Comparison of a Novel Condensed Heat Acclimation Programme With a Traditional Longer-term Heat Acclimation Programme

NCT05600452 | Completed

• 1 other identifier: 1017/MoDREC/19
• Study Type: interventional
• Target: 37
• Locations: 1 country
• Sites: 1

Brief Summary

Repeated exposure to heat in a laboratory setting (acclimation) elicits a range of adaptations, which reduce heat illness risk and increase work capacity in the heat. Traditional approaches to heat acclimation require daily heat exposures of 1 to 2 hours over \~7 to 10 consecutive days. Heat acclimation approaches which reduce the number of days to achieve acclimation may have utility. The primary purpose of the proposed research is to determine whether it is possible to achieve a similar degree of heat acclimation to that seen with a traditional longer-term heat acclimation approach by increasing the frequency of heat exposure, utilising multiple daily heat exposures over a smaller number of days. Secondary aims of the research are to examine whether heat acclimation provides cross-adaptation to a hypoxic stressor and whether heat acclimation improves aerobic fitness.

Conditions

Heat Stress

Outcome Measures

Primary Outcomes (1)

• Reduction in the peak deep body temperature

  Rectal temperature measurement during a heat stress test

  Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week)

Secondary Outcomes (29)

• Reduction in the resting deep body temperature

  Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week)

• Reduction in the peak mean body temperature

  Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week)

• Reduction in the resting mean body temperature

  Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week)

• Increased plasma volume

  Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week)

• Increased sweating rate

  Pre heat acclimation intervention (up to 1 week) to post heat acclimation intervention (up to 1 week)

Study Arms (2)

Traditional heat acclimation

ACTIVE COMPARATOR

The traditional heat acclimation programme will consist of daily 75-minute heat exposures for eight consecutive days

Other: Heat acclimation

Condensed heat acclimation

EXPERIMENTAL

The condensed heat acclimation programme will consist of two consecutive days with four, 75-minute heat exposures undertaken on each day

Other: Heat acclimation

Interventions

Heat acclimation OTHER

Repeated heat exposures with light exercise sufficient to elevate deep body temperature to \~ 38.5C

Condensed heat acclimation; Traditional heat acclimation

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Male
• Physically active and healthy as determined by pre-participation health screening questionnaire.
• Free of COVID-19 symptoms (loss or change in sense of smell or taste, fever and new, continuous cough) as determined by pre-screening questionnaire.
• Resting diastolic blood pressure between 60 and 90 mmHg; resting systolic blood pressure between 90 and 150 mmHg A resting ECG is required if: individuals are over 30 years of age; they are unfamiliar with exercise of a maximal nature; they have a family history of adverse cardiac events. The ECG is to be reviewed by the Independent Medical Officer.

You may not qualify if:

• Current smokers
• Recent (\< 3 months) participation in a formal heat acclimation regimen, or regular frequent heat exposures that may render the participant partially heat acclimated (other than regular exercise)
• Recent (\< 3 months) high altitude (\>1 500m ) sojourn that may render the participant partially altitude acclimated
• Diagnosed cardiovascular, metabolic or respiratory conditions (excluding asthma)
• Prior history of heat illness
• Prior history of collapse or intolerance with exposure to altitude
• Recent blood donation (within 3 months of commencing study)
• Baseline serum sodium level \<135 mmol.L-1
• Any other extant medical condition which may be exacerbated by participation
• Participants with inadequate understanding of English.
• Any volunteers who are currently participating in any other research studies which may influence their responses or the results obtained

Sponsors & Collaborators

• University of Portsmouth: lead
• Coventry University: collaborator
• Teesside University: collaborator

Study Sites (1)

University of Portsmouth

Portsmouth, Hampshire, PO1 2ER, United Kingdom

Location

MeSH Terms

Conditions

Heat Stress Disorders

Condition Hierarchy (Ancestors)

Wounds and Injuries

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Reader in Environmental Physiology

Model Details: Parallel groups design

Study Record Dates

• First Submitted: October 21, 2022
• First Posted: October 31, 2022
• Study Start: January 17, 2020
• Primary Completion: January 4, 2023
• Study Completion: January 4, 2023
• Last Updated: December 6, 2023

Record last verified: 2023-12

Data Sharing

• IPD Sharing: Will not share

Locations

GB (1)