Training in the Heat: Heat Illness Basics for Young Athletes | Starke Industries

July and August are when fall-sport athletes ramp up, and they're also the hottest weeks of the year in the Chicago area. Hot weather doesn't mean you have to stop training, but it does change how you plan sessions.

This post covers the basics coaches, parents, and athletes should know. It is general education, not medical advice. Anyone showing signs of heat illness needs immediate attention from qualified medical staff, and suspected exertional heat stroke is a medical emergency: call 911.

Why heat matters for training

During exercise, the body produces heat and has to get rid of it, mainly through sweating and blood flow to the skin. In hot, humid conditions that's harder. Sweat doesn't evaporate as easily, and the body has to work harder to keep core temperature in check.

The National Athletic Trainers' Association (NATA) position statement on exertional heat illnesses describes a range of conditions, from exercise-associated muscle cramps and heat exhaustion to exertional heat stroke, which is the most serious [1]. The statement emphasizes prevention, recognition, and rapid treatment, particularly rapid whole-body cooling for exertional heat stroke [1].

Acclimatization: build up over days, not one session

The body adapts to heat over repeated exposures. Athletes who jump straight into full-intensity, full-gear practices in the heat haven't had time to adapt.

NATA published heat-acclimatization guidelines for secondary school athletics. These recommend a gradual, multi-day progression at the start of preseason, limiting practice time, the number of sessions per day, and the use of protective equipment during the early days [2]. Many state associations have adopted versions of these heat-acclimatization rules.

What this means for summer training:

• Ease into outdoor conditioning over the first one to two weeks.

• Schedule the hardest sessions early in the morning or in the evening when you can.

• Start the summer with shorter outdoor work, and build up duration before intensity.

Warning signs to know

The NATA statement lists signs that need attention [1]. In general terms:

• Heat exhaustion: fatigue, dizziness, nausea, headache, or heavy sweating, often with difficulty continuing exercise.

• Exertional heat stroke: central nervous system changes, such as confusion, irritability, disorientation, or collapse, with a high core body temperature.

The key point from the position statement: changes in mental status during hard exercise in the heat should be treated as a possible emergency, and cooling should start immediately [1].

Athletes should be told plainly: if you feel dizzy, confused, or "off" in the heat, stop and tell a coach. Pushing through is not toughness.

Practical rules for hot-weather sessions

Hot-weather sessions should be adjusted with more water breaks, longer rest intervals, and an indoor option when conditions demand it.

General guidelines for any program:

1. Water access. Water should be available at all times, with planned breaks. 2. Shade and rest. Longer rests between sprint efforts in heat. Speed work needs full recovery anyway. 3. Check the conditions. Heat and humidity together matter more than temperature alone. Many programs use wet bulb globe temperature (WBGT) to guide modifications [1]. 4. Know who's at higher risk. Athletes who are new to training, recently ill, poorly conditioned, or not yet acclimatized need closer attention [1]. 5. Have an emergency plan. Know who calls 911, where the cooling tub or ice is, and how to reach the athletic trainer.

Heat and hydration

Hydration is part of this, but it isn't the whole picture. Fluid needs vary a lot between athletes. Our hydration post covers why electrolytes matter, not just water.

How heat affects testing

If you test athletes in summer, run tests in controlled conditions. A jump or sprint test done outdoors in midday heat isn't directly comparable to one done indoors in the morning. When comparing a baseline to a re-test, keep the environment as consistent as you can.

Questions athletes ask

Can I just drink a lot of water and be fine? Fluids help, but they don't replace acclimatization, sensible scheduling, or rest. Heat illness can happen even when an athlete has been drinking.

Is it OK to train in a hoodie to "sweat more"? No. Extra layers make it harder to shed heat and add risk without a training benefit.

I felt fine yesterday. Why do I feel worse today? Sleep, illness, and fatigue all play a role. If you feel off in the heat, tell a coach. Sessions can be modified on the spot.

A note for coaches running summer camps

If you're running sessions for a group, assign someone to watch athletes, not just run the drill. Heat-related problems are easier to catch early when an adult is looking for them. Keep a simple written plan: how the session changes on hot days, where water and ice are, and who makes the 911 call. NATA's position statement stresses having a plan in place before it's needed [1].

The bottom line

Heat is a planning problem. Acclimatize gradually, adjust the session to the conditions, know the warning signs, and have a plan for emergencies. Training hard in summer is fine. Ignoring the heat isn't.

Related reading

• Summer Off-Season Training for High School Athletes: How to Plan the Break
• hydration
• comparing a baseline to a re-test
• Speed work needs full recovery

References

• Casa DJ, et al. National Athletic Trainers' Association position statement: exertional heat illnesses. J Athl Train. 2015;50(9):986–1000. https://doi.org/10.4085/1062-6050-50.9.07 (published Sep 2015)
• Casa DJ, et al. Preseason heat-acclimatization guidelines for secondary school athletics. J Athl Train. 2009;44(3):332–333. https://doi.org/10.4085/1062-6050-44.3.332 (published May 2009)
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