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 (VO2max). Secondary outcomes included changes in absolute VO2max, maximal ventilation (VEmax), and maximal heart rate (HRmax). 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 VO2max (MD = −1.83 mL·kg−1·min−1; 95%CI [−3.16, −0.49]; p = 0.007; I2 = 54%) and absolute VO2max (MD = −0.15 L·min−1; 95%CI [−0.29, −0.01]; p = 0.03; I2 = 0%). COVID-19 infection was associated with lower VEmax (MD = −7.99 L·min−1; 95%CI [−12.94, −3.04]; p = 0.002; I2 = 0%) but not with HRmax (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 VO2max and VEmax. 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.