The impact of COVID-19 on endurance athletes’ return to pre-illness level of participation

Abstract

The long-term impact of the highly infectious and pathological novel coronavirus disease of 2019 (COVID-19) on endurance athletes remains equivocal. For peak performance, the respiratory, cardiovascular and peripheral muscle systems must perform optimally. The respiratory system is fundamental for endurance athletes, who engage in extensive aerobic exercise and are thus expected to exceed the predicted thresholds for cardiorespiratory fitness. Participation in sport is an important determinant of quality of life for endurance athletes. Assessing both the psychosocial impact of COVID-19 and the physiological limitations to exercise capacity, will inform targeted interventions to assist endurance athletes’ return to their pre-illness level of sport. Paper 1 (Chapter 3) includes a cross-sectional study using a self-administered web- based questionnaire that was disseminated through running and cycling clubs’ social media channels. The study aimed to assess acute and exertional COVID-19 symptoms experienced by the endurance athletes, their fatigue score and exercise performance. A comparison between those athletes who had returned to their pre- illness level of sport and those who had not, was made. This study found that one third of endurance athletes, mean age of 45 years, had not returned to their pre-illness level of sport participation after COVID-19. Persistent cardiopulmonary symptoms including dyspnoea and fatigue contributed to a protracted return to sport. Paper 2 (Chapter 4) further explored the biopsychosocial impact of COVID-19 by conducting a mixed methods study. Quantitative data included symptom severity, management thereof, and barriers to resuming sports participation. Results showed that tachycardia, fatigue and dyspnoea were experienced on exertion, and the athletes had difficulty exercising at high intensities. Physical fatigue score significantly predicted return to sport. Qualitative data collected through open-ended questions were deductively grouped into three themes according to the biopsychosocial framework. Inductive coding revealed aspects of this novel disease that adversely affected quality of life including persistent cardiopulmonary symptoms, physical fatigue, emotional distress and social disengagement. Mixing the methods concluded that the quality of life of endurance athletes deteriorated due to protracted return to sport. vi Paper 3 (Chapter 5) included a prospective observational cohort study that aimed to determine the influence of COVID-19 on cardiovascular, pulmonary, and skeletal muscle function. Athletes experiencing exercise intolerance were invited to comprehensively investigate their cardiorespiratory fitness and potential limitations to their aerobic capacity. This assessment included resting lung function, maximal inspiratory pressure measurement, and cardiopulmonary exercise testing. The tests were repeated after eight weeks of self-directed endurance training and compared to published reference values and a control group that was unaffected by COVID-19. Results showed that the fifty-seven athletes with exercise intolerance had poorer ventilatory threshold, workload, and respiratory exchange ratio than the control group. The group that was adversely affected by COVID-19 showed a positive response to endurance training with improved parameters at follow-up, highlighting the need for tailored rehabilitation of these athletes. Study 4 (Chapter 6) includes a feasibility study of conducting a clinical trial of the effectiveness of inspiratory muscle training to enhance aerobic performance post- COVID-19. Given that respiratory function is crucial in endurance sports and inspiratory muscle training has been shown to improve dyspnoea in the general population, it is plausible that this intervention may be beneficial. The feasibility of a clinical trial was assessed in terms of practicality, acceptance and adherence, and implementation. The participants performed 30 breaths of inspiratory muscle training for six weeks, starting at 50% of the maximal inspiratory pressure and increasing progressively. Lung function, maximal inspiratory pressure and cardiopulmonary exercise tests were conducted before and after the intervention. Data were analysed per-protocol comparing the intervention and control group. Results showed that adherence and implementation were good, while acceptance and practicality could be amended in larger clinical trials. The intervention was effective in promoting recovery of respiratory muscle strength. In conclusion, it is vital that medical professionals, coaches, and athletes understand the acute symptoms, impact on quality of life, and long-term consequences of COVID- 19, as the imperative of a safe and successful return to sport cannot be overstated