Monday, November 19, 2012

Kennedy Fire Trail run: VAM analysis

A followup to my run report... a look at VAM.

VAM on running is a very different beast than on cycling. With cycling, once overcoming gravity becomes the dominanant task, wind resistance and rolling resis\ tance playing substantially minority roles, a relatively constant VAM can be maintained as long as there's an available gear to support a cadence in the target ra\ nge, at least until holding the front wheel on the road becomes a challenge. With running, the analog of rolling resistance is much larger, so there is no point \ where it can be trivially ignored, and by that point running becomes impractical and movement is more by walking or even scrambling. So VAM without the context o\ f road grade is meaningless.

I repeat the analysys I did for Soda Springs Road, which is to plot VAM and road grade, each smoothed by a 30-second Gaussian convolution, on the same plot. H\ ere's the result:

VAM and road grade

What I see is, on these axes, VAM and road grade track nicely until towards the end of my run the VAM curve rises above the grade curve. To me this indicates \ my pacing was fine, even conservative in the beginning. I was able to increase my pace toward what I perceived to be the finish.

Unfortunately, it wasn't actually the finish...

I went for a nice 15-miler on Sunday in San Francisco to try and get over my frustration from Saturday. It partially worked. I ran fine, maintaining a decent\ pace when not impeded by intersections, and not feeling especially fatigued toward the end. It helped that I came upon the San Francisco Urbanthon runner expo c\ losing shop and was able to eat a few Clif samples half-way through. I still took a few hours upon returning before I felt restored, but that's always the case w\ ith long runs with me. So physically I recovered well from Saturday. Mentally it takes a bit longer, however.

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