If you can recall back to high school biology class, you might remember learning the various parts of the cell. But, unless you work in the sciences, medicine, or education, you may not have the need to remember every single component of cells.
However, there is a good chance that if you are an endurance athlete, you have retained working knowledge of certain parts of anatomy, biochemistry, and physiology, namely mitochondria.
Mitochondria are the cellular organelles, or small specialized structures within the cell, that perform aerobic respiration to produce ATP.
Mitochondria play a key role in energy production, particularly during aerobic exercise, so learning the best exercise to increase mitochondria in your muscle cells can potentially improve aerobic performance, increase VO2 max, and make you a better athlete.
In this guide to mitochondria workouts, we will review what mitochondria are, the importance of mitochondria during exercise, the best exercise to increase mitochondria in your muscle cells, and the types of workouts that boost mitochondrial density and efficiency.
We will cover:
- What Are Mitochondria?
- What Is the Benefit Of Doing Exercise to Increase Mitochondria?
- What Is the Best Exercise to Increase Mitochondrial Function?
Let’s get started!
What Are Mitochondria?
First, a super-quick grammatical lesson:
A common question when discussing aerobic exercise and improving aerobic energy production is: “What is mitochondria?”
Note that the term mitochondria is plural and mitochondrion is singular, so the question should be: “What are mitochondria or what is a mitochondrion?”That covered, mitochondria are organelles, or little specialized components inside cells, that convert caloric energy from food into cellular energy (ATP) via a process termed cellular respiration.
ATP is vital for sustaining the life of any organism, including the human body.
Without ATP, cells would not be able to carry out their functions, muscles would not be able to contract, digestion would not occur, the heart could not beat, etc.
Basically, mitochondria can be thought of as tiny “factories“ inside of a cell with the function of converting caloric energy from food into usable energy for the cells.
This is why mitochondria are sometimes called the “powerhouses” of a cell.
These organelles have the ability to extract the caloric energy found in the food we eat (note that caloric energy from food is contained within the bonds of the carbs, proteins, and fat molecules) and convert calories from food into usable energy for the cells, which again, is the ATP molecule.
Although fats, proteins, and carbohydrates all provide calories, the primary food source that is used by the mitochondria to make ATP is carbohydrates.
Carbohydrates that we eat are digested into simple sugars, namely glucose, which then circulates the bloodstream.
In the presence of insulin, which is a hormone secreted by the pancreas, cells and tissues in the body are able to take up this blood glucose and use it to produce ATP.
Excess glucose that is produced but not needed right away is converted into a much larger molecule called glycogen.
Glycogen molecules are essentially long chains of glucose that serve as reservoirs of carbohydrate storage in the skeletal muscles and liver for use at a later time.
Then, when you are performing endurance exercise or have not eaten food for numerous hours, your body can start breaking down the glycogen into glucose and then using the glucose to produce ATP.
There are different types of cellular respiration, which is the process by which this energy conversion occurs. When cellular respiration occurs in the presence of oxygen, it is known as aerobic respiration.
Aerobic respiration takes place through a pathway known as the Krebs cycle or citric acid cycle and the electron transport chain.
This aerobic ATP production primarily takes place in the mitochondria of the cells.
According to research, when ATP synthesis occurs via aerobic cellular respiration within the mitochondria, approximately 32 ATP molecules are produced per molecule of glucose that is oxidized.
Typically, it is thought the body relies on the hydrolysis of 100 to 150 moles of ATP per day to support all of the various functions.
Because one mole is equal to 6.022 × 10²³ molecules, this represents a massive demand for ATP by the body per day.
When considering workouts that increase mitochondria, we are mainly trying to target the slow-twitch muscle fibers (type I muscle fibers), as these are the “aerobic” or endurance muscle fibers with a higher mitochondrial density.
Because the fast-twitch muscle fibers are responsible for producing rapid contractions for maximal force generation, these type II muscle fibers are considered anaerobic muscle fibers and they have very few mitochondria.
That is not to say that we can’t increase mitochondrial output (the “power” of the mitochondria, or how efficiently or quickly the mitochondria can produce ATP) from the fewer mitochondria fast-twitch muscle fibers have, however.
What Is the Benefit Of Doing Exercise to Increase Mitochondria?
Ultimately, the more mitochondria you have in your muscle fibers, the more “factories“ you have open to produce ATP (energy) during aerobic exercise.
Therefore, increasing mitochondrial density, or increasing the number of mitochondria you have in your muscles, can improve your VO2 max.
This is because you are able to produce more energy to sustain a higher workload aerobically before crossing over the anaerobic threshold.
In a way, you can think of increasing mitochondria in a muscle like hiring more factory workers or opening more energy factories; the rate of ATP production can increase significantly because there are more sites open to producing ATP at the same time.
The more ATP you are able to produce per minute through aerobic respiration, the greater the workload, faster running pace, higher cycling power, etc. you can sustain aerobically.
Therefore, any endurance athlete will benefit from trying to do the best exercise to increase mitochondria, so that aerobic energy production efficiency increases.
The best exercise to increase mitochondria quantity or density in a muscle will therefore also increase VO2 max.
What Is the Best Exercise to Increase Mitochondrial Function?
So, how do you target mitochondria in training?
It has long been thought that the total volume of endurance exercise will increase the number of mitochondria you have.
In other words, how much you train will correlate with how many mitochondria you have and the relative proportion of your slow twitch, type I, muscle fibers.
In contrast, the intensity of your training seems to impact the effectiveness, efficiency, or how “powerful“ your mitochondria are.
This is ultimately why there isn’t a single best type of exercise to increase mitochondria effectiveness, nor is there a single best type of workout to improve mitochondria energy production.
Rather, performing a combination of high-volume endurance training coupled with very high-intensity interval training seems to be the most effective exercise prescription for how to train to increase mitochondria ATP output for aerobic energy production.
The former—long, endurance workouts like long runs, long bike rides, and high total mileage or training value—helps trigger the synthesis of more mitochondria in your muscle cells, so mitochondrial density and the total number of mitochondria increase with consistent and sufficient endurance training.
The latter—high-intensity workouts—seems to be necessary to “train“ or condition these new and existing mitochondria to become more powerful and function more efficiently in terms of their ATP production or output.
From a practical training standpoint, you might then wonder:
“What are the best workouts to boost mitochondria function?”
As mentioned, to increase the number of mitochondria, you are looking at having a high total training volume and long endurance workouts.
The best exercises to increase mitochondria function are things like:
- Tabata running sprints
- Tabata workouts (8 x 20 seconds all out with just 10 seconds of rest in between each)
- Max effort hill sprints
- Sprint training while running or cycling
- Super short intervals of no more than 45 seconds at 90% of maximal effort or more
In a way, this seems counterintuitive since mitochondria are aerobic respiration organelles, but research studies have found that indeed these types of super high-intensity workouts are best for increasing mitochondria performance.
Additionally, evidence suggests that resistance training can also improve mitochondria function.
In sum, certainly don’t skip out on your long runs if you want to improve your aerobic energy production and VO2 max, but don’t shy away from sprint training, heavy resistance training workouts, and high-intensity workouts to improve VO2 max and mitochondria performance as well.
You can learn more about different types of running workouts here.