NCT05292170

Influences of Female Sex and Reproductive Hormones on Physiological Aspects of Heat Acclimation

Completed NA Last updated 7 August 2024

What this trial tests

NA trial testing Heat acclimation in Heat Stress, Exertional in 27 participants. Completed in 30 April 2024.

Timeline

1 October 2021

Primary endpoint
30 April 2024

30 April 2024

Quick facts

Lead sponsor	United States Army Research Institute of Environmental Medicine
Phase	NA
Status	Completed
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	none
Primary purpose	prevention
Enrollment	27
Start date	1 October 2021
Primary completion	30 April 2024
Estimated completion	30 April 2024
Sites	1 location across United States

Drugs / interventions tested

• Heat acclimation

Conditions studied

• Heat Stress, Exertional — all drugs for Heat Stress, Exertional →

Sponsor

United States Army Research Institute of Environmental Medicine

Who can join

Adults 18 to 40, any sex, with Heat Stress, Exertional. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

Women are often understudied in thermal physiology research, leaving recommendations for Soldier safety and performance in hot conditions based largely on data collected in men. Female sex hormones estradiol and progesterone clearly have non-reproductive physiological effects, including influences on thermoregulatory and cardiovascular function. However, mechanisms of differing physiological adaptations to repeated heat exposure (i.e., heat acclimation) as a function of reproductive hormone status have yet to be investigated in a systematic way. Understanding possible sex differences in adaptation or mechanisms for adaptation during heat acclimation is important to ultimately optimize interventions to maximize soldier health and safety during training and deployment in the heat. Our goals in the present study are to evaluate physiological and biophysical responses to a standard heat acclimation protocol in a group of young, healthy men and women. Thirty individuals (n=10 males, n=10 women with a low hormonal status (i.e. early follicular phase), n=10 women with a high hormonal status (i.e. midluteal phase)) will complete 10 consecutive days of exercise (treadmill walking: 3.1 mph/2% grade) in the heat (40°C /40% relative humidity) up to 3hr per day. Changes in core temperature, heart rate, and sex hormones will be assessed to examine differences in thermoregulatory response to heat acclimation.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. Inter-individual variability in physiological adaptations during heat acclimation in adults: Contributions of body mass index and body size.
   Brazelton SC, Charkoudian N, Bradbury KE, Salgado RM, et al · · 2026 · cited 1× · PMID 41546148 · DOI 10.14814/phy2.70713