AUTHOR=D'Isabel Susanne , Berny Lauren M. , Frost Alex , Thongphok Chanhtel , Jack Kepra , Chaudhry Sundeep , Arena Ross , Smith Denise L. 

TITLE=The effect of mild to moderate COVID-19 infection on the cardiorespiratory fitness of firefighters

JOURNAL=Frontiers in Public Health

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2023.1308605

DOI=10.3389/fpubh.2023.1308605

ISSN=2296-2565

ABSTRACT=<sec><title>Introduction</title><p>An adequate level of cardiorespiratory fitness (CRF) is critical for firefighters to perform the strenuous and physiologically demanding work of firefighting safely and effectively. The coronavirus disease 2019 (COVID-19) has been shown to negatively impact CRF in both the acute phase and longer-term following infection. This study aimed to determine changes to the CRF of firefighters pre- to post-mild to moderate COVID-19 infection and to investigate the impact of days past COVID-19 infection on change in CRF.</p></sec><sec><title>Methods</title><p>CRF measures from cardiopulmonary exercise testing (CPET) at annual occupational health exams that occurred pre-COVID-19 infection in 2019 were obtained for firefighters from seven Arizona fire departments. Measures were compared to CPET evaluations from annual health exams the following year in a cohort of firefighters who self-reported mild to moderate illness following COVID-19 infection between exams.</p></sec><sec><title>Results</title><p>Among a cohort of 103 firefighters, mean age 40 ± 9 years, CRF [as measured by peak oxygen consumption (VO<sub>2</sub>)] declined by an average of 2.55 ml·kg<sup>−1</sup>·min<sup>−1</sup> or 7.3% (<italic>d</italic> = −0.38, <italic>p</italic> &lt; 0.001) following COVID-19 infection (mean time from COVID-19 infection to CPET was 110 ± 78 days). The number of days past COVID-19 infection showed a small, yet significant, relationship to peak VO<sub>2</sub> (<italic>r</italic> = 0.250, <italic>p</italic> = 0.011). Estimated marginal effects indicated that when biological sex, age, and BMI are controlled for, predicted peak VO<sub>2</sub> returned to pre-COVID-19 values ~300 days after COVID-19 infection.</p></sec><sec><title>Conclusion</title><p>Peak VO<sub>2</sub> (ml·kg<sup>−1</sup>·min<sup>−1</sup>) declined 7.3% among firefighters an average of 110 days past reporting mild to moderate COVID-19 infection. This decrease has implications for the operational readiness and safety of firefighters.</p></sec>