The Heat Illness Spectrum

Heat illness is one of the most preventable causes of death in youth sports — yet it continues to claim lives, particularly in football during summer practices. Heat illness exists on a spectrum from mild to life-threatening, and recognizing where an athlete falls on that spectrum determines the response. The three stages are:

1. Heat cramps — muscle spasms, usually in the legs or abdomen. The mildest form. Treat with rest, hydration, electrolytes, and gentle stretching.
2. Heat exhaustion — the body's warning system. Heavy sweating, weakness, nausea, dizziness, headache, pale/clammy skin. Body temperature is elevated but typically below 104°F. Needs immediate cooling and hydration — and it can progress to heat stroke if ignored.
3. Heat stroke (exertional heat stroke) — a life-threatening medical emergency. Core body temperature rises above 104°F (40°C), accompanied by central nervous system dysfunction: confusion, agitation, slurred speech, loss of consciousness. Can be fatal within minutes if not aggressively cooled.

WBGT: The Right Way to Measure Heat Risk

Environmental heat risk should be measured using Wet Bulb Globe Temperature (WBGT), not just air temperature. WBGT accounts for four factors that together determine actual heat stress on the body: temperature, humidity, wind speed, and sun (solar) radiation. On a humid, still, sunny day, the WBGT can be dangerously high even when the thermometer reads in the 80s. Many schools and programs now use on-site WBGT monitors; smartphone apps and regional weather services also provide estimates.

WBGT Activity Thresholds (Korey Stringer Institute)

These thresholds are drawn from the Korey Stringer Institute (KSI) at the University of Connecticut, the leading research center on exertional heat illness prevention, named for the Minnesota Vikings lineman who died of exertional heat stroke in 2001. KSI guidelines are the basis for most state high school athletic association heat policies.

The 14-Day Heat Acclimatization Protocol (Football)

Most exertional heat stroke deaths in football occur in the first few days of preseason practice, before athletes' bodies have adapted to the heat. Heat acclimatization is the process of gradually adapting the body to exercise in a hot environment — it improves sweating, increases blood plasma volume, and reduces heart rate and core temperature during exercise. It takes 10–14 days to fully acclimatize, which is why a progressive plan is essential.

The standard 14-day protocol for football:

Key rules during acclimatization: Only one practice per day in the first 5 days. If a practice is missed, the athlete restarts the protocol from the phase they missed — heat adaptation is lost quickly. New athletes joining late must complete their own acclimatization before full participation.

Hydration Protocol by Age

Proper hydration is the foundation of heat illness prevention — but the amounts and types of fluid vary by age and activity duration. Children are not just "small adults"; they produce more heat per pound of body weight, sweat less efficiently, and heat up faster.

Electrolyte Needs

• Under 60 minutes of activity: Water is sufficient. Most youth activities under an hour don't require electrolyte replacement.
• Over 60 minutes or in extreme heat: Use a sports drink with electrolytes (a 6–8% carbohydrate solution is ideal). Sodium, potassium, and chloride are lost in sweat and must be replaced for prolonged or repeated sessions.
• Signs of electrolyte imbalance: muscle cramps, persistent fatigue, nausea, headache that doesn't resolve with water.
• Avoid energy drinks — they contain caffeine and stimulants that increase dehydration risk and are inappropriate for youth athletes.
• Never restrict water access during practice or games. Water should be unlimited and always available.

Recognizing Heat Exhaustion vs. Heat Stroke

Knowing the difference — and how fast heat exhaustion can become heat stroke — saves lives. The table below is the single most important reference on this page:

The critical distinction: Heat stroke involves central nervous system dysfunction — confusion, altered behavior, or loss of consciousness. If an athlete is confused, combative, or unconscious in the heat, assume heat stroke and act immediately. Waiting is what kills athletes.

Work-to-Rest Ratios by WBGT

As heat stress increases, the ratio of work to rest must decrease. These ratios are based on KSI and military heat stress guidelines:

• Normal conditions (WBGT <82°F): Rest breaks every 20–30 minutes as needed.
• Caution (WBGT 82–90.5°F): Rest breaks every 15–20 minutes (minimum 10 minutes each).
• High risk (WBGT 90.5–92°F): Work-to-rest ratio of 3:1 (30 min work, 10 min rest) — or more conservative.
• Extreme (WBGT 92–98°F): Work-to-rest ratio of 1:1 (20 min work, 20 min rest). For football, no full equipment.
• Dangerous (WBGT >98°F): No outdoor activity.

Cooling Stations

Every hot-weather practice and game should have a designated cooling station — a shaded or air-conditioned area where athletes can actively cool down during rest breaks. Essential elements:

• Shade or AC — a tent, canopy, or indoor space
• Cold water immersion tub — the gold-standard treatment for heat stroke. A kiddie pool or stock tank filled with ice water can save a life. Target cooling rate: ~0.15°C/minute.
• Ice packs and cold towels — for rapid cooling of the neck, groin, and armpits (where large blood vessels are near the skin)
• Fans and misters — evaporative cooling is highly effective in dry heat
• Unlimited cold water and sports drinks
• A designated person trained to recognize heat illness and activate the emergency action plan

Additional Risk Factors

Certain athletes are at higher risk for heat illness. Pay extra attention to athletes who:

• Are overweight or obese
• Are not acclimatized to the heat (just arrived from a cooler climate)
• Are deconditioned (returning from injury or inactivity)
• Have a fever, GI illness, or recent dehydration (especially vomiting/diarrhea)
• Take certain medications (ADHD stimulants, antihistamines, some antidepressants, diuretics) that affect heat regulation
• Have sickle cell trait — elevated risk of exertional collapse in extreme heat
• Wear heavy equipment (football linemen, catchers)
• Have a previous history of heat illness

Guidelines based on the Korey Stringer Institute (KSI) at the University of Connecticut, the NCAA Sport Science Institute, the National Athletic Trainers' Association (NATA) position statement on exertional heat illness, and the American Academy of Pediatrics (AAP) policy on heat illness in children.