During our October 2010 Product Party with Cycleops, I gave a brief talk on how training with power can benefit your riding. For those that were unable to make it, I’ll try to touch on the highlights of the talk and Q&A in this post.
I began by explaining what power is. If you want a really scientific explanation, look up the Wikipedia article on power—but make sure you use the German version. Seriously—the German version is a much more reputable source than the English version of the popular online, user-edited encyclopedia (probably the result of stricter encyclopedic guidelines). But here’s my definition provided by my memories of 9th grade honors physical science: Power=the ratio of work done over time. And you get work by multiplying force (on an object) and displacement (how far the object moves). And force is mass times acceleration. Basically what this boils down to is this: The harder you press into the pedals (accelerating those pedals faster or pushing with more muscle mass into tem) or the faster you spin those pedals (more displacement in a given amount of time, plus faster acceleration), the more power you produce. Power is measured in watts, or if you’re my boss Joe or his comparably-sized teammate Brett (see at 5:06), horsepower (735.5 watts—or so says de.wikipedia.org/wiki/Pferdestärke).
What all that sciencey amounts to is that power is an absolute measurement of how hard or strong you’re going. 300 watts is always 300 watts, whether your speed is 10 or 60kph, whether your heart rate is 120 or 180, whether your perceived exertion is a 2 or a 10, and so on. Every other training tool you can use—speed, cadence, heart rate, exertion—is a mere physiological response to one thing: the work being done—symptoms, not the source.
There are several devices for measuring power, called powermeters, amongst them the Computrainer, the Powertap, SRM, Quarq, and the iBike. At RPM workouts in the breakaway training center, we use the Computrainer. We also rent out a Powertap. In 2010 I trained and raced with a Powertap. There are advantages and disadvantages to each, and I leave it to you to sort through what’s out there with regard to those. I will only note that I suspect prices of these powermeters to go down, as the market is quite likely going to be flooded with a number of new powermeters currently in various stages of development and testing, including cleat- and pedal-based systems, along with something called a LaserSpoke.
Once you start training with power, there are two “tests” you need to do to get maximal benefit from owning the power meter: a functional threshold power test & a power profile test. The FTP test will establish your training zones, and it is the first and most crucial step in tracking your fitness and evaluating your training. The power profile test helps you discover what sort of rider you are. By sort, I mean what your relative strengths and weaknesses are when it comes to utilizing different respiratory processes and recruiting different muscle fiber types. Without getting too sciencey again, suffice to say that some people are natural born sprinters, built for speed, at the expense of their stamina, and others end up like me, a rather compact, efficient animal built for endurance. These are the first workouts we have any of our RPM students and coached athletes do.
In the lecture, I went on to show how I track data from ride to ride, month to month, season to season, and so on. By using a powermeter along with TrainingPeaks and WKO+ software, we can get an objective Training Stress Score for every ride. We can track that score to plan peaks and tapers, see when you’re most fit, when you tend to overreach, how much you’re improving season to season, what sorts of training rides best suit you, and all sorts of other useful information. A powermeter can help you pace a time trial or bike-leg in a triathlon perfectly. It will calculate your caloric requirements during and after a ride. I’ve used one to determine optimum cadence. Really, the only limits to what you can do with a powermeter are the creative ones of you and your coach.