A sweeping analysis of past studies suggests that cardiorespiratory fitness (CRF)—how efficiently the heart and lungs work during exercise—is linked to healthier bodies and minds in children and teens.

What’s new

Researchers pulled together 14 systematic reviews with meta‑analyses, covering 33 health outcomes and 125,164 observations in people under 18. Across the board, findings were favorable for 26 outcomes and neutral for 7—none showed harm from higher fitness. Stronger fitness most consistently aligned with healthier body composition (e.g., lower skinfolds and waist size), better blood‑lipid profiles (especially higher HDL “good” cholesterol), and more positive self‑perception. By contrast, links with blood pressure, LDL cholesterol, fasting glucose, and anxiety were generally non‑significant.

In young people managing health conditions, fitness levels were often substantially lower than in healthy peers. The largest gap appeared in newly diagnosed pediatric cancer (average CRF was 19.6 mL/kg/min lower) and low fitness in cystic fibrosis was tied to an approximately five‑fold higher risk of all‑cause mortality. CRF was typically measured using treadmill or cycle tests (sometimes with gas analysis) or field tests like the 20‑meter shuttle run.

Why it matters

Major heart‑health bodies already recognize CRF as a vital sign across the lifespan. This review adds pediatric weight, indicating that improving fitness in childhood is associated with better health now and may help flag future risk, including in clinical populations.

A cautious note

Overall evidence quality ranged from very low to moderate—many studies were observational or methodologically mixed. The authors call for large, diverse, long‑term studies to test whether boosting fitness causes better outcomes and to examine under‑studied areas like kidney and immune health.

Bottom line

Making daily, age‑appropriate physical activity a norm at home and at school—and tracking fitness where practical—could support healthier bodies and minds in childhood, with benefits that may carry forward into adulthood.

Source: Demchenko I, Prince SA, Merucci K, et al. “Cardiorespiratory fitness and health in children and adolescents: an overview of systematic reviews with meta‑analyses,” British Journal of Sports Medicine (first published March 18, 2025; doi: 10.1136/bjsports-2024-109184).