Effect of Rapid Heat Stress on Firefighters Musculoskeletal Injury Risk

NCT06442956 | Completed

• 1 other identifier: STUDY00002549
• Study Type: interventional
• Target: 26
• Locations: 1 country
• Sites: 1

Brief Summary

This study will examine the effect of heat stress on factors that influence musculoskeletal injury risk in firefighters. Participants will attend 4 data collection sessions. 1: informed consent, screening, and familiarization. 2: pre-tests (strength, balance, and movement quality). 3: heat stress (rapid or gradual) followed by post-tests (strength, balance, and movement quality). 4: heat stress (rapid or gradual) followed by post-tests.

Conditions

Occupational Injuries; Heat Stress; Leg Injury; Back Injuries

Keywords

firefighter; musculoskeletal; slip; trip; fall

Outcome Measures

Primary Outcomes (5)

• Forward-Step-Down Test

  a step-down task that is performed off a 20 cm box. Five repetitions are performed to give one score (minimum score 0, maximum score 6). A higher score is worse.

  Familiarization trials (session 1, recruitment); pre-testing (baseline, session 2 (approximately day 7)); post-control and post-experimental sessions (session 3 (approximately day 14) & 4 (approximately day 21)).

• Y-Balance Test

  A dynamic balance test that is performed on the dominant leg, reaching in the anterior, posteromedial, and posterolateral directions. The length of reach is standardized to participants' leg length. A higher score is better, with 0 being the minimum distance and the maximum distance in anterior reach being 126cm, and the maximum posteromedial and posterolateral directions being 149cm.

  Familiarization trials (session 1, recruitment); pre-testing (baseline, session 2 (approximately day 7)); post-control and post-experimental sessions (session 3 (approximately day 14) & 4 (approximately day 21)).

• Firefighter Specific Functional Balance Test

  A dynamic balance test performed by stepping down from a 15cm box, walking across a low beam (4cm high), and stepping up onto a 10cm box, turning around, and returning to the original box. 8 Trials are performed. In 4 trials, a bar is placed at 75% of the participant's height for them to negotiate while on the beam. A faster time with fewer errors is better.

  Familiarization trials (session 1, recruitment); pre-testing (baseline, session 2 (approximately day 7)); post-control and post-experimental sessions (session 3 (approximately day 14) & 4 (approximately day 21)).

• Knee Flexor/Extensor Isokinetic Test

  Knee flexor/extensor isokinetic strength will be tested at 60°, 180°, and 300° per second from the seated position with 5, 10, and 10 concentric contractions for each speed. A higher reading of strength is better.

  Familiarization trials (session 1, recruitment); pre-testing (baseline, session 2 (approximately day 7)); post-control and post-experimental sessions (session 3 (approximately day 14) & 4 (approximately day 21)).

• Hip Abductor/Adductor Isokinetic Test

  Hip abductor/adductor strength will be tested at 30°, 60°, and 120° per second from the standing position. A higher reading of strength is better.

  Familiarization trials (session 1, recruitment); pre-testing (baseline, session 2 (approximately day 7)); post-control and post-experimental sessions (session 3 (approximately day 14) & 4 (approximately day 21)).

Secondary Outcomes (1)

• Injury Occurrence

  6 months, 12 months, 18 months, 24 months after session 4.

Study Arms (2)

Rapid Heat Stress

EXPERIMENTAL

Participants in the rapid heat stress arm will perform an exercise protocol on a treadmill in a hot, humid environment while wearing firefighter protective gear. This results in an uncompensable heat environment with a rapid increase in core temperature.

Other: Rapid Heat Condition

Gradual Heat Stress

ACTIVE COMPARATOR

Participants in the rapid heat stress arm will perform an exercise protocol on a treadmill in a hot, humid environment while wearing light exercise clothing. This results in an uncompensable heat environment but with a gradual increase in core temperature.

Other: Gradual Heat Condition

Interventions

Rapid Heat Condition OTHER

The heat condition is the intervention. Personal protective equipment will be used to create the rapid heat stress condition, resulting in a rapid rise in core temperature. This will be in combination with the physiological heat produced by the treadmill protocol.

Rapid Heat Stress

Gradual Heat Condition OTHER

The gradual heat condition is the control. Physiological heat will be produced by exercise on a treadmill, and light exercise clothing will help moderate the rise in core temperature.

Gradual Heat Stress

Eligibility Criteria

• Age: 18 Years - 57 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• professional firefighter
• healthy per the Physical Activity Readiness Questionnaire+ screening

You may not qualify if:

• unable to swallow core temperature capsule
• unable to follow pre-testing hydration criteria
• musculoskeletal injury in the past 3 months that limits ability to perform outcome measures
• females with known pregnancy (risk of hyperthermia to fetus)

Sponsors & Collaborators

• Louisiana State University Health Sciences Center Shreveport: lead

Study Sites (1)

LSUHSC-Shreveport

Shreveport, Louisiana, 71103, United States

Location

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MeSH Terms

Conditions

Occupational Injuries; Heat Stress Disorders; Leg Injuries; Back Injuries

Condition Hierarchy (Ancestors)

Wounds and Injuries

Study Officials

• Erin McCallister, DPT

  LSUHSC-Shreveport

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: randomized crossover

Study Record Dates

• First Submitted: May 29, 2024
• First Posted: June 5, 2024
• Study Start: January 7, 2025
• Primary Completion: November 7, 2025
• Study Completion: November 7, 2025
• Last Updated: March 30, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)