The effects of SARS-CoV-2 infection on the cardiopulmonary exercise response in athletes

Abstract

BACKGROUND : Acute respiratory infections (ARinf) are common in athletes but their effects on exercise and sports performance remain unclear. SARS-CoV-2 infection can result in multi-organ involvement, persistent symptoms, or prolonged recovery in athletes. However, there is limited evidence describing the recovery and return to training in athletes after SARS-CoV-2 infection. OBJECTIVES : To explore the effects of recent SARS-CoV-2 infection compared to a control group on cardiopulmonary parameters, to explore selected factors affecting the cardiovascular (CV) response to submaximal exercise, and to explore the CV response to exercise over time during recovery from SARS-CoV-2 infection. STUDY DESIGN(s) : A systematic review, a case-control study and a prospective, cohort, experimental study with repeated assessments and longitudinal follow-up. The included studies formed part of the Athlete With Acute Respiratory InfEction (AWARE) international, multicentre research program. SETTING : A ‘COVID-19 Recovery Clinic’ for athletes at the Sport, Exercise Medicine, Lifestyle Institute (SEMLI), at the University of Pretoria, South Africa. PARTICIPANTS : Athletes recovering from SARS-CoV-2 infection. METHODS : A systematic review was conducted according to the Preferred Reporting for Systematic Reviews and Meta-analyses (PRISMA) guidelines. For the case control study, athletes with recent (<28 days) SARS-CoV-2 infection (EXP; n=72) were compared to a control group (CON; n=107). CV variables [heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP)] were measured at rest and during exercise (stages 1-3; modified Bruce protocol). Pulmonary function (PF) variables [forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1 as a percentage of FVC (FEV1/FVC), and peak expiratory flow (PEF)] were measured at rest. Selected factors affecting the CV response to exercise were analysed including demographic variables, sport, pre-infection training variables, comorbidities, and symptoms during the acute infection. For the prospective, cohort study athletes with recent SARS-CoV-2 infection (n=82) completed 2-5 repeat assessments to describe the CV (HR, SBP and rating of perceived exertion (RPE)) response to exercise over 16 weeks (12-lead ECG submaximal exercise challenge test; stages 1-5 Modified Bruce protocol). MAIN RESULTS : A trend towards impairment in acute and longer-term exercise and sports outcomes after ARinf in athletes was reported in the systematic review. Between the EXP and CON groups there were no significant differences for PF and CV variables. During submaximal IV exercise HR was significantly higher in the EXP group (p=0.0001) and exercise HR in the EXP group was still significantly higher irrespective of detraining (p=0.0001). Higher RPE during exercise was associated with greater number of symptoms during the acute infection (whole body p=0.006; total number p=0.004). Submaximal exercise HR, SBP and RPE decreased significantly over 16 weeks (p<0.01). The HR and RPE decreases were non-linear, with a steeper rate of decline <30 days after SARS-CoV-2 infection compared to >30 days during submaximal exercise (stage 5; HR; p=0.0001, RPE; p<0.0001). CONCLUSIONS : An evidence base is provided to guide athletes with SARS-CoV-2 infection in return to sport decisions, expectations, and monitoring. Mechanisms and potential clinical implications of the findings require further investigation to determine whether the findings can be directly attributed to a disease effect.