How I qualified for Boston - The numbers behind running a BQ

Another opportunity to go runner nerd in this post. This is going to be a good one!

Below is a table (shamelessly constructed in Excel) containing the 5 km split times that I ran at Chicago, compared to the expected time I had to run at to meet my Boston qualifying (BQ) target of 3 hours 5 minutes. The Surplus/Deficit column represents how much time I was in front or behind at each stage of the race, while Time Gained/Lost shows the amount of time I gained or lost from the previous split. 

Splits from the Chicago Marathon, October 2012

Compare this with Paris in April 2012, where I had a goal time of 3 hours 10 minutes to qualify for the London Marathon.  

Splits from the Paris Marathon, April 2012

At Paris, I had a slower start, despite starting with the 3:10 pace group, where it took me 15 km to wipe the deficit. At Chicago, I made a conscious effort to stick with the pace leaders responsible for the 3:05 pace group. This might explain why I was bang on target after 5 km.

However, depending on how you look at it, what followed was either very brave or very foolish. It was there and then that I decided to abandon the pace group and go out on my own. I had a very good section up to the 10 km mark with a gain of 33 seconds, and continued making gains all the way up to 35 km. Surprisingly the best gain was at the 30 km mark with 44 seconds where I was already tired and hurting! Making a move early on definitely contributed to the overall result in a positive way.

The point at which I finally stopped gaining time was also deeper in Chicago at the 35 km mark, whereas in Paris I stopped gaining time after 30 km. This is probably the best thing to take away from this race as it means I was able to work at the required intensity for a longer period of time, even when I was tired.  

It must be said that the move to go out early on could have been disasterous as well, as it's often said that gaining a second early in the race will cost you two seconds in the later stages. Between 35-40 km at Chicago, I lost more time than I did in the last 7 km at Paris! Thankfully I had more than enough time to play with - 164 seconds at Chicago vs 93 seconds at Paris. It was just a matter of holding on till the end and thankfully I only managed to lose 54 seconds off my surplus, although this figure is almost over double the amount of time I lost in Paris.  

The pacing in the first and second halves was also pretty much spot on with absolutely nothing between the two races - 1:31:08 and 1:32:02 at Chicago vs 1:34:00 and 1:34:53 at Paris. While it ended up being a small positive split, even the very best runners in the world win races with these sorts of time differences between halves, although this year's Chicago Marathon winner, Tsegaye Kebede of Ethiopia, ran a huge negative split to set a new course record. Had I continued to make gains, or even hold the required effort at Chicago, I would've also run a negative split and set an even bigger personal best. However, it's hard to say whether sticking with the pace group for longer would have led to a better time. 

Overall, I'm very happy with these figures. A metronomic start, with several surges in pace throughout the middle and later stages of the race, the only downer was that I lost far too much time than I would've liked. However, a PB of 5 minutes 43 seconds, and with 140 training days available in that period, it doesn't get any better than that!