Heat Related Illness - Prevention, Signs and Symptoms, and Heat Index Chart

Oct 12, 2026

Heat related illness guidance explains how ambient air temperature and humidity increase the body’s risk of failing to cool through sweat evaporation, especially when temperature exceeds 90 and humidity is high. It outlines adolescent acclimatization compared with adults, emphasizes environmental checks before contests, and provides common signs and symptoms. Immediate action is required: stop activity, remove the athlete from sun, and seek healthcare. Prevention includes hydration, rest, light clothing, sunscreen, education, and scheduling workouts using a heat index chart.

LanguageEnglish

CategoryGeneral

FormatPDF

Pages2

Reading Time1 min

AccessFree to download

Heat Related Illness

How Heat and Humidity Affect Cooling

Adolescent Acclimatization

Prevention Plan for Events and Practices

Signs and Symptoms

Immediate Response

Prevention Measures

Heat Index Chart

HEAT RELATED ILLNESS Ambient air temperature and humidity have a direct effect on the ability for a body to cool itself through the evaporation of sweat. When the air temperature is above 90, and/orthe relative humidity is high, the body is at a higher risk to not stay cool. It is important for all coaches to know that adolescents take longer to acclimatize to the heat than adults. Acclimatization means becoming adapted to the weather or climate. Asa result of acclimatization, the athletes core body temperature does not rise as high during exercise, perspiration increases and occurs earlier, the heart rate decreases, and the supply of oxygen to the muscles is improved. Local managers should check the environment prior to contest to see what the conditions are for participating athletes. All IESA Member schools should have a plan in place for the prevention of heat related illness/injury at outdoor events, practices and poorly ventilated gyms. SIGNS AND SYMPTOMS OF HEAT RELATED ILLNESS The following are common signs and symptoms of heat related illness, but are not a complete list. ° Exhaustion ° Headache ° Muscle Cramping/Spasms ° Dizziness ° Nausea, Rapid Pulse, Weakness ° Thirst ° Shallow Breathing ° Heavy or Profuse Sweating ° Loss of consciousness In the event that an athlete is suffering from one or more of the above symptoms, the athlete should immediately stop activity, be removed from the sun and be referred to appropriate health care professional for a full evaluation. Under no circumstances should an athlete with any of the symptoms above be allowed to return to play the same day. PREVENTION-The best management of heat related illness is prevention. ° Light colored, loose clothing is suggested during activity in hot weather. ° Adequate fluid supply should be readily available at all times. (Do not wait until thirsty to maintain hydration.) ° Coaches should allow frequent periods of rest and hydration. Additionally water should never be withheld form exercising individuals. ° Encourage athletes to fully hydrate prior to coming to practice. (Ex. 17-20 oz of Water 2-3 hours prior to practice and additional 17-20 oz sport drink 20 min. before.) ° After competition or practice, drink enough fluids to replace any weight loss within two hours of completion of the activity. ° Encourage the use of sunscreen. ° Educate all those involved with the signs and symptoms of heat related illness. ° Overweight athletes are at increased risk for heat illness and should be monitored closely. ° Schedule activities at the coolest time of day and if this can’t be done then you are strongly encouraged to postpone or cancel for extreme heat and humidity conditions. Use the chart below when you have any question on participating or practicing. Cross-reference the relative humidity (top row) with the temperature (1st column) to determine the humiture or apparent temperature chart. HEAT INDEX CHART Relative Humidity | TEMP | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% | 100% | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | 105 | 100 |
105 |
113 |
123 |
135 |
149 | | | | | | 104 | 98 | 104 |
110 |
120 |
132 |
143 | | | | | | 102 | 97 | 101 |
108 |
117 |
125 |
139 | | | | | | 100 | 95 | 99 |
105 |
110 |
120 |
132 |
144 | | | | | 98 | 93 | 97 | 101 |
106 |
110 |
125 |
132 | | | | | 96 | 91 | 95 | 98 | 104 |
108 |
120 |
128 | | | | | 94 | 89 | 93 | 95 | 100 |
105 |
111 |
122 |
128 | | | | 92 | 87 | 90 | 92 | 96 | 100 | 106 |
115 |
122 | | | | 90 | 85 | 88 | 90 | 92 | 93 | 100 |
106 |
114 |
122 |
130 | | 88 | 82 | 86 | 87 | 89 | 93 | 95 | 100 |
106 |
115 |
125 | | 86 | 80 | 84 | 85 | 87 | 90 | 92 | 96 | 100 |
109 |
111 | | 84 | 78 | 81 | 83 | 85 | 86 | 89 | 91 | 95 | 99 |
105

FAQs

How do air temperature and humidity affect the body during exercise?

High air temperature and high relative humidity reduce the body’s ability to cool through sweat evaporation, increasing the risk of overheating.

What should coaches do immediately if an athlete shows symptoms of heat related illness?

Stop the activity right away, move the athlete out of the sun, and refer them to appropriate healthcare for a full evaluation; the athlete must not return to play the same day.

What hydration and rest practices help prevent heat related illness?

Provide fluids at all times, avoid waiting until the athlete is thirsty, schedule frequent rest and hydration, and encourage full hydration before practice.

How is the heat index chart used?

Cross-reference relative humidity with temperature to find the humiture/apparent temperature and guide participation and practice decisions under heat and humidity conditions.

Oct 12, 2026

Uploaded by pixelkiddo