Normal Physiology
1. Increase work of muscle and metabolic rate produce heat and an increase in body temperature.
2. Vasodilatation and increased blood flow to the skin lead to a dissipation of heat.
3. Adequate hydration is an important component for heat dissipation.
4. Evaporation of sweat plays an important role in lowering body temperature.  The process of evaporation causes loss of fluids and electrolytes.
5. High humidity and ambient temperature interfere with the bodyís mechanisms to lose heat
6. Children have greater heat production during exercise compared to adults
7. Children have less efficient adaptation to exercise and less ability to lose heat by sweating.
8.Children have a greater surface area to body ratio
9. When the air temperature is greater than 35 C, children have lower excercise tolerance.

Heat Cramps
1. Usually affect the hamstrings and calve.  May feel mass in the muscle
2. Treat by supplying fluids and electrolytes and mild stretching

Heat Exhaustion
1. Usually temperature < 40.5 C.
2. The patient is sweating and may be volume depleted
3. Pale, dizzy, syncope, nausea, headache, malaise
4. May have increased heart rate and decreased blood pressure
5. Treatment includes rest, lying with legs elevated to enhance venous return hydration, remove clothing, and place in cool environment

Heat Stroke
1. This is a medical emergency
2. Temperature > 40.5, mental status changes, confusion,
3. Classically, skin is often warm and dry.
4. Sports related heat stroke may be associated with profuse sweating resulting in vasoconstriction and the inability to dissipate heat
5. There is release of endotoxins, and cytokines leading to end organ damage, possible DIC, and rhabdomyolysis

6. Treatment
     a. Fluids
     b. Cool rapidly
     c. Remove clothing and place in cool area
     d. Ice packs, spray with cool water, use fans to help cooling
     e. May immerge in ice water or ice bath

7. Prevention
     a. Training- with time there may be acclimatization to the environment
     b. Highest risk in overweight individuals, very young, and elderly
     c. Wear proper clothing to allow the skin to breathe- shorts, T's, meshed tops.
     d. Drink even if not thirsty during practices.  There must be mandatory water breaks and weighing of athlete at start of practice to track loss of water
     e. Leave the head exposed to allow heat dissipation through the scalp  At frequent breaks remove the helmets in football
     f. Avoid use of drugs
     g. Have individuals around to organize activities and breaks and be able to recognize signs and symptoms of heat related illnesses.