Longitudinal Analysis Of Cardiorespiratory Fitness Among Brazilian Male Military Firefighters

Cardiorespiratory fitness (CRF) is one of the main components of health-related physical fitness and has been more recently considered as a vital sign. In the general population, low CRF is strongly associated with higher cardiometabolic risk and all-cause mortality. Among firefighters (FFs), a CRF ≥12 METs is recommended by the US National Fire Protection Association (NFPA) to safely and efficiently perform their jobs, considering that firefighting is a physically demanding profession associated with high cardiovascular strain. Importantly, there is a well-documented age-related decline of CRF (≈-1%/year), which can start in early adulthood, and many FFs are extending their working career worldwide due to changes in retirement rules. PURPOSE: To evaluate longitudinal changes in CRF among Brazilian male military FFs over a 12-year period of follow-up. METHODS: We conducted a longitudinal retrospective study among 1,327 military male FFs from a Brazilian central-west region Fire Department. In the beginning, FFs' mean ± SD age and BMI were 32.0 ± 3.2 years and 25.1 ± 2.9 kg/m2. In this Fire Department, FFs perform a mandatory annual physical fitness assessment, which includes the Cooper 12-min running test to estimate CRF. Within the source population (n ≈ 5,000), we evaluated all FFs with valid CRF data who performed both the 2006 and 2018 assessments. We used a paired t-test to compare changes in CRF and Cohen's d to analyze the effect size (ES). RESULTS: In the whole sample, we observed a moderate decrease in CRF from 2006 (12.6 ± 1.7 METs) to 2018 (11.5 ± 1.8 METs) (p < 0.001; ES = 0.69). However, 52.4% (n = 696) of participants showed no reduction or increased CRF after 12 years. Also, among those who showed a reduction in CRF (n = 631; 47.6%), the majority (75.9%) showed a reduction lower than the age-expected one (i.e.,<1%/year). CONCLUSIONS: Although there was a significant decrease in the mean CRF during the 12-year period, the majority of participants in this cohort of Brazilian FFs showed no reduction or improved CRF. Also, only 24.1% (n = 152) showed a CRF reduction bigger than the one expected for age (i.e.,>1%/year). We hypothesize that the overall good profile of CRF over 12 years may be, at least in part, due to the annual mandatory physical fitness assessment program. Supported by: Edital FEF-PPGEF 07/2004 - Programa de Pós-Graduação - Faculdade de Educação Física - Universidade de Brasília