Mitochondria

Mitochondria are ATP factories. They make most of the ATP in your body, mostly from glucose (sugar) or fat (fatty acids). Mitochondria are found in all cells of your body except mature red blood cells and are often referred to as organelles. Mitochondria rely on oxygen to produce ATP.

Mitochondria (singular: mitochondrion) play a key role in energy metabolism in many tissues, including skeletal and cardiac muscle. The main role of mitochondria is to produce ATP in a process called oxidative phosphorylation. Carbohydrates (sugar, starch in the form of glucose or glycogen), fat, and to a lesser extent protein are the energy substrates from which ATP is derived. Oxygen is required for this process. CO2 and water are by-products of ATP synthesis.

In other words, the chemical energy (calories) stored in our food must be converted into a molecule that can be used by cells for cellular functions and to generate movement. This molecule is called ATP (adenosine triphosphate) and mitochondria synthesize the majority of ATP. Learn more about ATP and its importance here.

Aerobic synthesis of ATP by mitochondria yields large amounts of it but is relatively slow. There are faster, albeit less efficient, ways to synthesize much-needed ATP.

Schematic model of a mitochondrion in a mammalian cell.
Schematic model of a mitochondrion in a mammalian cell. Your muscle cells contain the same type of mitochondria. – Image credit: Wikimedia.

Mitochondria in health and aging

Mitochondria are also involved in the development and progression of numerous diseases, including cancer, neurodegenerative and cardiovascular disorders, diabetes, traumatic brain injury, and inflammation.

Healthy and well-functioning mitochondria are important for our survival, health and well-being, for performance in sports and they play a supporting role in slowing down the aging process.

Mitochondria in sports

Mitochondria are important for performance in sports, especially endurance performance. Their content and respiratory function have been linked to maximal oxygen consumption (VO2max).

Training to improve mitochondrial quality and function has a direct impact on health and endurance performance. Different types of training can provide a strong stimulus for mitochondrial biogenesis (the formation of new mitochondria and the improvement of existing mitochondria).

In particular, long endurance sessions and high-intensity intermittent training (high-intensity interval training) both stimulate mitochondrial biogenesis. This article is too general to go into the intricate details of the major molecular signaling pathways for mitochondrial biogenesis (AMPK and calcium signaling/CaMK). The interested reader is referred to the references at the end of this article.

Mitochondria in evolution

The following video shows some very interesting facts about mitochondria. I recommend you watch it, even though it does not directly talk about ATP production and sports performance. It tells the story of the evolution of mitochondria over the eons and their importance to almost all living organisms, including you.

Dig into the essential role that mitochondrial DNA played in the evolution of living things on Earth, and find out why it’s still evolving. – TED-Ed

Last updated Nov 2, 2021


References

Johannsen, D. L., & Ravussin, E. (2009). The role of mitochondria in health and disease. Current opinion in pharmacology, 9(6), 780–786. https://doi.org/10.1016/j.coph.2009.09.002

Javadov, S., Kozlov, A. V., & Camara, A. (2020). Mitochondria in Health and Diseases. Cells, 9(5), 1177. https://doi.org/10.3390/cells9051177

Warren, J. L., Hunter, G. R., Gower, B. A., Bamman, M. M., Windham, S. T., Moellering, D. R., & Fisher, G. (2020). Exercise Effects on Mitochondrial Function and Lipid Metabolism during Energy Balance. Medicine and science in sports and exercise, 52(4), 827–834. https://doi.org/10.1249/MSS.0000000000002190

Bishop, D. J., Botella, J., Genders, A. J., Lee, M. J., Saner, N. J., Kuang, J., Yan, X., & Granata, C. (2019). High-Intensity Exercise and Mitochondrial Biogenesis: Current Controversies and Future Research Directions. Physiology (Bethesda, Md.), 34(1), 56–70. https://doi.org/10.1152/physiol.00038.2018

Irrcher, I., Adhihetty, P. J., Joseph, A. M., Ljubicic, V., & Hood, D. A. (2003). Regulation of mitochondrial biogenesis in muscle by endurance exercise. Sports medicine (Auckland, N.Z.), 33(11), 783–793. https://doi.org/10.2165/00007256-200333110-00001

Little, J. P., Safdar, A., Wilkin, G. P., Tarnopolsky, M. A., & Gibala, M. J. (2010). A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms. The Journal of Physiology, 588(Pt 6), 1011–1022. https://doi.org/10.1113/jphysiol.2009.181743

Roberts, F. L., & Markby, G. R. (2021). New Insights into Molecular Mechanisms Mediating Adaptation to Exercise; A Review Focusing on Mitochondrial Biogenesis, Mitochondrial Function, Mitophagy and Autophagy. Cells, 10(10), 2639. https://doi.org/10.3390/cells10102639