Expanding Understanding of Age-Related Differences in Cardiorespiratory Fitness and Body Composition Among Firefighters: A Single, Large-Scale, Metropolitan-Departmental Study

Authors

Jisun Chun, Texas A&M UniversityFollow
Kelly Hines, University at BuffaloFollow
Michael J. Conner, Front Line Mobile HealthFollow
Brian Newman, Fort Worth Fire DepartmentFollow
Lisa C. Colvin, Texas A&M UniversityFollow
Steven E. Martin, Texas A&M UniversityFollow
Drew E. Gonzalez, Sam Houston State UniversityFollow

Abstract

While prior research has examined age-related changes in small firefighter (FF) cohorts, large-scale analyses are needed to clarify the effects of aging on cardiorespiratory fitness (CRF) and body composition (BC). PURPOSE: To examine age-related differences in CRF and BC among FF across four age groups. METHODS: Four hundred and ninety-nine FF completed a cycle ergometer cardiopulmonary exercise test (CPET) and bioelectrical impedance via an InBody BC assessment. Age group sizes were as follows: 20-29s = 62; 30-39s = 162; 40-49s = 153; and 50+ = 122. A general linear model (GLM) was used to evaluate the effects of age group on CRF and BC variables. Levene’s tests confirmed homogeneity of variance for most variables. Pairwise comparisons (LSD or Games–Howell when variances were unequal) were conducted after significant omnibus effects (p < 0.05). RESULTS: A multivariate effect of age was observed for both CRF (p < 0.001, ηₚ² = 0.183) and BC domains (p < 0.001, ηₚ² = 0.052). Univariate analyses revealed age-related differences across all CRF parameters (all p < 0.05). Particularly, aerobic capacity decreased progressively with age. Relative VO₂peak (ml/kg/min) (p < 0.001, ηₚ² = 0.152) demonstrated the most considerable age effect. Pairwise comparisons revealed that the 40-49 (31.8±5.1 mL/kg/min; p < 0.001) and 50+ (29.1±4.8 mL/kg/min; p < 0.001) age groups had lower average VO₂peak values than the 20-29 age group (35.1±5.1 mL/kg/min). In terms of body composition, univariate analysis revealed age effects on all variables (p < 0.001), with visceral body fat demonstrating the largest effect size (p < 0.001, ηₚ² = 0.074). Unsurprisingly, lean mass (p = 0.014, ηₚ² = 0.021) and skeletal muscle mass (p < 0.005, ηₚ² = 0.025) decreased progressively across the age groups. Pairwise comparisons consistently show that, as FFs age, they develop a poor body composition profile. CONCLUSION: Starting in their 40s and progressing further in their 50s, they decline in CRF. In addition to gaining body fat while losing skeletal muscle, thus increasing their risk for CVD. Implementing early preventive measures that aim to maintain high levels of CRF and lean muscle mass may reduce the risk of cardiovascular disease associated with aging in the fire service.

Recommended Citation

Chun, Jisun; Hines, Kelly; Conner, Michael J.; Newman, Brian; Colvin, Lisa C.; Martin, Steven E.; and Gonzalez, Drew E. (2026) "Expanding Understanding of Age-Related Differences in Cardiorespiratory Fitness and Body Composition Among Firefighters: A Single, Large-Scale, Metropolitan-Departmental Study," International Journal of Exercise Science: Conference Proceedings: Vol. 2: Iss. 18, Article 19.
Available at: https://digitalcommons.wku.edu/ijesab/vol2/iss18/19