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An Alternative Bike Pacing Strategy for a Hot and Humid IM

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  • Mike - I agree the 2 systems interact , and both come into play often at the same time just to differing degrees. My intent above by using the extreme cases was to try to highlight that there are 2 systems and the fact the solely focusing on muscular pace limits will likely set levels that you cannot maintain in high temp environments.
  • Rich- your warning is noted. being my first year with EN, these are the mistakes that I'm still gravitating to. gotz til Oct 9th to get these last wrinkles ironed out. thx.

    Matt- intense work. you're providing more ammo for the execution of a solid race day (versus the merciful execution of the athlete that doesn't account for these factors).

    More EN kits in 'not slowing down mode' passing many others stretching & retching on the curb.

    Thx guys.
  • And to second what others have said....

    Cool the neck and chest (see Macca's sponge boobies, famously photo'd)
    cool the radial arteries (underside of the wrist, notice the latex or similar gloves being worn these days, Torbjorn, and stashing ice in them as often as possible)
    dump the ice in the short to get the femoral's (don't try this before the sex)

    Problem: As Chris G said, not alot of ice or ice sponges on the bike course. Sux cuz, clearly, that's when I start cooking.

    Sorry, Matt, if that was another tangent to your op.
  • Matt, there is a third factor which IMO is the key. It is the circulatory system, more precisely, the ability of the blood to bring oxygen and fuel (both carbs and fat) to the muscles and their inernal energy factories. This becomes the limiter when the temp gets over 82-87, again IMO. At a temp of 90, you have plenty of power generating capacity in the muscles, as you note. What you don't have enough of are the raw materials (O2 and CHO and lipids) to generate the power on a sustainable level. If you try to rev up your muscles over their steady state activity, you'll start to use up the internally stored glycogen (because the circulatory system insists on givingyou less O2 and fuel), and once that's gone, it's gone, and you can't replace it in a race environment. Bada- Bing, bada-bang, bada-bonk.

    So the solution is to keep operating at whatever the steady state power level is, given the decreased blood flow (and thus lowered O2 and Fuel) when cooling requirements shunt more blood to the skin to off load the inernal heat. Your body is not trying to save its muscle (although you might look up rhabomyolysis in hot environments, just to get a little scare); it's really trying to keep the brain, kidneys, and liver from being fried and failing.

    So, the old rock and hard place. When your core temp goes over a critical number, and the outside temp forces the circulatory system to increase skin blood flow, you seem to have two choices: keep at the same power level (say, 0.72 IF) and start using up your stored fuel (muscle protein and glycogen) which you can't replace, setting up a crash at some point, as well as risk increasing your core temp above a safe level, or slow down to whatever steady state the reduced CHO and fat allows your muscles to operate at. You really have no choice.

    You're trying to figure out some metric(s) which will guide you in slowing down. When the temp starts going north of 84, I humbly offer again the combo of RPE first, with HR as a confirmation: sense of effort is staying the same, but HR and temp are rising, while IF is going down. Good luck on finding the perfect formula. Maybe you can swallow one of those little themometers researchers use, and get a constant read out of your core temp? But even for that to work, you'd need to do some testing to see what your critical temp is in the real world race environment, and combine it with some ability to measure increasing blood flow to the skin.

  • @ Al – Your point about the significant stresses on the fueling system(s) as heat increases is an excellent point. In the hot conditions even when core tamp has been maintained below threshold we see major blow ups form GI track issues and or a complete bonk due to no energy left.



    I think I have something simple that will help us pace in these environments – it explained my bike pacing actuals for 5 IM length rides in the heat. I am working on the post and will get my revised IM LOU plan and the supporting info up by tomorrow.  AL,  the results confirm your point that RPE is a solid metric in these situations



    A neat by product of this is a FTP test xls that will normalize your power back to a 60 degree base. I took my last FTP test which was at 90 degrees HI and when I was done I missed my targets significantly. Mentally was not in a good place. I put those watts by interval into this new tool and that test was very close to the power levels I should have put out! Mentally in a much better place.

     

  • Ok what have I learned in the last few days? Well for one thing I now am mentally in a good place with a better understanding as to what my power levels do in the long rides in the heat. I used the curve from the 30 min TT data I referenced in my original post and took the resulting equation and went back into my actual rides to see what this formula would say about my IM distance rides in the heat. Below are the results from IM LOU 2010, RR#2 for 2010 (IMCDA was 3 weeks before so no RR1), and my RR#1 and RR#2 this year. All these rides were in 80 – 107 degree heat index.

    The table following these comments will help in understanding of these points.

    A couple things come to light in the review of my prior 112 mile rides with the help of this tool.

    First – using normal pacing strategies, in a hot environment I end up with a bike of 0.2 IF points below what my plan was for the ride. At the end of each of these rides I was always mentally a bit down / frustrated that I did not hit my planed levels. The 0.2 IF points was a consistent issue if the ride temp went above 85 degrees (Al you and I agree - - this is seems to be an inflection point on temp).

    Second – the body is an amazing system that controls the amount of work via RPE levels to keep things on a relatively consistent temperature based view of the effort. Looking at the Heat Impacted Effective IF for each of the rides, the body’s regulatory systems reduced power levels to produce relatively consistent Heat adjusted IF levels within in the ride. In all cases the variation in the actual ride IF was significantly above that of the Heat adjusted IF. I think this more consistent level of heat based IF, is a phenomenon that is a result of the interaction of the multiple physiological systems impacting output that were discussed above in the thread. Learning – the body is a smart system with 100,000’s of years of learning’s coded into it – listen to it!!!!

    Third – I got a sense for my upper range of temperature impacted IF and TSS numbers that I could run off of. These will be used as a sanity check when I design my target race day pace strategy for a hot day.

    Fourth - Our couches are extremely smart and there guidance to go easy on the bike to have a good run is a prime factor in setting race day pace plans. Note to self, lower bike from “could to should”.   What reinforced this was in a review of info out on the net on bike power levels for an IM. Patrick of the 30+ power files I looked at for Kona, only 1 did not have a decreasing power curve and those that had temp data show the direct impact – of as temps went up they slowed down. The following 3 blog posts reinforce the message from our coaches and give some interesting guidance on how to split your energy between the bike and the run.




    The following tables are for my recent 112 mile rides with the actual watts and IF levels by time interval and the actual temperature and the resulting temperature impacted effective IF view.

     

    Ok so with my new learning’s, how should I best pace IMLOU 2011 based on last year’s temperature profile. I started with my overall pace objective of a .70 IF level. This should give me a TSS of 275 in the 3hr 35 mins that I estimate will be the result of that effort level. I start with our typical EN pace protocol of start slow for the first hour and then build and hold for the duration with a slight reduction in the power at the end to spin the legs into a good mood for the run. I put this info into the Heat Adjusted Bike Pacing sheet and added the Heat Index levels for each time period and I get the following results.

    So to hit my .70 IF overall level, I scheduled my effort as follows:  68% pacing for the first hour, a steady 71 % for hours 2-5 and a reduction to 68% for the last 35 min. What the Heat adjusted view showed was that due to the increasing temperatures, the Heat Adjusted IF on the back end of the ride was significantly higher that the front of the ride. The .77-.78 Heat adjusted periods are not maintainable with a reasonable RPE. This is where the power levels drop and I develop the IF gap of .02 to my overall target by the time the bike is finished.

    Next, I adjusted my IF targets for the intervals to try to level load the heat adjusted effort.  The hope is that by using a heat base pace view which paces our effort in relation to the impact temperature on our systems is that when I plan to execute a .70 IF bike segment that I actually execute a .70 level not a .68. The review of my historic 112 mile rides gives me a reference to what level of heat adjusted IF will support a run and what levels are too fast. I see I don’t want to go to the .78 – 80 temp adjusted levels. Also add in the don’t go to hard on the bike mantra. These factors mixed together produced the following pacing strategy.


    I see a resulting total IF of .694, which is close to my target of .70. My heat adjusted IF is relatively consistent through the day and lowers the power as the heat builds. This is a reality which I now understand and accept. Also not that the IF variation in the Heat Adjusted view is reduces from 9% in the base pacing view to 6% in the new pacing strategy. This is a 33% reduction in the heat based effort variability for the ride. We know riding steady is a good thing!

    So give all of the above – WHAT ARE THE BENEFITS of this strategy vs. the traditional one I started with. I believe it is worth .02 IF points based on my historic results. .02 IF points = 5.3 watts for my FTP level.   In a 112 5.3 watts is ~3.5 min faster bike. Also assuming that the Heat Adjusted Effective IF numbers are a direct impact on core temperature, the new pacing strategy lowers these levels for the lasts 3.5 hours of the ride. I should end up with a lower core temperature to start the run. Is this free speed?

    A byproduct of this is a Heat Index Adjusted FTP test sheet. This sheet takes the same heat impact curves and applies the impact to a FTP effort for temperatures above 60 degrees and calculates an equivalent performance at 60 degrees. The need for this came out of my frustration of training in the ST. Louis heat this summer and going out to do a FTP test in 90 degree temps. I started strong, first 10 min on target, the next 10 were a bit lower at a much higher RPE. After the 2 min rest things went from not pretty to ugly for the last 20 min. I finished and was upset with my numbers – you wimp!!! I knew I was stronger that the numbers showed by they were the numbers. Well the results below take the 244 watts as ridden but when adjusted for heat index give a value of 264 w.   I feel much better now!!!

     

    Attached is a spreadsheet that has a tab for Heat Adjusted IF calculations, a tab for FTP calculations and a TAB with my reference data.

    I’m my quest to race smarter, I think I am continuing to learn and this Heat Adjusted IF view may be a another small edge. 

    As a side note - One thing the discussing in this thread reinforced to me is the need to manage core temp from the start of the day. Don’t wait until you are hot to start to worry about getting cool!

    Stay cool – Bike should not could to run fast!

    Matt
  • Matt, you have totally overwhelmed me with this info...great stuff and I think we'll know a lot more once you have put it into practice on the big day. In my comments re Kona, I wasn't saying that the only reason the elites back off is the pack (heat affects us all), but having negative split that course for three straight years with my best power in the last hour of each year, I know it can be done...but since it's the only race that matters, these guys are on it right out of the gate.
  • Patrick, yes l look forward to seeing how race day plays out. The temps are lining up to be warm and humid, not as bad as last year – Darn!

    On Kona, I was surprising to see how consistent the decreasing power profile was for the pro’s. There is no doubt in my mind that you execute the bike better that most of the pros! It’s good to hear that Kona can have a building power profile if executed right!
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