Association of Pre-COVID Fitness With Post-COVID Fitness and Long COVID in the Cooper Center Longitudinal Cohort Study

BACKGROUND: Cross-sectional studies suggesting that SARS-CoV-2 infection and long COVID are associated with reduced cardiorespiratory fitness (CRF) lack preinfection CRF measures. The objective of this study was to determine the association of SARS-CoV-2 infection and long COVID with change in CRF. METHODS: Cooper Center Longitudinal Study is a cohort study based at the Cooper Clinic, a preventive medicine clinic in Dallas, Texas; we included adults ages 20 to 74 years old with CRF assessed at least twice between 2017 and 2023. COVID status was defined as “prepandemic” (2 CRF measures pre-2020), “uninfected” (no self-reported COVID), “recovered” (self-reported COVID with symptoms ≤3 months), or “long COVID” (self-reported COVID with symptoms >3 months). CRF was estimated in metabolic equivalents via a maximal modified Balke treadmill protocol. RESULTS: We included 4005 participants (mean age: 51.8 years, 26.8% women), of whom, 1666 (41.6%) reported COVID and 80 (4.8% of infected) reported long COVID along with 1826 uninfected and 513 pre-pandemic controls. At baseline, those who later developed long COVID had lower CRF (10.0 metabolic equivalents, 11.1 recovered, 10.7 uninfected, 11.3 prepandemic; P<0.001). All groups exhibited minor decreases in CRF (~0.2 metabolic equivalents; P<0.001 for each). CRF decreased slightly more among the infected (−0.1 metabolic equivalents greater decrease [95% CI, −0.1 to 0.0]; P=0.02) but not by long COVID status (P=0.10). CONCLUSIONS: Pre-COVID fitness, on average, is lower among people who developed long COVID. COVID does not greatly accelerate age-related declines in CRF, even among some with long COVID, although few included participants had severely disabling long COVID. Future longitudinal research will clarify if differences in CRF by infection status emerge over longer follow-up.