Cardiorespiratory fitness response to endurance training in athletes post-COVID-19 compared to unaffected athletes

Endurance sports primarily attract recreational athletes over 35 years, who impose an exceptionally rigorous and sustained demand on their cardiorespiratory systems.

This study aimed to determine the influence of COVID-19 on the cardiovascular, pulmonary, and skeletal muscle function of endurance athletes with exercise intolerance. Secondly, it aimed to compare the exercise response of endurance athletes post-COVID-19 to those unaffected using cardiopulmonary exercise test-related variables.

This is a prospective observational cohort study of endurance athletes. An exposure group with protracted exercise tolerance underwent a resting lung function test and maximal cardiopulmonary exercise test. These were repeated after eight weeks of endurance training and compared to the published reference values and a control group of athletes unaffected by COVID-19.

The post-COVID-19 exposure group (n=57), mean age 44.5±8.1years showed a poorer ventilatory threshold (p=0.004), and workload (p=0.05), with higher respiratory exchange ratio (p=0.05) than the control group (n=34), mean age 41.8±7.7 years. Maximal inspiratory pressure improved at follow-up in the COVID-19 group compared to the controls (p=0.03). Increased odds of pulmonary and skeletal muscle limitation to aerobic capacity were found in the COVID-19 group. The COVID-19 group responded positively to endurance training with improved VO₂peak (p=0.005), maximal inspiratory pressure (p=0.04), oxygenpulse (p=0.02), and maximal workload (p<0.001).

COVID-19 has led to pulmonary and extrapulmonary limitations to exercise capacity. Tailored intensity and duration of physical activity are vital after COVID-19 to restore skeletal muscle health. This multidisciplinary rehabilitation approach will optimise the resumption of participation in long-distance events.