The use of power meters on bikes led to a whole new way for cyclists to dial in their training. Cycling power meters are typically integrated into the wheel’s hub or the bike’s pedals or cranks. The power meter measures both the force applied by the cyclist and the speed at which it is applied to arrive at power.
Power meters are now also available for running, swimming, and cross country skiing. Using power eliminates many of the downsides of heart rate monitors, providing coaches and athletes a precise way to prescribe and monitor workout intensity.
Running Power Meters
Companies like Stryd, among others, have created power meters for running, using a foot pod that attaches to your shoe to record “running power,” or the amount of energy you expend per unit of time to move your body forward.
Running is a much more complicated activity than cycling, however. Rather than simply transferring energy into bike pedals, running power must take account of the body’s various movements through space as you run. Different running power meters take different approaches and use different algorithms to arrive at a running power number.
So, running power meters aren’t exactly the same as those used for cycling, but the general premise is similar. If we can measure the amount of power exerted by a runner; then we can use that as a tool for measuring and monitoring running intensity.
Running power meters tend to work best when training on the track or fairly standard surfaces, such as smooth trails or roads with mostly moderate undulations in the terrain. On these types of surfaces, running power can work well to keep you in your desired zone. As with pace, power also works well for track workouts.
But using power for trail running or mountain running presents additional complications. Once you start running on steeper grades — such as grades above 10%, not to mention mountainous terrain near 20% or greater — and on variable surfaces with lots of rocks, roots, and other obstacles typical of trail running; then the usefulness of a single set of running power zones goes away.
To make best use of running power for trail or mountain running, you need to set different power zones for each of the four disciplines of mountain running: flat running, uphill running, uphill hiking, and downhill running. Per the principle of specificity, those different sets of zones will work best on terrain similar to where you did the field tests to arrive at the numbers.
So, for example, your power zones for running uphill on a 10% grade would be less effective if you’re running uphill on a grade of 20%; of course, you should probably be switching to hiking on that steeper grade (and using poles), but the point remains that you’ll need to determine your zones specific to the various types of terrain on which you’ll be training or racing.
Functional Threshold Power (FTP, or FTPw)
Determining your power zones for each of the Alp Fitness intensity levels requires a field test to find your power at lactate threshold since the zones are based on percentages of that lactate threshold power.
Your power at lactate threshold is termed functional threshold power, or FTP where the “P” at the end indicates “power.” Sometimes the abbreviation FTPw is used instead to clearly distinguish “power” (Pw) from “pace” (Pa). I’ll use the abbreviation FTPw for functional threshold power so there is no confusion with the similar abbreviation for functional threshold pace (FTPa).
Remember, the word “functional” refers to the fact that we’re using a practical performance-based test rather than a lab test. Rather than directly testing for blood lactate concentration, as would be done in a lab to precisely pinpoint your lactate threshold (LT), we’re indirectly approximating your LT and are more interested in your effective, or functional power at that physiological point of interest than the precise biomarker itself.
