When you do aerobic exercise, your entire body gears up to power your workout. Your heart rate increases to deliver more oxygenated blood to your muscles. You breathe faster to deliver more oxygen to your lungs and release carbon dioxide. Hormones like epinephrine, norepinephrine, and cortisol also rise. Exercise is a stressor on your body but a good one.
What’s not as obvious is what’s going on at the cellular level. Inside each cell in your body are tiny organelles called mitochondria. Each cell contains several hundred or even a thousand mitochondria. Tiny as they are, these organelles are remarkably busy converting the food you eat and stored glycogen and fat into energy in the form of ATP. Cells use ATP to carry out all the activities cells have to do and muscle cells use it to fuel movement. You need mitochondria and the ATP they produce to survive.
Mitochondria Produce Energy That Powers Exercise
When you’re resting, your ATP requirements are lower than when you’re moving around, but during exercise cells greedily suck up ATP. Mitochondria have the capacity to increase their energy output by up to 400 times when the demand for ATP is greatest, such as during high-intensity exercise. Each mitochondria contains its own DNA, the genetic information that codes for proteins mitochondria use to produce more energy.
Mitochondria adapt to the stress of aerobic exercise by becoming more efficient energy producers. During aerobic exercise, more oxygen is delivered to muscle cells. Mitochondria use this oxygen to produce ATP aerobically. In response to exercise training and increased oxygen delivery, mitochondria boost its production capacity. Enzymes inside the mitochondria involved in making ATP aerobically rise and the number of mitochondria increases too. These changes lead to increased ATP production and improved exercise endurance because your muscles have more ATP available to fuel muscle contractions.
Other adaptations involving the heart and blood also contribute to improved aerobic capacity in response to exercise training. Small as they are, mitochondria are powerful energy producers that become even more efficient in response to aerobic training. At the same time, they become less efficient producers of ATP in people who lead a sedentary lifestyle. As a result, sedentary people experience fatigue quickly when they try to do anything aerobic.
Do Mitochondria Play a Role in Aging?
Mitochondria, because they’re such active energy producers, are also susceptible to oxidative damage. Some studies suggest oxidative damage to mitochondria, in the form of free radicals, at least partially accounts for aging. Free radicals damage the mitochondria’s proteins and DNA, ultimately causing the mitochondria to die. According to some research, damaged mitochondria play a role in age-related diseases including Alzheimer’s disease, Parkinson’s and metabolic problems such as diabetes. Aging mitochondria may contribute to insulin resistance and, as such, be a precursor to type 2 diabetes.
Mitochondria have antioxidant enzymes that help neutralize free radicals and protect against oxidative damage but aging hampers the ability of these “free radical scavengers” to do their job. As a result, mitochondria become more and more damaged over time. Aging has been linked with reduced mitochondrial function.
Exercise and Mitochondria: The Role of Exercise in Keeping Mitochondria Healthy
Some experts propose that a sedentary lifestyle along with aging reduces the ability of mitochondria to function properly. The reduction in healthy mitochondria makes it harder for older people to exercise. This creates a vicious cycle of sedentary behavior and a further decline in mitochondrial function.
Here’s the good news. Endurance exercise enhances the ability of mitochondria to do what they are programmed to do – produce energy. Exercise increases the production of new mitochondria and ramps up the activity of existing ones. In theory, the production of new mitochondria helps keep cells functioning at a more youthful level.
Although steady-state endurance exercise is known to enhance mitochondrial number and function, high-intensity interval training does too. In addition, a study showed a combination of resistance and endurance exercise increased mitochondrial production more than either alone.
What Role Does Diet Play in Mitochondrial Health?
Diet may play a role in mitochondria aging too. Since mitochondria are damaged by free radicals, antioxidants from food sources, like fruits and vegetables, may protect cells against oxidative attack by neutralizing free radicals. Some research shows an antioxidant called coenzyme Q10 helps protect mitochondria against oxidative stress. Your body produces coenzyme Q10 but the amount declines with age. Good food sources of coenzyme Q10 is oily fish, organ meats and whole grains.
One study showed exercise boosted production of coenzyme Q10 in older people, giving their cells greater protection against oxidative stress that damages mitochondria. Though exercise increases stress on the body, regular workouts ramp up the body’s antioxidant defenses and enhance the ability of cells to protect themselves against oxidative stress.
Eating more antioxidant-rich foods, especially fruits and vegetables, and less processed ones may also help keep mitochondria healthy.
The Bottom Line?
Mitochondria play are powerful energy producers inside cells. These tiny organelles are easily damaged by exposure to free radicals. This damage may play a role in aging. Until more is known, the best way to keep your mitochondria healthy is to do regular physical exercise, aerobic and a combination of aerobic and resistance training. Top it off with a healthy, antioxidant-rich diet that’s free of processed foods. Can’t go wrong with that!
References:
“The Marvelous Mitochondria” Le Kravitz, Ph.D.
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Proteome Res., 2014, 13 (4), pp 2045-2055.
Muscle Oxygen Monitor. “How Exercise Improves Mitochondrial Function and Slows the Aging Process”
Journal of Signal Transduction. Volume 2012. Article ID 646354. (2012)
Clin Invest. 2013;123(3):951-957. doi:10.1172/JCI64125.
Am J Clin Nutr January 2009 vol. 89 no. 1 467S-471S.
Journal of Exercise Science and Fitness. “Effect of aerobic exercise on mitochondrial DNA and aging”
Cell Death Dis. 2013 Oct 3;4:e820. doi: 10.1038/cddis.2013.341.
Oregon State University. “Possible Health Benefits of Coenzyme Q10” Roland Stocker, Ph.D. University of New South Wales Sydney, Australia.
Biogerontology. 2014 Apr;15(2):199-211.
University of Maryland Medical Center. “Coenzyme Q10”
Coach Calorie. “How to Increase Mitochondrial Density for More Efficient Fat Burning”
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