Heat Acclimation, Hand Cooling Efficacy, and Adaptation Maintenance.

Not Applicable

Completed

• Conditions: Heat
• Interventions: Other: Heat acclimation; Other: Exercise in a cool environment

• Registration Number: NCT04053465
• Lead Sponsor: University of Connecticut

Brief Summary

This study had three aims:

1. To determine the impact of consecutive days of exercise on thermoregulation and cardiovascular strain.

2. To determine the efficacy of a hand cooling device to cool individuals throughout a heat acclimation period.

3. To assess the maintenance of thermoregulatory and cardiovascular adaptations derived from heat acclimation during a 25-day intermittent exercise-heat exposure protocol.

Detailed Description

Participants completed 14 days of exercise heat acclimation in either a hot or cool environment, followed by a heat or cool exercise exposure every 5th day for 25 days. Cardiovascular, thermoregulatory, and perceptual strain were measured throughout exercise each day. Hydration assessment and stress response via blood biomarkers were measured before and after exercise. Aerobic capacity was measured before and after heat acclimation as well as after the intermittent exercise-heat exposure. Hand cooling was implemented periodically during exercise-heat stress visits to determine cooling efficacy before and after heat acclimation.

Study Timeline

• Study Start: 2014-08-01
• Primary Completion: 2015-03-31
• Study Completion: 2015-03-31
• Study First Submitted: 2019-08-07
• Study First Submitted QC: 2019-08-09
• Study First Posted: 2019-08-12
• Results First Submitted: 2020-01-06
• Status Verified: 2020-02
• Results First Submitted QC: 2020-02-13
• Last Update Submitted: 2020-02-13
• Results First Posted: 2020-02-27
• Last Update Posted: 2020-02-27

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Male
• Target Recruitment: 34

Inclusion Criteria

• no chronic health problems
• no previous history of exertional heat stroke within the past 3 years
• no history of cardiovascular, metabolic or respiratory disease
• no current musculoskeletal injury that limits physical activity

Exclusion Criteria

• women
• exercise less than once per week
• VO2max < 45 ml/kg/min

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Exercise in heat group	Heat acclimation	Exercise in a hot environment
Exercise in cool group	Exercise in a cool environment	Exercise in a cool environment

Primary Outcome Measures

Name	Time	Method
Internal Body Temperature	5 days	Rectal temperature was assessed five days following measurement at baseline.

Secondary Outcome Measures

Name	Time	Method
Heart Rate	5 days	Heart rate was assessed five days following baseline.