The metric is becoming more widely available on running watches—and can help you get more out of every workout.
Runners love their data, and there are so many ways to analyse performance: distance, pace, heart rate, cadence—and now power. Cyclists have long been clued into tracking power as a metric for effort, but it’s a little harder to measure when you’re not settled into a saddle. With technological advances, though, devices like the Stryd footpod, NURVV running insoles, certain running watches, and even treadmills can now measure running power from your foot or wrist.
Even the pros are paying attention to it. “One huge component I lacked in college and my early career was power,” Stephanie Bruce Tweeted on January 5. “I’m proud that after years of strength work and heavy lifting and hills we have greatly improved my power and stayed essentially injury free for 6 + years.” Less than two weeks after that Tweet, she won the Rock ‘n’ Roll Phoenix Half Marathon.
Who wouldn’t want to run faster and injury-free? Power is yet another piece of the puzzle that can inform your training so you can get the most out of every run—and, since it’s more accessible than ever, here’s what you need to know.
What is running power?
Imagine a sprinter’s wide open stride, and the amount of force they generate with each massive step. That’s power. When it comes down to the numbers, though, “power is one of those metrics that you can use to gauge how hard you’re working,” says Chris Myers, Ph.D., C.S.C.S., a coach with Peaks Coaching Group and co-author of Triathlon Training with Power.
What sets it apart from other metrics is that it’s giving you a real-time effort assessment. Pace doesn’t do that; pace is the result of how hard you’re working. With heart rate, there’s often a slight delay in tracking when you switch between effort levels (plus, it can be affected by alcohol, lack of sleep, and stress). And both can be affected by things like temperature, elevation, and wind.
Power, then, is kind of like your rate of perceived exertion—but instead of subjectively rating your perception of your effort during a workout (or at any given moment) on a scale of 1 to 10, you’re getting a quantifiable metric that can inform your training.
How do you measure running power?
Power is measured in watts, and tracking devices use a built-in accelerometer—a tiny sensor that measures non-gravitational acceleration and senses general orientation, vibration, and shock—to calculate it.
It’s a simple physics equation: Force equals mass times acceleration. In running, the supercomputers in your tracker (and their partner apps) are using your body weight, how fast you’re running, and other metrics like cadence, stride rate, and vertical oscillation (how much you move up and down while running forward) to come up with your running power, explains Myers.
What does that mean for you? “The higher the watts, the more power you’re generating with every step,” says Colleen Brough, P.T., D.P.T., a doctor of physical therapy, orthopaedic clinical specialist, and director of Columbia RunLab at Columbia University.That’s not to say there’s a gold standard number for running power, à la the so-called “optimal” 180 strides per minute for your cadence. What you want to see is a steady level of output, says Bough. “Throughout a run, you should ideally be able to keep your power at around the same number despite that hill, despite your fatigue, despite that little bit of knee pain.”
Why would you want to measure running power?
For starters, it’s a measure of efficiency: “If you can generate more power with every step while at a lower heart rate or faster pace than in previous workouts, that’s a sign of improvement,” says Brough. Running efficiency is all about running faster while using less energy, and power can help quantify that.
Just like heart rate, it can also be a tool for training in the right zones. “The function threshold power (FTP) test is the baseline benchmark to calculate training zones,” explains Myers. “FTP is defined as the power one can sustain for 60 minutes or a 10K time trial run.”
Most people won’t actually go out and run a 10K time trial FTP test though, says Myers, but a 5K time trial can be a great way to calculate your FTP at shorter distance. (You’ll need a device that measures power to actually get your running power reading.)
To do the FTP test, after performing a warmup, increase your pace to the maximal effort you think you can hold for 5K—between an RPE of 6 and 7. After finishing the 5K, make sure to cool down. The average power, or FTP, from that run can then be used to determine your power zones to use during training.
Using power measurements can normalise incline changes during training. “When you run uphill, your pace drops, and it’s like ‘shoot, am I still in my zone?’” says Myers. But slowing down doesn’t necessarily mean you’re working less intensely. So instead of focusing on pace, zero in on your power measure to make sure you’re maintaining the correct effort level.
Where power measurements really come in handy is for effort-based pacing. Let’s say you’re running a super hilly race. There’s no way you’ll be able to maintain equal splits on the ups and downs. But if you can hold your power steady, that means you’re running at the appropriate intensity.
How to improve your running power
“Power and speed are very closely linked,” says Brough. Speed training (from interval workouts to hill repeats to strides) function as a kind of strength training, she explains, because they engage your fast-twitch muscle fibres—a.k.a. the ones you use for sprinting, not steady-state runs. Training those fibres is important for all runners, because they’re what kicks in during that final push to the finish line.
Otherwise, you need strength training. Plyometric exercises—fast, explosive bodyweight movements like box jumps—pay off big time in terms of power. Middle- and long-distance runners who performed plyometric workouts twice a week for a month boosted their running economy, time trials, and sprint speed, a review published in Sports Medicine in 2018 found.
But traditional, heavier lifting is just as important. Weightlifting (think weight lunges and squats) improves speed, running economy, and muscle power, according to a 2017 study published in the same journal. The key, says Bough: You’re increasing the load on your body. And when you can generate the necessary force to handle that load, it will translate over to the force you need to push your body off the ground with each running step.
You can’t do one without the other, though. “One, you need to strength train. Two, you have to then take that newfound strength and train it in the context of running—i.e. with specific speed workouts,” explains Bough. “Then, those two elements together will transfer into improved power over longer distances.”
