The Claim

Endurance athletes exhibit a dilated left ventricle with normal or mildly reduced ejection fraction, a significantly enlarged left atrium exceeding 34 mL/m², and an elevated E/A ratio as physiological adaptations to chronic high-volume training, and these structural and functional cardiac changes are not indicators of pathology when assessed in the context of endurance training.

Source: Diastolic function and dysfunction in athletes

What the research says

Roughly balanced

Support and challenge are close. The picture may shift as more studies come in.

Supports
2score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Description
1 study reviewed
In plain English

Endurance athletes have a larger left ventricle, a larger left atrium, and a higher E/A ratio than non-athletes, and these changes are normal adaptations to long-term intense training, not signs of heart disease.

See the scientific wording

Endurance athletes exhibit a dilated left ventricle with normal or mildly reduced ejection fraction, significantly enlarged left atrium exceeding 34 mL/m², and an elevated E/A ratio, which are physiological adaptations to chronic high-volume training and not indicators of pathology when assessed in context.

Why this might work

The heart's left chamber grows larger and its walls stretch slightly to handle more blood flow during endurance training. This allows the chamber to refill faster between beats by snapping back more forcefully after squeezing and by relaxing more quickly. The upper chamber also gets bigger to hold more blood and push it into the lower chamber efficiently. These changes make the heart pump more blood with each beat without overworking, and they are normal responses to long-term intense exercise.

Verified mechanismbased on 1 study

What the research says

1 study

  1. Study: Diastolic function and dysfunction in athletes

    Elite endurance athletes often have bigger heart chambers and faster blood flow patterns on heart scans, but these aren't signs of disease — they're just how their hearts adapt to years of intense training.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

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