Until you really use power it is really hard to outlay the earned $$, when you really don’t know what you are getting. So I thought I would show a data plot to try to outline the benefit. Last week I did my FTP test and although I did the best I could, I could have finished with a higher number if I was more consistent with my power output, but really did not know a solid number to aim for. Yesterday I did an interval set, with the aim to keep my power consistent and at the right level. I think I nailed it (I know my number’s aren’t that high, only got a little engine ;)), and pushed my limits, although my legs did show signs of fatigue towards the end (power fluctuations). When you look at the data you can see the benefits of power quite clearly. So here it is (BTW click on the pic to enlarge):
As you can see I did lots of short intervals ranging in time but incorporated it into 4 major sets. My power (yellow) was very consistent across 3 sets and only dropped a little in the 4th where my cadence (green) was increased to over 100rpm. The first 2 major sets I kept my cadence the same and increased it a little in each of the last 2 sets. My Heart rate (red) increased throughout the whole first set (10min), then remained steady for the second set. The 3rd and 4th sets Heart rate increased throughout and followed my power level to some extent, the heart rate increased compared to the first 2 sets was due to the increase in cadence.
In any interval set you want to keep consistent throughout the whole set (unless there are planned surges), in my first set it took 8-9 minutes till I my heart rate caught up to my power output. If I was working from my heart rate I would no doubt have been pushing too hard at the beginning and then not hard enough towards the end. Even in the 2nd set after a 3 minute recovery it took a minute to rise and was not till I went a little harder (harder than I should have) that it rose to the right level. So especially short intervals or sets where you are not totally warmed up you will not have a consistent output. Heart rate can also be influenced by fatigue or stress; you may find working with Heart rate some days it just does not go up even though your perceived effort feels like it should be higher. Without power you will never truly know what your effort is, there is always the heart rate delay, and in-consistency’s for it to be used as a measure.
In summary there are benefits to both. Heart rate shows the body’s response to the effort and other stress’s in life, while power is the right tool for intervals and being consistent, measuring efforts, and testing for improvements. But it is not till you work with both till you have the right tools to answer your question’s as long as you have right knowledge, know your limits, you should have a good chance of stopping yourself from over-training or at the other end train that bit harder to get the most out of yourself.
Now I’m no expert just the things I have picked up from my own experiences and reading, but hopefully if someone is thinking of going with power hopefully I have answered some questions. For reference I used my ibike on the trainer setup specifically for that trainer so values are accurate, I currently also use a powertap on the mountain bike. To be honest in the future I would only buy a “true” power meter like the Power Tap or SRM or Quark or Metrigear that either use torque or strain gauges. It seems all other units need to be setup accurately and calibrated correctly which is very hard to do, how can you tell if it is correct or not? The MetriGear unit I really like measured at the pedal with lots of torque sensor’s to indicate the angle and force of every point on each pedal stroke, you got to love that. Check this out for the geeks ;)
http://www.metrigear.com/news/ have a look at the pedal force profile link, hopefully it will be released soon. Torque will be the next thing after power without a doubt, for high power outputs you need to be efficient don’t you, and being able to check these values for each leg is another bonus.
Now does it all work and make you much better compared to just listening to your body don't know there are alot of awesome riders out there without all this data, and insead of looking at it maybe we should just ride ;).
