Thursday, September 3, 2009

Raising Metabolism - the Afterburn Effect

Guest Blog from Alwyn Cosgrove, CSCS - owner of Results Fitness (Newhall, CA)
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Here's a study I looked at recently and mentioned in the Fat Loss University Manual

Schuenke MD, Mikat RP, McBride JM.
Effect of an acute period of resistance exercise on excess post-exercise oxygen consumption (EPOC): implications for body fat management.
Eur J Appl Physiol 2002 Mar;86(5):411-7

This group looked at the effects of circuit weight training on EPOC. EPOC (Excess Post-Exercise Oxygen Consumption) is defined scientifically as the “recovery of metabolic rate back to pre-exercise levels”.

The exercise routine consisted of three exercises (the bench press, the power clean and the squat), performed with 10RM loads as a circuit. The circuit was performed four times (i.e. twelve total sets) and took 31 mins.

EPOC was elevated for 38 hours post workout (possibly longer as this was when the researchers stopped measuring). The duration and magnitude of the EPOC observed in this study indicates the importance of the role of high intensity resistance training in a fat loss program.


This type of information should go a long way in helping fitness professionals design and implement effective fat loss programs. It's not the workout - it's the effect of that workout on caloric burn over the other 23 hours of the day.

This ties in with some of the interval training studies we've already looked at. They showed that despite burning less calories during the session (when compared to other workout), more calories were burned by the body outside of the workout - which quickly added up and resulted in more real world fat loss.

I call this post-workout phenomenon Afterburn - the post workout period that results in metabolic disturbance, elevating EPOC, fat burning enzyme activity and total body fat oxidation to maximize caloric burn for the other 23+ hours per day.

Is there much of a real world effect of burning 300 calories per workout (e.g. aerobic work) if I don't create some form of 'Afterburn'?

If we could elevate metabolism even an apparently insignificant 1/4 of a calorie per minute for the 38 hours that the study showed, then that 31 minute resistance training workout would burn X calories during the session plus an extra 570 calories over the next 38 hours. That becomes significant.

As a side note - this was a pretty simple workout plan with fairly profound results. The study itself was designed to look at the effect of a simple weight training workout (4 sets of 3 exercises) on EPOC.

But what if we actually designed a metabolic resistance training program that was designed to create an afterburn effect? A workout that was designed to create fat loss in the first place - not as a side effect?

And then we combined that program with a cardio routine that did the same - and added a nutrition program that in and of itself resulted in significant fat loss? Everything would combine synergistically for a better effect overall.

The key is to look at the programs effect on the entire 24 hours, week, or several months on a program. Ignore the acute effects and look at the long term results.

In the past - fitness professionals and researchers have looked at how much fat is burned during the exercise session itself. This is extremely short-sighted.

As my colleague Alan Aragon said:

"Caring how much fat is burned during training makes as much sense as caring how much muscle is built during training."

Think about that. If we looked at a weight training session that started at 9am and finished at 10am - how much muscle would we see built if we stopped looking at 10am? None.

In fact - we'd see muscle damage. We could make the conclusion that weight training does not increase muscle - in fact it decreases muscle right? It's only when we look at the big picture - and look at the recovery from the session - that we find the reverse is true - weight training builds muscle.

Fat loss training is the same way. Someone talking about the benefits of the "fat burning zones" or "fasted cardio" is a sure sign that the individual has stopped looking at the end of the exercise session. They have come to the conclusion that fasted, lower intensity steady state exercise burns the most fat and made a massive leap of faith to suggest it is best for real world fat loss.

Using that same logic these same people would suggest avoiding weight training if you want to grow muscle.

Take home message - focus on the Afterburn effect not just what happens during the exercise session.

PS - My question is - could we get ANOTHER boost if we trained again using a similar or different workout routine less than 38 hours later? Could we raise an already elevated metabolism further? These are the questions that keep me up at night....


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