Have you given up on exercise? If you have, who can blame you? Putting in effort without seeing results makes it hard to keep going. If you haven't, would you like to see better results from all the hard work you put in?

If either of those are you, we're going to talk about a different way to think about exercise...

When you’re about to train, focus on one specific energy system with each workout: burning fat or glucose.

Ask yourself: Which energy system—fat or glucose—do you want to train today?   You need to train appropriately, depending on your selection. To train your fat burning system: use Zone 2 training. To train your glucose burning system: use Zone 5 training, like REHIT workouts.

Zone 2 training is aerobic training for longer periods (45-90 minutes) at a lower intensity (still able to speak). Zone 5 training is based on the idea that exercise intensity is more important than exercise duration. You exercise in short bursts of intense effort, followed by a low-intensity recovery period. In Zone 2 training you're burning fat for energy. In Zone 5 training you're burning glucose for energy.

Zone 2 and Zone 5 training reprogram your mitochondria to be more efficient and work better, which is the key to living a longer and healthier life. By selecting Zone 2 or Zone 5 training you're optimizing your metabolic health by concentrating on two ends of the exercise spectrum.

Don't know about Zone 2 training? You might be interested in our article What is Zone 2 Training? If you'd like to learn more about Zone 5 training you might be interested in our article What is REHIT?

Every day as you age you're becoming less and less insulin sensitive, less and less carbohydrate resistant. Why is this important?

A common thread in Type 2 diabetes, obesity, cardiovascular disease, and Alzheimer’s is mitochondrial dysfunction. Mitochondrial dysfunction is when your mitochondria are not working properly or as efficiently as they could be.

When mitochondria are not working properly, we cannot burn glucose efficiently. As a result, the pancreas releases insulin to move glucose into the mitochondria. But since the mitochondria aren't functioning properly the glucose cannot be absorbed, so it begins to accumulate. As excess glucose builds up, it gives rise to insulin resistance, Type 2 diabetes, and the other problems just mentioned. Managing glucose by repairing your mitochondria is key for living a longer and healthier life.

The same thing happens with fat. Fat can only be burnt in the mitochondria. When the mitochondria is dysfunctional we can't burn fat properly. That causes fat to build up, which gives rise to a wide variety of pro-inflammatory responses related to cardiovascular disease and weight gain. So again, repairing your mitochondria is key for living longer.

Type 2 diabetics, for example, have poor metabolic flexibility. In other words, they have a poor capacity to burn fuels. One of those fuels is fat and as we said, fat can only be burned in the mitochondria. The good news is through Zone 2 training, which burns fat, you can reprogram your mitochondria and regain mitochondrial function. And as an added benefit, you'll see a steady decrease in blood sugar levels during a workout.

By choosing to train your mitochondria, you're consciously choosing to improve your metabolic health. Both training types improve your mitochondria, they just do it differently.

Improving your muscle's mitochondrial function by increasing metabolic efficiency and by increasing your capacity to burn fat and glucose optimizes your metabolic health and heals metabolic dysfunction.

How do you improve mitochondrial function? Zone 2 and Zone 5 training.

The more Zone 2 training you do, the better your mitochondria become at burning glucose for fuel. The hallmark of metabolic health and living longer is your ability to dispose of glucose by using glucose as fuel.

Zone 2 is also great for reducing insulin resistance, increasing insulin sensitivity, and non-insulin dependent glucose uptake (it's just a different way for glucose to enter a muscle). Since insulin resistance is a major marker for metabolic disease, what's not to love about making your mitochondria more efficient?

The intense bursts of activity in Zone 5 training tells your body it needs to improve itself, that it needs to change and adapt so that next time your body will perform better and be less stressed. Your body senses decreases in the fuel stores of muscle cells. Normally, it takes over an hour of moderate exercise to trigger these changes. But something remarkable happens with interval training: it gives your body the same signals as endurance training with a lot less effort. Intense exercise recruits more muscle fibers, which causes the fuel stores in the muscle cells to rapidly decrease. It's thought that this rapid decrease of energy stores triggers the same sort of exercise benefits that happen with endurance training. So it's not about how long you exercise, it's about exercising hard enough to draw down your energy stores fast enough that your body will give you all the amazing benefits of exercise in a fraction of the time.

I know this is a different way of thinking about training, but it’s a very powerful way, once you understand what’s going on in your body and how being conscious in your training plan can supercharge your health.

The Mighty Mitochondria

Mitochondria are small structures found in most cells of the body. Their job is to transform food into energy. The fuels are glucose, fat, and lactate.

Mitochondria are free living bacteria that about 2 million years ago were engulfed by eukaryotic cells. These two different cells formed a symbiotic relationship. Eukaryotic cells offered protection in exchange for the fuel for life in all living things.

Mitochondria now only have 37 genes that encode for 13 proteins, all having to do with energy production. Mitochondrial DNA does not have the ability to repair themselves or replicate themselves. They have out-sourced those functions to the nuclear genome, for reasons we don't really understand. Nucleus DNA contains about 1200 proteins involving the mitochondria structure, membrane structure biogenesis, and mitochondrial DNA repair.

To learn more about mitochondria you might like:

The deterioration of mitochondria function is one of the hallmarks of aging. The idea is that reduced mitochondrial density and function will lead to the metabolic issues described earlier. Anything we can do to delay that process and enhance mitochondrial function is going to be a benefit.

How do you improve mitochondrial function?

Stress them. Mitochondria respond well to stress.

One of the best stresses we know of—is you guessed it—exercise! Why is the answer to any health question always exercise?

At least the answer is specific, the best way to improve your mitochondria is to train your mitochondria using mostly Zone 2 training and some Zone 5 training. Just one HIIT workout has been shown to increase the number of mitochondria. In general, exercise improves mitochondrial function by increasing metabolic efficiency and increasing capacity to burn fuel.

How are mitochondria improved? It's actually hard to find a straightforward answer to this question. The thought is exercise makes the mitochondria larger; increases the number of mitochondria; makes your existing mitochondria more efficient at doing their job of producing energy—or some combination of all the above.

The good news is mitochondrial function is not specifically age related. An older person can have the same mitochondria function as a younger person. Obesity and inactivity drive a decrease in mitochondrial function, not aging. That's why consistent Zone 2 training is a key pillar of any longevity program. Exercise is the stimulus causing mitochondria to grow and work better. Without exercise, mitochondrial atrophy and mitochondrial functions declines significantly in as little as two weeks.


It’s not just what we eat that matters. We have mitochondrial dysfunction because we don’t use them. But all that can change by performing more Zone 2 and some Zone 5 exercise. This is especially true the older we get.

And what's a good way to introduce Zone 2 and Zone 5 exercise to your life? You guessed it: Max Workout.

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