The impact of COVID-19 on soccer players' health: A systematic review and meta-analysis.

Despite growing research, the health effects of COVID-19 on soccer players remain poorly integrated. This meta-analytic review synthesized evidence across competitive levels and pandemic phases to characterize the effects of SARS-CoV-2 infection and pandemic-related restrictions. The study adhered to PRISMA 2020 and Cochrane standards, with searches conducted in PubMed, Scopus, SPORTDiscus, and Web of Science. Eligibility criteria followed the P.E.C.O.S. framework. From 6,048 records screened, nine studies (>1,525 players from Tiers 1-5) met the inclusion criteria. These observational investigations included predominantly male samples (94.2%) and assessed cardiovascular, respiratory, endocrine, metabolic/biochemical, hematologic, anthropometric, musculoskeletal, and gastrointestinal outcomes. Comparisons between pre- and during-pandemic periods suggested preserved cardiac integrity with infrequent post-infection sequelae, alongside mild pulmonary effects in infected players that tended to resolve with training resumption. Amid inconsistent endocrine findings, testosterone-to-cortisol ratios declined in non-infected players. Metabolic, hematologic, and anthropometric parameters were mostly stable, whereas hemoglobin exhibited a significant pooled increase. Musculoskeletal and gastrointestinal data were insufficient for broad conclusions. Moreover, meta-analytic estimates require cautious interpretation owing to few studies and very low certainty. Altogether, COVID-19 was associated with modest and mostly reversible effects, with structured home-based training potentially offsetting detraining. Rare cardiac abnormalities still warrant careful medical supervision.