When given a medicine that opens up heart arteries, endurance athletes show a much bigger increase in artery space relative to heart muscle size than non-athletes, which might mean their arteries respond better to the drug.
Scientific Claim
Endurance athletes who received sublingual nitroglycerin showed a higher coronary volume-to-mass (V/M) ratio (21.1 vs. 14.8; p<0.001) compared to those who did not, while no such difference was observed in sedentary controls, suggesting endurance training may be associated with enhanced vasodilatory response to nitroglycerin.
Original Statement
“V/M-ratio was different between athletes who received nitroglycerin compared with those who did not (V/M: 21.1 vs. 14.8; p < 0.001), but these differences were not observed in the control subjects.”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design cannot support claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The study is observational and retrospective; the nitroglycerin administration was not randomized. The claim implies a causal effect of training on vasodilation, but only an association with a subgroup interaction is observed.
More Accurate Statement
“Endurance athletes who received sublingual nitroglycerin showed a higher coronary volume-to-mass (V/M) ratio (21.1 vs. 14.8; p<0.001) compared to those who did not, while no such difference was observed in sedentary controls, suggesting an association between endurance training and enhanced vasodilatory response to nitroglycerin.”
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.
Randomized Controlled TrialLevel 1bWhether endurance training causes enhanced coronary vasodilatory response to nitroglycerin.
Whether endurance training causes enhanced coronary vasodilatory response to nitroglycerin.
What This Would Prove
Whether endurance training causes enhanced coronary vasodilatory response to nitroglycerin.
Ideal Study Design
A 12-month double-blind RCT of 120 sedentary adults aged 50–65 randomized to 150 min/week supervised endurance training or control, with coronary CTA and CFD analysis of V/M ratio before and after standardized sublingual nitroglycerin administration at baseline and follow-up.
Limitation: Ethical and logistical challenges in long-term blinding; nitroglycerin effects may be transient and not reflect chronic adaptation.
Prospective Cohort StudyLevel 2bWhether individuals who adopt endurance training develop a progressively enhanced V/M response to nitroglycerin over time.
Whether individuals who adopt endurance training develop a progressively enhanced V/M response to nitroglycerin over time.
What This Would Prove
Whether individuals who adopt endurance training develop a progressively enhanced V/M response to nitroglycerin over time.
Ideal Study Design
A 5-year prospective cohort study of 300 sedentary adults aged 45–60, measuring V/M ratio before and after nitroglycerin at baseline and annually, while tracking endurance training volume and intensity, adjusting for confounders.
Limitation: Cannot control for changes in medication, diet, or other lifestyle factors over time.
Cross-Sectional StudyLevel 3In EvidenceThe association between endurance training status and V/M ratio response to nitroglycerin at a single time point.
The association between endurance training status and V/M ratio response to nitroglycerin at a single time point.
What This Would Prove
The association between endurance training status and V/M ratio response to nitroglycerin at a single time point.
Ideal Study Design
A cross-sectional study of 200 endurance athletes and 200 sedentary controls aged 50–65, all undergoing standardized coronary CTA with CFD and sublingual nitroglycerin administration, measuring V/M ratio before and after, with blinded analysis.
Limitation: Cannot determine if training preceded the enhanced response or if pre-existing differences led to training adoption.
Case-Control StudyLevel 3Whether individuals with high V/M response to nitroglycerin are more likely to be endurance athletes.
Whether individuals with high V/M response to nitroglycerin are more likely to be endurance athletes.
What This Would Prove
Whether individuals with high V/M response to nitroglycerin are more likely to be endurance athletes.
Ideal Study Design
A case-control study comparing 100 individuals with V/M ratio increase >50% after nitroglycerin to 100 with <10% increase, matched for age and risk factors, assessing lifetime endurance training history via validated questionnaires.
Limitation: Prone to recall bias and selection bias; cannot establish causality.
Systematic Review & Meta-AnalysisLevel 1aWhether endurance training is consistently associated with greater V/M ratio response to nitroglycerin across studies.
Whether endurance training is consistently associated with greater V/M ratio response to nitroglycerin across studies.
What This Would Prove
Whether endurance training is consistently associated with greater V/M ratio response to nitroglycerin across studies.
Ideal Study Design
A systematic review and meta-analysis of 10+ studies measuring V/M ratio before and after nitroglycerin in endurance athletes versus sedentary controls, using standardized CFD protocols and adjusting for age, sex, and cardiovascular risk factors.
Limitation: Cannot establish causation or timing of exposure relative to vascular adaptation.
Evidence from Studies
Supporting (1)
Athletes who took a nitroglycerin tablet under their tongue had much more open coronary arteries than athletes who didn’t, but sedentary people didn’t show this difference — suggesting their training made their blood vessels respond better to the drug.