Running with Power: A Primer
Power meters on bicycles have long been the gold standard for measuring performance progression. In recent years, bike power meters have become more and more affordable, putting them within reach of most triathletes who are serious about measuring and tracking metrics.
The great benefit of power is that…power is power. It’s a measurement of force times velocity. Power doesn’t care about whether you’re going uphill or downhill; whether you got good sleep or tossed and turned the night before; whether you feel good or like crap; whether it’s hot outside; whether you’re caffeinated; and so forth. It simply measures the amount of work you’re doing over time.
Enter the running power meter. There are several research labs and companies working on creating running power meters. The market leader at this point is clearly Stryd. I’ve been using Stryd power meters for several years, starting with their first-generation heart-rate-strap mounted version. In the beginning, I found the data to be interesting, but not very reliable. It wasn’t useful as a training tool because of its inconsistency, among other issues. A couple of years ago, they introduced a small footpod to replace the chest strap version and it was immediately evident that they were onto something better. They have recently introduced their third generation version and, as both a coach and an athlete, I think running power is finally ready for prime time.
There are several ways to calculate running power. While initially, most people thought of mechanical tools like force plates, Stryd uses other metrics like ground contact time and vertical oscillation to calculate a power number. I’m sure that smart people could engage in lengthy conversations about whether Stryd is really measuring actual power, but even without a degree in engineering (my situation), there is a point at which it doesn’t matter. I’m not convinced, nor do I care, that what Stryd says is a watt is actually a watt. In research, you consider two factors: validity and reliability. Validity considers the accuracy of a measurement. Reliability considers the consistency of a measurement. It’s reliability that I’ve always been interested in when thinking about metrics that will help me as an athlete, and the athletes I coach. I don’t care whether 300 watts is actually 300 watts as long as every time I run up the same hill at the same speed, using the same form, in the same wind conditions, etc.—I see my power meter showing me 300 watts. Stryd seems to have that dialed in now.
Stryd’s phone apps are very good at collecting and displaying relevant information, interacting with Garmin and other watch brands, and uploading to Training Peaks. If you’re a data geek, Stryd’s PowerCenter website will give you a lot more feedback than Training Peaks will show in your uploaded workout. The app will assess your runs and provide you with a threshold value.
If you decide to give running with power a try, I have a few thoughts and recommendations:
1. Just run with it for a few weeks. Observe the power numbers that you see during your runs, but don’t adjust your running based on what you see.
2. Vary your running effort/pace. This is part of your training plan, no doubt. The Stryd software uses data from different kinds of efforts to determine your threshold power.
3. Once Stryd gives you a threshold power number, multiply that number by 1.05 (5% higher) to set your run power threshold in Training Peaks. I don’t have any hard data behind this recommendation but the zones that Training Peaks sets based on the 5% increase seem to me to give more accurate TSS numbers for any given run.
4. Let your coach know that you’re using Stryd. As of this writing, there’s not a coach portal to Stryd’s PowerCenter website so as an athlete, you’ll have more information about your running power than your coach will have. You may need to be in communication with your coach outside of Training Peaks in order to get the most out of the Stryd data.
5. When you run on a treadmill, use the Stryd phone app to collect data (rather than your watch). To calculate running power accurately on a treadmill, you need to tell the app what percent grade you have the treadmill set for. (Yes, this is an argument that Stryd isn’t actually measuring power, but see my note about reliability vs. validity.)
6. Once your threshold power and zones have been calculated, use power to pace your workouts (and races)—and stick with it over time. I have used power to pace quite a bit of training as well as a few 70.3 race runs and have been very pleased by how much I can rely on my power number. For shorter efforts, like sprint race runs or open 5ks, where you’re running close to or above your threshold, relying on power for pacing in the moment is less valuable in my experience. For high-intensity interval workouts, the power data provides great feedback when reviewing the workout, even if not in the moment. You don’t want to be checking your watch constantly as you run high intensity.
Note that there are several interesting metrics that Stryd generates for you beyond a simple power number (e.g., leg spring stiffness, form power, vertical oscillation, etc.). These metrics can be helpful as you work to improve your run. They will surely come up in a future article.
I hope this doesn’t read like an advertisement for Stryd. I don’t receive any kickbacks from Stryd. (Disclosure: I did get a discount on my personal Stryd unit and Stryd does offer a discount to D3 athletes—check with your coach for details.) I’ve been a curious user for years—hoping that a good running power meter option would emerge that I could recommend to my athletes. Stryd has gotten there first, in my opinion.
Coach Dave Sheanin is a USA Triathlon and USA Swimming Certified Coach. He believes that becoming “triathlon literate” is key to meeting your goals. Triathlon is indeed a lifestyle and like the other important areas of your life, knowledge is power. I encourage you to explore the nuances of the sport, be open to new ideas and ask questions – of yourself, of fellow swimmers, cyclists and runners, and of your coach. Whether you’re training to win or new to the sport, the most accomplished athletes are those who are open to coaching, eager to take on new challenges, and are committed to continuous improvement!