Heat Illness: Prevention and Response

By 4Football Staff · October 1, 2026 · 11 min read

How heat cramps, heat exhaustion and exertional heat stroke differ, how coaches prevent them with acclimatization and monitoring, and why cooling first and calling 911 saves lives.

It is the third day of preseason practice, and a lineman in full pads is slower than usual in a blocking drill. He stumbles, gives a confused answer when a coach asks him a simple question, and sits down on the grass. A teammate jokes that he is out of shape. Nobody has yet called anyone, because he seems tired, and tired players are normal in August.

That scene is hypothetical, but the pattern is real. Heat illness in football often looks like fatigue or lack of toughness until it becomes an emergency. The most severe form, exertional heat stroke, is treatable if recognized and cooled immediately, and can be fatal if it is not. It is also one of the most preventable causes of death in football.

This article explains the three main conditions, who is at greater risk, how programs reduce that risk, and the response steps that matter most. It is general education, not medical advice. Your school, league or athletic trainer should have a written heat policy, and in an emergency the instructions of emergency medical services take priority.

Why football carries a special heat risk

Football combines several factors that rarely appear together in other sports:

• The season starts in summer. Preseason practices happen during some of the hottest weeks of the year in most of the country.
• Equipment traps heat. A helmet, shoulder pads, pants and padding cover much of the body and limit the sweat that can evaporate. Evaporation is the body's main cooling method.
• Intense, repeated bursts of effort. Sprints, blocking and tackling produce a great deal of body heat.
• Large bodies. Bigger players generate more heat and have less surface area compared with their mass for shedding it.
• Team pressure. Players do not want to appear weak, and coaches may push the pace in early practices.

Sports medicine organizations have studied football heat illness for decades, and one painful event stands out in public memory. In 2001, Korey Stringer, an offensive tackle for the Minnesota Vikings, died of heat stroke after a training camp practice. His death led to widespread changes in how teams think about heat, and the research center in his name at the University of Connecticut now studies and publicizes heat safety guidelines. High school and college deaths from heat have also been documented over the years, which is why many state associations now publish detailed policies.

The three conditions

Heat illness is a spectrum. The three conditions below are the ones coaches and parents most often hear about.

Heat cramps

Cramps are common in players who sweat heavily. They are not considered dangerous by themselves, but they can be a sign of heavy fluid and salt loss, and the same conditions that produce cramps can lead to a worse problem. A player with cramps should rest, drink fluids and be watched.

Heat exhaustion

Heat exhaustion is the body struggling to keep up. A player may feel faint, sick to the stomach or severely fatigued, and may not be able to continue. Typically the player is still thinking clearly. That is the key difference from heat stroke. If a player with suspected heat exhaustion becomes confused, stops responding normally or does not improve quickly with rest and cooling, treat it as heat stroke.

Exertional heat stroke

Exertional heat stroke occurs when the body's temperature rises to dangerous levels during exercise and the central nervous system is affected. It is usually defined by a core body temperature above about 104 degrees Fahrenheit (40 degrees Celsius) along with changes in mental status or behavior. The skin may be wet with sweat. In an athlete, it is not necessary for the skin to be dry, so a sweaty player can still have heat stroke.

Signs include confusion, disorientation, irritability or strange behavior, inability to answer simple questions, stumbling, collapse and seizure. Because these signs resemble other emergencies, such as a concussion, a heart problem or low blood sugar, a trained medical professional should assess any collapsing athlete. In hot conditions, though, heat stroke should be on the list from the start.

Who is at higher risk

Heat illness can affect anyone, but certain factors raise the risk:

1. Lack of acclimatization. Many cases happen during the first few days of hot-weather training or after a return from a break or illness.
2. Poor fitness or being overweight. These increase heat production or reduce heat loss.
3. Dehydration. A player who begins practice already short on fluids has less capacity to sweat.
4. Recent illness. Fever, vomiting or diarrhea in the previous days.
5. Poor sleep. Fatigue lowers the body's ability to cope.
6. A past history of heat illness. Some athletes are more sensitive afterward.
7. Certain medications and supplements. Stimulants and some other substances can raise heat production or interfere with cooling. Players should tell the athletic trainer or doctor what they take.
8. Sunburn or skin problems. These can reduce sweating.
9. Equipment and clothing. Dark, heavy or layered clothing and full padding.
10. Surface and weather. Artificial turf and blacktop can be much hotter than the air temperature, and high humidity makes sweat less effective.

Coaches cannot control all of these, but they can learn which players are at risk and watch them more closely.

Prevention starts before the first practice

Acclimatization

The human body adapts to heat over about one to two weeks of gradually increased exposure. During that time, it begins to sweat earlier and more efficiently and holds on to salt better. Programs use that adaptation by easing into hot-weather practices instead of starting at full speed.

A widely used model in college football and many high schools limits the first several days of preseason to one practice per day, with helmets only for the first couple of days, then helmets and shoulder pads, and full pads and live contact only after the first week. The exact schedule varies by state association and level, so check your association's policy. Our article on preseason practice limits and heat acclimatization rules covers how those rules typically work.

Players who miss days or return from illness may need to be eased back in, because acclimatization fades after a break.

Monitoring the weather correctly

The temperature on a phone does not tell the whole story. The wet bulb globe temperature, or WBGT, is a measurement that combines air temperature, humidity, sun and wind. Sports medicine groups consider it a better guide for athletes than the temperature or heat index alone. Many state associations now provide WBGT-based tables that show how practices must change as readings rise:

• At moderate readings, add more water breaks.
• At higher readings, shorten practices, remove helmets and pads during breaks, or reduce equipment.
• At very high readings, limit or cancel outdoor practice.

If your school or league does not measure WBGT, ask what it uses instead. A handheld WBGT monitor is a worthwhile investment for a program. Families can also check kickoff times on our schedule page and plan fluids and shade around early-afternoon starts.

Smart scheduling and practice design

• Hold practices in the early morning or evening on hot days, avoiding the midday peak.
• Build in scheduled rest breaks in the shade, with helmets off.
• Reduce the intensity and length of practice when readings are high.
• Never withhold water as punishment or a motivator.
• Avoid back-to-back hard days in the first week.
• Remove equipment when the conditions require it.

Hydration and weight checks

Fluid plans keep players closer to normal. Our article on hydration plans for practice and games explains how to build one. Many programs also use simple tools such as urine-color charts and weighing players before and after practice, which can identify those who are not replacing sweat losses. Hydration helps but does not by itself prevent heat illness, because a well-hydrated player can still become overheated.

Cooling tools on site

A well-prepared program keeps equipment ready for emergencies. This often includes a tub or portable pool, plenty of ice and cold water, towels, shade tents or an air-conditioned space, and a way to measure body temperature accurately. An athletic trainer is the best person to manage this, which is why the presence of one at practice is so valuable.

Recognizing trouble during practice

Coaches, trainers and teammates should look for changes in how a player acts and moves. Warning signs during practice include:

• Unusual slowness, stopping in the middle of a drill or lagging behind
• Stumbling, poor coordination or inability to follow instructions
• Confusion, irritability or inappropriate behavior
• Headache, nausea, vomiting or dizziness
• Complaints of feeling very hot or, sometimes, chills
• Pale skin, extreme sweating or, in some cases, sweating that stops
• Collapse

A buddy system helps. Players pair up and watch each other for the signs above, and any player may stop a teammate and tell a coach. The rule is simple: if in doubt, pull the player out and check.

Do not assume that a player who is slow is simply unmotivated. And do not decide that the cause is a concussion or an ordinary collapse without considering heat.

What to do for suspected heat stroke

The most important message about heat stroke is that time matters. The longer the body temperature remains very high, the greater the risk of organ damage and death. The widely accepted approach is "cool first, transport second," which means to begin cooling on the spot while emergency services are on the way and to continue until the player's temperature has fallen to a safe level.

A typical sequence for trained staff and coaches follows:

1. Call 911 or activate the emergency plan. Do not wait to see if the player improves.
2. Remove equipment and excess clothing. Take off the helmet, pads and jersey.
3. Start cooling immediately. The best method is immersion in a tub of cold water and ice, with the player's body in the water up to the neck. If a tub is not available, use the best alternative: cold wet towels or sheets that are rotated frequently, ice packs on the neck, armpits and groin, or a cold shower or hose.
4. Keep cooling until emergency staff take over or the player's temperature has dropped to a safe level. Trained personnel can measure the temperature, and sports medicine organizations recommend using a rectal thermometer, which is more accurate than other methods in exercising athletes. The target commonly cited is about 102 degrees Fahrenheit (39 degrees Celsius), and cooling in an ice-water tub commonly takes on the order of ten to fifteen minutes. Aim to start cooling within minutes of collapse.
5. Monitor breathing and consciousness. If the player stops breathing or has no pulse, begin CPR and use an AED. Our article on cardiac safety and AEDs at football fields is a good companion.
6. Do not give fluids to a player who is confused or not fully alert.
7. Give emergency staff the facts. Tell them what happened, when the player collapsed, what has been done and the temperature if you have it.

Heat stroke is an emergency even if the player seems to improve after a short rest. A player must be evaluated by a doctor.

What to do for suspected heat exhaustion

If the player is alert and thinking clearly, then the following steps are standard:

1. Stop activity and move the player to a shaded or air-conditioned place.
2. Remove the helmet, pads and extra clothing.
3. Cool the body with cold wet towels, fans, ice packs or a cool shower.
4. Offer cool fluids if the player is alert and not vomiting.
5. Stay with the player and monitor.
6. If symptoms do not improve quickly, if the player becomes confused or if you cannot be sure of the diagnosis, treat it as heat stroke and call for emergency help.

The player should not return to practice that day, and a medical professional should check on him.

Returning after heat illness

A player who has had heat exhaustion or heat stroke should be cleared by a physician before returning. After heat stroke in particular, doctors usually advise a gradual return to activity under supervision, because the body may take time to regain normal heat tolerance. The athletic trainer and doctor should manage the plan.

Putting it all together: the heat plan

A good heat plan is written down, practiced and shared. It includes who monitors conditions, the thresholds for changes, the schedule of breaks, where water and cooling supplies are kept, who is trained to respond, how to reach emergency services at each field and what happens afterward. Our article on emergency action plans for football teams shows how to put these elements together.

Parents can help by making sure players are rested, fed and hydrated, by sending them to practice in light, moisture-wicking clothing, by telling coaches about illness or medications, and by asking what the heat policy is. Players should be taught to speak up at the first sign of trouble. A team's culture matters more than any single rule. If you want to look up programs near you, our high school directory and the Play section are good places to start.

The short version

• Exertional heat stroke is a life-threatening emergency, defined by a very high body temperature plus confusion, collapse or unusual behavior.
• Heat cramps and heat exhaustion are milder, but heat exhaustion can progress, especially if the player keeps going.
• Risk is highest in the first days of training, with poor fitness, illness, dehydration or certain medications.
• Prevention uses gradual acclimatization, weather monitoring that includes humidity, scheduled breaks, hydration and cooling supplies on site.
• If heat stroke is suspected, call 911 and start cooling immediately, ideally with cold water immersion.
• Do not return a player to play after a heat illness without medical clearance.
• Every team needs a written plan, trained responders and a culture in which players can say when something is wrong.