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

Primary Purpose

Heat Stress, Exertional

Status

Recruiting

Phase

Not Applicable

Locations

United States

Study Type

Interventional

Intervention

Heat acclimation

About this trial

This is an interventional prevention trial for Heat Stress, Exertional

Eligibility Criteria

18 Years - 40 Years (Adult)All SexesAccepts Healthy Volunteers

Inclusion Criteria:

• Males and females, age 18-40 y (17 y for active duty military)
- Eumenorrheic females (menstrual cycle length between 24-35 days) or females taking oral contraceptives
- In good health as determined by OMSO (Office of Medical Support and Oversight) General Medical Clearance and willing to report all medications and dietary supplements (i.e. cold medication, Tylenol. Aleve) to the PI and OMSO.
- Passed his/her most recent Army Combat Fitness Test (ACFT) (military volunteers only) or exercise at least 2 times per week (civilian volunteers)
- Willing to not exercise, or drink alcoholic beverages for 24 hours before each testing session
- Willing to not consume caffeine 12 hours prior to any testing sessions
- Willing to refrain from additional moderate to strenuous physical activity throughout testing period
- Males and females with BMI <30

Exclusion Criteria:

• Females who are pregnant or planning to become pregnant during the study
- Females utilizing implantable contraception (intrauterine device, implantable bar)
- Tested positive for COVID-19 within the past 30 days.
- Taking prescription or over the counter medication, other than a contraceptive (unless approved by OMSO and Principal Investigator (PI))
- Tobacco users, or anyone who has used tobacco within the last four months
- Physical problems/injuries that would affect walking or running on a treadmill
- Allergy to skin adhesive
- Heart, lung, kidney, muscle, endocrine, or nerve disorder(s)
- History of heat intolerance or orthostatic intolerance
- Diagnosed and/or treated for fluid/electrolyte imbalance within the last 30 days
- History of obstructive disease of the gastrointestinal tract including (but not limited to) diverticulosis, diverticulitis and inflammatory bowel disease, peptic ulcer disease, Crohn's disease, ulcerative colitis.
- Scheduled MRI during testing

Sites / Locations

U.S. Army Research Institute of Environmental MedicineRecruiting

Arms of the Study

Arm 1

Arm 2

Arm 3

Arm Type

Experimental

Arm Label

Males

Females + high hormones

Females + low hormones

Arm Description

10 consecutive day heat acclimation in males

10 consecutive day heat acclimation in females with high hormonal dose

10 consecutive day heat acclimation in females with low hormonal dose

Outcomes

Primary Outcome Measures

Core temperature

Heart rate

Secondary Outcome Measures

Full Information

NCT ID

NCT05292170

First Posted

March 14, 2022

Last Updated

May 10, 2023

Sponsor

United States Army Research Institute of Environmental Medicine

1. Study Identification

Unique Protocol Identification Number

NCT05292170

Brief Title

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

Official Title

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

Study Type

Interventional

2. Study Status

Record Verification Date

May 2023

Overall Recruitment Status

Recruiting

Study Start Date

October 1, 2021 (Actual)

Primary Completion Date

September 2024 (Anticipated)

Study Completion Date

September 2025 (Anticipated)

3. Sponsor/Collaborators

Responsible Party, by Official Title

Sponsor

Name of the Sponsor

United States Army Research Institute of Environmental Medicine

4. Oversight

Studies a U.S. FDA-regulated Drug Product

Studies a U.S. FDA-regulated Device Product

Data Monitoring Committee

5. Study Description

Brief Summary

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.

6. Conditions and Keywords

Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study

Heat Stress, Exertional

7. Study Design

Primary Purpose

Prevention

Study Phase

Not Applicable

Interventional Study Model

Parallel Assignment

Masking

None (Open Label)

Allocation

Randomized

Enrollment

40 (Anticipated)

8. Arms, Groups, and Interventions

Arm Title

Males

Arm Type

Experimental

Arm Description

10 consecutive day heat acclimation in males

Arm Title

Females + high hormones

Arm Type

Experimental

Arm Description

10 consecutive day heat acclimation in females with high hormonal dose

Arm Title

Females + low hormones

Arm Type

Experimental

Arm Description

10 consecutive day heat acclimation in females with low hormonal dose

Intervention Type

Other

Intervention Name(s)

Heat acclimation

Intervention Description

10 consecutive days of heat acclimation

Primary Outcome Measure Information:

Title

Core temperature

Time Frame

10 days

Title

Heart rate

Time Frame

10 days

10. Eligibility

Sex

All

Gender Based

Yes

Gender Eligibility Description

Cis gender males and females

Minimum Age & Unit of Time

18 Years

Maximum Age & Unit of Time

40 Years

Accepts Healthy Volunteers

Eligibility Criteria

Inclusion Criteria: • Males and females, age 18-40 y (17 y for active duty military) Eumenorrheic females (menstrual cycle length between 24-35 days) or females taking oral contraceptives In good health as determined by OMSO (Office of Medical Support and Oversight) General Medical Clearance and willing to report all medications and dietary supplements (i.e. cold medication, Tylenol. Aleve) to the PI and OMSO. Passed his/her most recent Army Combat Fitness Test (ACFT) (military volunteers only) or exercise at least 2 times per week (civilian volunteers) Willing to not exercise, or drink alcoholic beverages for 24 hours before each testing session Willing to not consume caffeine 12 hours prior to any testing sessions Willing to refrain from additional moderate to strenuous physical activity throughout testing period Males and females with BMI <30 Exclusion Criteria: • Females who are pregnant or planning to become pregnant during the study Females utilizing implantable contraception (intrauterine device, implantable bar) Tested positive for COVID-19 within the past 30 days. Taking prescription or over the counter medication, other than a contraceptive (unless approved by OMSO and Principal Investigator (PI)) Tobacco users, or anyone who has used tobacco within the last four months Physical problems/injuries that would affect walking or running on a treadmill Allergy to skin adhesive Heart, lung, kidney, muscle, endocrine, or nerve disorder(s) History of heat intolerance or orthostatic intolerance Diagnosed and/or treated for fluid/electrolyte imbalance within the last 30 days History of obstructive disease of the gastrointestinal tract including (but not limited to) diverticulosis, diverticulitis and inflammatory bowel disease, peptic ulcer disease, Crohn's disease, ulcerative colitis. Scheduled MRI during testing

Central Contact Person:

First Name & Middle Initial & Last Name or Official Title & Degree

Gabrielle EW Giersch, PhD

Phone

5082062421

gabrielle.e.giersch.ctr@mail.mil

Facility Information:

Facility Name

U.S. Army Research Institute of Environmental Medicine

City

Natick

State/Province

Massachusetts

ZIP/Postal Code

01760

Country

United States

Individual Site Status

Recruiting

Facility Contact:

First Name & Middle Initial & Last Name & Degree

Gabrielle EW Giersch, PhD

Phone

508-206-2421

gabrielle.e.giersch.ctr@mail.mil

12. IPD Sharing Statement

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

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