There’s a new performance measurement tool for runners on the market, and I predict that it’s going to dramatically evolve the way we train, race, and perform down the road. It’s called a running power meter and it offers a bunch of benefits for runners. But before I get into that, let’s talk about what power is and how it’s measured.
WHAT IS A RUNNING POWER METRE?
It’s a device that objectively measures the power output of a runner. More specifically, power is the measurement of how much work you are doing and how fast you are doing it, and is expressed in wattage (or watts). It measures or estimates force or speed (or both) using sensors inside the shoe or at the core of the body, similar to a heart-rate chest strap.
HOW IS RUNNING POWER MEASURED?
This varies based on the device you’re using. Some devices, like Stryd, measure the motion pattern of your body’s center of mass and how much of an incline you’re running on using a chest sensor. After you input your weight, the device can figure out how much power your muscles are producing to make your center of mass move that way. The RPM2 device calculates power directly from an insole and measures step time, ground contact time, flight time, power, and foot strike.
WHAT ARE THE BENEFITS?
Here are three ways running with power can help improve your running performance:
- Improved running form and efficiency
A running power meter can help you better see how your running technique and form correlate to your energy cost. Seeing your energy output as your form changes can help you smooth inefficiencies that can lead to fatigue later in a race. For example, improving your turnover cadence from 172 to 180-ish may help reduce your energy output (power), which helps you conserve energy and strength throughout your run or race. Runners who run with too much vertical oscillation (that is, bouncing up and down) can learn to translate more power into moving forward in the horizontal plane. This would show up as a savings of wattage and an increase in pace. Power meters allow you to see in real-time the energy output effects of changes to your form, and to compare those energy output effects to other metrics like pace and heart race.
- More precise workouts
One of the coolest things about power meters is that they are an objective measurement of your effort. A power meter directly measures how much output is happening in the moment. Your heart rate is a physiological response to the stress on your body and can be affected by the temperature, how much you’ve slept, illness, stress, medications, and more. There is also a lag in the heart-rate response, so if you’re running uphill, it can take several seconds to catch up to the demands of the intensity. The same is true when running downhill. While power immediately drops as you begin to run downhill, your heart rate remains elevated until your body begins to recover from the stress of the climb. If you’re using heart rate to gauge effort, it will be lagging and can be inaccurate in real time.
Running by pace is similar. If I were to prescribe a workout at a specific tempo pace, and the runner ran it against a 20 mph headwind, that runner’s energy output and heart rate would be much higher than if she ran the same pace on a calm day. The same is true on a hilly course. By following a prescribed pace, the runner might train at higher stress loads than intended, which could affect performance and recovery.
By adding power to your other performance metrics, you can put your heart rate, pace, and how your body feels (perceived effort) in the context of your exact work output.
- Pace like a champion
My Ironman friend who uses a power meter on his bike once described it as “cheating,” because once you know your threshold power, you can dial in your power zones and hold that number through your workout or race. Whether it’s windy, hilly, on a trail, or on a flat road, by learning how to pace by power, you can always be in the optimal zone on the given day and on any terrain.
It’s like a more accurate version of heart-rate training, as power is a direct measurement of your work output in the moment. You can set your device to stay within a lower power zone for your longer runs, in a moderate zone for tempo workouts, and higher for speed workouts. So, if you run that tempo run into a headwind, and follow your power zone instead of pace, you’ll run slower, but in the optimal zone on the given day. If there is a tailwind, you’ll be sailing along quite faster at the same amount of output. The same holds true for race day. By setting your power zones lower in the early stages of the race, you can conserve energy to push in the second half.
It’s fair to mention that this is a very new technology in the running space, and because it is, the timing devices we use still need to catch up. Some of the power meters are compatible with a few speed and distance watches while others aren’t. For this reason, it is wise to do your research before purchasing. The power meter devices do have their own apps that make it easy to use and upload to your logs like Strava. But it’s only a matter of time before you begin to see power as a measurement source that can be connected via your timing devices.
I’m just covering the tip of the iceberg in this column. There is so much we can gain by learning to train and race with power. If you want to learn more, I highly recommend reading Jim Vance’s new book Run with Power. Knowledge is power, and power is going to revolutionise how we run.