COACH Study: COVID-19 Influence on Cardiorespiratory Fitness in Athletes-A Systematic Review and Meta-Analysis

Objectives: We aimed to systematically review and meta-analyze the impact of COVID-19 infection on cardiorespiratory fitness (CRF): (1) within-athlete (the same participants before and after infection), and (2) between-athlete (infected vs. healthy reference participants). Methods: In this systematic review (PROSPERO Registry: CRD42024540430) we included observational studies enrolling recreational or competitive athletes ≥18 years old with laboratory confirmation of SARS-CoV-2 infection. The primary outcome was change in relative maximal oxygen uptake (VO_2max). Secondary outcomes included changes in absolute VO_2max, maximal ventilation (VE_max), and maximal heart rate (HR_max). We searched Embase, PubMed, Medline, Scopus, and Web of Science up to August 9th, 2025. Risk of bias was assessed with the JBI critical appraisal tool. Meta-analyses were performed with a random-effects model. Results: Twelve studies enrolling a total of 1595 participants met the eligibility criteria. COVID-19 infection was associated with lower relative VO_2max (MD = -1.83 mL·kg^-1·min^-1; 95%CI [-3.16, -0.49]; p = 0.007; I² = 54%) and absolute VO_2max (MD = -0.15 L·min^-1; 95%CI [-0.29, -0.01]; p = 0.03; I² = 0%). COVID-19 infection was associated with lower VE_max (MD = -7.99 L·min^-1; 95%CI [-12.94, -3.04]; p = 0.002; I² = 0%) but not with HR_max (MD = -0.34 bpm; 95%CI [-1.54, 0.86]; p = 0.58; I² = 0%). High heterogeneity of included studies was addressed with subgroup analyses. The risk of bias in most studies was high. The certainty of evidence was very low for each outcome. Conclusions: COVID-19 infection in athletes was associated with reduced VO_2max and VE_max. The relationships were highly dependent on the quality of the studies. CRF and athlete profile should be considered when making shared decisions regarding safe return to sport after infection.