A Question of Power

I’ve been without power for a month. Throwing my derailleur among the spokes, midway through Wimbleball, pulled the wheel out of true, rendering my Powertap unrideable; at least until I take it into the shop. The wheel rests, forlorn, behind my as yet unpacked bike bag, both victims of my decision to step back from racing. In its absence I continued to train, substituting heart rate for wattage on my Garmin’s display, not that I ever looked at this number. It still worked. I knew if I’d ridden hard, my legs told me, and could feel myself becoming fitter. Training remains a simple process of effort and duration however I chose to measure it. So, who needs power?

Whether it’s a new athlete wondering if they need a power meter in order to work with me, or one of my current stable considering upgrades for next year, the second most common question I receive is: should I buy a power meter? And, were it not for their price tag, I would always answer yes. Unfortunately power meters are what might euphemistically be termed an investment, they are expensive and the returns on them are subtle and long-term. So rather than a straightforward yes, I break down the benefits these tools bring, and leave it to the athlete to decide if the price is right.

And I start, as I did with this post, by highlighting that you can train perfectly well without them, athletes managed long before the advent of any of the monitoring tools we have become so reliant on. They will not change training: whether you use power, heart rate or feel the basic structure, the periods of work, remain the same. They can help you train, they can help you train precisely, and while there are increasing numbers of them at the front of the pack, ownership of a power meter is not a guarantee of performance; like any tool it’s what you do with it that matters.

What power gives is an impartial measure of the work we are doing, independent of how we feel or where we are. Any number of factors may influence heart rate and perceived exertion, but wattage is simply a product of the rate at which force is applied through the pedals. Push harder, push faster and it will rise. Power tells us about the energy we are expending, the metabolic cost of each turn of the cranks. This ability to convert chemical energy into kinetic energy is what we train, what we develop, and power gives us our closest measure. Behind it heart rate lags, it tells us how the whole body is responding to those demands, in comparison it’s a muffled report of what’s going on.

Practically though the changes are subtle. Slowly those of us who use it learn. We learn that, however it feels, 200 watts is the same every day. We learn how variable our output is when we ride and the high cost of our surges. We learn to focus on the efforts that matter most to our discipline and we learn to precisely control our training accordingly. For Ironman we think about our threshold, consistency of our pacing and our fatigue resistance over time. We learn to apply that during a race. More broadly we may learn to compare rides through power, to measure their impact and to utilise the information over a longer term. We get data and we get graphs. The result is a meticulous, scientific, approach to planning and managing our training.

Which, of course, isn’t for everyone.

I’ve scratched the surface. Hinted at topics I’ve previously covered in more depth. It’s hard to be succinct while sufficiently selling the benefits of training with power. In some cases the impact can be huge, transforming an adrenaline-fuelled sprint athlete into a carefully paced Ironman. If only the price point would let me always give an emphatic yes.

Ironman Training Library

From nutrition to pacing - a collection of CoachCox blog posts focused specifically on Ironman training and racing.