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The VO2 max series. Part 1: The powerhouse of the cell



Everyone breathes the same air, at roughly the same pace. Provided you have healthy lungs you probably inhale just as much oxygen as the person next to you. And oxygen is the most important factor to facilitate enough energy for the body.
So why is it that some people are fitter than others? Since the outside factors are roughly the same for everyone, how come some people have a much higher work capacity than others?

In the VO2max series I'm going to explain those differences in physiology between people and by which rules you can improve them. In the fitness world it is a often talked about value. But what does the VO2max consist of? This is where Dr. Fick comes into play (amongst other important discoveries his surname also means "to fuck" in German).

 \mathrm {VO_{2}\;max} =Q\times \ (\mathrm {C_{a}O_{2}} -\mathrm {C_{v}O_{2}} )

 The Fick equation. 
Now let's break this intimidating formula down.
Q stands for cardiac output. This is the volume of blood that the heart pumps out every minute.
Image previewEasy.
Now the part of the formula in between the brackets represents the arteriovenuous oxygen difference.
What?
So the artery arrives with a lot of oxygen, but when you check the oxygen in the venule part of it has disappeared. The formula tells us that the less oxygen you find in the venule, the higher someones VO2max is. 
So who's taking up all the oxygen in the capillaries?

The powerhouse of the cell, the mitochondria.

 Image previewBefore delving into what the mitochondria does, it's important to understand the concept of ATP,
adenosine triphosphate. ATP is the currency for energy in a cell. The more ATP you have the more energy the cell will be able to produce.
So how do you create energy with ATP?
The most important thing here is that you have a molecule with three phosphates stuck to it. Now as soon as one of the phosphates splits of, you create ADP (Adenosine diphosphate, easy right?) and in the process energy is created.
But now we're stuck with a problem right? Because what happens with ADP and how do we create ATP again?


Image previewThis is where the mitochondria react. Through a series of enzymatic reactions called the Electron transport chain, the mitochondria use kinetic energy to fuse the phosphate to the ATD and recreate ATP. This is an oxygen dependent process and therefore relies on the blood supply to the cells. When mitochondria activity increases, more oxygen will be utilised. I'll give a more in depth explanation on this subject later on in the series. 

Take home message:
When increasing VO2max it is desirable to have more or more-active mitochondria. A faster recycling of ATP leaves you with more durable energy.

Two easy ways to improve your mitochondria:
- Exercising at least 30 minutes/day, Gary Dudley  (1982) studied how different muscle fiber types react to different duration of exercise. Here he found what amount of exercise is optimal for each type. 
- Intermittent fast (12 hour fast will already yield results), will improve mitochondria count and function (Pengyun Li, 2017)

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