Tag Archives: fluid intake

TT062: Hydration & Heat Prep From a Hot Ironman Lake Placid and Mont-Tremblant

Canadian Allan MacKenzie recently completed Ironman Lake Placid and Ironman Mont-Tremblant in hot conditions.  We talked about that experience and his heat and hydration questions following the race.  I answer his questions from my own knowledge, but I also add George Dallam’s answers.  

George, a guest on episodes 3, 4, and 25,  is a professor at Colorado State University in Pueblo.  He was the first USA Triathlon National Teams coach and he coached Olympic triathlete Hunter Kemper.  His answers were originally in response to my email, and he allowed me to publish his email here.

Each of Allan’s questions is listed below, and George’s answers follow.

  1. For someone who doesn’t have the opportunity to train much outdoors in high temperatures, what are the best ways to be prepared if race day ends up being really hot?

Acclimate – hot tub, sauna, indoors with heater/humidifier, any stationary training as well. It is all about producing a high sweat rate.

Here is the link to George’s two week hot tub protocol –http://triathletetraining.com/heat-acclimation-protocol/

  1.   How long does it take to get acclimatized/prepared to race in warmer than normal temperatures?

Even one session can help and you can probably maximize over as little as 2-3 weeks with daily sessions.

  1.    Other than adding more sodium to my diet, are there other things I can do with my diet to help get better acclimatizes to the heat?

I’m not an advocate of adding more sodium to the diet, just the opposite.  The currently in vogue notion that “salty sweaters” need more sodium ignores the underlying issue.  Salty sweaters are inevitably consuming more sodium than they realize so the body must constantly excrete the excess.  By reducing sodium in the diet your body will improve in its ability to preserve sodium over time..  Further by greatly increasing your sodium intake over normal in a given racing situation you probably increase the risk of heat stroke – sodium reduces our sweating capacity by holding water in the vascular and interstitial spaces.  The best approach to heat tolerance is appropriate acclimation and a low salt diet in my estimation.

  1.     What are your thoughts on using arm coolers and/or knee coolers to help to stay cool during races?

Pre cooling to lower the core temperature prior to a hot race is certainly very useful.  If you can create a cooling effect on the fly that is certainly useful as well.  However, to do so means carrying extra weight in most cases in the form of a cold solution or ice.  The idea that any clothing enhances cooling in comparison to what the bare skin can accomplish during periods of heavy sweating is misleading.  See this review.  http://link.springer.com/article/10.2165/00007256-200333130-00001#page-1 Some fabrics are relatively more cooling than others (cotton versus wool for instance) but all limit cooling to some degree by  inhibiting the evaporative cooling process in some manner. Maximum skin exposure provides the greatest surface area for sweating and the resulting evaporative effect created as air moves past the body.  The thought with white reflective clothing is that you might avoid radiant heat gain, however the loss in evaporative cooling potential offsets that possible effect.   Of course wearing or not wearing clothing must also be considered in the need for limiting UV exposure and for creating both aero and aquadynamics.   Consider, however that shaved body parts are often nearly as aero/aquadynamic as fabrics designed for the purpose and shaving further increases the potential for evaporative heat loss.  Basically in the heat you should wear the minimal clothing necessary or required and it should be white or light colored.

Very likely your arms and legs have sufficiently keratinized  (tanned) through normal training exposure so that you shouldn’t need to cover them with clothing to prevent sun burn – doing so will reduce your evaporative cooling potential.

5.  And what is your opinion on salt tabs?

See above – this is a worst case scenario.

  1.      When I raced Ironman Mont Tremblant (MT) this year I didn’t pee during the bike portion at all.

That is an obvious indication to me that I was dehydrated. I’m don’t think it had a significant effect on my bike, but I feel it adversely effected my run. Usually I have a good gauge on this and am often guilty of drinking too much. What would you recommend to help prevent this from happening again?

Some relative dehydration can actually be beneficial to performance (although less than ideal when it comes to the possibility of thrombus formation) because you are simply lighter.  This might be true up to about 2% loss in body weight – possibly more if you train in those conditions.  The primary key to maintaining hydration is to drink fluids that are isotonic (similar salt concentration to your body fluids)  – this approach maximizes absorption at the gut and reduces the tendency for diuresis during the race (you’d really rather not pee if possible).    I would drink on schedule in small amounts if you want to prevent dehydration based on your typical weight loss (2 cups per pound). Something like traditional Gatorade cut in  half with water gets you there – most conventional “salty” drinks have way more salt than is present in the blood stream.  I would use Tim Noakes advice and drink to thirst if you want to allow for a little normal dehydration.   If you have had a reason to believe that you are at risk for thrombus formation I would take the first option and stay hydrated when training and racing.   You can also pre-hydrate pretty effectively using a glycerol solution if you have great concerns for dehydration.

  1.       I wore a visor in Lake Placid (LP), but opted for a hat during MT (so that I could put ice under my hat to try and stay cool). Which do you recommend for a really hot day?

Ice under the hat is effective on the fly cooling strategy – see above.

  1.       I have fair skin and usually need sunscreen to prevent getting a burn. In LP I applied it in the am before the swim and again in T2. I planned to do the same in MT, but I forgot to do so in T2 and I think this really played a role with my run time. Does a sun burn have a significant effect on my ability to stay hydrated?

Interesting question.   I’m not aware of any direct effect of sunburn and/or sun screens on evaporative cooling potential.  However, a quick search reveals the following studyhttp://search.proquest.com/openview/3ca96ce6df9654a03c18b6e0cb47d8bd/1?pq-origsite=gscholar which suggests no negative effect of wearing sunscreen and a possible type II statistical error – suggesting there may even be a small positive effect through an improved temperature gradient (core to skin temperature differential) which the study failed to find probably due to too few subjects or the fact that the difference were so small.  You might also experiment in training with sunscreens that are more water resistant – Bull Frog comes to mind – so you can avoid reapplication after the swim.