ASK DR. LOWE : Take precautions when exercising in hot weather
Posted on Sunday, August 12, 2007
Question: My 14-year-old son has just started football practice and is very excited. It's so hot and humid in August though and I'm worried he will get dehydrated. What can I do to help protect him from getting a heat injury ?
Answer: You are right to be concerned. Arkansas is known for its hot summers and high humidity. These factors will certainly lead to problems with the heat unless precautions are taken. The three most common heat injuries are Heat cramps. These are painful, persistent muscle cramps (usually in the legs ). In the case of heat cramps, exercise should stop and the child should rest in a comfortable position with a general massage and stretching of the affected muscles. Most importantly, drink fluids.
Heat exhaustion. When exercising in the heat, an athlete can sweat profusely; body temperature may increase to 104 degrees and significant dehydration occurs. These children can have nausea, dizziness, vomiting and mild confusion. The child should be moved to a cooler environment with vigorous re-hydration, using oral fluids, ice bags, fans, etc. to cool and decrease body temperature. If the child does not respond promptly, he should be treated as a medical emergency.
Heat stroke. Heat stroke is an acute medical emergency due to extreme body heat because the body's mechanisms, especially sweating, to reduce heat have failed. Body temperature may be more than 105. Symptoms are more severe than heat exhaustion, and are more severe with prominent mental changes and perhaps shock. Cooling and re-hydration should begin promptly. A child with heat stroke should be immediately transported to an emergency medical facility. Occasionally, heat stroke is associated with death.
Children's bodies are less efficient in controlling body heat and the normal body mechanisms to control heat such as radiation, convection and, in particular, sweating. Those mechanisms may become overwhelmed and ineffective more quickly. High humidity, in particular, retards sweating. Inadequate intake of fluids, or loss of body fluids, is the most important thing to watch since dehydration is the underlying cause of all heat-related injuries. As a rule, these heat-induced injuries are preventable if coaches, parents and children are aware of the hazards of exercise in hot, humid climates and know what to do.
Hydration - Your child should be well-hydrated before physical activity starts and during the activity. Periodic drinking every 15 to 20 minutes should be enforced. Fluids should be chilled, which provokes gastric emptying and stimulates thirst. Water is a good choice but if flavoring and additional electrolytes are added, they stimulate thirst and encourage further oral intake. This is particularly important because children frequently do not feel the need to replace their fluid loss. Sports drinks are generally excellent (ask the coach or your physician ); however salt tablets should not be used. The new fad of power drinks should be completely avoided in athletics. It takes a fair amount of fluid to maintain body weight during exercise, for instance, an 88 pound child should drink five ounces and an adolescent weighing 192 pounds should drink nine ounces every 20 minutes or so, even if they do not feel thirsty. A good way to make sure your child is drinking plenty of fluids is to weigh him before exercise and after. If he has lost more than five percent of his body weight, he is not maintaining adequate fluid intake during exercise.
Acclimatization - Most children have essentially been in air conditioning and must be acclimatized to the outdoor heat. This is also true if the child has just moved to a warmer climate. The intensity and duration of exercise should initially be limited and gradually increased over a period of 14 days.
Clothing - Clothing should be light-colored and light weight and limited to one layer of absorbent material. Sweat-saturated garments should be replaced by dry garments. Rubberized sweat suits should never be used.
Environment - It is harder for the body to control heat when the temperature is higher, especially when humidity is high. Limiting activities in excessive heat and humidity is essential to athletes' safety. Coaches and parents should decrease or stop practices during periods of excessive heat and humidity. There is an index of climatic heat stress utilizing temperature and humidity that can be measured and provides coaches and trainers a guide as to potential heat injury. (American Academy of Pediatrics Sports Medicine Committee: www. aap. org )
Children should be encouraged to exercise and generally sports are a tremendous outlet. Nevertheless, problems can occur in our Arkansas heat, particularly associated with high humidity. If children, parents and coaches pay proper attention to hydration in particular, along with duration of exercise, rest breaks, acclimatization and proper clothing, these problems can be avoided. More information can be obtained from the American Academy of Pediatrics (AAP ) and various sports organizations, and you should certainly discuss these issues with your school and coaches.
Dr. Betty Ann Lowe is an Arkansas pediatrician, past Medical Director of Arkansas Children's Hospital in Little Rock and professor emeritus at the University of Arkansas for Medical Sciences. Questions for Dr. Lowe may be sent to askdrlowe @ archildrens. org.
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