The aims of this pilot study were to examine the acceptability, feasibility, and fitness and occupational performance outcomes among firefighter recruits after a 10-week randomized trial. The institutional review board (IRB) of Kansas State University (KSU) approved the study (IRB #8063). All participants provided written consent prior to initiation of their involvement in research.
We solicited study volunteers by visiting a midwestern fire academy that is hosted by a community college fire science degree program with permission from the Fire Academy Program Director. Participants (N = 13; 92.3% male) reported they were in good health and without physical limitations that prevented them from completing any of the required TF20 workouts and fitness assessments.
Participants were individually randomly assigned to either the intervention (TF20) or comparison group (CG). Microsoft Excel was used to generate the random allocation sequence. Both groups completed baseline assessments, 10-weeks of either the TF20 or CG, and follow-up assessments.
Because recruits also were students in the community college degree program, passing the CPAT prior to entry into the fire academy was not required. The fire academy provided instruction to prepare recruits to take state tests for firefighter certification, but they were not professional firefighters. Figure 1 shows participant randomization and progress through the study (TF20 = 7 and control [CG] = 6).
TF20 is an innovative online training program developed by firefighters specifically for firefighters that provides foundational educational principles around physical fitness, mental wellness, and nutrition. Using a holistic approach combined with empirical evidence [19,20,21] TF20 is a comprehensive program that addresses firefighters’ unique physiological challenges by simulating tasks performed on the fire ground. Specifically, the program’s goals are to optimize a firefighter’s occupational performance, resilience to injury, stability, mobility, strength, and endurance through a series of high intensity circuits, focused on both resistance and endurance exercises. TF20 online platform allows participants to apply and track these principles on a daily basis and record their progress. The portal includes private account settings, health programs, fitness tracking with exercise and workout videos, nutrition tracking, health education, results tracking, and communication and social media tools.
TF20 Intervention Group (TF20) workouts were part of an online training program that provided endurance and resistance exercises, nutritional information, and mental performance guidance. The original program was a 24-week periodized program which was condensed into a 10-week exercise program to accommodate the time frame of the study and fire academy academic semester. A National Strength and Conditioning Association (NSCA) Certified Strength and Conditioning Specialist (CSCS) and Tactical Strength and Conditioning Facilitator (TSAC-F) condensed the program but kept the periodization scheme consistent to mimic the longer cycle of workouts. The workouts are summarized in Table 1.
Workouts contained a combination of aerobic (e.g., running, rowing, jumping), body weight (e.g., air squats, pushups, sit-ups), and weight lifting (e.g., presses, back squats, weighted lunges) exercises with workouts designed to use equipment available in an exercise facility (e.g., weight racks, benches) or in a fire station/on the fire ground (e.g., equipment carry, dummy drag, etc.). Sixty-minute TF20 sessions included a warm-up, workout, and cool down. All completed workouts were logged in TF20 software program, which was used to assess intervention adherence.
The comparison group (CG; i.e.: control group) followed their regular workout routine for 10 weeks. Participants chose the time, duration, frequency, and type of workouts completed. For the study, participants were asked to log all exercise/workouts online using Google Sheets.
Both the TF20 and CG met weekly with a firefighter fitness trainer with current CPR and First Aid certifications (Firefighter/EMT, CPR/First Aid, TSAC-F certified). Weekly meetings ensured education on proper movements used in TF20 program, and discussion of proper movement progressions. Both groups were reminded to log their workouts. Any questions the participants had were also discussed during the meetings.
The research team enrolled participants during the first week of their 16-week fire academy. The research team generated the random allocation and assigned participants to intervention groups. Baseline testing occurred during the second week of the fire academy, the intervention took place the next 10 weeks and the follow-up assessments were completed within the following two weeks.
As an incentive to participants, this study took the place of the one credit hour physical fitness course requirement for the fire academy. This one credit hour course was offered through the local community college and allowed participants to access the community college gym. The class was not associated with the fire academy nor was it instructor-led; it solely provided access to a gym. The fire academy in this study did not have a structured exercise (fitness training) component.
During the initial (baseline) and final 10-week (follow-up) of the study, participants’ health, fitness, and performance were assessed. A Seca stadiometer (Chino, CA) was used to assess height. The Tanita TBF-300A digital bioelectrical impedance analysis (BIA) scale (Arlington Heights, IL) was used to assess body composition including percent body fat (%BF), fat mass (FM in kg), fat-free mass (i.e., muscle mass; FFM in kg), body mass index (BMI in kg/m2), and weight (to the nearest 0.1 kg). Research has shown that BIA correlates well (r > 0.8) with the gold-standard measure dual X-ray absorptiometry (DEXA) analysis for body composition .
Maximal aerobic capacity (VO2max) was estimated from the linear relationship between heart rate (HR) and work rate during a submaximal graded exercise test using a StairMaster StepMill 7000PT [23, 24]. A standardized protocol recommended for firefighters by the Joint Labor Management Wellness Fitness Initiative (WFI) was used . This test is recommended for firefighters because, unlike other submaximal graded exercise tests, this one requires the participant to exercise to maximal volitional fatigue, similar to completing a physically exhausting task on the fireground [23, 24]. Additionally, studies using this test and prediction equation demonstrated accuracy and validity, with no false positives or negatives .
Upper body muscular strength (grip strength; GS) was assessed with the Takei 5401 Hand Grip Dynamometer (Digital; Niigata City, Japan). A hand grip dynamometer is a valid and reliable measure (p < 0.05) and is a strong correlate (r > 0.9994) with upper body muscular strength [25, 26]. Participants’ dominant hand was noted; GS was recorded three times for both hands in an alternating fashion. The best of three attempts was recorded for each hand. GS was examined alone (unadjusted) and in relation to the participant’s body weight (adjusted).
Upper body muscular endurance was assessed with a 2-min timed push-up (PU) test . The PU test required participants to touch their chin to the mat at the bottom of each repetition, and the score was the number of continuous repetitions completed .
Muscular power was assessed with a counter-movement jump (Jump, Sunnyvale, CA). The best of three jumps was recorded. Participants’ standing reach height was subtracted from their maximal jump height, so their total vertical displacement was recorded to the nearest cm.
Core strength was assessed with a cadence curl-up test . Two strips of masking tape were placed 12 cm apart. Participants lay supine across the tape with knees bent 90°. A metronome was set at 40 beats/min. At each beep the participant curled their body upwards so as to move their hands to the second tape line. Repetitions were counted each time the participant reached the bottom position. The test was concluded either when the participant completed 75 curl-ups or the cadence was broken .
Agility was assessed with a timed agility T test . This assessment required participants to move in a T-shaped pattern requiring lateral and front-to-back movements. The agility test was recorded in seconds to completion.
Trunk flexibility was assessed using a standardized sit-and-reach box (Canadian Trunk Forward Flexion test; 27).
A simulated fire ground test (SFGT), the Candidate Physical Ability Test (CPAT) was used to measure occupational performance, fitness, and agility. The CPAT provides a traditional frame of reference to evaluate increases or decreases in physical fitness and occupational readiness and provides a firefighter-specific assessment. The CPAT consists of eight separate events that require the participant to progress along a predetermined path from event to event in a continuous manner. It is a pass/fail test based on finishing all events in a maximum total test time of 10 min and 20 s or less. Participants were provided with a familiarization session prior to taking the CPAT for the first time as is suggested by the IAFF/IAFC . Participants were able to familiarize themselves with the equipment at each event but did not take the entire test during the familiarization period.
In all eight events (i.e., Stair Climb, Hose Drag, Equipment Carry, Ladder Raise and Extension, Forcible Entry, Search, Dummy Drag, and Ceiling Breach and Pull), candidates wore a 50-pound (22.68-kg) vest to simulate the weight of self-contained breathing apparatus (SCBA) and firefighter protective clothing. An additional 25 pounds (11.34 kg), using two 12.5-pound (5.67-kg) shoulder weights that simulated a high-rise pack (hose bundle), was added for the stair climb event. Throughout all events, candidates wore long pants, a hard hat with chin strap, work gloves and footwear with no open heel or toe. Watches and loose or restrictive jewelry were not permitted. All props were designed to simulate critical fire ground tasks and test the candidate’s physical ability . Participants’ heart rate and blood pressure were taken immediately (within two minutes) following completion of the CPAT.
A questionnaire was completed at baseline and follow-up and included standard demographics (baseline only), health behaviors, current exercise habits, and current nutritional habits. Physical activity was measured using the modified International Physical Activity Questionnaire (IPAQ) short form, which provided a global, physical activity self-rating during the last 30 days . Participants were asked to indicate the amount of moderate and vigorous aerobic activity and strength training completed. From this, researchers created a dichotomous variable for meeting/not meeting the physical activity guidelines for the previous 30 days. Participants were also asked if they followed any current diet/meal plans and if their diet had changed in the previous 12 weeks.
A feasibility analysis was completed to examine participant adherence, their reactions to the intervention, and suggestions for future physical exercise training for the Fire Academy.
Microsoft Excel and SPSS Version 21 (Armonk, NY) were used for statistical analyses. Means, standard deviations, and proportions were calculated for all variables. However, the small sample size and uneven groups precluded the use of typical parametric between-groups comparisons. In order to examine outcomes of all participants initially recruited in the study, we used an Intention to Treat (ITT) Model carrying forward the baseline observations for those that did not have post-test values. This allowed us to examine all participants, assuming no change for those that did not complete the intervention. The Mann-Whitney U Test was used to examine differences between the two groups. Within-group changes over time for both groups were examined for the completers using the Wilcoxon Signed Rank Test to compare repeated measures (pre- and post-intervention) for each group separately. The Wilcoxon converts scores to ranks and compares them at Time 1 (pre-) and Time 2 (post-) . Statistical significance was set at p < 0.05.
Written responses to questionnaires (baseline and follow-up) were analyzed qualitatively by coding and analyzing recurrent themes, areas of consensus and convergence of opinions, experiences, and perceptions about the wellness program using a grounded theory approach . Data were then coded by identifying passages exemplifying key concepts or ideas related to the major themes using NVivo 10 (QSR International, 2016). A feasibility analysis also was completed to examine the relevance of offering this intervention in a fire academy. Adherence to the prescribed workouts for TF20 group and their feedback to the intervention were examined in a follow-up questionnaire.