Impact Of Body Mass Index On Non-conventional Physiological Stress, Oxidative Stress, And Inflammatory Biomarkers Among Fire Responders

Firefighters and responders face stress from activity, irregular hours, and hazards, raising obesity and cardiometabolic risks. Higher BMI is linked to inflammation and oxidative stress, but few studies examine these in tactical groups using unconventional biomarkers. Studying BMI-related markers could identify early signs of stress and aid in developing tailored wellness program strategies. PURPOSE: Archival data for 170 (n = 170) first responders were analyzed from annual clinical testing. BMI groups were considered. The first responders were stratified into three BMI groups: “healthy” (18.5–24.9 kg/m2), “overweight” (25.0–29.9 kg/m2), and “obese” (≥30.0 kg/m2). General linear models (GLM) were used for multivariate and univariate analyses to evaluate the effect of BMI group and occupational group on blood and salivary biomarkers: advanced oxidation protein products (AOPP), C-reactive protein (CRP), blood cortisol (CORT), salivary cortisol (sCORT), and salivary α-amylase (AA). Fisher’s Least Significant Difference (LSD) tests and 95% upper and lower confidence intervals were used to assess pairwise comparisons of means and post-hoc tests. The type I error (p-level) probability was set at 0.05 or less. Partial Eta squared (ηp2) values were used to assess effect size, where values of >0.01 and 0.06 and 0.14 (large effect) were obtained for the GLM statistics. RESULTS: The GLM multivariate analysis revealed an overall Wilk's Lambda for the occupational group (p = 0.026, ηp2 = 0.114) with no statistically significant effect for the BMI group (p = 0.133, ηp2 = 0.068) nor BMI by occupational group (p = 0.589, ηp2 = 0.039). Univariate analysis showed a difference in C-reactive protein (p = 0.014, ηp2 = 0.076) for the BMI group. Pairwise comparisons revealed that the normal BMI group displayed lower CRP concentrations than the obese BMI group (-0.087 mg/mL [-0.152, -0.021], p = 0.010). No other differences were noted. CONCLUSION: Higher BMI is linked to increased inflammation, shown by elevated C-reactive protein in obese vs. normal-weight first responders. BMI wasn't associated with oxidative stress or stress-response biomarkers. Results suggest excess body mass contributes to low-grade inflammation, not general stress. Monitoring inflammatory markers and weight-management programs could enhance cardiometabolic health and readiness among first responders.