Saturday was my second IM, first with power. My pre-race strategy was to ride relatively aggressively at the beginning since the first half of the ride was predominantly into a headwind. I divided the course mentally into 4 segments: start to Hwy 20 turn, the Hwy 20 stretch, turn on Hwy 231 til turn on 77, then 77 to finish. Data for these 4 segments and then the total/overall is as follows, arranged as norm. power, avg. power, hr, IF(based on FT of 240), and speed.
196 193 130 0.817 21.1
185 180 137 0.773 19
169 161 136 0.706 22.4
165 156 134 0.687 21.9
179 171 135 0.747 21.1 - Total
Bike split was 5:18. No stops but 2 coasting pee breaks. I was surprised to see the diminshing power numbers on post race analysis as I was passing riders late who had passed me earlier. Felt strong the entire ride.
The marathon time was 3:56 - 1:46 and 2:10 (yuck!). Did a poor job taking in sufficient fluids on the run as evidenced by 12 lb. wt loss and trip to the “19th hole” for a couple bags of IV fluid.
From reading your post it sounds like there was a tailwind coming in, which if so, that would account for lower power numbers. Your HR looks fine in terms of no significant drop or rise but am not sure about whether that’s the right HR as we don;t know you or your HR.
Regarding the IF, personally, I think it’s fine as the last two IM’s I tracked with power show my IF as higher than that. Also, we don;t know your run fitness or training but maybe you wne out too hard on the front half of the marathon!? A blow up on the run is not always from riding too hard. It could be from not running enough, not many mnetion that…
But for sure if you lost 12 lbs., you lost performance! That is for sure…
Thanks for the input. As for the run, my marathon PR is 3:14 at Boston this year. My IM goal was 3:40 which I thought might be 1:45 and 1:55. I think the run blow up had more to do with dehydration than other factors, but who knows.
The prior poster (skeeter) is absolutely right that not all run blowups are the product of too much effort on the bike. Many an IM has been hurt in the first 10K of the run. Now that being said, I can see some indications of too much effort too early on the bike. As you noted, the diminishing power numbers are potentially troubling, but if you deliberately tried to ride a tad harder early, that would be expected. I see two signs that the early efforts were a bit too pronounced. First, your Variability Index (VI) goes up a good deal from 1.02 in the first section to 1.06 in the last section. These numbers are great in general but whenever VI increases significantly, I wonder if the rider was getting tired toward the end of the ride. Second, could the early effort on the bike have limited your fluid consumption early in the ride? That seems like a lot of fluid to lose solely in the run. Just a couple of thoughts.
I agree with some of the other comments. Overall it looks like you did a good job of pacing on the bike, maybe a bit too hard on the first section as I believe an IF of .817 is a little high.
The other thing to think about was the first half run split. This may have had more to do with the tough second half than the bike. Running the first half at 3:32 pace may have been a bit aggressive based on an open marathon time of 3:14. For most athletes a 30 to 40 minute differential between an open and Ironman marathon really good. The higher pace early on may have also influenced fluid/food absorption.
Great race by the way! Hope this helps and you did a much better job at pacing than most Ironman athletes.
Out of curiosity and for a “dirty” comparison (I am aware CDA can vary greatly) how tall are you and what do you weigh? While I am at it, are there any ST members that have files for IMAZ that they’d be willing to “share”?
Thanks to all for the replies. I do think I was running too aggressively the first 4 miles, clicking along at 7:30-7:40 pace. Whether logical or not, I justified a bit quicker pace based on the flatness of the IMFL run course vs. the hills at Boston.