Cardiorespiratory fitness and health in children and adolescents: an overview of systematic reviews with meta-analyses representing over 125 000 observations covering 33 health-related outcomes

Objective To synthesise data on the associations between cardiorespiratory fitness (CRF) and health in children and adolescents, evaluate the certainty of evidence and identify knowledge gaps. Design An overview of systematic reviews with meta-analyses. Results were pooled using forest plots and certainty of evidence evaluated with GRADE. Data sources Medline, Embase, Scopus, CINAHL and SPORTDiscus were searched from January 2002 to March 2024. Eligibility criteria for selected studies Systematic reviews with meta-analyses exploring CRF and health in children and adolescents aged <18 years. Results From the 9062 records identified, 14 reviews were included. Meta-analysed data from 125 164 observations covering 33 health outcomes were compiled, showing favourable (n=26) or null (n=7) associations with CRF. Among general populations, the associations were weak-to-moderate, with favourable links between CRF and indicators of anthropometry and adiposity, cardiometabolic and vascular health, and mental health and well-being. Among clinical populations, CRF was lower in participants with a condition compared with healthy controls, with the largest difference for newly diagnosed cancer (mean difference=−19.6 mL/kg/min; 95%CI: −21.4,–17.8). Patients with cystic fibrosis had a greater risk for all-cause mortality when comparing low CRF vs. high (relative risk=4.9; 95%CI: 1.1, 22.1). The certainty of evidence ranged from very low to moderate. Conclusion CRF shows promising links to numerous health outcomes in paediatric populations, though the low certainty of evidence calls for further research. High-quality longitudinal evidence is warranted to confirm the findings and investigate a predictive role of childhood CRF for future health.