Adapted with permission of VeloPress from Run with Power: The Complete Guide to Power Meters for Running by Jim Vance
If you’re a triathlete, a bicycle racer, or a fan of either pro sport, you are probably already familiar with the use of power meters in cycling. The power meter transformed training and racing in the cycling world. It has surpassed every other training tool because it delivers an objective and repeatable assessment of overall fitness without any of the drawbacks of previous measurement methods, such as heart rate, speed, and perceived exertion.
In fact, the advantages of the cycling power meter are so great—and the margin of error so small in the world of competitive cycling and triathlon—that to ignore the information and the advantage from a power meter would be to concede victory before the race had started.
In the running world, we have recently seen a surge in the popularity of GPS units whose main advances are mapping your route and elevation gain/loss and displaying pace, which is a measure of how long it takes to cover a unit of distance (minutes per mile). The increased adoption of GPS shows that the running world, like the cycling world, is open to embracing technology and its benefits.
While the GPS unit is a useful tool, its contribution to training pales in comparison with the advantages the power meter can provide. The leap in technology is something like the difference between using a typewriter and a computer. In the history of running technology, a stopwatch is probably equivalent to using a typewriter—pretty good at its job, but severely limited in scope. Running’s step up to heart rate monitors was a revelation, but in retrospect, it was like moving from the typewriter to what we would now regard as an old, heavy, slow desktop computer. Today’s GPS wrist units are like the first cellphones, much like a flip-phone. The portable power meter for running is the next step, equivalent to the laptop, tablet, and smartphone coming into existence all at once. And while you can still accomplish a lot with a desktop computer, you likely will be much more effective in many ways if you add the laptop, tablet, and smartphone to your arsenal. This is what the power meter brings to the world of training and racing for competitive running.
In this post, we’ll take a look at two more ways cycling and running power meters are different.
#3: Running Average Power and Normalized Power Are Pretty Similar
If you are familiar with Normalized Power (NP) through your use of a power meter in cycling or triathlon, you’re probably familiar with the extreme range of power outputs during a ride. In cycling, big surges and jumps are common, as is coasting along in the draft generating zero watts whenever possible.
In running, however, it is rare to see a number of high sprinting outputs in a race, especially in races of 5K distance and longer. Runners can never coast down a hill or sit in a pack, so the range of power outputs is generally small.
Because of this small range, there usually is not a large difference between average power and Normalized Power values from a run workout, unless the workout includes a lot of intervals. Normalized Power is especially helpful, therefore, in analyzing interval workouts, but NP is also important for other metrics that we introduce in my book Run with Power.
#4: Runners Can’t Coast
Variability Index is a measure of how steadily an athlete puts out power. If you’ve been using a power meter on your bike, you’ve surely seen very high Variability Index values in your cycling power files.
On the bike, riding with a pack of other cyclists is crucial for success in racing, so there tend to be big surges of power to stay with the group. Also, cyclists can coast at zero watts and get pulled along by the group, or just sit on the bike on long downhills, not pedaling at all.
Runners can never coast at zero watts, so VI values are not likely to be as high for runners as we commonly see in cycling power files, unless you’re doing a lot of intense stop-and-go running, as with intervals on a track.
One other way a runner might see a high VI value would come from a performance where the athlete paced so poorly that the early power outputs couldn’t come close to being sustained later in the workout. This would surely be the result of a poor workout or race performance by the athlete, so I am hopeful you don’t see many of those situations.
More often, if a running power file shows a high VI, it likely means the session was intense, with alternating periods of high power outputs and low power outputs (like an interval workout).
RUN WITH POWER is the groundbreaking guide you need to tap the true potential of your running power meter like SHFT, Stryd, or RPM2. From 5K to ultramarathon, a power meter can make you faster—but only if you know how to use it. Just viewing your numbers is not enough; you can only become a faster, stronger, more efficient runner when you know what your key numbers mean for your workouts, races, and your season-long training. In Run with Power, TrainingBible coach Jim Vance offers the comprehensive guide you need to find the speed you want.
Run with Power is available now from your local bookstore, tri or running shop, and from these online retailers:
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