The Study
A Prospective Study on Maximal Oxygen Uptake and Cardiovascular Functions in 12‐Year‐Old Endurance Athletes and Their Non‐Endurance‐Trained Peers
This study looked at kids who already train a lot and kids who don’t, and found the athletes had stronger hearts and could run longer. But it doesn’t prove that training made their hearts stronger — maybe they were already healthier and that’s why they chose to train more.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Young kids who train hard for sports like skiing have stronger hearts and can use more oxygen than kids who don't train much.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 539 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means their hearts pump more blood with each beat, helping them run or ski longer without getting tired.
- 2Athletes had 18% higher oxygen use per pound of muscle, bigger heart chambers, and trained 7 hours/week vs.
- 32.5 hours for non-athletes.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Scandinavian Journal of Medicine & Science in Sports
Year
2025
Authors
Halvard Grendstad, Sigrun Ådnegard Skarstad, T. Edvardsen, J. Hallén
Related Content
Claims (4)
Endurance athletes have a longer time for blood to fill the heart between beats while at rest, which allows more blood to enter the heart with each cycle, without their heart beating faster than that of non-athletes.
Twelve-year-old endurance athletes train an average of 7.0 hours per week, while non-athletes train 2.5 hours per week, but both groups show similar changes in VO2max, stroke volume, and left ventricular dimensions over 14 months.
Twelve-year-old endurance athletes have 18% higher maximal oxygen uptake per kilogram of fat-free mass than peers who do not train in endurance sports.
Twelve-year-old endurance athletes have larger heart chamber sizes and more blood pumped per heartbeat relative to their lean body mass than other children their age who do not train in endurance sports.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.