Cooling Strategies Guide for Athletic Trainers

Exertional heat stroke (EHS) is the third leading cause of death among high school athletes in the United States, and it is entirely preventable. The science is unambiguous: when a collapsed athlete’s core temperature exceeds 105°F and central nervous system dysfunction is present, the clock starts. Every minute without aggressive cooling increases the risk of permanent organ damage and death.

Yet every preseason, athletes collapse on practice fields under conditions that were foreseeable, measurable, and manageable. The gap between what the evidence demands and what happens on the sideline is not a knowledge problem at the top of the profession. It is a dissemination problem. Protocols exist. The clinical evidence is settled. What is missing is consistent, accessible, protocol-grade resources that reach every athletic trainer, coach, and sports medicine professional who works with athletes in the heat.

This guide does two things: It consolidates the evidence-based cooling strategies that the sports medicine consensus has validated, presented in a format athletic trainers can use immediately. And it examines what makes a heat safety resource credible enough to earn citation from the professional bodies that matter most to this audience.

Free for athletic trainers: Download the Preseason Heat Safety Checklist as a printable PDF to share with your coaching staff before the first practice. No paywall, no login required.

Who This Guide Is For

This resource is written for:

Certified athletic trainers (ATCs) at secondary school, collegiate, and professional levels
Sports medicine physicians and team physicians overseeing practice environments
Strength and conditioning coaches responsible for preseason conditioning programs
Athletic administrators developing institutional heat illness policies

The protocols described here are consistent with published position statements from major sports medicine governing bodies. This guide does not replace those statements; it translates them into actionable steps for the sideline.

Step 1: Understand the Spectrum of Exertional Heat Illness

Not all heat illness is the same, and the treatment decision tree branches sharply depending on severity. Misclassifying heat exhaustion as heat stroke (or vice versa) has direct consequences for patient outcomes.

The Four Categories

Condition	Key Symptoms	Core Temp	Immediate Action
Heat cramps	Muscle spasms, no CNS changes	Normal	Rest, oral electrolytes, gentle stretching
Heat syncope	Fainting, dizziness, pallor	Normal or mildly elevated	Supine position, cool environment, oral fluids
Heat exhaustion	Heavy sweating, weakness, nausea, headache	Up to 104°F	Remove from activity, cool environment, oral or IV fluids
Exertional heat stroke	CNS dysfunction (confusion, collapse, coma) + rectal temp >105°F	>105°F	Cool first, transport second. Initiate CWI immediately.

The critical distinction: Heat exhaustion does not require cold water immersion. Heat stroke does, immediately. The differentiating factor is central nervous system status, not temperature alone, because field thermometers measuring oral, axillary, or tympanic temperature are unreliable during exercise. Rectal temperature is the clinical gold standard for diagnosing EHS.

Why Rectal Temperature Matters

Oral, axillary, and tympanic readings can underestimate core temperature by 3 to 5°F in a hyperthermic athlete. An athlete with a rectal temp of 106°F may register 101°F orally, which can delay the CWI decision by critical minutes. Every institutional protocol should include a rectal thermistor in the sideline emergency kit and training for its use.

Clinical standard: Rectal temperature greater than 105°F (40.5°C) combined with CNS dysfunction confirms EHS. Begin cold water immersion before EMS arrives.

Want this decision tree in a laminated sideline format? Get the free EHS Recognition and Response Card sized for a clipboard or equipment bag. Join the National Stay Cool Day resource list and we’ll send it directly to your inbox.

Step 2: Monitor Environmental Conditions with WBGT

Heat illness risk is not determined by air temperature alone. Humidity, solar radiation, and wind speed all affect how efficiently the body can dissipate heat. The wet-bulb globe temperature (WBGT) integrates all four variables into a single index and is the measurement standard recommended by the American College of Sports Medicine, NATA, the NCAA, and the National Federation of State High School Associations.

The heat index is not an acceptable substitute for WBGT. The heat index omits solar radiation, which can add 10 to 15°F of effective heat load on an outdoor practice field. An athletic trainer relying on the heat index is making decisions with incomplete data.

WBGT Activity Modification Guidelines

Use the following thresholds, consistent with the NATA position statement on exertional heat illnesses, to guide practice decisions:

WBGT Reading	Risk Level	Required Modifications
Under 82.0°F (27.8°C)	Low	Normal activity; minimum 3 rest breaks per hour (3 min each)
82.0–86.9°F (27.8–30.5°C)	Moderate	Discretion for intense or prolonged exercise; 3 rest breaks per hour (4 min each)
87.0–89.9°F (30.5–32.2°C)	High	Max 2-hour practice; football limited to helmet, shoulder pads, and shorts; 4 rest breaks per hour (4 min each)
90.0–92.0°F (32.2–33.3°C)	Very High	Max 1-hour practice; no protective equipment; no conditioning; 20 min total rest
Over 92.1°F (33.4°C)	Extreme	Cancel or delay all outdoor activity

How to Measure WBGT Correctly

Use a calibrated WBGT device, not a weather app or online heat index calculator
Take readings on-site, at practice field level, not from a nearby weather station
Monitor every 15 minutes throughout practice, beginning at the scheduled start time
Document readings and the modifications implemented; this creates an institutional record

Key takeaway: WBGT readings should be taken at the location where athletes will be active. A reading from a shaded instrument shelter 200 meters away from a turf field in direct sunlight is not representative of actual athlete heat load.

Get the WBGT Sideline Threshold Card. A laminate-ready quick-reference with all five risk levels and required modifications, formatted for a clipboard. Download free at nationalstaycoolday.com/resources when you join the athletic trainer resource list.

The CDC’s occupational heat resources provide additional context on WBGT and heat stress measurement for practitioners working across multiple environments.

Step 3: Implement a Heat Acclimatization Protocol

The highest-risk period for exertional heat illness is the first two weeks of preseason practice, when athletes transition from relatively sedentary summer routines to high-intensity, equipment-intensive training in hot, humid conditions. A structured acclimatization protocol is the single most effective prevention tool available.

Acclimatization works by triggering physiological adaptations including increased plasma volume, earlier onset of sweating, reduced heart rate at a given workload, and lower core temperature during exercise. These adaptations develop over 10 to 14 days of progressive heat exposure and persist for several weeks.

The 14-Day Acclimatization Framework

Follow this progressive structure for all athletes beginning preseason training in warm conditions:

Days 1 through 7:

One practice per day maximum
Limit practice duration to 3 hours including warm-up and cool-down
Minimize protective equipment; introduce helmets and shoulder pads gradually
Prioritize instruction over conditioning intensity
Provide unlimited hydration access throughout

Days 8 through 14:

Two-a-day practices permitted, but separated by a minimum of 3 continuous hours of rest
Practice schedule should not exceed a 2-1-2-1 format (two-a-days, one-a-day, two-a-days, one-a-day)
Full equipment can be introduced progressively as WBGT conditions allow
Continue unlimited hydration and mandatory rest breaks per WBGT thresholds

Individual Risk Factors That Require Modified Acclimatization

Not all athletes acclimatize at the same rate. The following populations require closer monitoring and potentially extended acclimatization periods:

Athletes with a prior history of EHS
Athletes with sickle cell trait
Athletes who are obese or significantly deconditioned
Athletes returning from illness, particularly febrile illness
Athletes taking medications that impair thermoregulation (diuretics, antihistamines, stimulants)

A pre-participation physical examination (PPE) conducted before the start of preseason should screen for all of these risk factors. Athletic trainers should be notified of at-risk athletes before the first practice, not after an incident occurs.

Step 4: Apply the Right Cooling Modality for the Situation

Cooling strategy selection is not one-size-fits-all. The appropriate modality depends on the severity of the condition, the resources available on-site, and the time elapsed since symptom onset. Athletic trainers should know every option in the hierarchy before they need it.

Cold Water Immersion (CWI): The Gold Standard for EHS

For confirmed or suspected exertional heat stroke, cold water immersion is the most effective cooling modality available. Exertional heat stroke is 100% survivable. No other field intervention comes close to this outcome.

CWI Protocol, Step by Step:

Remove all equipment and excess clothing immediately to maximize skin surface area
Position the athlete in a tub or stock tank filled with cold water (35 to 59°F, or 1.7 to 15°C)
Immerse the body from the neck down; wrap a towel across the chest and under both arms to prevent sliding
Ensure ice covers the water surface at all times; stir the water continuously to prevent a warming boundary layer from forming around the body
Place an ice-cold towel over the head and neck; replace and re-wet every 2 minutes
Monitor rectal temperature continuously; remove the athlete when core temp reaches 102°F (38.9°C) to prevent overcooling
If rectal temperature cannot be measured, cool for 10 to 15 minutes then transport to a medical facility
After cooling is initiated, activate EMS; do not delay cooling to wait for EMS arrival

Required sideline equipment for EHS readiness:

Cold water immersion tub or stock tank (minimum 100-gallon capacity for larger athletes)
Sufficient ice supply (at least 40 pounds per tub)
Rectal thermistor and lubricant
Towels
IV fluid supplies if a qualified provider is available

When CWI Is Not Available: Rotating Cold Wet Towels

If a tub is not accessible, rotating cold wet towels applied over as much body surface as possible is the next best option. This is significantly less effective than CWI and should be treated as a bridge to definitive care, not a substitute. Cover the trunk, neck, groin, and axillae with ice-cold towels, rotating them every 2 to 3 minutes.

Cooling Modality Effectiveness Hierarchy

Modality	Cooling Rate	Appropriate For
Cold water immersion (35–59°F)	Fastest	EHS; first-line treatment
Rotating cold wet towels	Moderate	EHS when tub unavailable; bridge to transport
Ice bags to neck/axillae/groin	Moderate	Heat exhaustion; supplemental for EHS
Misting fans	Slow	Heat exhaustion; prevention during rest breaks
Shade and air conditioning	Slowest	Heat cramps, syncope, mild exhaustion

The real risk: Many programs have a tub on-site but fail to keep it filled and iced before practice begins. A tub that takes 20 minutes to prepare during an EHS emergency is a tub that does not exist. Pre-fill, pre-ice, and position the tub before the first athlete takes the field.

Run a tabletop drill before preseason. National Stay Cool Day offers a free CWI Incident Drill Worksheet that walks your staff through a simulated EHS event, role assignments, and equipment checks. Download it here and sign up for preseason heat safety updates timed to your athletic calendar.

Step 5: Manage Hydration Strategically

Hydration management sits at the intersection of prevention and performance. Both ends of the hydration spectrum, dehydration and overhydration (hyponatremia), carry serious risk. The goal is euhydration: replacing approximately what is lost, not drinking to a fixed schedule regardless of sweat rate.

Pre-Practice Hydration Protocol

Athletes should arrive at every practice euhydrated. The simplest field check is urine color: pale yellow (similar to lemonade) indicates adequate hydration; dark yellow or amber indicates dehydration. Coaches and athletic trainers should make urine color charts visible in locker rooms.

Recommended fluid intake before exercise:

17 to 20 ounces of water or sports drink 2 to 3 hours before activity
8 ounces approximately 20 to 30 minutes before activity begins

During-Practice Hydration

Provide unrestricted access to fluids throughout practice; do not limit drinking to scheduled breaks
Encourage athletes to drink 6 to 8 ounces every 15 to 20 minutes during activity
In sessions lasting longer than 60 minutes or in high-sweat conditions, electrolyte drinks are preferable to water alone to prevent hyponatremia
When WBGT exceeds 86°F, rest breaks must be in a designated cooling zone, not in direct sunlight, with fluids available at all times

Post-Practice Rehydration

Body weight monitoring before and after practice is the most accurate field method for assessing sweat loss. Each pound of body weight lost equals approximately 16 ounces of fluid deficit. Athletes should replace approximately 20 to 24 ounces of fluid for every pound lost before the next practice session.

Athletes must arrive euhydrated at the next session. An athlete who begins practice already dehydrated from the previous session faces compounded heat illness risk, particularly during the first two weeks of acclimatization.

Key takeaway: Thirst is a lagging indicator. By the time an athlete feels thirsty during exercise in the heat, they are already 1 to 2% dehydrated, a level that measurably impairs thermoregulation and performance. Hydration must be proactive, not reactive.

The Mayo Clinic’s guidance on exercise and fluid needs offers accessible supplemental reading for athletes and parents.

Share this with athletes and families. National Stay Cool Day publishes a free Parent and Athlete Heat Safety Handout Pack covering hydration, warning signs, and when to contact medical staff. Sign up to receive it along with preseason heat safety reminders sent to your inbox each July.

Step 6: Build and Practice Your Emergency Action Plan

A cooling protocol that exists only in a binder is not a protocol. The emergency action plan (EAP) for heat illness must be written, posted at every practice site, rehearsed before preseason begins, and reviewed with all staff including coaches, strength and conditioning personnel, and administrators.

What an EAP for Heat Illness Must Include

Recognition criteria: The specific signs and symptoms that trigger activation (CNS changes plus suspected high core temperature)
Role assignments: Who initiates CWI, who calls 911, who manages the tub, who communicates with EMS on arrival
Equipment location: Where the tub, ice, rectal thermistor, and fluids are staged before practice
Communication chain: How coaches are notified, how parents are contacted, which hospital receives the transport
Documentation: What gets recorded and by whom during the event

Rehearsal Is Not Optional

An EAP that has never been practiced will fail under the stress of an actual EHS event. Run a tabletop drill before the first preseason practice. Walk through the physical steps: who fills the tub, who gets the thermistor, who makes the call. The 10-minute window between collapse and the start of cold-water immersion is shorter than it feels in a real emergency.

Institutional reality: Many EHS deaths occur not because the protocol was wrong, but because the tub was not set up, the thermistor was in a locked storage room, or staff disagreed about whether the athlete was “really” in heat stroke. Rehearsal eliminates all three failure modes.

Return to Activity After EHS

Athletes who experience EHS require physician clearance before returning to any physical activity. The minimum standard:

Rest period of at least one week post-release from medical care, with no exercise
Gradual return-to-activity protocol beginning in a climate-controlled environment
Progression to moderate exercise in a cool environment, then strenuous exercise in cool conditions
Progression to exercise in heat, then exercise in heat with equipment (sport-specific)
Written physician clearance confirming the athlete is asymptomatic and laboratory values are normal

The CDC’s heat-related illness guidance for healthcare providers provides supporting clinical context for EAP development.

Get the ready-to-use EAP template. National Stay Cool Day’s Heat Illness Emergency Action Plan Template is co-developed with sports medicine professionals, formatted for institutional use, and aligned with published position statement language. Download it free when you join the resource list. No cost, no commitment.

Quick-Reference Checklist: Preseason Heat Safety Readiness

Use this checklist before the first preseason practice. Every item should be confirmed, not assumed.

Environmental Monitoring

WBGT device calibrated and on-site
WBGT monitoring schedule established (every 15 minutes during practice)
Activity modification thresholds posted for coaching staff
Designated staff member assigned to WBGT monitoring role

Equipment

Cold water immersion tub positioned at practice site
Tub pre-filled and iced before athletes arrive
Additional ice supply on-site (minimum 40 lbs)
Rectal thermistor and lubricant in sideline kit
IV fluid supplies available if qualified provider is present
Towels staged at tub location

Athlete Screening

Pre-participation physical exams completed for all athletes
At-risk athletes identified and athletic trainer notified
Urine color charts posted in locker rooms
Pre-practice body weight baseline recorded for all athletes

Emergency Action Plan

EAP written and posted at all practice sites
Role assignments confirmed with all staff
Tabletop drill completed before first practice
EMS contact information current and posted
Receiving hospital identified and notified of preseason dates

Acclimatization

14-day acclimatization schedule established and communicated to coaches
Two-a-day practice restrictions for Days 1 through 7 confirmed
Equipment phase-in schedule aligned with acclimatization protocol

This checklist is a starting point. Institutions should adapt it to their specific sport, climate, and staffing resources. For the full clinical evidence base underlying each item, consult the OSHA heat illness prevention resources and current published position statements from sports medicine governing bodies.

About This Resource

This guide was developed by National Stay Cool Day to support athletic trainers, sports medicine professionals, and coaches with evidence-aligned heat safety protocols. The clinical protocols described here are consistent with published position statements from major sports medicine governing bodies. All threshold values and procedural recommendations reflect the current sports medicine consensus.

National Stay Cool Day is committed to expanding its library of protocol-grade heat safety resources for athletic and clinical audiences. If you are a certified athletic trainer, sports medicine physician, or sports science researcher interested in contributing to or co-developing resources for this platform, we welcome the conversation.

Get the Full Resource Pack Before Preseason

Everything in this guide is available as a downloadable, print-ready resource kit for athletic training staff. Sign up at nationalstaycoolday.com/resources to receive:

Preseason Heat Safety Checklist (printable PDF, all five categories)
WBGT Sideline Threshold Card (laminate-ready, clipboard-sized)
EHS Recognition and Response Card (decision tree format)
Heat Illness EAP Template (institutional format, position-statement aligned)
CWI Incident Drill Worksheet (tabletop format for staff rehearsal)
Parent and Athlete Heat Safety Handout Pack (shareable with families)
Preseason heat safety email reminders sent each July before training camp

Resources are free. We send one preseason reminder per year and occasional updates when the clinical evidence changes. No promotional email, no upsell.

Interested in contributing? If you are a certified athletic trainer, sports medicine physician, or sports science researcher who wants to co-develop or peer-review resources for this platform, reach out here. Named expert contributors are credited on all resources they help develop.

Share this guide with your athletic training staff, coaching team, and athletic administration before preseason begins. Prepare now.

Evidence-Based Cooling Strategies for Athletic Trainers: A Heat Injury Prevention Resource Guide