated EPOC can last for only a couple of minutes for light exercise (aerobic training) or up to several hours for high intensity exercise (anaerobic cardio training.) It can even effect our metabolism for up to 12 to 24 hours for prolonged, exhaustive exercise (interval training or circuit weight training). It is now becoming clear that our earlier approach to fat burning (Part 1) is being supported by further evidence that high intensity styles of exercise have a greater effect on energy expenditure than low intensity exercise. Understand that the EPOC effect exists after both low intensity (aerobic) exercise and high intensity (anaerobic) exercise, but all studies comparing the two show that anaerobic exercise is the more effective. Just as high intensity styles of exercise provided us with greater total calorie (and fat) burn during the session we now find that high intensity exercise also serves to elevate calorie burn after a session.
I hope that reading Exposing the Myth has stimulated some internal thought and dialog, prompting you to constantly challenge what you know and how you perceive different styles of training. There are always a variety of methods available to achieve training goals. All have strengths and weaknesses, some are just more effective than others.
Joshua Humphrey
Lecturer
Australian Fitness Academy
1 Haltom, R.W. et al. 1999. Circuit weight training and its effects on excess postexercise oxygen consumption. Medicine & Science in Sports & Exercise, 31, 1613-8.
2 Burleson, M.A. et al. 1998. Effect of weight training exercise and treadmill exercise on elevated post-exercise oxygen consumption. Medicine & Science in Sports & Exercise, 30, 518-22.
Article contributed by:
Australian Fitness Academy
701 Glenhuntly Road
Caulfield South VIC 3162
03 9532 7800
www.fitnesseducation.com.au
