Exertional heat stroke (EHS) is the most serious form of heat-illness that can occur during sports and exercise. If not recognized and treated immediately mortality rate of EHS is high. Early recognition and initiation of cooling are paramount. If temperature is reduced to < 40°C within 30 minutes of symptom onset, most patients recover completely. There are several strategies for cooling in EHS, including cooling with rotating in ice water soaked towels which cover the body of a patient.

The aim of this research is to investigate the effectiveness and safety of treatment of EHS with ice water soaked towels to lower body temperature.

Rationale: Exertional heat stroke (EHS) is the most serious form of heat-illness that can occur during sports and exercise. If not recognized and treated immediately mortality rate of EHS is high. Early recognition and initiation of cooling are paramount. If temperature is reduced to < 40°C within 30 minutes of symptom onset, most patients recover without sequelae. Exertional heat exhaustion (EHE) is a precursor of EHS, and might develop in EHS if exercise is not terminated. There are several strategies for cooling in EHS, including cooling with rotating in ice water soaked towels which cover the body of a patient.

Objective: The aim of this research is to investigate the effectiveness and safety of treatment of EHS with ice water soaked towels to lower body temperature. Secondary objectives include cooling rate of ice water soaked towels, morbidity of EHS and HE, productivity loss related to EHS and EHE and the development of posttraumatic stress symptoms and PTSD after treatment for EHS and EHE.

Study design: We will conduct a prospective longitudinal observational study. Patients will be monitored and treated according the national guideline in the medical facility. A follow-up survey will be performed after two weeks and two months.

Study population: All participants of 18 years and older who received medical care for EHS or EHE at the City Pier City race on March 12th 2023 and Rotterdam Marathon on April 16th 2023.

Main study parameters/endpoints: Primary outcome will be the cooling rate of treatment with rotating in ice water soaked towels. Secondary outcomes will be percentage of patients with EHS that were cooled to a temperature lower than 40°C within 30 minutes after entering a medical facility (or collapse).

Hypothesis: Cooling with rotating in ice water soaked towels is an effective method for cooling patients with EHS by reducing the body temperature < 40°C within 30 minutes after symptoms.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: There will be no risk from participating in the study and the burden will be low. The questionnaire will take approximately 20-30 minutes at two weeks and two months and 15 minutes at six months.

Inclusion Criteria:

In order to be eligible to participate in this study, a subject must meet all of the following criteria:

• ≥18 years
• Receive medical care at in the medical facility the City Pier City and Marathon Rotterdam 2023
• Tympanic temperature >38.0°C

Exclusion Criteria:

A potential subject who meets any of the following criteria will be excluded from participation in this study:

• Language barrier (not proficient in Dutch or English)

Adult runners who received medical care for EHS of EHE in the medical facility at the running events organized by Golazo Sports® at the City Pier City and Marathon Rotterdam 2023.