Original research| Volume 18, ISSUE 3, P333-337, May 2015

Incidence and predictors of exertional hyperthermia after a 15-km road race in cool environmental conditions



      Current knowledge about the incidence and risk factors for exertional hyperthermia (core body temperature ≥40 °C) is predominantly based on military populations or small-sized studies in athletes. We assessed the incidence of exertional hyperthermia in 227 participants of a 15-km running race, and identified predictors for exertional hyperthermia.


      Observational study.


      We measured intestinal core body temperature before and immediately after the race. To identify predictive factors of maximum core body temperature, we entered sex, age, BMI, post-finish dehydration, number of training weeks, fluid intake before and during the race, finish time, and core body temperature change during warming-up into a backward linear regression analysis. Additionally, two subgroups of hyperthermic and non-hyperthermic participants were compared.


      In a WBGT of 11 °C, core body temperature increased from 37.6 ± 0.4 °C at baseline to 37.8 ± 0.4 °C after warming-up, and 39.2 ± 0.7 °C at the finish. A total of 15% of all participants had exertional hyperthermia at the finish. Age, BMI, fluid intake before the race and the core body temperature change during warming-up significantly predicted maximal core body temperature (p < 0.001). Participants with hyperthermia at the finish line had a significantly greater core body temperature rise (p < 0.01) during the warming-up compared to non-hyperthermic peers, but similar race times (p = 0.46).


      15% of the recreational runners developed exertional hyperthermia, whilst core body temperature change during the warming-up was identified as strongest predictor for core body temperature at the finish. This study emphasizes that exertional hyperthermia is a common phenomenon in recreational athletes, and can be partially predicted.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Science and Medicine in Sport
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Armstrong L.E.
        • Casa D.J.
        • Millard-Stafford M.
        • et al.
        American College of Sports Medicine position stand Exertional heat illness during training and competition.
        Med Sci Sports Exerc. 2007; 39: 556-572
        • Carter 3rd, R.
        • Cheuvront S.N.
        • Williams J.O.
        • et al.
        Epidemiology of hospitalizations and deaths from heat illness in soldiers.
        Med Sci Sports Exerc. 2005; 37: 1338-1344
        • Rav-Acha M.
        • Hadad E.
        • Epstein Y.
        • et al.
        Fatal exertional heat stroke: a case series.
        Am J Med Sci. 2004; 328: 84-87
        • Wallace R.F.
        • Kriebel D.
        • Punnett L.
        • et al.
        The effects of continuous hot weather training on risk of exertional heat illness.
        Med Sci Sports Exerc. 2005; 37: 84-90
        • Taylor B.A.
        • Zaleski A.L.
        • Capizzi J.A.
        • et al.
        Influence of chronic exercise on carotid atherosclerosis in marathon runners.
        BMJ Open. 2014; 4: e004498
        • Bouchama A.
        • Knochel J.P.
        Heat stroke.
        N Engl J Med. 2002; 346: 1978-1988
        • Coris E.E.
        • Ramirez A.M.
        • Van Durme D.J.
        Heat illness in athletes: the dangerous combination of heat, humidity and exercise.
        Sports Med. 2004; 34: 9-16
        • Simon H.B.
        • Hyperthermia
        N Engl J Med. 1993; 329: 483-487
        • Cheuvront S.N.
        • Haymes E.M.
        Thermoregulation and marathon running: biological and environmental influences.
        Sports Med. 2001; 31: 743-762
        • Ely B.R.
        • Ely M.R.
        • Cheuvront S.N.
        • et al.
        Evidence against a 40 degrees C core temperature threshold for fatigue in humans.
        J Appl Physiol (1985). 2009; 107: 1519-1525
        • Maughan R.J.
        Thermoregulation in marathon competition at low ambient temperature.
        Int J Sports Med. 1985; 6: 15-19
        • Maughan R.J.
        • Leiper J.B.
        • Thompson J.
        Rectal temperature after marathon running.
        Br J Sports Med. 1985; 19: 192-195
        • Noakes T.D.
        • Myburgh K.H.
        • du Plessis J.
        • et al.
        Metabolic rate, not percent dehydration, predicts rectal temperature in marathon runners.
        Med Sci Sports Exerc. 1991; 23: 443-449
        • Casa D.J.
        • Armstrong L.E.
        • Kenny G.P.
        • et al.
        Exertional heat stroke: new concepts regarding cause and care.
        Curr Sports Med Rep. 2012; 11: 115-123
        • Sawka M.N.
        Physiological consequences of hypohydration: exercise performance and thermoregulation.
        Med Sci Sports Exerc. 1992; 24: 657-670
        • Bedno S.A.
        • Li Y.
        • Han W.
        • et al.
        Exertional heat illness among overweight U.S Army recruits in basic training.
        Aviat Space Environ Med. 2010; 81: 107-111
        • Howe A.S.
        • Boden B.P.
        Heat-related illness in athletes.
        Am J Sports Med. 2007; 35: 1384-1395
        • Wilkinson D.M.
        • Carter J.M.
        • Richmond V.L.
        • et al.
        The effect of cool water ingestion on gastrointestinal pill temperature.
        Med Sci Sports Exerc. 2008; 40: 523-528
        • Byrne C.
        • Lim C.L.
        The ingestible telemetric body core temperature sensor: a review of validity and exercise applications.
        Br J Sports Med. 2007; 41: 126-133
        • Gant N.
        • Atkinson G.
        • Williams C.
        The validity and reliability of intestinal temperature during intermittent running.
        Med Sci Sports Exerc. 2006; 38: 1926-1931
        • Casa D.J.
        • Clarkson P.M.
        • Roberts W.O.
        American College of Sports Medicine roundtable on hydration and physical activity: consensus statements.
        Curr Sports Med Rep. 2005; 4: 115-127
        • Byrne C.
        • Lee J.K.
        • Chew S.A.
        • et al.
        Continuous thermoregulatory responses to mass-participation distance running in heat.
        Med Sci Sports Exerc. 2006; 38: 803-810
        • Pugh L.G.
        • Corbett J.L.
        • Johnson R.H.
        Rectal temperatures, weight losses, and sweat rates in marathon running.
        J Appl Physiol. 1967; 23: 347-352
        • Casa D.J.
        • Armstrong L.E.
        • Ganio M.S.
        • et al.
        Exertional heat stroke in competitive athletes.
        Curr Sports Med Rep. 2005; 4: 309-317
        • Cheuvront S.N.
        • Kenefick R.W.
        • Montain S.J.
        • et al.
        Mechanisms of aerobic performance impairment with heat stress and dehydration.
        J Appl Physiol (1985). 2010; 109: 1989-1995
        • Nielsen B.
        • Nybo L.
        Cerebral changes during exercise in the heat.
        Sports Med. 2003; 33: 1-11
        • Schlader Z.J.
        • Simmons S.E.
        • Stannard S.R.
        • et al.
        Skin temperature as a thermal controller of exercise intensity.
        Eur J Appl Physiol. 2011; 111: 1631-1639
        • American College of Sports Medicine
        • Sawka M.N.
        • Burke L.M.
        • et al.
        American College of Sports Medicine position stand. Exercise and fluid replacement.
        Med Sci Sports Exerc. 2007; 39: 377-390