Why do our bodies deteriorate with age?
Why is overcoming obesity so difficult?
Why are some of us prone to disease while others are healthy and vital?
The answers to these questions are found in parts of our body known as mitochondria that are a million times smaller than a grain of sand.
You probably remember from elementary science class that mitochondria are the energy factories of your cells. They make ATP, the energy currency in the body that fuels everything from exercise to breathing. But mitochondria play a much larger role in our health and fitness, enabling peak performance, preventing disease, and slowing the aging process.
What Are Mitochondria?
Mitochondria are tiny organelles (basically, little organs) in your cells that use the corrosive power of oxygen to strip electrons from the food we eat to create energy in the form of ATP. As a part of oxidative metabolism, which uses oxygen to transfer energy from carbs, fat, and protein, mitochondria produce ATP that powers all physiological processes. When mitochondria become dysfunctional, disease increases and energy levels go down. It also becomes difficult to lose body fat because energy expenditure decreases and the body’s ability to use glucose and fat is compromised.
How Does Mitochondrial Dysfunction Occur?
Every cell contains genes that make new mitochondria. Normally, you get two functioning pairs of genes from your parents—one from your mother and one from your father. With mitochondrial disease, you don’t receive a normal pair of genes. Instead, the gene that codes for new DNA is mutated, meaning it is defective, which leads to diseases of the nervous system, such as muscular dystrophy.
Mitochondrial dysfunction can also be acquired. Aging, inactivity, obesity, and chronic disease are all major causes.
Let’s take aging: As we grow older, we experience mitochondrial DNA mutations. When these mutations accumulate mitochondria are not able to produce sufficient ATP to power the cell, causing an energy crisis that results in a progressive decline in tissue and organ function. This loss of mitochondrial function is believed to be a primary cause of the physical breakdown we experience as we grow older.
For example, using gene editing, scientists designed mice that have a genetic mutation that gives them dysfunctional mitochondria. Compared to normal mice, those with malfunctioning mitochondria aged prematurely and lived only half the normal lifespan. They had accelerated graying of fur, decreased hearing, loss of muscle, and smaller brains.
Another example is in the aging of human skin. Once you’re over 40, you begin to see changes in skin quality. The inner layer of skin begins to lose moisture, cells, and elasticity. These changes coincide with a drop in mitochondrial capacity, which leads to a thickening of the layer of dead skin, that makes skin dry and rigid.
How Do Mitochondria Impact Exercise Performance?
One solution for protecting mitochondria is exercise. It makes intuitive sense that mitochondria would have a large impact on exercise performance because they are the power plants muscle cells, converting fat, glucose, and protein into usable energy, powering activity.
Three things matter when it comes to how mitochondria impact performance:
- The number of mitochondria in your cells, especially muscle cells,
- The density of mitochondria per cross-sectional area of muscle ,
- The function of existing mitochondria
Let’s break these three factors down:
As new mitochondria are born, cells have increased energy available. Where do new mitochondria come from?
Getting your body to create new mitochondria requires a stressor, literally, a challenge to the system. Exercise is a primary stimulus for the growth of new mitochondria. When you start to exercise, you place pressure on your system to produce high amounts of energy fast. The mitochondria respond by becoming better able to take oxygen from the blood and use it to make energy.
Having more mitochondria is obviously beneficial, but where things get interesting is in regards to the density of mitochondria. As new mitochondria are created, the density per cross-sectional area of muscle increases. This means there is more energy available to each muscle fiber to power activity.
For a long time, researchers thought that only aerobic exercise could increase mitochondrial density—anaerobic training modes like intervals and strength training were written off because they stimulate an increase in muscle mass. It was believed that because muscle mass was increasing, mitochondrial density (the number of mitochondria per given unit of muscle) decreases. The theory went that the pathway that stimulates muscle building (mTOR) inhibited the pathway that led to the growth of new mitochondria. However, more recent research shows that it is not so simple: Although anaerobic forms of exercise like high-intensity training may increase muscle mass, they also increases mitochondria, so density remains the same or increases.
When strength training is combined with aerobic or interval training, the same thing happens. It appears that only with strict muscle building programs (such as 8-12 reps with moderate loads and a high volume) does mitochondrial density decrease. This is why its important to include some form of conditioning exercise that overloads the cardiovascular system on a regular basis.
The third factor to worry about is how the mitochondria you’ve got are functioning. For mitochondria to function properly they require the presence of specific enzymes and proteins. For example, different enzymes are necessary for mitochondria to burn fat than to burn carbohydrates. This is the reason that shifting to a low-carb high-fat diet from a high-carb diet can induce flu-like symptoms: The mitochondria aren’t functioning optimally because they don’t have the necessary enzymes for using fat to make ATP. Over time, the cells adapt and fat burning enzymes increase, making you feel better and improving mitochondrial function.
Exercise is a particularly powerful catalyst for stimulating an increase in fat burning enzymes and for generally improving overall mitochondrial function. In fact, in diabetics and the obese, exercise may be necessary to trigger mitochondrial adaptations.
For example, in a study that took 12 lean and 10 obese men and had them eat a high-fat, low, carb diet for three days, the lean subjects increased the amount of fat their bodies burned for energy, whereas the obese subjects did not. It was concluded that if you are not overweight and you restrict carbohydrates, gene signaling and fat burning will quickly improve to help run on fat. At least over the short term, obese people don’t respond to such a switch, likely because their mitochondria are dysfunctional.
In a second part of the study, exercise was the great equalizer: After a washout period, the same two groups of men did 10 days of aerobic exercise. Results showed that this time both the lean and obese subjects increased fat burning in response to training. Scientists theorized that exercise facilitated positive changes to mitochondrial function that allowed for greater metabolic flexibility.
Which brings us to the other key factor that it’s worth worrying about when it comes to mitochondrial health: Diet
The impact of different dietary components on mitochondrial health is out of the scope of this article, however, here are a few key points to focus on:
- Avoid added sugar and refined carbohydrates to lower your production of free radicals that are the byproduct of oxidative metabolism.
- Eat omega-3 fats from fish because these fats improve mitochondrial function.
- Eat plenty of fruits and vegetables. Brightly colored plant foods contain antioxidants that decrease your body’s free radical load and reduce damage to mitochondria.
- Don’t shun saturated fat. When mitochondria have saturated fat in their membranes they are less susceptible to damage and produce fewer free radicals that bounce around and harm DNA.
- Supplement: Magnesium, coenzyme Q10, creatine, carnitine, lipoic acid, and vitamin D have all been shown to improve mitochondrial function.
Final Words: By fine tuning your nutrition and hitting the gym, you can fire up your mitochondria to transform your health and fitness. With the simple recommendations in this article, you will feel more energized, lower your risk of chronic disease, for a long and fulfilling life.