Power Meters – How useful are they?

Wearable tech and the data it produces is constantly evolving and giving us all sorts of new data to help training and racing. A relatively new innovation is measuring running power. The big names like Garmin and Polar are now offering this option (with the right kit) as well as smaller companies like Stryd and there’s been lots of chat about it’s use, including an extended article in this month’s Runners World. I know some of you have been using this metric and clearly it’s going to become ever more sophisticated, so as your coach I thought I should investigate more! To that end, I went out on my run today with my Garmin set up to display my running power – Grrrr!

The basic idea behind running power is that is can show you how much effort it is costing you to run at a given pace over your current terrain. So, if you are looking to run at a consistent effort on a run, power can be a more useful measure than pace – maintaining the same pace uphill will cost more effort than flat or downhill, and heart rate can be slower to respond to changes in exertion and can vary with how you are feeling. So, in theory using running power as a measure might be a better way of running a race with a measured consistent effort. This could be great for ensuring you pace a marathon in the most efficient way possible to hit your goal.

So, onto my run. I was heading out for an undulating mixed terrain run of 7.5 miles at an easy effort. To understand how power, pace and effort interacted I set up a data screen on my Garmin with three fields, Power, Pace (that’s actual pace, not average) and Heart Rate. A flatish road section to start showed me that my running power at easy pace was around 350-400 watts (running power meters are not as precise as ones for cycling, as explained in the RW article, so a decent range is probably the most useful thing to base your run on). As I hit the first bit of uphill (on a narrow offroad track) I suddenly found my power leapt to over 500, even though I felt I was taking it fairly easy up the slope and my pace had dropped quite considerably. This confirmed what I already knew; that for me in my current state of fitness (not very), running uphill at any pace costs me a lot of effort! And so it continued – I found myself on occasion reigning myself in on easier sections as I noticed I was pushing the power too much, and this did help me keep consistently to the easy effort I’d set myself, and I noticed how much variance in pace I needed over changing terrain to maintain a consistent effort.

It was interesting data and I definitely think it could be useful in several ways for training. First, as in my run, to keep tabs on your effort levels to make sure the run is achieving what you want it to (e.g. aerobic, threshold). Second, as a gauge to fitness – repeating the same run with the same power but seeing your pace increase will tell you that you’re making gains. You’ll need to create some baselines for both of these but from there you can track how you are doing. But thirdly, and for me most importantly, you can improve your internal awareness of perceived effort. This is such a valuable tool and once honed with experience is a better guide than any tech could ever be. One way you could test how well you are doing with this is to repeat a run you have done at a certain effort while following your power, but this time cover your watch with some tape, try and run at the same effort, then compare the data afterwards.

But what about racing? The theory is sound, but I’d have my concerns about using it in a race as it could easily lead to what I call “tech fatigue”. It’s the sort of metric that compels you to look at your watch a lot and this is tiring both physically and mentally – every time you look at your watch you raise your arm and this interrupts your most efficient arm/leg cadence (think of those drills!) costing you a bit of energy each time, which over a marathon (for example) adds up, and your brain will be working hard to process and interpret the data (especially if it’s off target), causing stress and taking your focus away from the job in hand. Better would be to use the third of my training benefits to hone your perceived effort and be disciplined with that as you race to your goal.

To conclude, power meters and the concept of running power are without doubt valuable training tools. If you want to use them, my advice would be to make them part of your overall ‘data gathering’ from both your device, but also from within yourself and you should start to see gains in your training efficiency and your performance.