How Do Firefighters Differ Between Years of Fire Service Experience: Part 3 – Blood Biomarker Profiles

Authors

Jonah C. White, Texas A&M UniversityFollow
Michael Conner, Bond UniversityFollow
Jacob A. Mota, Texas Tech UniversityFollow
Payton Miller, Texas Tech UniversityFollow
Steven E. Martin, Texas A&M University, College StationFollow
Lisa C. Colvin, Texas A&M University, College Station, TXFollow
Drew E. GonzalezFollow

Abstract

Firefighters (FF) face a higher risk of cardiovascular disease (CVD) due to aging, job-related stress, and irregular physical activity. Years of experience (YXP) in the fire service have been shown to have a unique impact on FF health and performance; however, profiling the differences between those with less or more YXP has not yet been assessed. PURPOSE: To examine YXP-related differences in conventional blood cardiovascular disease (CVD) risk biomarkers among firefighters. METHODS: Archival data from annual clinical testing of 142 male firefighters were analyzed (33.4±8.6 years; 29.3±4.1 kg/m2; 38.8±6.9 mL/kg/min). Groups were defined as those with <5 YXP and >5 YXP.  General linear models (GLM) analyzed YXP's effect on blood CVD biomarkers. Fisher’s LSD tests, 95% confidence intervals, and post-hoc tests assessed pairwise mean differences. Significance was set at p<0.05. Effect sizes used η_p². Data shown as mean difference with 95% confidence intervals. RESULTS: Overall GLM multivariate analysis revealed a Wilk's Lambda for YXP (p = 0.003, η_p² = 0.173). Univariate analysis revealed differences in total cholesterol (TC; p < 0.001, η_p² = 0.085), low-density lipoprotein cholesterol (LDL; p < 0.001, η_p² = 0.094), apolipoprotein B (ApoB; p < 0.001, η_p² = 0.114), triglycerides (TAG; p = 0.002, η_p² = 0.065), fasting glucose (p = 0.010, η_p² = 0.048), hemogolbin-A1c (HbA1c; p = 0.005, η_p² = 0.056), fasting insulin (p = 0.015, η_p² = 0.043), and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR; p = 0.006, η_p² = 0.055). Pairwise comparisons revealed that firefighters with fewer years of experience demonstrated lower TC (-22.2 mg/dL [-34.6, -9.9]), LDL (-20.6 mg/dL [-31.4, -9.2]), ApoB (-17.5 mg/dL [-25.7, -9.2]), TAG (-33.4 mg/dL [-54.8, -12.0]), fasting glucose (-0.3 mmol/L [-0.4, -0.1]), HbA1c (-0.1 % [-0.2, -0.03]), fasting insulin (-17.9 pmol/L [-32.2, -3.6]), and HOMA-IR (-0.9 [-1.5, -0.3]). CONCLUSION: Less experienced firefighters had better blood biomarker profiles, with lower TC, LDL, TAG, and insulin resistance indicators. The data suggest cardiometabolic health declines with more years of service, likely due to cumulative stress and lifestyle. City leaders should prioritize early screening and proactive measures, such as controlling lipid and glucose levels, to reduce long-term cardiovascular risks and improve firefighter health and citizen safety.

Recommended Citation

White, Jonah C.; Conner, Michael; Mota, Jacob A.; Miller, Payton; Martin, Steven E.; Colvin, Lisa C.; and Gonzalez, Drew E. (2026) "How Do Firefighters Differ Between Years of Fire Service Experience: Part 3 – Blood Biomarker Profiles," International Journal of Exercise Science: Conference Proceedings: Vol. 2: Iss. 18, Article 193.
Available at: https://digitalcommons.wku.edu/ijesab/vol2/iss18/193