It is obvious that athletes who train in a colder environment and race in heat will suffer negative side effects if precautions such as heat training, proper clothing, correct nutrition, and proper pacing are not taken. The fact that many athletes do their training in the mornings/evenings rather than in the middle of the day with the sun high above also makes heat issues more likely to occur on race day.
Heat acclimatization fully develops after 7 to 14 days after training in heat. Any method to induce an excessive rise in body temperature during exercise will suffice, either by training in the highest heat of the day and/or wearing layers of clothing.
Heat acclimatization can be fully retained for about a week after the training ends and can last in some degree for up to a month.
The changes that occur during acclimatization are heart rate, body temperature, metabolic rate, rate of muscle and blood lactate accumulation, and sweat salt all decrease during exercise. The sweating rate increases due to the increased secretory capacity the sweat glands develop during training.
My 50 mile race on October 29th of 2011 will likely not be a terribly hot race. Being during the fall and at a very northern area of the United States. However, there is no doubt that the physiological changes I mentioned in the previous paragraph are a huge advantage whether the race be in a warm or mild environment. Unfortunately it will be rather impossible for me to tell if the heat training I will be participating in during the next couple weeks actually make a difference, but I suppose it can't hurt.
