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OpenTrials
Completed

NCT Number: NCT07307391

Exercise in Extreme Hot Weather Conditions

Background: Core body temperature increases in hot climates due to exercise workload, disrupting heat gain and loss of balance. The human thermoregulatory system regulates core body temperature through factors such as metabolic heat production, air temperature, humidity, and clothing. The study investigates physiological thermoregulatory responses in semiprofessional athletes during walking and jogging in different climatic conditions.

Methods: A factorial experimental interventional design was used to evaluate different physical activity (low (L)=5 km/h and high (H)=8 km/h) and climatic conditions within the Thermal Environment Laboratory at Lund University, Sweden. The temperature within the climatic chamber was set at 40°C and 31°C, with a relative humidity of 20% and 70%, (hot dry (HD) and hot humid (HW), respectively, to account for a 28°C WBGT. The study used independent T-tests, ANOVA and simple linear regression models to analyse the physiological responses of semiprofessional athletes under different test conditions, comparing gender differences.

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Key information

Conditions

Heat Acclimation and Thermotolerance Heat Effect Heat Stress Disorders Wounds and Injuries

Age range

18 year–50 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Faculty of Health Sciences, University of Valladolid Soria Campus, Soria, Soria 42004

Soria, 42004, Spain

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Participation at the regional competition level
  • Receiving monetary remuneration for their sports engagement
  • Participating in sports activities in the previous six years
  • Average training experience of 6.0±1.4 years
  • A weekly volume of 6.3±0.7 days for 2.3±0.7 hours (h)·day-¹.

Exclusion criteria

  • A 2 kg weight change in the previous month
  • Adherence to special diets
  • Use of nutritional supplements
  • Smoking
  • An acute or chronic communicable or noncommunicable disease
  • Heat allergic problems.

Treatment and study plan

hot wet high (HWH)

Other

Air Temperature (ºC) 30.6±1.2 Relative Humidity (%) 68.6±1.3 Vapour Pressure (kPa) 1011±1.1 Bruel and Kjear (WBGT ºC) 27.3±0.8 Heat Stress (WBGT ºC) 27.8±0.8 Air Velocity (m/s) 0.45±0.19

hot dry high (HDH)

Other

Relative Humidity (%) 39.7±0.3 Vapor Pressure (kPa) 29.0±1.2 Bruel and Kjear (WBGT ºC) 1007.9± 6.4 Heat Stress (WBGT ºC) 28.9±0.6 Air Velocity (m/s) 28.4±0.3

Experimental: hot dry low (HWL)

Other

Relative Humidity (%) 31.1±0.1 Vapor Pressure (kPa )67.1±1.0 Bruel and Kjear (WBGT ºC)1005.7±8.0 Heat Stress (WBGT ºC) 27.4±0.6 Air Velocity (m/s) 27.9±0.3

Experimental: hot wet low (HWL)

Other

Relative Humidity (%) 39.8±0.1 Vapor Pressure (kPa) 26.4±0.4 Bruel and Kjear (WBGT ºC) 1004.7±10.7 Heat Stress (WBGT ºC) 28.3±0.3 Air Velocity (m/s) 27.7±0.1

Primary outcomes

  1. Exposure Time

    Time frame: Just one day, the day of the test, in those weather conditions

    duration an athlete is exposed to a specific intensity or environmental condition

  2. Heart Rate

    Time frame: Just one day, the day of the test, in those weather conditions

    measures how hard your heart works to gauge fitness

  3. Oxygen Uptake

    Time frame: Just one day, the day of the test, in those weather conditions

    how much oxygen your body uses during activity

Secondary outcomes

  1. Core Body Temperature

    Time frame: Just one day, the day of the test, in those weather conditions

    the body's internal temperature regulation

  2. Skin Temperature

    Time frame: Just one day, the day of the test, in those weather conditions

    The temperature of your body's surface

  3. Body Temperature

    Time frame: Just one day, the day of the test, in those weather conditions

    the internal heat level of the human body

  4. Sweat Rate

    Time frame: Just one day, the day of the test, in those weather conditions

    the amount of fluid your body loses through sweat per hour during exercise

  5. Perceived Exertion Level

    Time frame: Just one day, the day of the test, in those weather conditions

    is a subjective scale that measures how hard your body feels it's working during exercise

  6. Thermal Sensation Level

    Time frame: Just one day, the day of the test, in those weather conditions

    The Thermal Sensation Level is a standardized, subjective rating system used to quantify a person's perception of warmth or coolness in their environment

Sponsors and collaborators

Lead sponsor

University of Valladolid

Other

Registry information

Official study title

Physiological Responses in Semi-professional Athletes: a Comparison of the Effects of Hot Weather Conditions

Acronym: EXHOTCON

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Dec 29, 2025
Registry last updated
Dec 31, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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