Power Pyramid

Recently there was a two part article on the TrainingPeaks blog that took a look at the power files from a couple of pro cyclists. One was a roadie, and the other a mountain biker. The main point of the article was to show how aerobic the efforts were in these very different cycling races.

And my reaction was, "Of course!"

But maybe it really points out the misunderstandings many people have out there of our basic physiology, and how it drives all of our cycling efforts. I will try to put it another way that should be simple to remember. It all comes down to our Power Pyramid.

Let me explain...

The Power Pyramid

When you build a pyramid, you lay down the first layer of stones, and then the next, slightly smaller layer, and then the next again, with yet fewer stones. I'm sure you know what I mean. The key point to remember is that the first layer doesn't disappear when you start working on the next layer - not only does the first layer stay, but the next layer is always slightly smaller.

Now consider the energy systems discussed in the TrainingPeaks blog: Oxidative; Fast Glycolysis; and Phosphagen. Briefly simplified: oxidative burns fat; glycolysis burns sugar; phosphagen burns creatine-phosphate.

Everybody, even people with single-digit body fat percentages, has days worth of fat stores for oxidative efforts. We've all got about two hours worth of sugar stores for glycolysis. We've got just a handful of seconds worth of creatine-phosphate stores.

These map essentially (for our understanding) one-to-one to the following energy systems that you are probably more familiar with: Aerobic; a combination of Aerobic and Anaerobic; completely Anaerobic.

As you raise your level of effort, and ride faster, you add-on the next higher layer to the Power Pyramid. That bottom layer doesn't disappear. It stays there, and continues to contribute to your effort. But the added speed is now coming from the new layer of the pyramid you've just laid down.

Your Aerobic System Is Always On

Every cycling effort will always have an Aerobic component, and it will always be the largest component. It may not be contributing the most power to your effort, but it is always there. Your body only starts adding in the Anaerobic system as you call on even more power from your engine room. But it doesn't shut off the Aerobic component.

That's why, when you look at power analyses like the ones discussed on the TrainingPeaks blog, you'll see the Aerobic component is the largest.

This all maps over to your muscle fibres as well. Type I fibres are the slow-twitch fibres that are always being triggered in your legs. Type IIa fibres begin being triggered as you raise your effort. And Type IIb fibres are firing when you're sprinting. But those Type Is and IIas are still firing too; they just aren't contributing the highest bursts of your power like the IIbs are.

What This Means For Your Workouts

Every workout you do, you'll be working your aerobic energy system. What you are building up are the size and density of your mitochondria and the volume of enzymes your body needs to break down fat to fuel the aerobic system. To a certain degree, you'll also build some red blood cell density that will increase the oxygen-carrying capacity of your blood. This all leads to your basic increase in endurance.

High Intensity Interval Training (HIIT) adds anaerobic pieces to every aerobic workout. But the anaerobic parts take longer to recover, both between efforts and from one workout to the next.

You need at least five minutes to rebuild the creatine-phosphate stores for sprinting. While your sugar stores are depleted, it takes time for your body to digest any recently eaten sugars before they show up in your blood stream.

If you look again at the pyramids I've drawn, you'll always benefit from training aerobically. And in fact you are always training aerobically. To start riding faster, you'll need some anaerobic help as well. You'll need to do some HIIT at some point in your training.

The traditional approach is to begin with multiple weeks of simple aerobic riding, followed by more and more HIIT rides as you get closer to your goal event. Now this isn't always the way to train, but it is traditional, and based on real-world results, and the easiest way for a self-coached rider to plan.

But if you don't have huge amounts of time to train, then HIIT is for you. It works all of your energy systems and all of your muscle fibres, leading to your best training bang for your time buck. Just be sure you have recovered before riding your next HIIT session. You can usually tell that you are ready if you no longer feel any muscle soreness from your last HIIT session.

For a more in-depth discussion about your various muscle fibre types, please have a look at my post: Getting To Know - Your Muscle Physiology.