It's been the coldest spring in memory, but upcoming races may be quite hot, and few are acclimated. What are the best ways to prep for hot race conditions when your training hasn't really prepped you for it?
Excerpts from the 2003 US Army Ranger and Airborne School Student Heat Acclimatization Guide:
How do you become heat acclimatized?
a. Heat acclimatization occurs when repeated heat exposures are sufficiently stressful to elevate body temperature and provoke perfuse sweating. Resting in the heat, with limited physical activity to that required for existence, results in only partial acclimatization. Physical exercise in the heat is required to achieve optimal heat acclimatization for that exercise intensity in a given hot environment.
b. Generally, about two weeks of daily heat exposure is needed to induce heat acclimatization. Heat acclimatization requires a minimum daily heat exposure of about two hours (can be broken into two 1-hour exposures) combined with physical exercise that requires cardiovascular endurance, (for example, marching or jogging) rather than strength training (pushups and resistance training). Gradually increase the exercise intensity or duration each day. Work up to an appropriate physical training schedule adapted to the required physical activity level for the advanced military training and environment.
c. The benefits of heat acclimatization will be retained for ~1 week and then decay with about 75 percent lost by ~3 weeks, once heat exposure ends. A day or two of intervening cool weather will not interfere with acclimatization to hot weather.
How fast can you become heat acclimatized?
a. For the average soldier, heat acclimatization requires about two weeks of heat exposure and progressive increases in physical work. By the second day of acclimatization, significant reductions in physiologic strain are observed. By the end of the first week and second week, >60 percent and ? >80 percent of the physiologic adaptations are complete, respectively. Soldiers who are less fit (APFT run times >15 min) or unusually susceptible to heat may require several days or weeks more to fully acclimatize.
b. Physically fit soldiers (APFT run times <14 min) should be able to achieve heat acclimatization in about one week. However, several weeks of living and working in the heat (seasoning) may be required to maximize tolerance to high body temperatures.
What are the best heat acclimatization strategies?
a. Maximize physical fitness and heat acclimatization prior to arriving in hot weather. Maintain physical fitness after arrival with maintenance programs tailored to the environment, such as training runs in the cooler morning or evening hours.
b. Integrate training and heat acclimatization. Train in the coolest part of the day and acclimatize in the heat of the day. Start slowly by reducing training intensity and duration (compared to what you could achieve in temperate climates). Increase training and heat exposure volume as your heat tolerance permits. Use interval training (work /r rest cycles) to modify your activity level.
c. If the new climate is much hotter than what you are accustomed to, recreational activities may be appropriate for the first two days with periods of run / walk. By the third day, you should be able to integrate PT runs (20 to 40 minutes) at a reduced pace.
d. Consume sufficient water to replace sweat losses. A sweating rates of >1 quart per hour are common. Heat acclimatization increases the sweating rate, and therefore increases water requirements. As a result, heat acclimatized soldiers will dehydrate faster if they do not consume fluids. Dehydration negates many of the thermoregulatory advantages conferred by heat acclimatization and high physical fitness.
Also, hopefully you have some historical knowledge of yourself as an athlete. Possibly with a race report or two to draw from in 2012 as one of the hottest years in recent memory.
One of the key pieces of information I try to document in every race is my nutrition and hydration consumed. On my more thorough race reports I documented the weather conditions. How you as an individual have successfully dealt with nutrition/hydration in various conditions in the past is the best information to draw from for similar conditions in the future.