Heat Acclimatization

With summer coming, let’s look at how heat acclimatization plays a vital role in modulating the body’s physiological responses and general ability to manage with exposure to heat. Heat acclimatization is an encompassing term that means a succession of adaptations that take place over seven to 14 days (with 75% of adaptations taking place the first five days), in an environment exposed to heat stress.  This is important for the regular and/or tactical athlete because it allows him/her to better manage heat stress. The beneficial adaptations that occur with heat acclimatization are:

·       Increased overall ability to perform in heat

·       Improved exercise economy  

·       Sweat onset (sweat starts earlier) and sweat rate

·       Increased plasma volume 

·       Decreased heart rate

·       Decreased skin temperature

·       Decreased core temperature

·       Decreased oxygen consumption requirements

·       Increased heat loss via skin blood flow (radiation and convection) 

·       Decreased perceived exertion

·       Improved blood pressure response

·       Decreased salt losses in sweat and urine

It is very important, however, to remember that the adaptations occur similarly to training adaptations because they are highly specific.  Acclimatization in hot and humid environments greatly increase sweat rates and perceived effort contrasted to hot and dry environments.  Acclimatization will additionally depend on exercise intensity and volume, and maintaining an elevated body temperature during training.  Prior to heat acclimatization, tactical athletes should have a base level of fitness because physically fit individuals acclimate to heat more efficiently.

Here are some heat acclimatization tips for tactical athletes:

·       Gradually increase the intensity and volume of training

·       Have four to 14 days of heat exposures prior to mission or deployment

·       Maintain heat exposure of at least 100 minutes daily

·       Be properly hydrated before, during and after training

·       Increase sodium in diet to make up for sweat salt loss