A Sideline Life-Threatening Emergency
- EXERTIONAL HEAT ILLNESS is a spectrum - HEAT CRAMPS, HEAT EXHAUSTION, and EXERTIONAL HEAT STROKE - and EXERTIONAL HEAT STROKE (EHS) is the LIFE-THREATENING emergency: strenuous physical activity producing severe HYPERTHERMIA (core temperature over about 40 C / 104 F) together with central nervous system DYSFUNCTION (confusion, agitation, collapse, seizures, loss of consciousness).
- According to PubMed, unlike classic heat stroke, EHS can occur in YOUNG, HEALTHY individuals and even in TEMPERATE climates, when heat production exceeds the body's ability to dissipate heat; rising global temperatures and increased participation in endurance events are increasing its incidence.
- The DISTINCTION from heat exhaustion is the central one: HEAT EXHAUSTION has relatively preserved mental status (and core temperature usually below the heat-stroke threshold), whereas EHS has CNS dysfunction with severe hyperthermia - a collapsed/confused athlete who is HOT must be treated as heat stroke until proven otherwise.
- EARLY RECOGNITION and RAPID COOLING are essential to prevent MULTI-ORGAN FAILURE and DEATH; the recognised complications of EHS include ACUTE KIDNEY INJURY, COAGULOPATHY (DIC), LIVER dysfunction, rhabdomyolysis and neurological impairment.
- The GOLD-STANDARD treatment is WHOLE-BODY COLD-WATER IMMERSION, and the guiding principle is 'COOL FIRST, TRANSPORT SECOND' - aggressive on-site cooling to lower the core temperature rapidly takes priority over transport, because the duration of severe hyperthermia drives outcome; cooling should continue until a safe core temperature is reached.
- IN-HOSPITAL care focuses on continued cooling (if needed) and managing the complications (AKI, coagulopathy, liver dysfunction, rhabdomyolysis, neurological injury), with the orthopaedic/sideline relevance being recognition and immediate cooling at the event - PREVENTION (acclimatisation, hydration, work-rest cycles, heat-policy/wet-bulb-globe-temperature monitoring) reduces incidence.
- “Exertional heat stroke (EHS) = LIFE-THREATENING: severe hyperthermia (core >~40 C) + CNS dysfunction (confusion/collapse/seizure) during exertion. Distinguish from heat exhaustion (preserved mental status, lower core temp).
- “Occurs in YOUNG HEALTHY athletes even in TEMPERATE climates (heat production > dissipation). Untreated -> multi-organ failure (AKI, coagulopathy, liver, rhabdo) and death.
- “GOLD-STANDARD treatment = whole-body COLD-WATER IMMERSION; principle = 'COOL FIRST, TRANSPORT SECOND' (rapid on-site cooling before transport). Prevent with acclimatisation/hydration/work-rest/WBGT monitoring.
Severe hyperthermia (core >~40 C) + CNS dysfunction (confusion, collapse, seizure) during exertion = exertional heat stroke. Can occur in young healthy athletes even in temperate climates.
Cool first, transport second - whole-body cold-water immersion is the gold standard. Rapid cooling prevents multi-organ failure and death; continue until a safe core temperature.
The Spectrum, Recognition & Treatment
Exertional heat illness spans heat cramps, heat exhaustion (preserved mental status, core usually below the heat-stroke threshold) and exertional heat stroke (EHS) - the life-threatening emergency of severe hyperthermia (core over ~40 C) with CNS dysfunction (confusion, collapse, seizure). EHS occurs in young, healthy athletes and even in temperate climates when heat production exceeds dissipation. Early recognition and rapid cooling prevent multi-organ failure (AKI, coagulopathy, liver dysfunction, rhabdomyolysis, neurological injury) and death. The gold-standard treatment is whole-body cold-water immersion, guided by 'cool first, transport second' - aggressive on-site cooling before transport, continued until a safe core temperature. Prevention (acclimatisation, hydration, work-rest cycles, wet-bulb-globe- temperature monitoring) reduces incidence.
The single most important principle in exertional heat stroke is that outcome is driven by how long the core temperature remains dangerously high, so the priority is immediate, aggressive cooling - 'cool first, transport second' - rather than rushing the athlete to hospital while still hot. Whole-body cold-water immersion is the gold-standard cooling method and should be started on site without delay and continued until a safe core temperature is reached. The diagnosis hinges on recognising central nervous system dysfunction - confusion, agitation, collapse or seizures - together with severe hyperthermia in an athlete during exertion; this distinguishes heat stroke from heat exhaustion, which has relatively preserved mental status, and a collapsed or confused, hot athlete must be treated as heat stroke until proven otherwise. Crucially, exertional heat stroke can strike young, healthy individuals even in temperate climates, so it must not be dismissed because conditions seem unremarkable. Untreated or slowly cooled, it progresses to multi-organ failure - acute kidney injury, coagulopathy, liver dysfunction, rhabdomyolysis and neurological injury - and death; in-hospital care continues cooling and manages these complications, while prevention through acclimatisation, hydration, work-rest cycles and heat-policy (wet-bulb-globe-temperature) monitoring reduces the risk.
Evidence & Key Studies
Exertional heat stroke - recognition and management
- Exertional heat stroke is a life-threatening condition caused by strenuous physical activity leading to severe hyperthermia and central nervous system dysfunction; unlike classic heat stroke it can occur in young, healthy individuals and in temperate climates.
- Early recognition and rapid cooling are essential to prevent multi-organ failure and death; whole-body cold-water immersion is the gold-standard treatment, and 'cool first, transport second' is key to improving survival.
- In-hospital care focuses on continued cooling when necessary and managing complications such as acute kidney injury, coagulopathy, liver dysfunction and neurological impairment.
According to PubMed, the definition of exertional heat stroke (life-threatening severe hyperthermia with CNS dysfunction occurring even in young healthy individuals in temperate climates), the central role of early recognition and rapid cooling, whole-body cold-water immersion as the gold-standard treatment, the 'cool first, transport second' principle, and the complications (acute kidney injury, coagulopathy, liver dysfunction, neurological impairment) come from the cited Stomeo review. The wider heat-illness spectrum (cramps/exhaustion), the distinction from heat exhaustion (preserved mental status), and prevention (acclimatisation, hydration, work-rest, wet-bulb-globe-temperature monitoring) are standard, well-established teaching. (See also our Rhabdomyolysis, Hyponatraemia / Exercise-Associated and Sideline Emergencies topics.)
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A young athlete collapses, confused and very hot, during a race. What is the diagnosis and what is your immediate priority?”
Mnemonics & Memory Aids
COOL
Hook:COOL: CNS dysfunction + Core >~40 C, Occurs in young/temperate, On-site immersion (cool first), Life-threatening (organ failure).
Spectrum
- Heat cramps; heat exhaustion (preserved mental status, core usually below threshold)
- Exertional heat stroke (EHS): severe hyperthermia (core >~40 C) + CNS dysfunction
- Can occur in young, healthy athletes even in temperate climates
Recognition
- Collapsed/confused/agitated, hot athlete during exertion
- CNS dysfunction + severe hyperthermia = heat stroke (not exhaustion)
- Measure core (rectal) temperature; treat as heat stroke until proven otherwise
Treatment
- Immediate aggressive cooling: 'cool first, transport second'
- Whole-body cold-water immersion = gold standard; continue until safe core temperature
- Hospital: continued cooling + manage complications (AKI, coagulopathy, liver, rhabdo, CNS)
Prevention
- Acclimatisation; hydration
- Work-rest cycles
- Wet-bulb-globe-temperature monitoring / heat policies