Friday, January 11, 2013

Three Google Charts

The longer I ride, the more I'm curious about long term improvements.  When I first started racing in 2008, I needed to get fast right away.  This was partly because I started training in March for a racing season that began in March.  I was also just starting two years of graduate school where I knew my winter training would be sporadic.

Also, I doubted the traditional approach of long, slow riding.  I couldn't find evidence, other than the anecdotes of professionals who had used it for years.  And there didn't seem to be many other approaches.

Five years later, and I still don't feel like I understand long term progress.  I can see it happening, little by little, but I haven't been able to find precise causation.  I've found some correlation--the simplest explanation for my improvement is time on the bike.  The more I ride, the faster I get.  Complicated, huh?

The primary thing I mean by improvement is better 1-hour power--the term of the moment for this being functional threshold power (FTP), as they call it.  What you can theoretically sustain for an hour if you sort of give your all.  In practical terms, it's 95% the power or speed (ceteris paribus) you can sustain for 20 minutes.

Time on bike, miles ridden, and intensity--all of these seem to lead to improvement in FTP.

The problem here is that they also correlate with each other for me.

So tracking energy, distance, time, and TSS may be redundant at this point--I may only need to keep track of one of these variables.*
In the next chart I compare my 20-minute power (CPI20), the steady red constant line, with my TSS (the blue line)--the amount of stress I put my body through from September through this week.
You'll notice that CPI20 rises slightly over the five or so months.

The relationship between speed and training time is not simple
Notice that even as my training line goes up and down frequently, my power (CPI) stays flat.  This suggests that the relationship between how much we ride and how fast we go is far from simple.  If, for instance, we could put out 10 Watts more for every additional 100 miles we rode in a week, we'd see the lines going up and down together.

But maybe the effect is lagged.  For instance, if I ride 100 miles more this week, I may not see the results until next week.  This is not the case--we can see it clearly enough in the graph.

But what if we think of FTP as a much less reactive thing?  Maybe it tends to change in the way erosion does--slowly, over time and through the accumulation of many efforts.  Here we get back to the long-term, short-term concept.

We can't conclude much from looking at this data.  Yes, CPI slowly rose, and yes, the trend of my training and the trend of my FTP loosely matched (it declined in October and has since gradually risen).  But the really interesting and complex question is whether, over time, I'll be stronger in April, and what kind of training will get me there.

The trend line seems pointed toward continued improvement, but as we all know, and especially as we age, everything that goes up must someday come down.

And then one last chart, just for the hell of it, because I'm inspired by, showing a fellow racer's critical power intervals (1 minute, 5, minute, 20 minute, and 60 minute) over time:

In the future, I plan on developing these charts to show more types of correlation. Hopefully, they'll help us visualize growth over the long term. I'm lacking in imagination for this sort of thing at the moment.

*I've put everything in log so my true, depressingly shameful numbers are obscured


idmguy said...

Kevin - nice talking with you on the 10 AM. Here is a link to the runner featured on radio lab we were discussing:

Kevin Cross said...

That is really incredible. I'm going to have to ponder the implications of that for a while. Also, good chatting and looking forward to seeing you out there.

Myke said...

Based on my (much more limited) experience, the longer it takes to build something up, the longer it takes to go away.

I spend 3 months training just FTP to see a 15% gain
I spend 1.5 months training VO2 to see a 15% gain
I spend 1 month training AC to see a 15% gain.

Interestingly, the "fade out" correlates the same. My FTP never seems to go down unless I take a full month off. I'll lose what seems like all my AC power after a couple weeks off.