A new umbrella review pulls together data from more than 125,000 observations to ask a simple question with big stakes: does cardiorespiratory fitness (CRF) in childhood and adolescence matter for health? The short answer: yes—across body, heart–metabolic, and mental health measures—though researchers say higher‑quality studies are still needed.
What’s new
Researchers analyzed 14 systematic reviews with meta‑analyses, spanning 33 health‑related outcomes in young people under 18. Most associations were favorable (26 outcomes) and the rest were null (7 outcomes)—none were harmful. The review covered both generally healthy youth and those with chronic conditions. The flow chart on page 4 shows the team screened 9,000+ records to arrive at the final 14 reviews.
Key numbers at a glance
- In the general population, fitter kids tended to have healthier body composition and blood markers. For example, Figure 2 on page 6 shows the strongest links were with skinfold thickness (r = −0.34) and waist circumference (r = −0.29)—lower is better—as well as higher HDL (“good”) cholesterol and better self‑perception (r = 0.27). Results for blood pressure, LDL cholesterol, fasting glucose, and anxiety were mostly non‑significant.
- In clinical groups, CRF was markedly lower than in healthy peers. Figure 3 on page 7 highlights the largest gap in newly diagnosed pediatric cancer (mean difference −19.6 mL/kg/min VO₂; 95% CI −21.4 to −17.8). Children with congenital heart disease also showed substantially lower fitness (−7.9 mL/kg/min).
- Fitness also tracked with clinical risk: among youth with type 1 diabetes, higher CRF correlated with lower HbA1c (r = −0.31), and in cystic fibrosis, low fitness was linked to a ~5‑fold higher risk of all‑cause mortality(RR 4.9; 95% CI 1.1–22.1).
How fitness was measured
CRF was assessed using standard lab or field tests (for example, treadmill/cycle tests with or without gas analysis, or the 20‑meter shuttle run), reported as VO₂max/VO₂peak or related estimates—tools familiar to clinicians and school fitness programs alike.
Why it matters
Major heart‑health organizations already view CRF as an important marker across the lifespan. This review adds pediatric weight by showing consistent links between better fitness and better health now, and hints that fitness might help flag future risk—including in children managing chronic disease.
A note of caution
The authors grade the overall certainty of evidence as low to moderate, mainly because many included studies were observational, varied in methods, and sometimes small. They call for large, diverse, longitudinal studies to test whether improving fitness causes better outcomes and to expand research beyond weight, metabolism, and mental health to areas like kidney and immune health.
Bottom line for families and schools
Encouraging age‑appropriate, enjoyable physical activity—and tracking fitness in routine health or school settings—could support healthier bodies and minds in childhood, with potential benefits that carry into adulthood. The science is promising; now it needs the long‑term studies to match.
Source: Demchenko, I., Prince, S. A., Merucci, K., Cadenas-Sanchez, C., Chaput, J. P., Fraser, B. J., Manyanga, T., McGrath, R., Ortega, F. B., Singh, B., Tomkinson, G. R., & Lang, J. J. (2025). 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. British journal of sports medicine, 59(12), 856–865. https://doi.org/10.1136/bjsports-2024-109184
Editor’s note: This article is for information only and is not a substitute for professional medical advice.