Heat Acclimation in Females

April 7, 2025 updated by: Anita Cote, Trinity Western University

The Cardiovascular, Hematological, and Performance Response to Heat Acclimation in Healthy Trained Females

Heat acclimation is when you repeatedly exposure yourself to heat so that your body adapts and better tolerates heat.

This project will determine if completing a heat acclimation maintenance period after heat acclimation is more beneficial than heat acclimating alone for exercise performance in the heat. To determine this, participants will exercise in the heat before heat acclimation, after heat acclimation, and after heat acclimation maintenance. Researchers will assess the heart's pumping capacity, blood volume, body temperature, and exercise performance to determine which approach is more effective.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Purpose and Hypothesis: Global warming combined with increased frequency of heat waves exposes those who are working, exercising, or competing outdoors to considerable thermal strain. Excessive heat stress decreases exercise performance and can lead to heat illnesses. Deliberate serial exposure to natural (acclimatization) or artificial (acclimation) heat (HA) is the most efficacious method to defend homeostasis at rest and during exercise in hot environments. Our project will determine if three weeks of heat acclimation maintenance (HAM) further potentiates exercise performance in the heat than exercise performance measured after 10 days of HA in females.

Justification: Female participation in arduous occupations and professional sport is increasing. Presently a paucity of data regarding the female response to heat acclimation exist. Findings from this study will help females undertake effective and efficient strategies to mitigate thermal strain.

Research design: This is an experimental trial with a treatment and a control group. VO2max, plasma volume (PV), core temperature, and cardiac output will be measured pre-, mid-, and post-intervention. Participants will complete 10 sessions of HA over two weeks. Participants will then undergo three weeks of HAM with three heat sessions per week. A heat performance test will be completed pre-, mid-, and post-intervention to examine performance changes. A control group will complete the same test schedule but will not perform any HA or HAM.

Statistical analysis: Sample size will be 8 females in the experimental and 6 females in the control group. Data will be analyzed for normality using the Shapiro-Wilk test. Descriptive statistics will be presented as the mean and standard deviation. Statistical significance will be determined at P <0.05. A two-way repeated measure ANOVA will be used to measure differences between groups and hemodynamic, cardiovascular and performance variable differences pre- and post-HA, and pre- post-HAM. If significant effects are present, these will be followed by a post-hoc Tukey's test. Pearson's r correlations (two-tailed) will be conducted between VO2max, and intravascular volumes and heat performance test outcome.

Study Type

Interventional

Enrollment (Estimated)

14

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

  • Name: Normand A Richard, MSc
  • Phone Number: 3726 604.513.2121
  • Email: nar11@sfu.ca

Study Locations

  • Canada
    • British Columbia
      • Langley, British Columbia, Canada, V2Y 1Y1
        • Recruiting
        • Trinity Western Unversity
        • Contact:
          • Anita T Cote, PhD
          • Phone Number: 3726 1 604-513-2121
          • Email: acote@twu.ca

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Familiar with the sport of cycling and own a bicycle and smart trainer (or a trainer and a power meter).
  • Endurance athlete or currently engaging in endurance exercise
  • Maximal oxygen consumption (VO2max) greater than 40 ml/kg/min
  • Between the ages of 18 and 55
  • Able to speak, read, and write in English

Exclusion Criteria:

  • Unable to exercise
  • Previous or current heat intolerance
  • Pregnant

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Heat Acclimation
Participants in this arm will undergo heat acclimation sessions
Other: Heat exposure
Participants will exercise at home while wearing a clothing ensemble over 19 one hour sessions. They will use validated perceptual scales to guide their effort and thermal sensation.
Active Comparator: Control
Participants in this arm will undergo heart rate matched training volume
Other: Control group
Participants will exercise at home over 19 one hour sessions. They will use heart rate to guide their effort. The exercise will take place in cool conditions

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Performance
Time Frame: 2 weeks and 5 weeks
Participants will complete a timetrial on a cycle ergometer in a heat chamber. Faster times following HA or HAM will be considered a marker of performance
2 weeks and 5 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Intravascular volumes
Time Frame: 2 weeks and 5 weeks
Expanded plasma volume or increased hemoglobin mass will be considered a positive response to heat acclimation
2 weeks and 5 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Trinity Western University

Investigators

  • Principal Investigator: Anita T Coté, PhD, Trinity Western University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

September 1, 2024

Primary Completion (Estimated)

April 24, 2026

Study Completion (Estimated)

April 24, 2026

Study Registration Dates

First Submitted

August 9, 2024

First Submitted That Met QC Criteria

August 9, 2024

First Posted (Actual)

August 13, 2024

Study Record Updates

Last Update Posted (Actual)

April 10, 2025

Last Update Submitted That Met QC Criteria

April 7, 2025

Last Verified

April 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • 22G18

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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