What is it?
It’s nothing short of foundational. Nothing we want to achieve with our health or fitness is possible without a solid base of aerobic capacity. This is the system you use from complete rest up to activities of a certain intensity (with that intensity varying by person, age and training as I will explain below). When you are walking, getting up from the couch, playing with your grandkids, shopping, going on a slow jog, weight lifting, having sex, etc. you are using your aerobic energy system.
If you are going to pay heed to only one facet of your health, I would argue strongly this is the one.
Aerobic capacity is your body’s ability to produce energy in the presence of oxygen. Now you might be thinking, well I am always in the presence of oxygen since otherwise I’d be dead, but the way the body works is that when we are at rest or doing activities up to a certain intensity, our bodies can use a high efficiency energy producing system that relies on oxygen getting into and being used by our mitochondria (that pretty bean shaped object pictured on this page). But there is a level of intensity beyond which our system cannot keep up (you literally cannot inhale, transport and use the oxygen fast enough) and our body switches to a less efficient anaerobic energy system. Aerobic respiration/energy production produces something on the order of 19x more energy than anaerobic respiration/energy production.
Why do I want it?
So when we train our aerobic energy systems we actually cause our bodies to adapt at the organ and cellular level. First, we can create new mitochondria through a process called mitochondrial biogenesis. We can also make the mitochondria we have more efficient at taking up and using oxygen. Finally, we can also improve the systems required to get oxygen to the mitochondria.
Functionally, what this means is that through aerobic capacity training we can (i) push up the threshold at which the anaerobic system kicks in (meaning we can spend more time in the more efficient aerobic system), (ii) use less energy since we are using that more efficient system, (iii) burn fat (the aerobic system likes to run on fat) more efficiently, (iv) make the activities of everyday life less taxing and (v) push harder before our system kicks over into the anaerobic system.
As importantly, the aerobic system, much like most of our carefully evolved systems, is use it or watch it degrade. Lack of use and also age degrades this system. Mitochondria that are not used wither and die. So all the benefits of training the system above will flip against you in time if you don’t train it. The anaerobic system will kick in sooner, you will use more energy, you will burn less fat, the activities of everyday life will get more taxing and you will not be able to push very hard before kicking over into anaerobic energy production. But loss of aerobic capacity is not a foregone conclusion! We just need to train the system and we can at the very least delay the insults and aggravations of old age, if not head them off completely for our entire life.
Here’s another benefit. The aerobic system loves to use fats for energy. It’s the most energy efficient source for the system. However, over time the ingestion of far too many carbohydrates and simple sugars and far too little use of the aerobic system leads the body to be less able to run on fat. When we train the aerobic system we can restore our ability to run on fat. And that’s a powerful tool not just for energy production, but also weight management.
To bring it home, you know what the difference is between the person who can jump from superset to superset in the gym for an hour and half and then get on the treadmill and run all out sprints at the end of their workout and the person who needs to rest two minutes sitting down between every set and has to limit their workouts to less than an hour? Not willpower. Not talent. Not grit. It’s their aerobic energy systems.
I’ll say it again. Foundational.
How do I train it?
The Danish have many words for exercise. In fact, their wonderful language has many single words or small phrases that stand for broad all encompassing concepts. My personal favorite is hygge. It literally refers to the psychological state of being warm, contented and cozy, as if one is by a fire surrounded by family, after sipping a small bit of schnapps. Now that’s not just a word, it’s a concept and way of life wrapped up in a single word! The Danish are admirably efficient. I digress a bit, but with a purpose. The Danish also have another wonderful word for exercise, which is dyrke motion. This literally translates as “cultivate movement”.
We train the aerobic system by cultivating movement. All it takes is consistency and low to mid intensity effort that you love. Do you love to walk? Then walk. Do you love to dance? Then dance. Do you love to chase your grandkids around? Then chase them around. Just do it consistently and keep upping the dose more and more.
We will find the movement drug that you love to take and we’ll just keep upping the dose.
That’s the secret.