The longer a man has trained for marathons, the more likely he is to have serious artery blockages—even if he’s otherwise healthy, with no high cholesterol or blood pressure.
Scientific Claim
The number of years of endurance training is the only independent predictor of significant coronary artery disease (CAC >70th percentile or ≥50% stenosis) in male athletes, with each additional year of training increasing the odds by 8%.
Original Statement
“The number of years of training was the only independent variable associated with increased risk of CAC >70th percentile for age or luminal stenosis ≥50% in male athletes (odds ratio, 1.08; 95% confidence interval, 1.01–1.15; P=0.016);”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The study used multivariable logistic regression to identify an independent association, and the authors correctly report odds ratios with confidence intervals without implying causation.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Prospective Cohort StudyLevel 2bWhether cumulative endurance training dose linearly increases coronary calcification over time in healthy individuals.
Whether cumulative endurance training dose linearly increases coronary calcification over time in healthy individuals.
What This Would Prove
Whether cumulative endurance training dose linearly increases coronary calcification over time in healthy individuals.
Ideal Study Design
A 25-year prospective cohort of 1,500 healthy men starting at age 25, with annual exercise logs and CAC scoring, stratified by training volume (e.g., <10, 10–20, >20 hrs/week), controlling for diet and smoking.
Limitation: Cannot control for lifelong adherence or changes in training intensity over decades.
Systematic Review & Meta-AnalysisLevel 1aWhether the association between years of endurance training and CAC is consistent across populations and independent of other risk factors.
Whether the association between years of endurance training and CAC is consistent across populations and independent of other risk factors.
What This Would Prove
Whether the association between years of endurance training and CAC is consistent across populations and independent of other risk factors.
Ideal Study Design
A meta-analysis of 10+ prospective studies measuring years of endurance training and CAC scores in low-risk adults, using individual participant data to adjust for confounders and model dose-response curves.
Limitation: Relies on self-reported exercise history, which may be inaccurate.
Nested Case-Control StudyLevel 3bWhether athletes with >30 years of training have higher CAC than those with <15 years, matched for current fitness and risk factors.
Whether athletes with >30 years of training have higher CAC than those with <15 years, matched for current fitness and risk factors.
What This Would Prove
Whether athletes with >30 years of training have higher CAC than those with <15 years, matched for current fitness and risk factors.
Ideal Study Design
A nested case-control study within a cohort of 5,000 athletes, comparing 200 with CAC >70th percentile to 400 without, matched for age, BMI, and current VO2max, and comparing lifetime training hours.
Limitation: Retrospective recall of training history may be biased.
Evidence from Studies
Supporting (1)
The study found that male athletes who trained longer had a slightly higher chance of having serious heart artery blockages, and the more years they trained, the higher the chance—exactly what the claim says.