Moments of Clarity Part II
For fat loss - The post workout period is where “something” – probably the most important “something” happens.
Here’s a study that I came across about ten years ago (about 4 or 5 years after it was published I’m embarrassed to admit):
Tremblay A, Simoneau JA, Bouchard C.
Impact of exercise intensity on body fatness and skeletal muscle metabolism.
Metabolism. 1994 Jul; 43(7):814-8.
The premise of the study was to compare twenty (20) weeks of steady state endurance training and fifteen (15) weeks of interval training.
When comparing total calories burned from exercise, the researchers found that the endurance training burned 28,661 calories, while the interval training group burned 13,614 calories. In other words the interval training group burned less than half the calories of the endurance training group.
However when the researchers adjusted the results and corrected for the difference in energy cost, the interval training group showed a 900% greater loss in subcutaneous fat than the endurance group. In other words – calorie for calorie – interval training was nine times more effective than steady state exercise.
Additionally the researchers noted that the metabolic adaptations taking place in the skeletal muscle in response to the interval training program appear to favor the process of fat oxidation.
This piqued my interest because until this point we had been told that it’s all about “Calories in versus calories out”. So we assumed, or at least I did, that burning more calories in training would result in greater fat loss. This study (and several others since) have shown that to be completely incorrect.
So the “ah-ha!” moment showed me that we can’t ignore the post workout period. That’s where the adaptations happen. That’s where the results are.
Why did this occur? I’ve hypothesized that it is related to EPOC – a post exercise elevation of metabolism but some studies have shown that EPOC is not as big of a contributor to caloric burn as we originally thought– that the calories burned during the exercise period is the biggest factor.
And it still doesn’t explain the very significant difference in real world fat loss.
Simply put – the subjects doing interval training lost more fat by burning less calories than the steady state group.
But that still doesn’t explain it. An increase in fat oxidation doesn’t necessarily mean an increase in total caloric burn or fat lost (as other studies have shown that fuel source during exercise appears to be irrelevant – so fuel source at rest shouldn’t matter either unless there is a total caloric deficit).
The bottom line is that perhaps we don’t know why. But we do know that it’s more effective because of something that happens post workout. And that something is beneficial.
Looking at aerobics for fat loss and ignoring the post workout period is short-sighted. If we studied weight training the same way – looked at what happened during the workout and ignored the post workout adaptations – we’d have to conclude that weight training would destroy muscle tissue and make you smaller and weaker. We know that doesn’t happen!
Conclusion- the workout is just the stimulus. The adaptation is the goal.
posted by Alwyn Cosgrove at 10:36 AM
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