Saturday, January 02, 2010

Power Profiling - Now and Then

Often I am asked how my cycling power ouput compares now, to before my accident and amputation.

As I progressed with my training during 2009, and as my fitness continued to improve under Ric Stern's guidance, the answer to that question kept changing, mainly as I started to close in on pre-amputation power levels.

Now that I have a full year's worth of data from 2009, I decided to take a look at my annual power profile and see how it compares to pre-amp levels.

Below is aggregate power profile data covering the past 5 years. It shows my best power to mass ratio (W/kg) for each of 4 separate durations for the years 2005 through to 2009:

The power durations shown are:
5 seconds
1 minute
5 minutes, and
95% of my 20-minute power.

Each of these power-durations represents key elements of cycling fitness, with different energy systems being the primary contributor to performance at each duration. That's why it's such a telling indicator of your overall cycling makeup, and an excellent indicator of your relative strengths and weaknesses.

This is provided of course the profile does in fact contain data from best efforts for the duration. Given it's aggregate data for whole years, then I think it's a reasonable assumption. Nevertheless, sometimes the 1-minute column can still be under stated as that usually requires dedicated efforts not often performed in training or racing.

You can read more about power profiling in this original item by Dr Andrew Coggan here:
Power Profiling

So the group of columns on the left shows my best 5-second power to mass ratio for each year from 2005 to 2009. Each group of columns moving to the right covers the other durations, with 95% of 20-minute power shown by the columns on the far right.

What matters with power profiling is the overall shape of the profile, rather than the absolute numbers. The shape in this case indicated by the lines joining the columns, which I have shown for 2006 (orange line) and for 2009 (blue line). I chose those two years as they are the two complete years representing pre-amputation and post-amputation training/racing data.

I notice a few things:
- the overall shape of each line is similar
- my short duration power has taken a large nosedive
- my longer duration power to mass ratio is actually higher than previously attained

This clearly demonstrates that it's my sprint power that has suffered the most from my lower leg amputation, yet the predominantly aerobic power durations (5-min and 20+ min) have not.

This suggests a few things to me.

One is it's an example of how we are not force (strength) limited when cycling at aerobic power levels, since even though I have lost significant leg musculature and with it strength, I have still been able to generate the longer duration power.

Another is that the lack of a lower leg muscular-skeletal system has a significant impact on sprint ability. The lower leg matters a lot more in the generation of short duration sprint power, than for longer duration aerobic power.

What can I make of this information? Well for one I no longer have the sprint I used to, yet I am as likely to be as well set up for the end of a race as I was before, since I have the engine to deliver me there. But now I lack the finishing ability. My strategy and tactics in racing may need to be modified a little as a result.

I can still work on improving my sprint of course (all track/roadie riders should) but I would say that reclaiming pre-amp sprint power levels is not going to be anywhere near as "easy" as it was for aerobic power durations, if in fact it is actually possible.

It also points to me reconsidering what events I may in fact focus on. They may change as well.

Plenty to ponder with a power profile.

What's yours look like?

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