Feasibility of a Train-the-Trainer Delivered Exercise Intervention in Firefighters

Purpose: To collect and report feasibility data for conducting a future cluster randomized trial to evaluate the efficacy of a TRAINER delivered integrated exercise program in career firefighters, and to determine intervention fidelity and preliminary effects of a TRAINER delivered integrated exercise program in career firefighters.

Participants: 52 career firefighters 18 - 60 years old (40 trainees, 6 trainers, 6 administrators).

Procedures (methods): Enrolled fire stations will be randomly assigned (3:2 allocation ratio) to a TRAINER or wait-list control (CON) group, stratified by city, using computer-generated random numbers. All enrolled firefighters will undergo a series of assessments at baseline (week 0) and post-testing (week 7) following the TRAINER delivered 6-week intervention.

Study Overview

• Status: Enrolling by invitation
• Conditions: High Intensity Interval Training; Firefighter
• Intervention / Treatment: Behavioral: Integrated Exercise Program

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Eric Ryan, PhD; Phone Number: 919-962-0297; Email: edryan@email.unc.edu
• Study Contact Backup: Name: Gena Gerstner, PhD; Phone Number: 518-878-1740; Email: gerstner@email.unc.edu

Study Locations

• United States
  • North Carolina
    • Chapel Hill, North Carolina, United States, 27599
      • UNC Chapel Hill
      • Contact: Eric Ryan, PhD; Phone Number: 919-962-0297; Email: edryan@email.unc.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 60 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Provide informed consent prior to any study procedures are performed
• Medically cleared for fire suppression duties
• A career firefighter from a local department (Carrboro, Chapel Hill, and Durham)

Exclusion Criteria:

• Highly active firefighters, defined as performing 4 or more days/week of vigorous exercise
• Pregnancy
• Recent injury preventing their participation in the exercise routine
• Involved in an active workers' compensation or personal injury case

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: TRAINER; The TRAINER group will receive an integrated exercise program, led by a peer-trainer, including a neuromuscular warm-up and high intensity interval training at their respective fire stations 2 times per week for 6 weeks.	Behavioral: Integrated Exercise Program; Neuromuscular warm-up: Each participant will perform a series of dynamic stretches, core stability, balance, and medicine ball exercises. The dynamic stretches include 8 repetitions of 6 stretches targeting the hip and thigh musculature, followed by 3 core stability isometric exercises (curl-up, side bridge, and bird dog). Participants will then perform 2 sets (per leg) of hop-to-stabilization (with a reach) balance exercises, followed by 3 separate medicine ball exercises emphasizing explosive full-body movements. High Intensity Interval Training (HIIT): HIIT will include a series of high intensity exercise bouts on a stationary bike that includes a 1:1 work-to-rest ratio. Training intensity will be determined from the peak power output obtained during the baseline VO2 peak assessment and progressively increased by the number of bouts and intensity. The number of work bouts will increase from 5 to 8 bouts and the intensity will increase from 90 to 110% of peak power output.; Other Names: High intensity interval training; HIIT; Neuromuscular warm-up
No Intervention: Waitlist Control; The waitlist control group will not receive training during the course of the study, but will be offered the opportunity to receive the integrated exercise program after the study ends.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Firefighters and Fire Stations Recruited to the Study (Feasibility)	To demonstrate the feasibility of an integrated exercise program. Feasibility will be defined as recruitment of 40 firefighters and the number of fire stations (out of 26 potential) to the study within 14 months.	Within 14 months
Percentage of Firefighters Retained (Feasibility)	To demonstrate the feasibility of an integrated exercise program. Retention will be determined from the percentage of firefighters retained at post-testing. Retention of 80% or higher will be considered good feasibility.	Week 7 (post-intervention)
Percentage of Sessions Attended (Feasibility)	To demonstrate the feasibility of an integrated exercise program. Adherence will be determined from the percentage of sessions attended out of total (12) sessions. Adherence of 80% or higher will be considered good feasibility.	Week 7 (post-intervention)
Qualitative Summaries of Participant Experience in Semi-Structured Interviews (Acceptability)	Acceptability will be assessed by semi-structured interviews with the firefighters, peer-trainers, and departmental administration (e.g. fire chiefs). Qualitative summaries for intrapersonal, interpersonal, and organizational constructs will be reported.	Week 7 (post-intervention)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in cardiorespiratory fitness as measured by VO2 peak during cycle ergometry	Cardiorespiratory fitness will be measured by peak oxygen consumption (VO2 peak). All participants will perform a cycling ergometer test with respiratory gases continuously monitored with open-circuit spirometry (True One 2400®, Parvo-Medics, Inc., Provo, UT). Data will be averaged over 15-second intervals, with the highest 15-second oxygen consumption recorded as the VO2 peak.	Baseline (i.e., pre-intervention), 7 weeks (i.e., post-intervention)
Change in body composition as measured by % body fat from a 4-compartment model	Body composition will be evaluated to determine the effects of the intervention on % body fat. Dual-energy x-ray absorptiometry (DXA;General Electric Lunar iDXA, Chicago, IL) and bioelectrical impedance spectroscopy (BIS; ImpediMed SFB7, Queensland, AU) will be used to determine a gold-standard DXA-derived four-compartment model of % body fat.	Baseline (i.e., pre-intervention), 7 weeks (i.e., post-intervention)
Change in explosive muscle strength as measured by dynamometry	All participants will perform a rapid and maximal isometric muscle action on a calibrated isokinetic dynamometer (CSMi, Stoughton, MA) against a padded and stiff lever arm for 3-4 seconds. The peak rate of torque development will be determined from the peak of the first derivative of the torque-time curve.	Baseline (i.e., pre-intervention), 7 weeks (i.e., post-intervention)
Change in low-back muscular endurance as measured by a modified Biering-Sorensen test	Low-back muscular endurance (time to task failure) will be examined using a modified version of the Biering-Sorensen test, using a variable angle Roman chair (Powerlift, Jefferson, IA).	Baseline (i.e., pre-intervention), 7 weeks (i.e., post-intervention)
Change in balance as measured by a modified star excursion balance test	Balance will be determined by using a modified star excursion balance test. Following a familiarization, participants will reach with their free limb as far as possible in the anterior, posterolateral, and posteromedial direction relative to the stance leg. Scores will be normalized to leg length.	Baseline (i.e., pre-intervention), 7 weeks (i.e., post-intervention)
Fidelity of the neuromuscular warm-up as measured by a rubric across sessions at Week 2	The fidelity of the neuromuscular warm-up will be examined using a scoring rubric. The rubric evaluates the leadership abilities of the trainers and the execution of the exercises by the firefighters. Each item is scored 1 to 5 with 1 indicating no correctness and 5 indicating complete correctness. Items will be summed for a total score. Higher values mean higher fidelity.	2 weeks (i.e., beginning of intervention following train-the-trainer completion)
Fidelity of the neuromuscular warm-up as measured by a rubric across sessions at Week 6	The fidelity of the neuromuscular warm-up will be examined using a scoring rubric. The rubric evaluates the leadership abilities of the trainers and the execution of the exercises by the firefighters. Each item is scored 1 to 5 with 1 indicating no correctness and 5 indicating complete correctness. Items will be summed for a total score. Higher values mean higher fidelity.	6 weeks (i.e., one of last 2 sessions)
Fidelity of the HIIT protocol as measured by rate of peak power output across sessions at Week 2	Fidelity will be assessed to ensure participant adherence to the intervention protocol in each session. The fidelity of the HIIT protocol will be examined by recording the prescribed peak power output (90-110%) during the training session. Training intensity will be established from a percentage of the baseline peak power output (Watts) achieved during the VO2 peak test. Higher fidelity is indicated as the percent power output more closely approaches the prescribed power output percentage.	2 weeks (i.e., beginning of intervention following train-the-trainer completion)
Fidelity of the HIIT protocol as measured by rate of peak power output across sessions at Week 6	Fidelity will be assessed to ensure participant adherence to the intervention protocol in each session. The fidelity of the HIIT protocol will be examined by recording the prescribed peak power output (90-110%) during the training session. Training intensity will be established from a percentage of the baseline peak power output (Watts) achieved during the VO2 peak test. Higher fidelity is indicated as the percent power output more closely approaches the prescribed power output percentage.	6 weeks (i.e., one of last 2 sessions)
Change in physical activity as measured by the International Physical Activity Questionnaire-Short Form	Physical activity will be examined using the validated 7-day recall International Physical Activity Questionnaire-Short Form. Higher scores represent greater total metabolic equivalent of task (MET) minutes of physical activity per week based on the following estimates: 3.3 MET units for walking, 4.4 MET units for moderate activity, 8 MET units for vigorous activity. Total MET minutes of physical activity is calculated from the questionnaire using the following calculation: Total MET-min/week = (Walk METs*min*days) + (Mod METs*min*days) + Vig METs*min*days) The study will test whether there is a BASELINE-to-POST increase in total scores on the International Physical Activity Questionnaire-Short Form (units: MET minutes/week) for the TRAINER group relative to the waitlist control group. The outcome for each group is computed as the main of the difference of the POST score minus the BASELINE score.	Baseline (i.e., pre-intervention), 7 weeks (i.e., post-intervention)
Change in nutrition as measured by the Rapid Eating Assessment for Participants-Short Form	Nutritional habits will be examined using the validated Rapid Eating Assessment for Participants-Short Form. Responses of 'usually/often' receives 1 point, 'sometimes' receives 2 points, and 'rarely/never or does not apply to me' receives 3 points. Possible scores ranged from 13 to 39 with a higher score indicating better nutritional habits. The study will test whether there is a BASELINE-to-POST increase in total scores on the Rapid Eating Assessment for Participants-Short Form for the TRAINER group relative to the waitlist control group. The outcome for each group is computed as the main of the difference of the POST score minus the BASELINE score.	Baseline (i.e., pre-intervention), 7 weeks (i.e., post-intervention)

Collaborators and Investigators

• Sponsor: University of North Carolina, Chapel Hill
• Collaborators: National Institute for Occupational Safety and Health (NIOSH/CDC)
• Investigators: Principal Investigator: Eric Ryan, PhD, UNC Chapel Hill

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2023
• Primary Completion (Estimated): September 29, 2024
• Study Completion (Estimated): September 29, 2024

Study Registration Dates

• First Submitted: March 9, 2022
• First Submitted That Met QC Criteria: March 9, 2022
• First Posted (Actual): March 18, 2022

Study Record Updates

• Last Update Posted (Actual): October 18, 2023
• Last Update Submitted That Met QC Criteria: October 17, 2023
• Last Verified: October 1, 2023

More Information

Terms related to this study

• Keywords: High intensity interval training; Firefighter; Train-the-Trainer; Neuromuscular warm-up; Fire and Rescue Personnel
• Other Study ID Numbers: 21-2522

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Deidentified individual data that supports the results will be shared beginning 9 to 36 months following publication provided the investigator who proposes to use the data has approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with the University of North Carolina (UNC).
• IPD Sharing Time Frame: 9 to 36 months following publication
• IPD Sharing Access Criteria: Investigator with IRB, IEC, or REB approval and an executed data use agreement with UNC
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No