How to build aerobic fitness and metabolic flexibility.

How to build aerobic fitness and metabolic flexibility.

The two typical approaches:

If you have done research on building aerobic fitness and fat burning capabilities you typically end up in two ways.
With the preface being that you understand that just riding or running won’t build your capacity like training in a prescribed intensity range only would.

  1. long slow aerobic sessions often only available to professionals. I called this the bottom-up approach as your building aerobic base from the bottom up by following long sessions of low intensity.
  2. The top-down approach is what I call the approach where you build your anaerobic capacity thereby lifting your aerobic capacity as well. This method is often used by those with less time available.

For the most part that sums it up. typically extensive aerobic training is done in the offseason to build the capacity for more work and more intensity during the season.

What are the benefits of having a good aerobic and fat burning capacity?

  1. Faster recovery.
  2. Ability to handle a larger workload.
  3. Ride or run faster while still burning fat, allowing you to stay out longer to do the things you enjoy. This is a big reason for me to increase my capacity.
  4. Less soreness due to the reduced production of waste products typically associated with the glycolytic cycle.
  5. Fueling longer endurance events becomes less critical as you rely more on fat storage then carbohydrates.
  6. New fueling strategies and reduced likelihood of upset stomach due to the high intake of carbohydrates.
  7. A shift in the functional threshold heart rate allowing you to to stay at a higher heart rate for longer, again due to the reduced waste product of the glycolytic cycle.
  8. preserving carbohydrates for the high-intensity part of the event. for example, doing a mountain bike Enduro race you don’t tap into the glycolytic cycle on the ride to the stages. Does preserving carbohydrates stores for the high-intensity part of the timed run.

Periodization and Nutrition

Most training programs use periodization with a focus on aerobic base (long slow sessions) training followed by a period of more intense training to boost V02max further.

One part that is often overlooked is the nutrition during these periods, you should adjust according to your volume and intensity.

Let’s say it’s the fat burning machine that you would love to build, so you follow the low-intensity training for longer periods to maximize fat-burning. However, the results are not satisfying!  Ask yourself how can I expect my body to run like a well-tuned efficient diesel engine when you are putting gas in the tank?

If you start your day with a bagel and a glass of orange juice before you head out the door on your endurance ride what are the chances that your body will burn fat efficiently? I would say slim.

European road cyclist used to get up in the morning for a black cup of coffee and then crank out slow steady miles to boost their capabilities to utilize fat for fuel. Often resulting in a miserable ride which ended in a delirious finish followed by a rapid refeed.

So what is my proposal?

It’s a period that syncronizes exercise and nutrition. Ideally done in the offseason I would recommend at least 90 days of low carb adequate protein and fat nutrition with the added intermittent fast here and there to reteach your body how to use fat for fuel.
Without going too deep into the coaching part, we are essentially born with metabolic flexibility only to lose this ability as we age. This loss is detrimental to our health and performance, think insulin resistance and diabetes. Don’t blame yourself though as conventional wisdom (mostly created by the food industry) steered you in the wrong direction starting with the high carb breakfast making you enter the blood sugar roller coaster every day.
This period I’m proposing will restore the metabolic flexibility and set you up to burn carbs and fat efficiently just like nature intended.

Does it work?

Absolutely in my case for cycling the FTP (functional threshold power) went up by about 15% and my FTHR (functional threshold heart rate) went up by almost 10 bbm. Allowing me to push harder without getting the treaded leg burn.

Current trends have us looking at two camps mostly:
A standard diet with higher amounts of carbohydrates or a low carb ketogenic approach.

The sweet spot is in the middle where you are metabolically flexible.
You are not creating insulin resistance in your muscles with a long-lasting ketogenic approach and you are not eliminating the ability to use ketones for fuel with constant carb loading.

Let me know you’re thoughts.



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