(conversation) – In most parts of the country, high school sports practices begin in the midst of a brutal summer. Heat illnesses are an increasing risk for athletes as temperatures rise, especially during the first few weeks of practice. We asked Susan Yeargin, co-author of the National Athletic Trainers’ Association, on heat illness, to explain the risks and what coaches and players should keep in mind to keep kids safe.
Why are athletes especially vulnerable to heat in the first few weeks of training?
When an athlete of any age begins exercising or training for a sport in hot conditions, the body needs time to adapt. In natural outdoor environments, this is called heat acclimation.
During the first three days of exposure to heat, the body has not started to adapt, which is why the days are dangerous for heat illness. Most acclimation occurs by day 10, but it takes about two weeks for the body to reach its peak heat acclimation.
A major change within the body is an expansion of plasma volume, giving the body more blood to dissipate heat and supply the exercising muscles. In short, it allows the cardiovascular system to function more efficiently.
Sweating also increases, allowing more heat to be dissipated from the body. The body increases salt retention, which is good because it allows for a better electrolyte balance within the body to maintain hydration and keep muscles working optimally. The heart rate decreases, so there is less stress on the cardiovascular system. And core body temperature is reduced, representing a reduced risk for exercise heat stroke.
But even with all these adaptations, the body is not completely protected from heat illness, which is why other preventive strategies are needed.
Also, just because athletes train in the summer does not mean they are fully heat-adapted to the conditions imposed during the sports season. Sports season brings new exercise intensities, more heat than before in the summer, and heavier equipment like pads and helmets and more pressure to perform.
At what point does temperature start to become dangerous for young athletes?
It varies across countries. Athletes living in mild climates should not practice in environmental conditions above 86.2 degrees Fahrenheit (30.1 degrees Celsius) based on wet-bulb globe temperatures. For those in traditionally hot climates, such as Texas, the recommended cutoff temperature for eliminating the habit is 92 F (32.2 C).
The danger is more than temperature – it’s also about humidity, sun and wind. Humidity inhibits the evaporation of sweat, which is the body’s primary heat dissipation mechanism. So when the humidity is high, the air temperature creates any heat safety concern.
Athletic trainers often use wet bulb globe temperature — which takes all four variables into account — to determine when teams should shorten or cancel practice and how often rest and cooling breaks are needed. It is a better gauge of risk than the heat index, which uses only air temperature and humidity.
Anyone can check the projected wet bulb globe temperature for their area using the National Weather Service website.
How can you tell if someone is suffering from heat illness?
There are several conditions that fall under the scope of “heat illnesses”, but these are the primary ones:
- Heat cramps, also known as exercise-related muscle cramps, are caused by dehydration and electrolyte losses or fatigued muscle groups. It is easy to identify when a group of muscles are tight and knots occur. Heat cramps can usually be treated with rest, stretching, and hydration with electrolytes. If someone complains of cramps but the muscles are knotted and not tight to the touch, that person may be experiencing an emergency related to sickle cell trait, called exertional sickling.
- Heat exhaustion can occur when a person is dehydrated and exercising in warm conditions. Eventually, the body is unable to send enough blood to the working muscles and skin to dissipate the heat. It favors heat dissipation, and the person collapses or is unable to continue exercising. This should be treated by keeping the person in the shade or in air conditioning, giving them something to drink and cooling them with fans or cold towels. If they don’t respond quickly, they may need medical attention.
- Exertional heat stroke is a medical emergency in which a person’s body temperature rises above 105 F (40.6 C). Unfortunately, traditional temperature devices such as oral and forehead thermometers do not accurately measure body temperature in these situations. If a person is exercising in warm conditions and their personality changes, they start acting weird or different, or become confused, you should suspect exercise heatstroke. First responders should place the heat stroke victim in an immersion tub of cold water up to their shoulders and cool the water as much as possible with ice. If that is not available, any form of water immersion such as a baby pool, creek, water-filled tarp, or dousing should be used. EMS should be called immediately.
An important clue in all these heat illnesses is that the person is always sweating. It is a myth that a person stops sweating; This rarely happens.
What do athletic trainers recommend to keep athletes safe in the heat, especially in the first weeks?
Teams should follow heat acclimation guidelines to gradually increase the length of training sessions and the intensity of workouts. For example, an expert group that reviewed research on youth sports recommended always keeping training or practice sessions to less than two hours and only once a day for the first week. Conditioning, repetitive running and timed drills should be performed in an air-conditioned area or not combined for the first two weeks.
Additionally, teams should pay attention to the wet bulb globe temperature tables for their part of the country and avoid exercising during the hottest part of the day, usually between 10am and 6pm.
The National Athletic Trainers Association also recommends: using “weight charts” to help players understand how much they need to drink to stay hydrated; having an on-site athletic trainer with therapy resources such as cold water tanks; promoting good sleep and nutrition; and providing a safe work-to-rest ratio during conditioning and warm-up periods. Breaks should be in the shade, ideally with cooling devices such as fans, misters and cold towels. If a hard or intense drill is completed, players should have an equally long break.
A buddy system is also beneficial. With a friend, someone is likely to notice when an athlete isn’t feeling well or starts acting out of character and needs to be stopped for evaluation.