Power Testing

As part of my rehabilitation from my scooter accident I decided to improve my heart and leg fitness by doing indoor bike training. Both my GP and physiotherapist recommended this and because of my background in cycling I thought it was a great idea.

My bike setup is pretty basic but it also provides me with not only good training equipment but also valuable technical feedback for monitoring my fitness. I have a Kurt Kinetic Pro Trainer, which comes calibrated for power. What this means is that if I know the speed of the rear wheel I can compute the power that I’m producing. To track the speed I have a “bike pod” (ie a speedometer) that works with my Suunto t6 heart rate monitor, and I can download all of this data to my PC. As well, the trainer came with a cheap bike computer which shows the wheel speed and the power (the Suunto simply shows the speed). To get all the data into the PC I download my heart rate and speed. I then use a spreadsheet to calculate the power from the known speed. This file is then imported into WKO+ and SportTracks. I use WKO+ as a great piece of software to track, monitor and analyze my fitness data. I also use SportTracks because it is a free program that also works with GPS devices. So if I also want to take my GPS with me on a ride (hike, run, whatever), I can import my downloaded tracks and show where I was on maps. Sure it’s geeky as hell but I like it. For more details on how I get all this data into useable formats using a Suunto t6, I’m planning on writing a future post about that.

So I suppose you’re riveted to your seat now and itching to find out “how fit” I am. When I first started riding the bike back in September I was comfortable only going for 15 to 20 minutes. I then started working a bit harder on the bike and finally did some power testing. The basic plan was to find my “FTP”, or Functional Threshold Power. One way to describe FTP is that it is the maximum power a person can maintain for 60 minutes. Once a person knows their FTP, they can calculate power zones and then perform specific workouts that require the athlete to target or maintain specific power levels. Different power levels will work different physical aspects, such as aerobic capacity, anaerobic capacity, strength, etc. Finally, once a person knows their FTP they can then re-test periodically to track how effective their training is. There are several ways to determine a person’s FTP. I chose to perform a MAP (maximal aerobic power) test, as outlined by Rick Stern. Once a person knows their MAP they can estimate FTP = 72% to 77% MAP. My first test at the beginning of October resulted in an FTP of 210W. I chose to use 75% MAP = FTP.

The first several workouts were quite difficult, especially the ones that I did at 88% FTP. Not only were they difficult in terms of my fitness but also in numbness in my hands, arm, shoulder and ass. Over time my arm and shoulder have adapted but my hands and ass still get sore. Maybe I’ll get some gel gloves or bike seat to see if that helps.

This week I decided to re-test my FTP after 2 months of training. One thing I noticed is that I actually started with too high of an FTP back in October. Instead of using 1min max average to determine MAP, which would have been 261W, I used 10s max average which was 280W. Therefore my initial FTP was calculated to be 210W instead of 196W. So it was possible that my new test would be only slightly higher than 210W. The results of the test are shown below. My new MAP was 302W, corresponding to 226W FTP. Actually, I punched the finish a bit too much and didn’t quite track the test protocol correctly. I manually tweaked the last few data points and estimate my FTP to be more like 223W. I think I’ll do a CP20 test on Friday though and it will give me a good idea on how accurate this number is. It should be pretty close though, I did a workout in the Tempo zone and my heartrate stayed in Zone 3 to low Zone 4. A few notes on this latest test… First, one extra reason for such a big improvement in 2 months is that until this week I was riding the bike using runners. I was cautious on knee alignment and twisting and therefore avoided clipless pedals. Now that I’m using proper pedals and shoes, I think my pedal stroke is more efficient and therefore I have more power. Secondly, you can see dip in power around the 14min mark. I actually dropped my chain at that point. I guess I need to tweak the front derailleur a bit!

The two guides I use the most for all of this workout stuff is The Cyclist’s Training Bible by Joe Friel, and Training And Racing With A Power Meter by Hunter Allen and Andrew Coggan. I’ve had the Training Bible for years, and it is really good for allotting training hours and intensities along with corresponding workouts. Training With A Power Meter is great for bring power into the equation, and it is the quintessential book on this topic.