Longitudinal Decline in Cardiorespiratory Fitness With Age Among Male Firefighters in San Diego, California, 2005-2015

Objectives. To determine age-associated changes in cardiorespiratory fitness (CRF) among firefighters. Methods. Male firefighters (n = 1169) underwent annual evaluations from 2005 to 2015 in San Diego, California. We assessed CRF, the ability to deliver and use oxygen, during a maximal graded exercise test and recorded it in metabolic equivalents (METs; 1 MET = 3.5 ml/kg/min). We investigated differences in baseline CRF among 10-year age groups and patterns of change over follow-up using cross-sectional and longitudinal analyses, respectively. Results. Both analyses support an inverse relationship between CRF and age. Mean baseline CRF decreased from 15.7 ±1.7 to 11.7 ±1.9 METs in the younger than 30 years and 50 years and older age groups, respectively. There was no interaction between body fat and age in predicting CRF (Page × body fat = .09). Longitudinally, there was a nonlinear decrease in CRF, which differed across age groups: the youngest age group demonstrated the greatest decrease in CRF. Conclusions. Results support a negative, nonlinear association between age and CRF without modification by body fatness. Public Health Implications. Fire departments should recognize the health and safety risks of declining CRF and institutionalize programs to promote firefighter fitness.