Physical fitness is a key indicator of current and future health in children and adolescents. Evidence suggests that fitness levels have declined then stagnated in recent decades, but it remains unclear how the coronavirus disease 2019 (COVID-19) pandemic has impacted this trend.

We conducted a systematic review and meta-analyses to assess pandemic-related changes in physical fitness among children and adolescents (0–19 years) in the World Health Organization European Region. Seven databases were searched up to February 28, 2025 for studies reporting validated pre- and during/post-pandemic fitness measurements. Two reviewers independently performed screening, data extraction, risk-of-bias assessment (Risk Of Bias In Non-randomized Studies – of Exposure) (ROBINS-E), and certainty grading (Grading of Recommendations, Assessment, Development and Evaluation) (GRADE). Random-effects meta-analyses yielded standardized mean differences (SMDs) with 95% confidence intervals (95%CIs). Subgroup analyses examined sex, age, year, and national restriction severity (Oxford Stringency Index).

Thirty-two studies comprising 270,179 participants and 1,519,386 fitness measurements from 17 European countries were included. Cardiorespiratory fitness declined significantly during the pandemic, especially in 2021, with reductions in endurance (SMD = –0.43; 95%CI: −0.61 to −0.25) and speed (SMD = −0.29; 95%CI: −0.61 to 0.03). While speed returned to baseline by 2023, endurance remained below pre-pandemic levels (SMD = −0.10; 95%CI: −0.12 to −0.08). Girls and adolescents were disproportionately affected. In contrast to cardiorespiratory fitness, muscular fitness remained largely unchanged. Stricter national regulations were associated with greater declines in cardiorespiratory fitness.

COVID-19 pandemic restrictions were associated with a marked decline in cardiorespiratory fitness in European children and adolescents, with levels not recovered by 2023. These findings call for urgent, targeted public health interventions to improve physical fitness and prevent long-term health consequences.