OBJECTIVE:Firefighters experience chronic stress that contributes to elevated cardiometabolic disease (CMD) risk. This study examined associations between blood and salivary biomarkers of inflammation, stress, and oxidative stress with measures of body composition, fitness, and cardiometabolic health among firefighters (n = 140). METHODS:Principal components analysis was used to reduce multicollinearity among body composition, physical performance, and cardiometabolic variables, followed by multivariate regression models predicting adiponectin, C-reactive protein (CRP), and interleukin-6 (IL-6) concentrations. RESULTS:Body mass and composition, fitness, and atherogenic dyslipidemia were associated with multiple biomarkers. Salivary IL-6 demonstrated robust associations with body composition, physical performance, and salivary CRP. Blood adiponectin and CRP were strongly associated with atherogenic dyslipidemia, insulin resistance and oxidative stress. CONCLUSIONS:Salivary inflammatory biomarkers, particularly IL-6, may provide a feasible complement to blood biomarkers for identifying CMD risk among firefighters.

Introduction: Cardiovascular disease (CVD) is a leading cause of on-duty mortality among firefighters, accounting for similar to 42% of duty-related fatalities. Aerobic capacity (VO2max) is inversely associated with CVD risk. Whether these protective effects persist across the occupational lifespan (i.e., years of service) with cumulative exposure to firefighting hazards and lifestyle factors remains unclear. The purpose of this study was to examine differences in CVD risk indices between firefighters classified above and below an occupational aerobic capacity threshold (i.e., 42 mL.min(-1).kg(-1)), while adjusting for years of service. Methods: A cross-sectional analysis was conducted on 144 career firefighters (143 male, 1 female; age 33.3 +/- 8.6 yr). Participants were classified into low aerobic capacity (<42 mL.min(-1).kg(-1); n = 92) or high aerobic capacity (>= 42 mL.min(-1).kg(-1); n = 52) groups based on estimated VO2max from treadmill stress testing. General linear models compared groups across dual-energy X-ray absorptiometry-derived body composition, blood lipid and glycemic biomarkers, and CVD risk scores, with years of fire service experience as a covariate. Results: The high AC group demonstrated significantly more favorable profiles across all cardiometabolic domains, including body fat, visceral adiposity, triglycerides, low-density lipoprotein cholesterol, atherogenic indices, fasting insulin, and homeostatic model assessment of insulin resistance (all P < 0.05), which persisted after adjustment for years of service. Adjustment strengthened several associations, with CVD risk scores reaching statistical significance. Clear separation was observed between groups based on the two aerobic capacity classifications. Conclusion: Higher aerobic capacity is associated with favorable cardiometabolic profiles in firefighters, independent of years of service. These findings support the use of occupationally derived, task-based aerobic capacity standards rather than age- and sex-adjusted population percentiles to determine fit-for-duty decisions. Fire departments should prioritize aerobic capacity assessment and maintenance programs to mitigate cardiometabolic risk across the occupational lifespan.

OBJECTIVE:This study examined blood and saliva cortisol (CORT), interleukin-6 (IL-6), and C-reactive protein (CRP) in first responders to evaluate the accuracy and practicality of using saliva samples in operational contexts. METHODS:Data from 207 first responders were analyzed. Spearman's correlation, simple linear regression models, and Bland-Altman analyses were performed. RESULTS:Salivary CORT ( ρ = 0.713, P < 0.001) closely aligned with blood CORT, accounting for nearly half of the variance and showing narrow Bland-Altman limits. Salivary CRP ( ρ = 0.306, P < 0.001) and IL-6 ( ρ = 0.281, P = 0.007) exhibited weak correlations and poor agreement. CONCLUSIONS:Overall, while salivary CORT is practical for noninvasive monitoring in operational settings, caution is warranted with salivary CRP and IL-6, which need further research as blood substitutes.

Objective: This study aimed to characterize trends in body roundness index (BRI) among first responders and examine differences in health and fitness across BRI-based quartiles. Methods: Archival data from 158 first responders—97 firefighters and 61 law enforcement officers (LEOs)—were analyzed. Results: Differences were observed in body composition and physical performance parameters, with the first quartile (Q1) BRI group exhibiting the most favorable profiles. These differences remained after adjusting for age, especially compared with the Q4 group. Blood biomarkers showed minimal differences, with a trend toward lower fasting blood glucose in Q1. Firefighters showed poorer health indices but higher fitness than law enforcement officers, consistent with past research. Conclusions: BRI is a useful, potentially cost-effective tool for first responders to assess health and wellness annually and quarterly without clinical equipment.

Firefighters (FFs) and law enforcement officers (LEOs) have heightened cardiovascular disease (CVD), with data suggesting that ≈45% of on-duty FF fatalities are related to CVD, while LEOs have a 1.7 times higher CVD prevalence than the general public. This study compared CVD risk biomarkers, fitness, and body composition between FFs and LEOs. Ninety-eight career, structural male FFs (age = 35.1±9.6 yrs; weight = 94.3±15.4 kg; height = 178.4±13.2 cm) and seventy-three career LEOs (age = 41.4±9.0 yrs; weight = 92.3±16.8 kg; height = 179.6±8.1 cm) from local departments were studied. Participants completed a maximal cardiopulmonary exercise test (CPXT), where VO2max was estimated from the Foster equation. Fasted blood was collected to assess CVD risk biomarkers. Dual-energy X-ray absorptiometry assessed body composition, and waist and hip measures were taken. Analyses with and without women participants were conducted to assess differences in CVD risk biomarkers, fitness, and body composition between the FFs and LEOs. Effect sizes were calculated and reported as Cohen’s d. Univariate general linear model (GLM) analysis of covariance (ANCOVA) were conducted to account for age as a covariate, wherein partial Eta squared (ηₚ²) values were used to assess effect size for the GLM statistics. FFs had higher (p<0.05) CPXT exercise times (FFs: 10.9±1.6 min; LEOs: 10.3±2.0 min; d=0.366) compared to LEOs. FFs also had higher (p<0.05) advanced oxidation protein products (FFs: 134.8±90.1 µM; LEOs: 106.8±67.6 µM; d=0.342), blood cortisol (FFs: 14.2±5.0 µg/dL; LEOs: 12.5±5.6 µg/dL; d=0.325), and waist-to-hip ratios (FF: 0.95±0.06; LEO: 0.89±0.08; d=0.792). These findings suggest that while FFs demonstrated greater CPXT time-to-exhaustion, they also expressed higher stress and CVD risk biomarkers concentrations than LEOs. These data suggest that occupation-specific characteristics and stressors may play a role in the CVD risk profile of first responders.

OBJECTIVE:The present study examined novel and classic cardiovascular disease (CVD) risk factors among career firefighters to understand better the associations between physiological stress, oxidative stress, inflammation biomarkers, and CVD risk. METHODS:Associations between muscular and cardiorespiratory fitness (CRF) measures, body composition, physiological stress, and novel/classic CVD risk factors were assessed among 97 career male firefighters. RESULTS:Muscular fitness/CRF, adiposity, body composition, and blood lipids were associated with CVD risk as measured by biomarkers for insulin resistance, inflammation, and oxidative stress. No associations between physiological stress biomarkers and CVD risk factors were found. CONCLUSIONS:Firefighters should improve their muscular fitness/CRF and body composition to reduce CVD risk.

OBJECTIVE:This study aimed to assess relationships between standard and advanced lipids, body composition, and physical fitness. METHODS:Associations between standard and advanced blood lipid biomarkers, body composition, and physical fitness parameters were assessed among 43 law enforcement officers. RESULTS:Across separate and hierarchical regression models, the standard lipids consistently accounted for greater variation in the dependent variables, while the advanced lipids rarely provided additional explanatory power, even after controlling for multicollinearity. CONCLUSIONS:The standard lipid panel is likely sufficient and the most cost-effective way to identify lipid-related associations with body composition and fitness among law enforcement officers.

Introduction: Reserve Officer Training Corps (ROTC) and Corps of Cadets face unique challenges that make them susceptible to poor nutritional habits. We evaluated cadets’ dietary beliefs, habits, barriers, and food choices, as well as general and sport nutrition knowledge. Methods: Cross-sectional data were analyzed from 184 members of the University’s ROTC and Corps of Cadets, using validated questionnaires, including the Nutrition Knowledge Questionnaire for Athletes (NKQA), the Food Choice Questionnaire (FCQ), the Rapid Eating Assessment for Participants, Shortened Version (REAP-S), and the Perceived Barriers to Healthy Eating. The categorical data were reported as frequencies (n) and percentages, and Chi-square (χ2) analyses were used to determine group independence (p < 0.05). Continuous data were checked for normality and then analyzed for differences between sexes and commission status using independent samples t-tests or Mann-Whitney U tests. Effects sizes were calculated using Cohen’s d and interpreted as follows: <0.2 trivial, <0.5 small, <0.8 moderate, <1.2 large, and >1.2 very large. Results: Participants exhibited poor overall nutrition knowledge (37.3±14.2%), with low scores for carbohydrates = 31.9±15.6%, protein = 52.6±20.7%, fat = 40.6±24.1%, vitamins = 35.3±23.2%, general nutrition = 29.1±14.6%, fluid = 28.8±20.4%, and sport nutrition = 36.2±17.5%. Further, the participants expressed being very willing (n=79, 42.9%) or willing (n=79, 42.9%) to change their dietary habits to healthier ones. However, a busy lifestyle (n = 164, 89.1%) and limited cooking facilities (n = 104, 56.5%) presented significant challenges to healthy eating. Conclusions: The participants reported having poor nutrition knowledge but valued healthier eating and expressed a willingness to improve their dietary habits to healthier ones. These findings suggest cadets may benefit from practical, registered dietitian nutritionist (RDN)-supported nutrition educational interventions that build culinary skills and address barriers like limited cooking facilities. Structured programs promoting sustainable eating habits could further enhance nutrition knowledge and dietary behaviors.

Background: Age is considered an independent cardiovascular disease (CVD) risk factor, but limited data exist concerning the impact of age and years in the fire service on firefighter health and physical performance. Objectives: We assessed the impact of age and years in the fire service on structural firefighter health and physical performance. Methods: 142 firefighters completed an annual clinical assessment. General linear model (GLM) multivariate and univariate analyses were performed across age groups, with years of fire service experience as a covariate. Partial Eta squared (ηp2) values for the GLM statics and Cohen’s d for pairwise comparisons were used to assess effect size. Results: GLM analyses revealed statistically significant differences (p < 0.05) for several demographic, body composition, blood biomarker, and physical performance parameters. Pairwise comparisons revealed that younger firefighters displayed more favorable health and fitness profiles than their older counterparts. Interestingly, when accounting for years of fire service experience, differences for only the following variables remained: body mass index, waist circumference, lean mass, visceral adipose tissue, triglycerides, cardiopulmonary exercise test time-to-exhaustion, and VO2max. Conclusions: These findings suggest differences in CVD risk biomarkers, physical fitness levels, and body composition metrics across age groups. However, years of fire service experience appears to have a greater impact on these variables, suggesting that firefighters’ time in the fire service may accelerate the effects of aging on these outcomes. While age-specific health interventions are recommended to manage and mitigate CVD risk effectively, there also should be consideration for the years of fire service.

OBJECTIVE:Law enforcement officers (LEOs) face numerous stressors that exacerbate cardiometabolic disease (CMD) risk. The current study examined novel and classic risk factors among a cohort of LEOs to better understand relationships between biomarkers of stress, oxidative stress, inflammation, and CMD risk. METHODS:Associations between measures of cardiorespiratory and muscular fitness, body composition, and cardiometabolic health with novel/classic CMD risk factors were assessed among 66 male LEOs. RESULTS:Muscular fitness and cardiorespiratory fitness were significantly associated with reduced insulin resistance. Moreover, higher fat mass and body fat percentages were significantly associated with increased markers of inflammation and insulin resistance. CONCLUSIONS:Maintaining high cardiorespiratory and muscular fitness levels and improving body composition profiles can ameliorate cardiometabolic health.

OBJECTIVE:This study assessed firefighters' physiological stress response to a live fire training evolution (LFTE). METHODS:Seventy-six ( n = 76) firefighters completed an LFTE. Salivary samples were collected pre-, immediately post, and 30-min post-LFTE and analyzed for α-amylase (AA), cortisol (CORT), and secretory immunoglobulin-A (SIgA). RESULTS:Concentrations of AA, CORT, and SIgA were elevated immediately post LFTE versus pre (P<0.001) and 30-min post (P<0.001). Cohen's d effect size comparing pre and immediately-post means were 0.83, 0.77, and 0.61 for AA, CORT, and SIgA and were 0.54, 0.44, and 0.69 for AA, CORT, and SIgA, comparing immediately-post and 30-min post, respectively. CONCLUSIONS:These data demonstrate the stress response and activation of the hypothalamic-pituitary-adrenal/sympathetic-adreno-medullar axis and immune system immediately after real-world firefighting operations. Future work is needed to understand the impact of elevated stress biomarkers on firefighter performance and disease risk.

Structural firefighters are responsible for protecting properties and saving lives during emergency operations. Despite efforts to prepare firefighters for these hazardous occupational demands, the unfortunate reality is that the incidence of health morbidities is increasing within the fire service. Specifically, cardiovascular disease, cancer, and mental health disorders are among the most documented morbidities in firefighters. Pubmed and Google Scholar search engines were used to identify peer-reviewed English language manuscripts that evaluated firefighters' occupational health threats, allostatic factors associated with their occurrence, and evidence-based strategies to mitigate their impact. This narrative review provides fire departments, practitioners, and researchers with evidence-based practices to enhance firefighters' health.

RATIONALE:Firefighters are at risk for cardiovascular disease due to occupational-related inflammation, oxidative stress, and lifestyle practices. Astaxanthin (AX) possesses anti-inflammatory/antioxidant and purported ergogenic properties. This study examined the impact of supplementing the diet with 12 mg/d AX for four weeks on markers of inflammation, oxidative stress, cardiometabolic health, exercise capacity, and occupation-related performance in career firefighters. METHODS:In a randomized, double-blinded, placebo-controlled, crossover fashion, 15 male career firefighters (34.5 ± 7.4 years; 177.7 ± 7.0 cm; 95.6 ± 12.0 kg; 30.1 ± 2.9 kg/m2; 11.03 ± 6.85 years of service) ingested 12 mg/d of AX (AstaReal®, AstaReal AB, Nacka, SWE) or placebo (PLA) for four weeks while following a standardized resistance training program. After each treatment, testing sessions were completed to assess inflammatory markers, oxidative stress markers, cardiopulmonary exercise capacity, and performance to a fire ground test (FGT) consisting of nine fire suppressive activities. Data were analyzed using general linear model (GLM) analysis with repeated measures. Clinical significance was assessed via mean changes from baseline with 95% confidence intervals. RESULTS:Analysis of mean percent changes from baseline revealed that AX supplementation lessened the inflammatory response to to performing an incremental maximal exercise test and attenuated increases in interleukin-1β, cortisol, and uric acid in response to performing fire suppressive activities compared to when they ingested PLA. However, most of these effects were within groups rather than between groups. Additionally, there was evidence that AX ingestion increased the ventilatory anaerobic threshold. Four weeks of AX supplementation did not significantly affect fasting markers of oxidative stress, blood lipids, performance during the FGT, general clinical chemistry panels, or self-reported side effects. CONCLUSIONS:Results provide some evidence that AX supplementation may help mediate occupation-related inflammation in response to high-intensity, short-duration exercise in firefighters. More research is warranted to determine if long-term supplementation can improve cardiometabolic risk in this population. CLINICAL TRIAL REGISTRATION:ISRCTN10901752.

Red meat is stigmatized as an unhealthy protein choice; however, its impacts on vascular function have not been evaluated. We aimed to measure the vascular impact of adding either low-fat (~5% fat) ground beef (LFB) or high-fat (~25% fat) ground beef (HFB) to a habitual diet in free-living men. Twenty-three males (39.9 ± 10.8 years, 177.5 ± 6.7 cm, 97.3 ± 25.0 kg) participated in this double-blind crossover study. Assessment of vascular function and aerobic capacity were measured at entry and in the last week of each intervention and washout period. Participants then completed two 5-week dietary interventions (LFB or HFB; 5 patties/week) in a randomized order with a 4-week washout. Data were analyzed via 2 × 2 repeated-measures ANOVA (p < 0.05). The HFB intervention improved FMD relative to all other time points, while lowering systolic (SBP) and diastolic blood pressure (DBP) relative to entry. Neither the HFB nor the LFB altered pulse wave velocity. The addition of either low- or high-fat ground beef did not negatively alter vascular function. In fact, consuming HFB improved FMD and BP values, which may be mediated by lowering LDL-C concentrations.

OBJECTIVE:Firefighters are plagued with cardiometabolic disease (CMD). Obesity, poor cardiorespiratory and muscular fitness, and blood lipids (low-density lipoprotein cholesterol, triglycerides, low high-density lipoprotein cholesterol) are risk factors for CMD. However, markers of oxidative stress, inflammation, and insulin resistance can provide further insight regarding CMD risk.METHODS:This study investigated the relationships between fitness metrics (cardiorespiratory and muscular fitness, percent body fat, waist circumference), blood lipids, blood pressure, and years of experience as a firefighter to blood markers of insulin resistance: Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), oxidative stress: advanced oxidation protein products (AOPPs), and inflammation: C-reactive protein.RESULTS:Waist circumference and blood concentrations of triglycerides were significantly related to AOPPs and HOMA-IR. Cardiorespiratory fitness was inversely related to AOPPs, HOMA-IR and C-reactive protein.CONCLUSION:These findings demonstrate the importance of high cardiorespiratory fitness and low waist circumference to reduce markers of CMD.

OBJECTIVE:High cardiorespiratory fitness (CRF) is associated with reduced markers of oxidative stress and cardiovascular disease (CVD) risk factors; however, this relationship has not been elucidated in firefighters. The purpose of this study was to examine differences in markers of CVD risk between firefighters who have either high or low levels of CRF.METHODS:Forty-six firefighters participated in a maximal graded exercise test and a dual-energy x-ray absorptiometry scan and provided a fasted blood sample. V˙O 2max values were categorized based on American College of Sports Medicine guidelines to establish high- and low-fitness groups.RESULTS:High fitness firefighters demonstrated significantly higher high-density lipoprotein cholesterol and lower markers of CVD risk: cholesterol, triglycerides, low-density lipoprotein cholesterol, insulin, homeostatic model assessment for insulin resistance, C-reactive protein, and advanced oxidation protein products concentrations.CONCLUSION:Firefighters are encouraged to maintain high CRF to reduce risk of CVD.