How do we get faster and cover longer distances? At the most basic level, this occurs as our body gets better at using oxygen to create the energy necessary to propel us forward. The body brings about this adaptation by increasing the size and number of our mitochondria.
There’s a good chance you learned about mitochondria in your high school biology class. There’s a higher chance of familiarity if you are involved in the world of exercise and physiology. However, many people have never heard of these tiny organelles, even though their function is the single most important piece of the performance improvement puzzle.
Mitochondria - which are, in fact, separate living organelles within our bodies - play a critical part in forming almost all of the body’s energy by turning oxygen into an energy molecule known as ATP. Despite living within our cells, mitochondria have their very own DNA. There are competing theories as to how they got into our cells, but the most likely explanation is that they were once independent organisms, similar to bacteria today, that got swallowed up by our cellular predecessors millions of years ago. Cells that formed this symbiotic relationship with mitochondria were able to thrive due to the increased amount of ATP (energy) they could produce. To this day, mitochondria have stayed with us throughout our evolution and can be found in almost all multicellular organisms.
In humans, the mitochondria produce ATP by consuming oxygen in order to metabolize fat, carbohydrates, or proteins. This process is called glycolysis, and it is essential for life to exist. All of our cells need ATP to function properly. However, the general energy requirements of different cells in our body vary, and so our mitochondria are distributed unevenly between different cells. More active cells require more energy, so these cells have a higher density of mitochondria. The muscles in our heart, for example, have a mitochondrial density of around 35% of its total cellular volume (1*) while skeletal muscles, like the hamstring or bicep, typically only consist of 3-8% mitochondria by volume (2*).
When mitochondrial activity is impaired or limited due to any number of contributing factors, less ATP will be produced. As ATP is the only currency of energy the body uses, this will impair all cellular functions in our bodies. One of the most notable conditions where a lack of mitochondrial ATP synthesis is prevalent is chronic fatigue syndrome (4*). Newer research is also starting to point towards mitochondrial inefficiency or deterioration with regard to multiple diseases and metabolic conditions.
Mitochondria have other roles as well, from maintaining proper signaling within the cell to controlling the process of cell death (3*). In recent studies, the decay of mitochondrial DNA has been linked to aging in general. Considering the side effects of limited ATP output or mitochondrial aging, having fully functional and efficiently working mitochondria in all cells in our body is a strong sign of longevity and health.
So how do you improve your mitochondrial health? And more importantly, can we somehow increase the number of mitochondria in our body? The answer to both questions is an unequivocal “yes.” We can increase their number, and we also know how to improve our mitochondria so that they function at their best abilities. This is where training and diet enter the discussion and both aspects need their own separate discussions. The next two blog posts in this series will dive into the relationship between mitochondria and exercise, and how diet and lifestyle affect these tiny organelles within our cells.
Siggi Ragnarsson
Hi! I’m Siggi, and I’m originally from Iceland. I got my start in Triathlon in 2015 and became a pro in Ironman 70.3's in 2018. Prior to competing in triathlon, I was a competitive swimmer. As both an athlete and engineer - my formal education includes a Bachelor and Masters in Mechanical Engineering from the University of Iceland - I’m extremely interested in optimizing the human body for exercise. After successfully transforming myself from an amateur to a pro triathlete, I wanted to use my insights to help others achieve their own health and fitness goals. I started a performance testing service and personal coaching business in Reykjavik where we offer blood analysis, metabolic testing, and personalized coaching for athletes of all abilities. I’m excited to share my research and thoughts with you and hope you will find it both interesting and useful in your own athletic journey!