Study of Thermoregulatory Processes in Ultra-endurance Runners in a Hot and Humid Environment

NCT05098925 | Completed

• 1 other identifier: 2021/CHU/25
• Study Type: interventional
• Target: 80
• Locations: 1 country
• Sites: 1

Brief Summary

Human beings are characterized by their extraordinary ability to thermoregulate. During a physical exercise, only 20% of the energy provided by the substrates is converted into muscular mechanical work. The remaining 80% is released as heat. In temperate environments, so-called metabolic heat is dissipated by several physical phenomena (radiation, conduction, convection and evaporation). However, if the dissipation capacity (in a hot and humid environment for example) is lower than the production of metabolic heat, the body temperature increases progressively until exercise stops or heat-related pathologies develop. This pathological entity defined by the acronym EHI for Exertional Heat Illness gather a wide spectrum of clinical forms ranging from oedema or heat rash, to muscle cramps, to syncope; up to more serious forms such as heat exhaustion or heat stroke during exercise. Heatstroke during exercise is the second most common cause of death in athletes after heart disease. However, the results of the epidemiological studies and the recommendations are limited to events with effort durations or distances not exceeding those of the marathon. They therefore do not consider ultra-endurance disciplines. These disciplines, defined by durations of effort of at least 6 hours, have specific characteristics (duration of effort, intensity, steep gradients, exotic destinations, extreme environments) which means that extrapolation of the results and knowledge of the physiology of thermoregulation from "classic" endurance events, such as marathons, to ultra-endurance events is hazardous. There are therefore significant areas of uncertainty in understanding the thermoregulatory function, prevalence of EHI (Exertional Heat Illness) and health implications of ultra-endurance running in a hot environment. This is the context of ERUPTION-2.

Conditions

Intensive Sport

Outcome Measures

Primary Outcomes (4)

• Core temperature measurement

  Measure of core temperature (°C) will be carried out by continuous monitoring using e-Celsius performance Bodycap technology sensors carried by the athletes through the race

  during 3 days of the race

• Natremia measurement

  Measure of natremia (blood sodium concentration) will be made by 5 measurements carried out on the eve of the start and during the race, by microcapillary blood sample using the i-STAT technology and CHEM8+ cartridges.

  during 3 days of the race

• Hydration saliva measurement

  Hydration will be measured 5 times carried out on the eve of the start and during the race using saliva sample to measure the salivary osmolarity with the MX3 testing device.

  during 3 days of the race

• Hydration by weight measurement

  Weight in kg will be measured 5 times carried out on the eve of the start and during the race

  during 3 days of the race

Study Arms (1)

Intervention

EXPERIMENTAL

Study of Thermoregulatory Processes in Ultra-endurance Runners in a Hot and Humid Environment

Other: Biological testing

Interventions

Biological testing OTHER

Blood sampling, microcapillary sampling, temperature monitoring, saliva testing, EHI questionnaire

Intervention

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Runners participating in " La diagonale des fous " race of the "Grand Raid" 2021 on Reunion Island

You may not qualify if:

• Runners who do not understand French

Sponsors & Collaborators

• Centre Hospitalier Universitaire de la Réunion: lead

Study Sites (1)

CHU Réunion

Saint-Denis, 97400, Reunion

Location

Related Publications (1)

• Bouscaren N, Berly L, Descombes G, Tounkara B, Lacroix E, Lemarchand B, Racinais S, Millet GY. Thermoregulation and Hydration Dynamics in a 160-km Ultra-Endurance Race in a Tropical Environment: A Field Study on 80 Runners. Sports Med. 2025 Dec 4. doi: 10.1007/s40279-025-02356-6. Online ahead of print.

  PMID: 41343039 DERIVED

Study Officials

• Nicolas Bouscaren, MD

  Centre Hospitalier Universitaire de La REUNION

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 15, 2021
• First Posted: October 28, 2021
• Study Start: October 19, 2021
• Primary Completion: October 24, 2021
• Study Completion: December 31, 2021
• Last Updated: April 1, 2022

Record last verified: 2022-03

Data Sharing

• IPD Sharing: Will not share

Locations

RE (1)