Why Power Might Be the Ultimate Training Metric for Runners

Since the 1950s, distance runners have trained by following structured programs and workouts backed by physiological testing and years and years of positive results.

Beginning in the late 1980s, heart-rate monitors added a new dimension to training, allowing for the advent of workouts based on specific heart-rate zones. Both methods have helped runners and triathletes of all levels improve their performance. By the early 2000s, GPS-enabled smartwatches made it easy to monitor pace, distance, elevation and other types of data.

As the modern age of wearable tech has started to unfold, a new measurement technology has the ability to revolutionize training for runners: the power meter.

Cyclists have used power meters since the 1990s to accurately measure how much power they’re outputting and how that effort corresponds with their physiology. Power is the primary metric for cyclists, although, granted, it’s a much simpler metric to understand on the bike—essentially a function of how much force is being exerted on the pedals, crank arms or rear hub to make it move.

Power meters for runners—and the corresponding training protocols based on power output—have only become available recently, so the art and science of using power for run training are still very much in their infancy. But those closest to the new technology—including pioneering coaches and elite athletes who are already incorporating power into their training—believe it can be a very important metric for running.

“What we need, clearly, is a better way to measure the stress we are inflicting in our daily training routines. And that’s exactly what the power meter provides, and it is why the power meter has the potential to revolutionize your run training,” says elite-level running and triathlon coach Jim Vance, author of “Run with Power: The Complete Guide to Power Meters for Running.”

“With a power meter, you can measure your performance and training stress more precisely than ever before. No longer will you wonder whether you are meeting the intensity, recovery, pace and volume goals of your training plan. Instead, you will erase any doubts about your training, and you will be able to monitor changes and improvements in every aspect of your running fitness.”

Up until recently, the only way running power has been measured has been via a laboratory setting using ground impact force plates. However, recent advances in 3D motion sensor technology has led to the development of running power meters with a multitude of accelerometers that can gauge forward, vertical and lateral force. In other words, how much energy it takes a person to move through space.

The use of power in run training will likely have a slow to gradual uptake among runners—and not until devices that track and support power (see below) become ubiquitous. There has already been (and will continue to be) pushback in favor of traditional training methods. But monitoring power—and understanding how to use it—could lead to true next-level advancements in run training, several experts have said.

“The importance of power is that it can give you some insights into the determinants of a runner’s performance beyond what a stopwatch can do—in particular, knowledge about your VO2 max, your lactate threshold and your efficiency or effectiveness of running,” says pioneering exercise physiologist Andrew Coggan, Ph.D., the co-author of “Training and Racing with a Power Meter.”  

This is really an exciting new time in that we haven’t had this data available previously outside of a laboratory setting,” Coggan adds. “So in many regards, the whole story that has evolved in cycling over the last two decades is now starting up again in respect to running.”

VIDEO: What is Power?

Why is power potentially so, well, powerful? First, power can allow a runner to precisely manage their training intensity—no matter if it’s on a hard workout such as an 8×400-meter interval session, a long progression run, a hill workout or a recovery run. In other words, it can tell precisely how hard a workout is as it relates to physiological markers like a runner’s lactate threshold. It’s one thing for a runner to run a 8×400 workout “hard” but it’s quite another to understand precisely how hard that actually is and how hard it should be. That kind of precision can help athletes train better, recover better and ultimately compress training cycles, Vance says, once coaches and athletes learn how to get more fitness from every workout.

Secondly, power—and only power—can help a runner monitor efficiency. That’s possible by showing how both immediate form tweaks during a run and long-term changes in running mechanics (based on form drills, increased strength, higher cadence or even better footwear) can allow a runner to run with less power output. If a runner can learn and train to run at the same pace using less power output for a given distance on a consistent basis—whether it’s a 5K or a marathon—it means that runner is becoming more efficient. The longer the race, the more important efficiency becomes.

Also, a runner can use power to optimize pacing and performance by using real-time power monitoring to understand the physiological demands of a workout or a race. Unlike heart rate or running pace (which have limitations and monitoring lag times), power is a near-instantaneous measure of the changes in a runner’s effort and also accounts for changes in terrain—for example, running uphill, downhill or over rolling terrain. Based on their own critical power number, runners can look at their power meters and understand precisely how hard of an effort to put out once a race begins.

“As advanced technology becomes available for runners, the opportunity to get a step on the competition increases dramatically for the early adopters. The runner’s power meter is the latest example of that,” says Joe Friel, founder of TrainingBible Coaching, co-founder of TrainingPeaks, and author of “The Triathlete’s Training Bible” and “The Power Meter Handbook.” “It’s a complex tool, but one with great potential for enhancing performance.”

Several running power meters are available on the market now or coming out very soon, including devices made by Stryd, RPM², SHFT and Lumo Bodytech. The purpose of this article is not to review the merits of each of those monitoring tools—all of which also record numerous other pieces of data—but instead to talk about the role of power as a key metric in running.

Several key training platforms have adopted power (including Training Peaks, Strava, 2Peak, Garmin Connect, Suunto Movescount and Golden Cheetah) and more smartwatch companies have begun making devices capable of displaying power output from a wireless connection to a power meter. (Polar, Garmin and Suunto are among those that already do in various ways.)

By itself, having a singular power output number on the face of a smartwatch face is no more relevant than having a singular heart rate statistic. It’s what that power number means relative to a runner’s individual fitness, workout or training plan.

When it comes to using power, there are three main things for a runner to understand:

1) An understanding of your individual power baseline; in other words, what is your capability or performance limitation, and your critical power or lactate threshold power number is what essentially measures that.

2) Once you have your baseline capability, you can create your own personal training zones, which are similar to segmented heart rate training zones, but, of course, based on power output. Vance has defined seven power zones in his book, ranging from walking/recovery (zone 1) to anaerobic/peak power (zone 7), and when, why and how to train in each zone.

RELATED: Seven Power Zones for Run Training

3) From there, workouts and training plans can be retrofitted to focus on power as the most critical metric.

“The problem for most runners is that they may be training in a gray area,” says Li Shang, Ph.D., Stryd co-founder and associate professor of engineering at the University of Colorado. “Athletes may not train themselves hard enough, but they also don’t get enough recovery. With power as the key metric, they know exactly how much power output they need.”

The ability to run more efficiently has always been a primary goal of runners. That’s what training and racing are all about. But the ability to make form changes—both in real time during a run or race and via longer term changes via drills and strength development—has always been an inexact science. That might be the most immediate way runners can benefit from power.

“Up until now, you could tell an athlete that they have to run taller or pick up their knees, but the athlete was only doing it because it sounded right. Now we have a device that can actually analyze it after you do it,” says Frank Jakobsen, a Danish triathlon and running coach with the Sansego training program. “Late in a race, an athlete can say, ‘I’m going to do this, I’m tough. I’m going to make it.’ But actually what they should be doing is creating a physiological response to make themselves more faster and more efficient.”

And what that can lead to, Jakobsen says, is the creation of mental picture—based on the understanding of efficient form gained from using a power meter—that will send synapses and nervous signals out to the muscles and create a certain movement.

“Saying ‘I’m tough’ is not going to create a movement. It’s going to move you forward, but it’s not going to create a certain movement in the muscles (that will make you more efficient). Whereas saying, ‘I’m going to run tall, I’m going to lead with my chest,’ that’s actually going to create a movement.’” With the advent of power monitors, a runner or triathlete can truly understand what physical movements need to be made to become more efficient late in a race by glancing at their wrist.

Combined with the idea of matching workouts to a specific race course—understanding precisely what kind of power output is needed at different parts of a course—power meters could help unlock another level of development for marathoner runners, trail runners, triathletes and everyone in between, Vance says.

But, just as with heart-rate monitors and GPS-enabled heart rate monitors, there will be early adopters, eager followers, skeptics and never-evers among the runner/triathlete population.

“New technology can be intimidating, and there will be some who will reject the very idea of using a power meter. They’ll say they are happy with the way they are doing things,” Vance says. “Once the best athletes come into contact with the best coaches, who know and understand how to use this technology and data to design training programs and improve an athlete’s weaknesses, the next revolution will begin.”

Brian Metzler is the editor of Competitor.com and Competitor magazine.

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