One thing that makes humans unique in the animal kingdom is our ability to do it all. We are capable of a diverse array of athletic feats, from split-second explosiveness to all-day endurance. We can sprint 100 meters in under 10 seconds and we can also traverse entire mountain ranges on foot!
While we can do it all, there is nothing that we as a species do better than endure. Endurance is the crowning athletic achievement of humans. It’s what we do better than any other living creature. The reason for our supreme aerobic performance is simple—it’s how we evolved.
Humans are not the biggest, the strongest, nor the fastest animals. But over the past 2 million years we have survived by covering ground more efficiently than other species to gather food, hunt prey, and communicate with other groups. This preference has led to adaptations such burly, elastic tendons, springy lower-leg architecture, and metabolic changes that allow us to go long and far with little to no fuel.
The secrets of training don’t lie in the latest gadgets or fads. They stem from our evolutionary history and our biological code. Understanding how we came to be who we are also enables us to understand how to capitalize on the athletic gifts that took us millions of years to develop. And we know that the key to becoming great, well-rounded athletes is to train each of our three energy systems individually.
Let’s dive into the art and science of how to train the most important and long-lasting facet of human performance—aerobic capacity.
Let's Get Practical
The goal of aerobic capacity training is to improve the performance of your body’s most efficient engine. Think of it this way: whenever you start moving your body relies on one of three engines to power its movement. The choice depends on the rate of work. The more demanding and explosive the work, the more powerful (and inefficient) the engine. We dive into this topic here.
If you want to be an endurance athlete, the single most important factor is how much work you can do, efficiently. That outcome relies on a highly-developed aerobic system. The aerobic pathway will generate 38 ATP molecules (cellular energy) for every glycogen molecule, as opposed to only two ATP molecules via the faster, yet far less efficient anaerobic pathway. That’s an almost 20-fold improvement in efficiency. If you want to outlast the competition or the terrain you need exceptional aerobic capacity.
Building aerobic capacity is shockingly simple, and gets back to the roots of our evolution as human beings. Part of our challenge today is that our societal habits are constantly degrading our evolutionary adaptations. We eat too often, exercise too hard, and for too short a period. Let’s get back to the roots of our abilities with these four simple strategies for building a strong aerobic base.
The Four Pillars of Endurance
Go Long – Effective aerobic capacity training requires long(ish) and sustained efforts. Most of these workouts can occur between 70 to 120 minutes, provided the effort is uninterrupted. That last part is key. Endurance training is worthless if you only move in short spurts. As soon as you take a break, even a short one, you are reminding your body that it doesn’t need to make endurance adaptations because you plan on giving it a chance to rest.
Go Slow – If you want to encourage your body to improve its efficiency, you have to cooperate with it. Stay right at or just below your aerobic threshold, and avoid spiking your heart rate. The ideal pace for aerobic capacity training is one at which you can breath through your nose and converse comfortably. It should feel rather effortless—like you could maintain the pace all day.
When you stay below your aerobic threshold, you’re primarily relying on your aerobic, fat-burning metabolism to power your efforts (more on this below). If you try to push the pace and trip over the threshold, you’ll need to convert energy faster than this engine can provide, which will result in glycogen being the primary source of fuel. These kinds of mixed messages result in poor training outcomes. Plus, it sets you up to bonk!
Stop Faffing – No fiddling with gear, no chatting on the trail, no food and water breaks, just move. The biggest mistake athletes make is stopping. Stop for 5 minutes and you have erased much of the value of your session. If you want to teach your body endurance, give it something to endure. You can spend a whole day in the mountains with lots of breaks and get far less value than if you had just turned up the music (reggae obviously!) for 90 minutes and gone non-stop.
Train Fasted when Possible – One of the keys to endurance is to rely on a plentiful fuel source. Your body carries a very limited store of glycogen in the bloodstream and muscle tissue. As soon as that is used up, you bonk. If you want to go all day, you’re going to need a much more reliable fuel—fat. The human body stores enormous supplies of calories in the form of fat, and as an athlete if you are habituated to fueling your work on fat, you will have energy for days. Our daily western eating habits constantly remind our brain that if it feels any sensation of hunger it needs food. It doesn’t, of course, but we (myself included!) are guilty of succumbing to the slightest hunger.
When you train at a slow enough pace your body will learn to rely on the fat-burning pathway. The easiest way to do that is to do your long, slow, and sustain work on an empty stomach. If your body has lots of available glycogen, it will default to glycogen because it is the most readily available fuel source. Encourage your system to rely on the slower (longer process of recycling ATP) fat-burning metabolism, and your all-day performance will sky rocket.
Training fasted does not mean living in a caloric deficit. The purpose of fasted training isn’t to lose weight, it’s to foster helpful adaptations. So when you’re done with your run, have a feast to recover! Give your body all the good food it needs to repair and replenish.
Also keep in mind that fasted training is meant for training, not performance. When you put the training to the test and go for the big missions, fuel yourself adequately for optimum performance.
Remember that these suggestions apply strictly to the aerobic capacity phase. Aerobic capacity is the single most important adaptation for the endurance athlete in my mind, but not the only necessary adaptation for high performance. Other training habits will give other adaptations, but we must give each one due time in order for the physiological changes to take place.
Hope that helps,
– Coach Z