Managing Heat and Limiters in Kona

January 20, 2017

D3 Staff



IM Hawaii is unlike any other IM. I raced there in 2001 and was not happy with my race but looking back on my limited experience and knowledge at the time I think I did ok. In 2005 I should have had more experience but I made every mistake possible and had to walk it in on the second half of the run. I’ll just call that one a complete lack of respect for the course and conditions.

My reason for wanting to race in 09 was that I needed to find something in triathlon that would really challenge me. Kona seemed like the puzzle that I had not figured out yet. My preparation for 09 was going well but work commitments got in the way two weeks from the race and there was no way I could make the start line. I was bummed for sure but the positive was that it made me motivated and hungry for success in 2010.

So now I was looking at a full year to prepare myself for Kona. Since 2005 I had learned so many things about my racing. The most important was that my sweat rate was the highest I have come across. I have measured as high as 96oz per hour on an 85 degree day. At least now I knew why I struggled in hot races.

Over the winter I did as much research as I could on racing in the heat, sweat rates, core temperatures etc. I didn’t even realize how much a high core temperature can slow an athlete not only on the run but the bike as well. With more blood going to your skin for cooling that’s less blood for your muscles, which means less oxygen and a slower pace. I read everything I could find that Torbjorn Sinballe has written on the subject. I identified what my limiting factors would be for Kona 2010, high sweat rate, high core temperature and liquid absorption.

The Athletes Stomach

For my high sweat rate I learned that an IM athletes stomach would only absorb about 45oz per hour. Experts disagree somewhat on this number but most are in that 40-50oz per hour range. I did figure out that my sweat rate on the bike is not as high as the run, so I planned to be able to come off the bike mostly hydrated. As long as I didn’t go too hard.

Curt Chesney

Since I would need so much liquid on the bike I planned to get all my calories as liquid. Drinking 200oz and eating solid food in a 5hr period would have trashed my stomach. I kept track of everything I drank and ate on my key training sessions. I used this info to see a pattern develop for what worked the best.

Once the summer heat settled in I was fine tuning my nutrition plan. I experimented with increasing my calories and realized that 400/hr on the bike was the max my stomach could deal with at IM intensity. My runs off the bike I really had to practice getting in max liquid even if I didn’t need it to get thru a session. Even a short 20-30min run off the bike would include drinking 20+ oz of race day mixture. I even did some one hour brick runs where I slammed 30oz in the first 20min just to train my stomach. If I could do more in training than I needed in the race then race day would be no problem. I even figured out which bottles would deliver the most liquid the easiest.

Core Temperature

My core temperature was my other limiting factor. I had learned that being acclimated would be the one thing that would help me the most with the heat so I arrived almost two weeks early.

Once In Kona I experimented with some cooling clothing and didn’t notice any difference so I went with the old school skin suit I had been racing with. Practicing to stay cool was difficult. On some of my brick runs in the heat I would either carry bottle of ice water to dump on my head or run a one mile loop from my house using my garden hose to dowse myself every loop. I did notice a big difference in how I felt. On actual race day I took a minimum of one cup of ice at every aid station.

In my previous 15 IM’s I have never done anything to keep my core temperate down and stay cool. On the bike I opted for a vented helmet rather than aero and got fully doused at every aid station.

I entered T2 hydrated, relatively cool and ready to run. Keeping my effort easy to moderate was probably the most helpful. Even on sections of the run where I felt good I kept my pace easy. I certainly could have run parts faster but the risk would have been too high. Managing the day is way more important than taking risks when circumstances can flip on your so quickly on the Big Island. 

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