Introduction
Heat acclimatization confers biological adaptation, including thermoregulatory (body temperature), cardiovascular, fluid-electrolyte, metabolic, and molecular responses. Repeated heat exposures invoke profuse sweating and elevate whole body temperatures. Heat acclimatization usually requires 90 minutes of daily heat exposure for one to two weeks. To acclimatize individuals, one must adapt to a gradual increase in temperature and exposure for seven to fourteen days. New workers need more time to acclimatize than the workers who have already had some exposure.
What Is Acclimatization?
Acclimatization is a physiological adaptation that occurs during repeated exposure to hot environments. The physiological adaptations include:
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Increased sweating efficiency.
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Stabilized blood circulation.
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Ability to perform work with lower heart rate and temperature.
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Increased blood flow.
What Is the Acclimatization Schedule?
There should be a gradual increase in temperature and exposure for seven to fourteen days.
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For new workers, who have not been exposed previously, the schedule should be no more than 20 percent exposure on the first day. With each additional day, there should be less than 20 percent exposure.
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For previously experienced workers, the acclimatization schedule should be no more than 50 percent on the first day, 60 percent on the second day, 80 percent on the third day, and 100 percent on the fourth day.
However, each individual's acclimatization level is proportional to physical fitness and total heat stress.
What Is Heat Acclimatization?
Suppose a healthy person is given enough time to adjust to heat, access to shade, appropriate water, and other basic facilities. In that case, he or she can tolerate prolonged exposure to heat or any other naturally occurring heat stress. Heat stress results from interaction with natural environmental conditions such as solar radiation, temperature, humidity, or physical work, and wearing heavy clothes and equipment that leads to heat loss.
Physical exercise and heat stress interact proportionally, increasing strain on the body's physiological system. For example, exercise (or physical activity) in a warm environment induces elevated body temperature, altered metabolism, and cardiovascular strain.
Thus heat acclimatization is necessary to confer biological adjustments that can reduce all the adverse effects and impacts of heat stress.
Heat acclimatization develops through repeated natural or artificial heat exposure that is sufficient to elevate body temperature and induce profuse sweating. The magnitude of biological adaptations largely depends on duration, intensity, frequency, and the number of heat exposure. Even resting or exercising in heat allows acclimatization. Optimal heat acclimatization requires daily heat exposure for about 90 minutes (up to two hours) and aerobic exercise. Athletes should gradually increase the exercise duration and intensity or the heat exposure daily to acclimatize. However, heat acclimatization disappears if continuous exposures do not maintain it.
What Are the Benefits of Heat Acclimatization to Athletes?
Heat acclimatization has shown the following benefits such as:
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Improved thermal comfort.
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Improved sweating and skin blood flow response.
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Improved cardiovascular stability.
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Better fluid-electrolyte balance.
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Lower metabolic rate.
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Improve exercise capability.
What Are the Three Classical Signs of Heat Acclimatization?
The three classical features of heat acclimatization are:
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Lower heart rate.
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Lower core temperature.
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Higher sweat rate.
In addition to this, skin temperature also decreases, and sweating starts early. Sweat glands become resistant to fatigue and can sustain higher sweat rates. The more sweat, the more the evaporative cooling and thus reduced body temperature and heat storage. Lower skin temperature decreases the cutaneous blood flow required for maintaining heat balance and facilitates venous compliance so that the blood is redistributed from the peripheral to the central circulation. All these factors ultimately contribute to reducing cardiovascular strain and enhancing better performance.
Fluid balance improvements can result in better fulfillment of thirst to body water needs, increased blood volume, and total body water. An unacclimatized person may secrete sweat with higher sodium concentration. If they sweat profusely, it can lead to the loss of large amounts of sodium.
With heat acclimatization, the sweat gland conserves more sodium and ultimately contributes to increased total body water. Athletes must ensure that they consume enough water and salt to prevent dehydration, particularly in acclimatization.
What Are the Various Strategies for Heat Acclimatization?
Most strategies for heat acclimatization were developed for military or occupational settings and not for competitive athletes.
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Start Early:
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Focus on physical health before initiating heat acclimatization.
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Start at least three weeks before the competition.
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Be flexible and patient.
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Give enough time to a heat exposure routine.
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Mimic the Competition, Climate, and Task Routine:
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Perform practice during the cooler part of the day and acclimatize during the afternoon.
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Put on cotton sweatpants.
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Follow an exercise routine and mimic future competition conditions.
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Ensure Adequate Heat Stress and Recovery:
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Induce profuse perspiration.
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Exercise for a minimum of 100 minutes in the day.
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Gradually increase the intensity and duration of exercise and heat exposure.
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Stay Hydrated and Eat Adequately:
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Focus on the thirst mechanism.
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Consume sufficient amounts of water to avoid dehydration.
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Emphasize eating foods and drinks containing electrolytes.
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Do not skip meals.
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How Quickly Does the Body’s Heat Tolerance Deteriorate Following Acclimatization?
• Acclimatization will be sustained for a few days after heat exposure ends but will begin to deteriorate after about one week of not working in the heat.
• After one month of not working in the heat, most people's heat tolerance will have been restored to normal.
• Working in cooler circumstances for one or two days or taking breaks in air conditioning will not hinder acclimatization.
Conclusion
Heat acclimatization is a biological adaptation that emphasizes improvement in heat tolerance that comes from a gradual increase in the duration and intensity of work performed in hot settings. It reduces physiological strain, improves comfort and exercise capacity, and reduces the risk of related heat illnesses. The best way to acclimatize is to gradually increase the work performed in hot settings. Heat acclimatization usually takes seven to 14 days of daily exposure for 100 minutes. The best results come from gradually increasing the time, duration, frequency, and number of exposures. Dehydration is seen to reduce the benefits of heat acclimatization. Things to keep up with include maintaining hydration and electrolyte balance and eating right without skipping meals.
