Aerobics, exercises designed to increase the efficiency of the aerobic stage of muscle metabolism, were introduced by Dr. Kenneth Cooper in the 1960’s. Dr Cooper assumed that the aerobic part of the metabolism was the most important part.
I hope from my previous posts you begin to see that Dr. Cooper was wrong in that assumption. Your muscles have a metabolic cycle that is dependent on BOTH aerobic and anaerobic processes. You cannot optimize one without optimizing the other.
Most people think that food is converted to energy via an aerobic process only. However, your muscles have a trick retained from our most primitive past that allows muscles to produce energy without oxygen (i.e. anaerobically. )
Somewhere in the misty past it was essential to human survival to be able to generate energy nearly instantly. If a big predator pounces, you need instant energy and lots of it. As we saw in my last post, aerobic metabolism is a rate limited process. In a life or death situation you do not have time for your body to aerobically convert sugar and carbohydrates into muscle energy (ATP).
Your body therefore keeps energy in reserve stored in the muscle fibers themselves in the form of glycogen (one of the chemical stages in breaking down blood sugars into pyruvate). In a life and death situation or under intense exercise, your body has the ability to convert this stored energy into usable energy (ATP) on the spot anaerobically (without oxygen).
This process is inefficient compared to the aerobic process. But, there is no rate limit. You can produce this energy as fast as needed until you run out of glycogen.
Following the immediate burst of energy, this processing of gylcogen has three important downstream effects.
These days big predators are hard to find outside of the zoo. For most of us this means that the energy stored in our muscle fibers NEVER get used. That’s bad.
It means our muscle fiber are literally a sticky mess. We burn energy less efficiently and store energy as fat. Worse, because the muscle cells are always full of glycogen, they become insulin resistant which is one of the leading causes of diabetes.
Fortunately we can simulate a tiger attack by pushing our bodies during exercise beyond the aerobic processes ability to keep up, thus triggering the anaerobic metabolism to kick in. This is the definition of “high intensity” exercise.
All of the resulting health benefits kick in.
- • We produce energy more efficiently for hours afterwards because pyruvate is now available in abundance.
- • We utilize more energy and burn more fat as the energy stores in muscles are replaced.
- • That fat burning is more efficient because we have released a flood of hormones that mobilize fat.
- • And! The muscle cells regain their insulin sensitivity.
High intensity exercise is the only form of exercise that triggers these benefits.
Now, my mother-in-law has diabetes. She argues that low intensity exercise must also be beneficial because if she measures her glucose levels before a walk and after, her blood sugar levels go down.
She’s right but she’s missing the point (please don’t tell her I said that! )
Any exercise requires energy. Of course, if there is sugar in your blood at the time of the exercise your body will use that readily available form of energy first and your blood sugar levels will temporarily go down. Then what?
They immediately go back up (because your muscle cells are still insulin resistant) and they stay back up until the next time you exercise.
On the other hand, if she had engaged in just 15 minutes of high intensity exercise she would have used more energy; then and for hours afterwards, mobilized fat and with repetition reestablished insulin sensitivity.
What would you rather do? 15 minutes of intense exercise with long-lasting payoff or stay on the treadmill?
More to come. Stay tuned. Please leave your comments below. I love hearing from you.