Eric D. Ryan

Purpose: The purpose of this cluster randomized controlled trial was to examine the effectiveness of a 14-week high-protein meal replacement (MRP) intervention on macronutrient intake, body composition, cardiometabolic health, and stair climb (SC) performance in career firefighters with overweight and obesity, and collect acceptability data to inform implementation efforts. Methods: Twenty-six fire stations (51 firefighters; 36.7±7.3yrs; 33.1±4.8kg·m ⁻² ) were randomized to a MRP or wait-list control (CON) group. The MRP group consumed one shake/day (week 1) and two shakes/day (weeks 2-14) ad libitum. The primary outcome was percent body fat (%BF) measured by dual-energy x-ray absorptiometry, and secondary outcomes included macronutrient intake, body mass (BM), body mass index (BMI), regional fat distribution, resting heart rate (RHR) and blood pressure (BP), blood lipids, a weighted and timed SC task, and HR recovery (HR _rec ) following the SC task. Intervention acceptability was assessed in the MRP group. Linear mixed models assessed intervention effects with an alpha level set at 0.05. Results: The MRP group improved %BF (-1.0 [-1.9, -0.06]; P =0.038) and secondary outcomes including dietary intake [increase in protein and fiber intake ( P≤ 0.044); decrease in the CHO:PRO ratio ( P =0.008)], body composition [BM, BMI, trunk fat mass (FM), and android:gynoid and trunk:limb %BF ratios ( P ≤0.026)], and SC HR _rec ( P P =0.135-0.985). Shake adherence was high (90.7±11.8%) and firefighters reported the intervention was convenient and they would continue long-term. Conclusions: The MRP intervention improved macronutrient intake, body composition, and SC HR _rec and was well accepted, supporting a practical nutritional strategy to improve health in firefighters with overweight and obesity.

Objective: The purpose of this study was to (1) examine the relationship between perceived work-related fatigue and performance fatigability, and (2) assess the impact of percent body fat (%BF) on perceived fatigue constructs in career firefighters. Methods: Thirty-nine career firefighters completed body composition testing, the Occupational Fatigue Exhaustion Recovery (OFER15) scale assessing three subscales of work-related fatigue (acute fatigue, chronic fatigue, and inter-shift recovery), and maximal leg extensor isometric strength testing prior to and following an isotonic fatiguing protocol. Results: Performance fatigability was not associated with any of the OFER15 perceived work-related fatigue variables (P ≥ 0.513). Greater %BF was associated with greater %∆ peak torque (r = −0.41, P = 0.010) but none of the OFER15 perceived work-related fatigue variables (P ≥ 0.638). Conclusions: Performance fatigability was not associated with OFER15 perceived work-related fatigue, and greater adiposity negatively impacted performance fatigability but not perceived fatigability.

Firefighters are paramount to public safety with over 360,000 career firefighters currently employed in the United States, protecting nearly 70% of the population (Fahy, Evarts, and Stein 2020). Oc...

Introduction: The purpose of this study was to examine the impact of age on the affective responses (attitude, feelings, self-efficacy, intention, enjoyment, and fondness) after a worksite circuit-style resistance exercise routine in career firefighters. Methods: Nineteen young (25.5 ± 3.3 yr) and 19 middle-aged male career firefighters (50.3 ± 3.5 yr) completed 2 d of physical testing at local fire stations. Participants were familiarized with the resistance training exercises (deadlift, shoulder press, lunge, and upright row) at visit 1 and performed a multirepetition maximum (RM) assessment to prescribe the appropriate loads for the resistance exercise bout on visit 2. The resistance training session included three sets of 8 to 10 repetitions per exercise at 80% 1-RM. Participants completed a postexercise questionnaire examining affective responses and a rating of perceived exertion (RPE). Mann–Whitney U tests and an independent t-test were used to determine differences between the young and middle-aged firefighters’ affective responses and RPE, respectively. Results: There were no significant differences between groups for any of the six affective responses (P = 0.062–0.819) or RPE (P = 0.142). Conclusions: Age did not influence the perceived effort or affective responses following an acute bout of worksite resistance exercise. Firefighters reported overall positive attitudes, feelings, and fondness paired with high self-efficacy and intention at a training frequency of twice per week. However, confidence, intention, and enjoyment decreased at higher training frequencies (i.e., 3–4x per week). Circuit-style resistance training performed twice per week may be a feasible and practical worksite exercise routine across ages in the fire service.

Upper body (UB) strength is important for occupational tasks and injury prevention in law enforcement officers (LEOs). Portable, reliable, and cost-effective assessments are needed to examine UB strength among LEOs in field settings. The purpose of this study was to examine the test-retest reliability and minimum difference (MD) values of a novel and portable isometric upright row assessment in probation officers. Thirty certified probation officers (18 women; age = 38.9 ± 9.0 years, body mass = 98.8 ± 27.1 kg, stature = 171.4 ± 14.0 cm) volunteered for this investigation. Testing occurred on-site across two sessions (2–5 days apart). Participants stood upon an aluminum plate with a chain attached to a handle and dynamometer. They grasped the handle with a pronated grip, two cm below the umbilicus, and performed three isometric maximal voluntary contractions. Intraclass correlation coefficient (ICC2,1), standard error of the measurement (SEM), and MD values were calculated. Results indicated no significant systematic error (p = 0.080) across sessions. The ICC2,1, SEM, and MD values for UB strength were 0.984, 27.20 N (4.1% of the mean), and 75.38 N (11.3% of the mean), respectively. These data suggest this isometric upright row assessment is a reliable, portable, and cost-effective measure of UB strength to assess and monitor LEOs in field settings.

Purpose: The purpose of this study was to examine the time course of health, fitness, and occupational performance changes in firefighter recruits across a fire academy. Methods: Nineteen recruits (24.9 ± 4.3 yr; 26.7 ± 3.1 kg·m⁻²) had their body composition, balance, vertical jump (VJ) performance, cardiorespiratory fitness (CRF), upper and lower body strength, hamstrings-to-quadriceps (H/Q) ratio, lower back endurance, and weighted stair climb (SC) performance assessed at the beginning (week 1 [W1]), midpoint (week 15 [W15]), and end (week 30 [W30]) of a fire academy. Results: The fire academy improved body composition, balance, CRF, leg extension strength, and SC performance from W1 to W15 (P ≤ 0.042) which then plateaued at W30 (P ≥ 0.314). Leg flexion strength and the H/Q ratio decreased from W1 to W15 (P ≤ 0.035) and plateaued at W30 (P ≥ 0.947). Upper body strength was similar at W1 and W15 (P ≥ 0.999), but decreased at W30 (P ≤ 0.033). However, no significant changes occurred across the academy for VJ performance or lower back endurance (P ≥ 0.090). Conclusions: These findings highlight the positive effect of the academy on body composition, CRF, balance, SC performance, and leg extension strength. However, the decreases in upper body and leg flexion strength, the H/Q ratio, and lack of changes in VJ performance and low back endurance may highlight key areas of need to maximize injury prevention and performance enhancement efforts in the academy. Further, the varied time course of changes may help fire departments identify opportunities to modify exercise programming across their academies.

Objective: Although workload monitoring is commonly used in athletic settings to mitigate injury risk, we are unaware of previous studies examining its feasibility among firefighters. Methods: Nineteen firefighter recruits completed a short online workload survey at the end of each training day (Monday–Friday) for 26 weeks during the academy. A modified System Usability Scale was provided at midtesting (3 months into the academy) and posttesting (end of the academy). Results: The recruits perceived the survey to be user-friendly throughout the academy (83.6 ± 13.6). However, questions 1 (survey frequency) and 6 (survey consistency) decreased and increased from midtesting to posttesting, respectively. Adherence was overall poor, decreasing from midtesting to posttesting. Conclusions: Our findings suggest that workload monitoring is a user-friendly tool within tactical populations; however, future research should consider optimal survey frequency to enhance compliance.

The purpose of this study was to examine the influence of repeated bouts of shiftwork on lower extremity maximal and rapid strength and reaction time in career firefighters. Thirty-five firefighters (3 females; 34.3 ± 9.1 years) performed a psychomotor vigilance test (PVT) and reactive maximal isometric strength assessment prior to and following a full shift rotation (three 24-hr on-off shifts). Reaction time (RT), maximal, absolute and normalised rapid strength (50, 100, 150, 200 ms), and PVT measures were assessed on-site. Separate linear regression models were used to evaluate the POST-PRE change in variables adjusted for BMI, age, sleep, and call duration. Early (50 ms) absolute rapid strength was the only variable significantly reduced (–25.9%; p = 0.031) following the full shift rotation. Our findings indicate that early rapid strength may be a sensitive measure in detecting work-related fatigue, despite minimal changes in sleep between work and non-work nights and a low call duration. Practitioner summary: We examined the impact of repeated shiftwork on changes in reaction time and neuromuscular function. Early rapid strength was a sensitive, portable lab assessment that feasibly measured work-related fatigue in career firefighters. Interventions that mitigate work-related fatigue may be impactful at preventing falls and/or risk of musculoskeletal injury.