Sports in the Summer Heat: A guide to preventing heat illness

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What is heat illness?

Heat illness is a spectrum of conditions which all result from physical activity in the heat. The temperature at which at athlete is at risk for heat illness depends on the athletes level of physical fitness, acclimation and preparation. Therefore it’s best to always keep an eye out for the signs and symptoms as these conditions can range in severity from a simple annoyance to severe life threatening conditions.

Heat illness is preventable. With proper hydration, preparation and knowledge of the signs/symptoms of heat illness athletes can safely enjoy their sport outside, even in the hotter months.

Are children and adolescents at a higher risk than adults?

It was previously thought that children and adolescents were at a higher risk for heat illness because their bodies were less efficient at regulating their body temperature. Recent research has shown that is not the case.

Children and adolescents may however be at a higher risk for other reasons. For example, some younger children may be less likely to notice changes in how they are feeling during vigorous activity as they are more easily distracted. Children may also be less likely to drink adequate amounts of water before, during and after play. In addition, adolescents or children playing highly competitive sports may be less likely to report symptoms for fear of embarrassment or disappointing their coaches or teammates. Taking these factors under consideration it is important that families and coaches encourage consistently encourage athletes to report early onset signs or symptoms of heat illness.

What are the risk factors for heat illness?

  • Hot and/or humid weather
  • Poor preparation: no heat-acclimation, poor pre activity hydration, lack of adequate sleep
  • Excessive physical exertion: lack of rest or recovery time
  • Multiple same-day sessions
  • Poor fitness, overweight/obesity, certain medications (alcohol, amphetamines, benzodiazepines, stimulants, tricyclic antidepressants, phenothiazines, some antihistamines and allergy medications)
  • Current or recent illness
  • Clothing, uniforms and equipment that contribute to heat retention

What are the signs and symptoms of heat illness?

  • Mild swelling in the extremities (hands, feet, ankles)
  • Heat rash is a red rash appearing in areas covered by clothing which is often itchy
  • Dizziness and generalized weakness which may improve with rest
  • Painful muscle cramps (often calf, thigh or abdominal muscles)
  • Heat exhaustion is a more serious form of heat illness which is characterized by a temperature of 98.6-104F, low blood pressure, elevated pulse, increased rate of breathing, dizziness, fatigue, nausea, vomiting, headache, flushed skin, profuse sweating (wet), cold clammy skin
  • Heat stroke is a medical emergency characterized by a temperature over 104F, symptoms similar to heat exhaustion plus mental status changes, hot skin without sweating (dry), confusion, irritability or coma-Call 911 this is a medical emergency!

If any of these signs or symptoms occur an athlete should report these to his/her coach or family member, move to a shaded or air conditioned area, remove excess clothing, lay down face up with their legs elevated and drink fluids.   Obtaining an accurate core temperature and assessing mental status are the 2 most critical measures to determine if emergent treatment is required.

Is there a treatment for heat illness?

Mild Heat Illness (heat cramps, edema, syncope, rash): Find cool shaded area to rest and hydrate. Lay supine with legs elevated.  Remove equipment/gear, prolonged light stretching for cramps, oral rehydration with sports drink that has electrolytes.

Severe Heat Illness (heat exhaustion, suspected heat stroke): Call for help.  Initiate immediate best accessible cooling measures.  Ice bath with temperature goal of 2 degrees C is most rapid cooling option.  Other options include cooling with wet towel and fan, ice to armpits and groin areas).  Oral rehydration and close monitoring by trained health care professional as emergent treatment will be necessary if heat stroke is suspected.

Heat Stroke: Call 911, monitor vital signs closely, immediate cooling measures (ice bath immersion) until emergency services arrive.

How do I prevent heat illness?

Acclimation preseason
Athletes should begin to slowly acclimatize to the heat over a 14 day period before beginning vigorous exercise in the heat. This can be accomplished by starting with mild activity and increasing the intensity.

For example, an athlete may begin acclimatizing at home 2 weeks before preseason practices by walking outside for 15 minutes the first day, slowing working their way to jogging or running outside for up to an hour at the end of 14 days.

Coaches may support players in acclimatization by scheduling initial preseason practices at a maximum of 1 hour per day for the first 5 days without high intensity activity, followed by a 2-1-2 practice schedule slowly increasing the intensity of activities over time.

Proper hydration
Athletes should be encouraged to increase their fluid intake before practice to pre-hydrate to minimize excessive fluid loss during physical activity. Do not minimize salt intake in the diet, encourage eating a balanced diet to maintain electrolyte balance.

During physical activity the following guide may be followed:

Children age 9-12 years: 100-250mL (3-8oz) of water every 20 minutes
Adolescents over 12 years of age: 1.0-1.5 L (approximately 34-50oz) of water per hour

To measure adequacy of hydration compare the athlete’s weight before activity and after activity, this will give you an indication of the amount of water lost during play. The athlete should replace this amount of weight lost by drinking water.

Monitoring urine color is another way athletes can monitor their hydration themselves.  If their urine is a dark yellow or the color of apple juice before it’s diluted in the toilet bowl, this may be a sign that they are not properly hydrating and should increase their water intake.

What about sports drinks?
Sports drinks can be a helpful form of re-hydration for those participating in vigorous activities lasting over 1.5 hours because they replace electrolytes which can be lost during sweating. The flavor of these drinks may also encourage additional fluid intake for those who are not motivated to drink plain water. However, these drinks contain high amounts of sugar. It is advisable to mix these drinks 50/50 with water.

Practices, clothing and equipment

To avoid heat exposure practices can be scheduled in the early mornings or late afternoon.

Athletes should wear loose fitting clothing and sun screen that will reduce their UV exposure without creating excessive heat retention.

Athletes should continue to maintain physical fitness through exercise during the off season to reduce the risk of heat illness when returning to practice.

By Michelle Larson, MPH and Mo Mortazavi, MD