COVID-19 and athletes: Endurance sport and activity resilience study—CAESAR study

Background: The COVID-19 pandemic and imposed restrictions influenced athletic societies, although current knowledge about mild COVID-19 consequences on cardiopulmonary and physiologic parameters remains inconclusive. This study aimed to assess the impact of mild COVID-19 inflection on cardiopulmonary exercise test (CPET) performance among endurance athletes (EA) with varied fitness level. Materials and Methods: 49 EA (n(male) = 43, n(female) = 6, mean age = 39.94 ± 7.80 yr, height = 178.45 cm, weight = 76.62 kg; BMI = 24.03 kgm(−2)) underwent double treadmill or cycle ergometer CPET and body analysis (BA) pre- and post-mild COVID-19 infection. Mild infection was defined as: (1) without hospitalization and (2) without prolonged health complications lasting for >14 days. Speed, power, heart rate (HR), oxygen uptake (VO(2)), pulmonary ventilation, blood lactate concentration (at the anaerobic threshold (AT)), respiratory compensation point (RCP), and maximum exertion were measured before and after COVID-19 infection. Pearson’s and Spearman’s r correlation coefficients and Student t-test were applied to assess relationship between physiologic or exercise variables and time. Results: The anthropometric measurements did not differ significantly before and after COVID-19. There was a significant reduction in VO(2) at the AT and RCP (both p < 0.001). Pre-COVID-19 VO(2) was 34.97 ± 6.43 ml kg·min(−1), 43.88 ± 7.31 ml kg·min(−1) and 47.81 ± 7.81 ml kg·min(−1) respectively for AT, RCP and maximal and post-COVID-19 VO(2) was 32.35 ± 5.93 ml kg·min(−1), 40.49 ± 6.63 ml kg·min(−1) and 44.97 ± 7.00 ml kg·min(−1) respectively for AT, RCP and maximal. Differences of HR at AT (p < 0.001) and RCP (p < 0.001) was observed. The HR before infection was 145.08 ± 10.82 bpm for AT and 168.78 ± 9.01 bpm for RCP and HR after infection was 141.12 ± 9.99 bpm for AT and 165.14 ± 9.74 bpm for RCP. Time-adjusted measures showed significance for body fat (r = 0.46, p < 0.001), fat mass (r = 0.33, p = 0.020), cycling power at the AT (r = −0.29, p = 0.045), and HR at RCP (r = −0.30, p = 0.036). Conclusion: A mild COVID-19 infection resulted in a decrease in EA’s CPET performance. The most significant changes were observed for VO(2) and HR. Medical Professionals and Training Specialists should be aware of the consequences of a mild COVID-19 infection in order to recommend optimal therapeutic methods and properly adjust the intensity of training.