Heat management or how to race when it's hot out.

It's getting hot out. Based on the theory of Global warming, it's getting hotter. So whatcha gonna do? Ok, maybe you can deny Global warming, but you can't deny the summer heat that is about to take place here in Mid-America. I'm talking 90s and an occasional trip into the 100s (32 to 37+ degrees Celsius).  There are several helpful tips to maximize your racing performance during high temperatures and they all involve heat management techniques listed below. 

The first and possibly one of the most important tips is to train/exercise in the high temperatures that you expect to race in.  The goal is heat acclimatization and will improve your ability to tolerate higher temps, feel more comfortable and most importantly be able to race better. A large portion of adaptation can occur within 3-4 days, but total effects are realized in 10-14 days.

Some really cool stuff happens in your body during this period. My personal favorite is plasma volume expansion resulting from increased plasma proteins and increased sodium chloride retention, ranges from +3 to +27%, and is accompanied by a 15-25% decrease in heart rate (Armstrong 1998). Cool stuff huh?

Here's why it's my personal favorite. After a sudden exposure to a large temperature gain last weekend, I suddenly gained 5-6 pounds about 2-3 days following the temperature change. The reason for this was a physiological adaptation to heat (or that 5 pound burrito from Chipolte's).  

My second tip is as important if not more and is just a little bit obvious: WATER! It's by far the biggest performance enhancer out there (and it's totally legal!!!).

There are tons of research to describe all the different aspects of this topic, but for pithiness I submit the following: Drink H20 until your urine is no longer dark yellow, but instead is lightly colored. Do not drink so much that you are peeing a lot and your urine is water clear (you absolutely can drink too much). For short criteriums (less than 1 hour) I think you can get away with 2 bottles of plain iced water (along with a normal healthy diet). For road races I strongly encourage a electrolyte powder such as "Hammer Endurolytes Powder", and some energy foods such as "GU" (I consume 2/hr). Drink one bottle every 30-45 minutes if possible. Evaporative cooling is KING!   Do spray water on your thighs and head. Pre-race pre-wet your jersey, shorts and hair (not groin area or shoes because of risk of rash and wet shoes are heavy rotating objects). For criteriums put ice packs in zip locks in your jersey pockets, combined with your circulatory system this will produce a heat exchange. Not to be redundant, but the reason for wetting your outfit is that as the water evaporates from your clothing/skin, and heat is taken away with the water,  which is 22 times more conductive than air. Keeping your tight fitting clothing wet can produce a huge cooling effect (with lower levels of humidity).  A loose flapping jersey will not transfer heat from your body nearly as effectively as a wet skin suit (this is a big deal actually).  Evaporative cooling is far superior to convective cooling.     Another trick is to consume an ice slurry before racing. This reduces core temperature and as a result increases your body's heat capacity and (most importantly) performance during high temperatures. 

Some other heat management tricks include wearing as little clothing as possible during racing.  I personally don't wear gloves, but if you do wear them, wet them.  Generally, I recommend not wearing large sunglasses or ANY if the conditions permit (they block heat transfer and evaporative cooling).  An exception may be when the face is exposed to direct sunshine (they can reduce radiant temperature in this case).    Additionally, try to avoid warming up on a trainer if at all possible.  Stay in the shade or  air-conditioning prior to racing and warming up.  Consider a very short warm up (again wet your clothing), then drink the ice slurry.

Click this link for greater information on thermoregulation, the body's basic responses to heat and humidity, fluid loss, clothing for exercise in the heat, and heat acclimation.  It's a pdf article written by Matt Richardson, and Stephen Cheung, entitled The Basics of Thermoregulation.

Some additional information:  A person should cease exercise if they begin experiencing heat exhaustion symptoms.  They include:  fatigue or weakness, nausea, headache, dizziness and can lead to worsening and additional symptoms.  Generally, once a person has experienced a heat injury their body is more susceptible to heat injury again.  (Perhaps this is the body's response to rising core body temperature to prevent it from overheating again by  making exercise unbearable).

Although training in heat is necessary for an adaptation to heat, there must be limits and restrictions.  I can not quantify this level. (variables include environmental temp., humidity, physical work load, cooling techniques used, subjects level of adaptation to heat environments).    High humidity combined with temperatures exceeding 90 can be potentially dangerous.  Duration and intensity of exercise should be shortened with higher heat index numbers.  I have read and believe that intensity of training trumps duration of training for athletic improvement or maintenance.  It could be feasible to split up a workout to a heavier exercise load in the cool of the morning a light short workout (or exposure event) in the high heat environment.
 


Remember, cooler heads prevail...... literally!  Stay wet my friends!

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