Heat Stress

Heat Stress: No matter where you live and play soccer, the weather can become an issue at some point during your season. Heat is probably the most universal problem, with the combinations of heat and/or humidity being a problem most anywhere in the country. Heat related illness is common is sports. The literature is full of documented events where athletes have died from heat stress related illnesses. Here in Arizona, it is obviously a situation to be closely monitored. Over exposure to heat, especially in the earlier part of the spring or summer can have disastrous effects on young soccer players as well as coaches, referees, and spectators. The human body is an amazingly adaptable organism, but it takes time for this to occur. I have listed some key elements for coaches to consider when attempting to “beat the heat”.

Heat Stress Susceptibility: Younger players and those who are overweight may be more susceptible to heat stress. Anyone who has had a heat related illness in the recent past should be watch more closely. Players who have been recently ill (Flu, cold, etc), as well as players who are taking certain medications may be more at risk.

Core Temperature and Dehydration: The two main physiological problems with exercising in the heat are the unsafe rise in body “core temperature” (hyperthermia) and loss of fluid volume in the body. I am not going to go into the physiological processes of these issues, but simply say that when core temperature rises, and fluid loss becomes excessive, the body no longer can function normally and very serious complications can result, including death. I recall when I was a runner in my more youthful days. I would check my body temperature after a run in a hot environment and it would always be in the range of 102-103 degrees. It would quickly return to normal, but that just shows how our body heat can accumulate with exercising in the heat.

Build Practice duration and intensity GRADUALLY: When heat arrives in your area, coaches need to be certain to build the duration and intensity of activity very gradually, permitting their players to adapt. It normally can take 3-4 weeks of graduated activity in a hot and/or humid environment for a body to adjust. There are physiological changes that occur within the body to permit it to better utilize internal fluids, adjust cooling mechanisms, and otherwise adapt to exercising in such an environment.

Provide breaks and shelter from the heat: Exercising in direct sunlight exposes the body to “radiant” heat from the sun, and results in more rapid heating than when in the shade. Giving players a shaded area to take breaks during practice and/or games is one method to reduce the heat accumulation. If there are no trees or other shelters present to produce a shaded area, then bring a portable shelter. When your local weatherman says the temperature is 100 degrees, it is always measured in the shade. If you put a thermometer in direct sunlight, the temperature would go up 20-30 degrees. If a game is being played in excessive heat, ask the referee about taking a few short “water breaks” during the game. I have done this on many occasions and have found that most coaches and referees have no problem with these short breaks in action, when the health and safety of players is in question.

Provide adequate fluids & electrolytes: There are many different opinions on how much fluid a player should intake during a period of time while exercising in a hot environment. The US Soccer Federation recommends a player pre-hydrate themselves prior to practice by drinking approx 12 oz of fluids about 30 min before the session. After that, players should drink 5-10 oz every 20 minutes depending on body mass. Refer to the following: US Soccer Heat Guidelines Coaches should monitor players on breaks to ensure they are drinking fluids and not just socializing and resting. Players needs to bring large containers of fluids to each practice. A one quart water bottle or sports drink will not be sufficient for a 1-2 hrs practice or game. When possible, coaches (or volunteer parent) should bring extra water or drinks to supplement what the players bring themselves. It is often difficult to determine if a player is drinking enough, however there are a couple of clues a coach can use. If players are making a couple of trips to the bathroom during a session, that is a good sign. I recall during my years in the Air Force Medical Service, that our flight surgeons would tell our fighter pilots to drink until their urine was very clear. If it is dark in color, that was a sign of dehydration. It is important to note that fluid loss can be cumulative, that is, gradual loss can occur over a period of time. Players need to drink not only before, during, and after sessions, but also when they go home and during the entire course of the day.

Water vs Sports Drinks: Years ago when sports drinks were packed with sugar, it was recommended that water was better at replacing fluids than a sports drink. Sports drinks have evolved significantly since that time, with reductions in sugar content and included elements that promote absorption of fluids. Water will always be a good choice for fluid replacement, however, there are advantages in using sports drinks when available. They replace lost electrolytes and more importantly, they taste better than water, so players are more likely to consume greater amounts. Caffeinated beverages should be avoided as they promote fluid loss through increased urine production. Carbonated drinks should be avoided, as they tend to make a player feel full and less likely to drink more.

Electrolytes: These are mineral elements (magnesium, calcium, phosphorous, sodium, chloride) that are essential in regulation body metabolic processes. These can be lost through sweating, urine production, and activity. Under normal circumstances, they are replaced through a good healthy diet, but when excessive amounts are lost through exercise, supplemental electrolytes may be necessary to maintain balance. Sports drinks are a good source of these essential elements. A good diet is also important to aid in replacement. Visit the following link for more information: Electrolyte Replacement

Heat vs Humidity: There are many Heat Index tables available on the internet to show how heat and humidity combine to produce varying degrees of heat stress. Visit the following link: http://www.weather.gov/os/heat/index.shtml Simply, when the humidity is up, the body has more difficulty dissipating heat through sweating as the air is already saturated with water. In a drier environment, sweat evaporates more quickly taking body heat with it. I have lived (and exercised) in a humid environment (Florida) and in a dry environment (Arizona) and have found both to present problems. As I mentioned above, humid environments slow the process of heat loss through sweating, however, in a hot dry environment, sweat evaporates quickly and gives an illusion that one is not sweating that much and not losing much water. The opposite is true. The one thing to remember about heat and humidity is that even though the air temperature may only be 80 degrees, if the humidity is in the 80-90 percent range, the potential of heat stress is high.

What to wear: With soccer players, this is usually not a problem, unlike American Football where pads and heavier clothing is worn. It is generally accepted that lighter clothing (color and texture) are prefered. Caps and other head gear are not generally worn in soccer, but I will remind you that a well ventilated hat is good protection for coaches and spectators. I recall many years ago, where athletes were under the illusion that if you sweat a lot with exercise, you would loss weight. They would show up at a practice field wearing closely woven nylon or rubberized suits and work out. Fortunately, athletes are a lot smarter these days, and I have not seen this in some time. These non-breathable materials should never be worn in a hot environment (or even mild temp environment) as they cause the internal temperature of the body to exceed safe levels and cause excess fluid loss. Protect your skin: Keep your dermatologist happy and wear sunscreen when outside. Here in Arizona, sunscreen lotions are a permanent part of player’s, coaches and spectator’s accessories.

Signs and Symptoms of Heat Stress: In most (but not all) cases, symptoms are gradual. Players may experience or exhibit the following: dizziness, in-coordination, weakness or fatigue, shortness of breath, tingling in the arms and legs, thirst, nausea, muscle cramps, etc. Please note that while thirst can be an indicator of fluid loss, it cannot be relied upon solely. Studies of marathon runners have shown that drinking only 25% of fluids lost will temporarily satisfy a thirst. Soccer players are encouraged not to wait for thirst to replace fluids. By that time, they are already building a fluid deficit. A good “rule of thumb” is to drink to prevent thirst rather than relieve it.

What to do when heat illness presents itself: If a player shows signs of heat stress, they should be immediately removed from activity and placed in a shaded or cooler environment. Fluids need to be given. Cooling the body with water on the chest, thighs and head, plus fanning the body with towels or other object will bring down body temperature. Even if symptoms are mild, the parents should be notified. If players drove to practice, caution should be taken regarding their ability to drive themselves home. If symptoms are severe, emergency medical attention should be summoned. It is not the purpose here to give medical advice on this subject. Coaches need to be aware of the seriousness of the problem and proceed cautiously and be conservative when dealing with young soccer players.

Respect the Heat: Coaches, players, parents, referees and administrators need to be aware of the dangers associated with activity in the heat, what signs to look for, measures of prevention, and what to do when heat stress occurs. The health and safety of all participants depends on our awareness of the problem.

I welcome comments from coaches, soccer officials, parents and players. Share your experiences in this area. Be sure to download the pdf file from US Soccer on “Heat Stress Guidelines” included in the body of this article. If it does not open easily, just save to your PC and open from there.