Exertional heatstroke can occur during physical activity, especially in warm and humid environments.

The American College of Sports Medicine position stand on Exertional Heat Illness during Training and Competition gives an indication of the risk, so you can adapt your physical activity and lower the risk for exertional heatstroke.

The tool assumes an open field condition with clear skies.

ACSM heat risk interpretation for competition and continuous exercise
Generally safe, exertional heatstroke may occur due to personal factors.
Generally safe, exertional heatstroke can occur
Risk of exertional heatstroke begins to rise; high risk individuals should be monitored or not compete.
Risk for all competitors is increased.
Risk for unfit, nonacclimatized individuals is high.
Cancel level for exertional heatstroke risk.
Cancel exercise, uncompensable heat stress exists for all athletes.

Contact information

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About Hittewijzer.nl

Hittewijzer.nl was made possible by TNO (The Netherlands Research Institute for Applied Science). In addition, the advice and recommendations of several experts were followed up and taken over. The developers are open to comments that promote or improve the use of Hittewijzer.nl.

Scientific themes

Theme Person
Defense & security Dr. Arend Woering (TNO)
  Dr. Boris Kingma (TNO)
Sport Dr. John IJzerman (Dutch Athletics Union)
  Tom Wiggers (Dutch Athletics Union)
  Dr. Thijs Eijsvogels (Radboud Universiteit Nijmegen)
Health and wellbeing Prof. Hein Daanen (VU Amsterdam)
Occupational health -
Thermophysiological Models Dr. Boris Kingma (TNO)


The information provided on hittewijzer.nl is derived from sources that can be considered as reliable. Hittewijzer.nl cannot guarantee the correctness or completeness of the information provided on hittewijzer.nl. The information given is purely indicative. No rights can be derived from information provided on hittewijzer.nl. The information on hittewijzer.nl can be changed at any time and without notice.

The user of this service is responsible for the choice and use of the information. Dutch law is applicable.



The weather forecast comes from www.openweathermap.org

Color codes correspond to the Wet Bulb Globe Temperature (WBGT), this temperature is a combination of air temperature, wind speed, humidity and maximal solar radiation.

The WBGT is calculated according to Liljegren et al. (2008) : "This product includes software produced by UChicago Argonne, LLC under Contract No. DE-AC02-06CH11357 with the Department of Energy."

Heat risk interpretation is according to ACSM: "Exertional Heat Illness during Training and Competition" (2007), 0195-9131/07/3903-0557/0

Icons come from www.icons8.com


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