The Study
Estimated exercise‐induced maximal myocardial blood flow in untrained and endurance‐trained men
We don't know what kind of study this really was, so we can't say if the results mean anything for real life. It's like seeing a picture of a dog and saying it proves all dogs are friendly — we just don't have enough info to know.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Athletes have bigger hearts, but their heart muscle doesn't get more blood per gram than non-athletes during max exercise — instead, their bigger heart pumps more total blood.
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 549 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — athletes' hearts work harder by being bigger, not by pumping more blood through each gram of muscle, which means their efficiency comes from size, not tissue-level changes.
- 2Max blood flow during exercise: 5.0 mL/g/min in untrained, 4.5 mL/g/min in athletes.
- 3Adenosine only gave 3.9 and 2.3 mL/g/min.
- 4Total blood flow was higher in athletes (1398 vs.
- 5972 mL/min).
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Experimental Physiology
Year
2026
Authors
I. Heinonen, K. Kalliokoski, J. Knuuti, Marko Laaksonen
Related Content
Claims (6)
During intense exercise, endurance athletes have faster blood flow in the heart's pumping phase to compensate for less time available for the heart to fill with blood between beats.
During exercise, the heart receives more blood flow than it does when given high-dose adenosine, with untrained men reaching 5.0 mL/g/min and endurance-trained men reaching 4.5 mL/g/min, showing that current drug-based methods do not fully replicate the heart's natural blood flow response to exercise.
Endurance training does not result in higher blood flow through the heart muscle per gram of tissue during maximum exercise, even though the hearts of trained individuals are larger and pump more blood overall.
When calculating myocardial vascular resistance during peak exercise, using mean arterial pressure versus systolic blood pressure produces different results, leading to inconsistent conclusions about vascular function in endurance-trained people.
Endurance-trained men have lower blood flow in the heart in response to adenosine compared to untrained men, showing a reduced ability of blood vessels to widen under pharmacological stimulation, even though their hearts are larger.
Endurance-trained men have higher total blood flow to the heart due to larger heart size, not because more blood flows through each unit of heart tissue.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.