Aerobic Fitness

Aerobic fitness forms the base for all your outdoor adventures. Training in aerobic fitness is essential if you want to play outside longer or improve your performance in sport.

The aerobic and anaerobic systems

There are two systems (three including the ATP-PC energy system) that provide your muscles with energy during exercise: aerobic respiration and anaerobic respiration. During physical exertion, these are active in varying degrees and the ratio of power each system provides depends on the type of activity.

The aerobic system requires lots of oxygen and can utilize fats, carbohydrates and proteins as fuel. It produces energy slowly but efficiently, and because it can metabolize energy-dense fat, it produces energy over long periods of time. Think of the aerobic system as the body’s diesel engine. Examples of aerobic exercise include walking, jogging, cycling, swimming, rowing, snow shoeing – anything you could do for hours.

Anaerobic exercise. Note unhappy facial expression. Credits: Fred Marmsater

Conversely, the anaerobic system does not require much oxygen and utilizes glucose for fuel. It comes into play during shorter, higher-intensity activity, making it analogous to a turbo charger. Examples of anaerobic exercise include heavy weightlifting (3-8 reps), sprints, hill climbing, interval training and isometrics – any burst of hard exercise that makes you want to cry.

I don’t cover the ATP-PC energy system here, but it basically kicks in when you need instantaneous energy for an even shorter period than the anaerobic system – 10 second sprints and single rep maximum efforts in the weights room. That kind of stuff.



Aerobic fitness and outdoor sports

As outdoor sports enthusiasts, one of our goals is to be able to stay out and active for as long as we want without having our fun cut short by fatigue. Given its higher efficiency and almost limitless energy supply, the better the performance of your aerobic system, the less you will rely on your anaerobic system and the longer you will be able to keep on going.

So the question is how best to train aerobic fitness?

MAF Training

Enter Dr. Phil Maffetone, the father of maximum aerobic function (MAF) training. MAF training is simply training in an activity at an intensity below a threshold heart rate (HR). According to Dr. Maffetone, training at the MAF HR is optimal for building endurance, as well as developing the body’s systems that sustain health and help the body recover from exercise.

He states that in order develop your aerobic fitness, the majority of your training volume should be at an intensity no higher than your MAF HR. The rest can be done at above the MAF HR, if you are healthy and stress-free. To put this in context, assuming you run 40km a week, about 30km of this should be at the MAF HR or lower. The remaining 10km can be sprints, tempo runs, or whatever other form of suffering you enjoy inflicting on yourself.

Finding your MAF

  • 180 minus your age

If you have access to a hear rate monitor then this is the easiest method of calculating the intensity you should train at to build your aerobic base. Simply deduct your age from 180 and make sure you run/bike/whatever at this heart rate or lower. I am 37 years old, so for aerobic base training I should run at a heart rate of 180 – 37 = 143 bpm or less. This method is exact but it requires an expensive heart rate monitor.

  • Nasal breathing

This method turns the activity into a meditative exercise. But, it is a good method of finding approximately the right intensity if you don’t have a heart rate monitor, once you get used to it. Assuming you are running, breathe through your nose at a rate of one complete inhale-exhale cycle for every 5-7 paces you take. Your intake of oxygen is more limited than breathing through your mouth, so the intensity of your exertion is naturally limited to about the right degree. In my case I get about 135-140 bpm. Note that I do not know of any studies supporting any performance benefits in nasal breathing itself, with the possible exception of in low-temperature, low-humidity conditions. It is only a means to keep your pace slow.

  • Talk Test

Run at a pace where you could talk on the phone and the other person wouldn’t notice you breathing heavily. This is the simplest and least accurate method of the three, but it will still do the job in an “80:20” kind of way. If in doubt, slow down.

But that’s so slow!

A lot of people can be surprised at how slow training at their MAF HR can be, especially when they have the “no pain, no gain” mentality. In some cases, you might even be “running” at a walking pace. Suck it up, swallow your pride and enjoy: who knew improving your performance could be so easy?

In time, your pace at your MAF will increase, meaning that you can achieve more at an intensity that feels almost effortless. In short: run slowly and longer to get faster.

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Make around 75% of your training volume low intensity to improve aerobic fitness and increase your endurance. Low intensity means at your MAF HR or lower. This can be calculated as about 180 minus your age. Training this way will enable longer sessions having fun outside.

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