A few days after the Chicago
Marathon in record-heat
, I was wondering just how much more I had been
slowing down, and exactly when during the course of the race this occurred.
Bigger races like Chicago provide the so-called 'splits' for every five
kilometer segment. Helpfully, they also keep these with the archived results
which are all accessible via the web. So it was easy enough to collect a
sequence of time such as '0:22:34', '0:45:30', ... and so on.
And thanks to R, my data slicing and
dicing and visualizing tool of choice, it was just a handful of lines to
produce the chart below.
The chart covers my four Chicago marathons (2004,
as well as Boston (2007)
--- the infamous '27.2
mile marathon' seems to have dropped off the net, and the smaller
does not have 5k split times.
The chart shows a few things quite nicely:
- The first marathon (dark blue squares) shows a marked slowdown after km
- The following year (medium blue circles) a similar yet more moderate slowdown appeared 5 km later.
- The next year (blue triangles) the pace was remarkably stable without noticeable
slowdowsn -- yielding the 'BQ' time.
- The Boston race (smaller green circles) was more prudent due to weather conditions, and a
lingering cold, and I managed to finish much stronger than I ran the middle
- Chicago this year (orange circles) was a different story: too fast at
the beginning, a cautious middle similar to the Boston race but two
fairly significant slowdowns after 25 and 35 km, followed by some acceleration
right before the finish.
While it was a tough race, I clearly ran a lot slower than previously,
in particular between 25 km and 40 km. So there.