Heat illness, exertional collapse and sudden death prevention

A sixteen-year-old cross-country runner collapses at the eight-kilometre mark of a hot August race, confused and combative, with hot dry skin and a rectal temperature of 41.2 degrees Celsius — exertional heat stroke, and the survival hinges on cold-water immersion begun within minutes. A fourteen-year-old football lineman slumps to the ground at the end of a full-contact two-a-day practice in heavy equipment, drowsy and vomiting, with a rectal temperature of 40.5 degrees Celsius — exertional heat stroke in the unacclimatised, heavily equipped athlete, the highest-risk combination the field knows. A seventeen-year-old collapses at the finish of a five-kilometre run, pale, dizzy, and sweaty but fully alert, with a normal core temperature — exercise-associated collapse from venous pooling, managed supine with the legs raised. And a fifteen-year-old basketball player slumps to the floor mid-drill without a pulse — sudden cardiac arrest, and the seconds to the defibrillator decide the outcome. ^{[1] [12]}

Overview & Definition

Exertional heat illness is the spectrum of illness that arises when the body's heat production during exercise outstrips its capacity to dissipate heat, and the young athlete is uniquely vulnerable because the paediatric thermoregulatory system generates more metabolic heat per kilogram and dissipates it less efficiently than the adult system. The National Athletic Trainers' Association position statement frames the spectrum as a continuum from exercise-associated muscle cramps and heat syncope through exertional heat exhaustion to exertional heat stroke, the life-threatening end. The fellowship candidate holds the spectrum in mind as a severity ladder, and the task at every collapse is to decide whether the athlete is at the benign end or the lethal end before the wrong treatment is given. ^[1]

The central concept is exertional heat stroke, defined as a core (rectal) temperature of 40 degrees Celsius (104 degrees Fahrenheit) or higher accompanied by central nervous system dysfunction. The central nervous system signs are the discriminator — confusion, aggression, irritability, ataxia, syncope, or loss of consciousness — and they distinguish heat stroke from heat exhaustion, which shares the high core temperature and the fatigue but preserves a normal mental state. The rectal temperature is the measurement that defines the diagnosis, and the field-side reliance on skin, tympanic, oral, or temporal readings is a documented cause of the missed diagnosis. The fellowship answer names the temperature threshold, the central nervous system criterion, and the rectal-temperature requirement aloud, because the examiner is testing whether the candidate would reach for the right measurement and the right treatment. ^{[1] [2]}

Exertional collapse is the parallel concept, and the term exercise-associated collapse describes the benign collapse that occurs when a runner stops and the calf-muscle pump ceases, allowing venous pooling and a transient drop in cerebral perfusion. The collapsed runner is pale, dizzy, and sweaty, the pulse is weak, and the mental state is preserved once supine; the management is rest with the legs elevated and oral rehydration. The collapse becomes dangerous when it is accompanied by central nervous system dysfunction, a very high or very low core temperature, or ongoing deterioration after the activity stops, because these features point to exertional heat stroke, exercise-associated hyponatraemia, or sudden cardiac arrest. The collapse pathway and the heat-stroke pathway meet at the point of collapse, and the skill is to separate them at the first assessment. ^[5]

Sudden cardiac arrest is the third collapse, and it is the leading medical cause of sudden death in young athletes. The athlete who collapses without a pulse, without breathing, or with seizure-like activity during or immediately after exertion has sudden cardiac arrest until a pulse is confirmed, and the treatment is immediate cardiopulmonary resuscitation and defibrillation. The prevention of sudden cardiac arrest rests on preparticipation screening, the recognition of warning symptoms, and the rehearsed emergency action plan that puts a defibrillator at the athlete's side within minutes. The fellowship answer treats exertional heat stroke and sudden cardiac arrest as the two survival-determining collapses and names the emergency action plan as the single intervention that links both. ^{[9] [11]}

References12ShowHide

1. [1]Casa DJ, DeMartini JK, Bergeron MF, Csillan D, Eichner ER, Lopez RM, et al. National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses. J Athl Train, 2015.PMID 26381473
2. [2]Casa DJ, McDermott BP, Lee EC, Yeargin SW, Armstrong LE, Maresh CM. Cold water immersion: the gold standard for exertional heatstroke treatment. Exerc Sport Sci Rev, 2007.PMID 17620933
3. [3]Demartini JK, Casa DJ, Stearns R, Belval L, Crago A, Davis R, et al. Effectiveness of cold water immersion in the treatment of exertional heat stroke at the Falmouth Road Race. Med Sci Sports Exerc, 2015.PMID 24983342
4. [4]Pryor RR, Haboian K, Fitts T, Stooks JJ. Tarp-Assisted Cooling for Exertional Heat Stroke Treatment in Wildland Firefighting. Wilderness Environ Med, 2023.PMID 37748988
5. [5]Asplund CA, O'Connor FG, Noakes TD. Exercise-associated collapse: an evidence-based review and primer for clinicians. Br J Sports Med, 2011.PMID 21948122
6. [6]Casa DJ, Csillan D, Armstrong LE, et al. Preseason heat-acclimatization guidelines for secondary school athletics. J Athl Train, 2009.PMID 19478834
7. [7]Adams WM, Hosokawa Y, Casa DJ, et al. Roundtable on Preseason Heat Safety in Secondary School Athletics: Heat Acclimatization. J Athl Train, 2021.PMID 33878177
8. [8]Cooper ER, Grundstein AJ, Miles JD, Ferrara MS, Curry P, Casa DJ, et al. Heat Policy Revision for Georgia High School Football Practices Based on Data-Driven Research. J Athl Train, 2020.PMID 32559286
9. [9]Casa DJ, Guskiewicz KM, Anderson SA, Courson RW, Heck JF, Jimenez CC, et al. National athletic trainers' association position statement: preventing sudden death in sports. J Athl Train, 2012.PMID 22488236
10. [10]Drezner JA, Courson RW, Roberts WO, Mosesso VN, Link MS, Maron BJ. Inter-association Task Force recommendations on emergency preparedness and management of sudden cardiac arrest in high school and college athletic programs: a consensus statement. J Athl Train, 2007.PMID 17597956
11. [11]Pelto HF, Drezner JA. Design and Implementation of an Emergency Action Plan for Sudden Cardiac Arrest in Sport. J Cardiovasc Transl Res, 2020.PMID 32300931
12. [12]Drezner JA, Peterson DF, Siebert DM, Thomas LC, Lopez-Anderson M, Suchsland MZ, et al. Survival After Exercise-Related Sudden Cardiac Arrest in Young Athletes: Can We Do Better? Sports Health, 2019.PMID 30204540