COVID-19 has harmful impact on health. It is especially important for endurance athletes (EAs). Sleep and psychology influence sport performance. Aims of this study were: (1) investigation of the consequences of mild COVID-19 on sleep and psychology and (2) assessment of the conse-quences of the infection on cardiopulmonary exercise test (CPET) results. 49 EAs (males= 43; 87.76%, females= 6; 12.24%, age= 39.9±7.8 years, height= 178.4±6.8 cm, weight= 76.3±10.4 kg; BMI= 24.0±2.6 kg·m−2) underwent maximal cycling or running CPET pre- and post- COVID-19 and completed a survey. Exercise performance was deteriorated after COVID-19 (maximal oxy-gen uptake; VO2max= 47.81±7.81 vs 44.97±7.00 ml·kg·min−1 respectively pre- and post- infection; p<0.001). Waking up at night affected heart rate (HR) at the respiratory compensation point (RCP) (p=0.028). Sleep time influenced pulmonary ventilation (p=0.013), breathing frequency (p=0.010), and blood lactate concentration (Lac) (p=0.013) at RCP. Maximal power/speed (p=0.046) and HR (p=0.070) linked with the quality of sleep. Stress management and relaxation techniques linked with VO2max (p=0.046), maximal power/speed (p=0.033), and maximal Lac (p=0.045). Cardiorespiratory fitness was deteriorated after mild COVID-19 and was correlated with sleep and mental health. Medical Professionals should encourage EAs to maintain proper mental health and sleep after COVID-19 infection to facilitate recovery.

Maximal heart rate (HRmax) is a widely used measure of cardiorespiratory fitness. Prediction of HRmax is an alternative to cardiopulmonary exercise testing (CPET), but its accuracy among endurance athletes (EA) requires evaluation. This study aimed to externally validate HRmax prediction models in the EA independently for running and cycling CPET. 4043 runners (age=33.58 (8.12) years; 83.53% males; BMI=23.66 (2.54) kg·m−2) and 1026 cyclists (age=36.88 (9.03) years; 89.67% males; BMI=24.04 (2.65) kg·m−2) underwent maximum CPET. Student t-test, mean absolute percentage error (MAPE), mean absolute error (MAE), and root mean square error (RMSE) were applied to externally validate 8 running and 5 cycling HRmax equations. HRmax was 184.60 (9.79) beats·min−1 and 182.66 (10.28) beats·min−1 respectively for running and cycling, p=0.001. Measured and predicted HRmax differed significantly (p=0.001) for 9 of 13 (69.23%) models. HRmax was overestimated by 8 (61.54%) and underestimated by 5 (38.46%) formulae. Overestimated HRmax ranged 0.08-4.94 beats·min−1 and underestimated HRmax ranged 0.03-4.90 beats·min−1. MAE and RMSE were 0.18-4.94 beats·min−1 and 9.13-10.47, respectively. MAPE ranged 3.95-4.69%. Prediction models do not allow for accurate estimation of HRmax. HRmax was more often underestimated than overestimated. Predicted HRmax can be implemented for EA as a supplemental method but CPET is the preferable approach.