COVID-19's Impact on Athletes: Reduced Cardiorespiratory Fitness after a SARS-CoV-2 Infection

This study aimed to identify potential changes in cardiorespiratory fitness among athletes who had previously been infected with severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). In this prospective observational multicenter hybrid study (CoSmo-S), cardiopulmonary exercise testing on treadmills or bicycle ergometers involving 2314 athletes (39.6% female) was conducted. German federal squad members (59.6%) and non-squad athletes were included in the study. A total of 1170 (37.2% female) subjects were tested positive for SARS-CoV-2 via polymerase chain reaction from which we had pre-SARS-CoV-2 infection examinations available for 289 subjects. Mixed-effect models were employed to analyze, among others, the following dependent variables: power output at individual anaerobic threshold (PO IAT ·kg -1 ), maximal power output (PO max ·kg -1 ), measured V̇O 2max ·kg -1 , heart rate at individual anaerobic threshold (HR IAT ), and maximal heart rate (HR max ). A SARS-CoV-2 infection was associated with a decrease in PO IAT ·kg -1 (-0.123 W·kg -1 , P < 0.001), PO max ·kg -1 (-0.099 W·kg -1 , P = 0.002), and measured V̇O 2max ·kg -1 (-1.70 mL·min -1 ·kg -1 , P = 0.050), and an increase in HR IAT (2.50 bpm, P = 0.008) and HR max (2.59 bpm, P < 0.001) within the first 60 d after SARS-CoV-2 infection. Using the pandemic onset in Germany as a longitudinal reference point, the healthy control group showed no change over time in these variables and an increase in PO max (+0.126 W·kg -1 , P = 0.039) during the first 60 d after the reference point. Subgroup analyses showed that both squad members and endurance athletes experienced greater decreases in cardiorespiratory fitness compared with non-squad members respectively athletes from explosive power sports. A SARS-CoV-2 infection is associated with a decline in cardiorespiratory fitness in athletes for approximately 60 d. Potential factors contributing to this outcome seem to be cardiopulmonary and vascular alterations in consequence of SARS-CoV-2. A minor effect on cardiorespiratory fitness has training interruption due to acute symptoms and/or quarantine.