Exercise in Extreme Hot Weather Conditions (EXHOTCON)

University of Valladolid (UVA)

Status: Completed

Conditions: Heat Effect; Heat Acclimation and Thermotolerance

Treatments: Other: hot dry high (HDH); Other: Experimental: hot dry low (HWL); Other: Experimental: hot wet low (HWL); Other: hot wet high (HWH)

Study type: Interventional

Funder types: Other

Identifiers

NCT07307391

2025.14.11

Details and patient eligibility

About

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.

Enrollment: 6 patients

Sex: All

Ages: 18 to 50 years old

Volunteers: Accepts Healthy Volunteers

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.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: None (Open label)

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6 participants in 4 patient groups

hot wet high (HWH)

Experimental group

Description:

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

Treatment:

Other: hot wet high (HWH)

hot dry high (HDH)

Experimental group

Description:

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

Treatment:

Other: hot dry high (HDH)

hot dry low (HWL)

Experimental group

Description:

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

Treatment:

Other: Experimental: hot dry low (HWL)

hot wet low (HWL)

Experimental group

Description:

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

Treatment:

Other: Experimental: hot wet low (HWL)