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Critically evaluate how issues associated with thermoregulation and dehydration influence athletic capacity during endurance events.

During endurance events prolonged muscular activity increases the body temperature of the athlete. Dealing with this temperature rise is the biggest challenge facing the athlete. As the body cools itself water is lost through sweat. It has been shown that this loss of water can decrease athletic capacity if not corrected. This essay looks at why thermoregulation and dehydration and its prevention are important in considering how best to keep endurance athletes safe and at peak performance during events.

The main factors influencing athletic performance during exercise are: technique and method; fuel supply to the muscles; and maintenance of the correct body temperature. In endurance events the most influential parameter from the above is the maintenance of correct body temperature. During endurance training athletes generate a large amount of heat; this is a result of the inefficiency of the conversion of the chemical energy in the muscles to kinetic energy. Only 25% of the energy produced during activity is used to create motion (MacAuley 2007). The remaining 75% is lost as heat. This heat is stored in the body and must be dissipated. For example, an athlete running for 50km at 16km/hr would expect to produce 9,240kJ of energy. Only 2,00KJ of that is used to propel the runner whereas 7,240 is spent creating heat inside their body.

There has been recent interest in the method of pre-cooling the body to enhance athletic performance. Pre-cooling involves reducing body temperature prior to an athletic advent using cool air, cold water immersion or ice vests. In reviewing the current research Marino (2002) concludes that in endurance events whole body pre-cooling can 'increase capacity for prolonged exercise at various ambient temperatures'. How this is achieved is not yet completely known. Evidence suggests that the benefits of pre-cooling are produced by the effects on the central nervous system.

During endurance events, maintaining core body temperature is required to keep the athlete safe. This is achieved by the body mainly through the loss of fluid through sweat and to a lesser extent via the respiratory membranes. As large amounts of fluid can be lost in preventing overheating, adequate hydration before during and after the event is of utmost importance. Dehydration has been shown to decrease athletic performance. The balance between correct hydration, dehydration and overhydration is a delicate one. Current guidelines favor aggressive rehydration before, during and after an event. However, recent research suggests that these guidelines are based on laboratory studies. Studies in the field suggest that an upper limit of hydration volumes is prudent to prevent overhydration, without a detrimental effect on performance.

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