New research from Amsterdam UMC (Amsterdam Cardiovascular Sciences) reveals that the classical distinction between a "strength-sport heart" and an "endurance-sport heart" does not hold up for the individual athlete. These assumptions, embedded in international guidelines, are insufficiently reliable. Physician-researcher Maarten van Diepen: "This study demonstrates that the rule of thumb that strength sports produce a thickened heart and endurance sports produce a dilated heart says too little about the heart of any one athlete. For a reliable assessment of an athlete's heart health, clinicians must look beyond sport type alone."

Since 1975, sports cardiology has operated on the concept of the "strength-sport heart", characterised by a thickened heart wall, and the "endurance-sport heart", characterised by dilated heart chambers. These assumptions are embedded in international guidelines and are used worldwide in the evaluation of athletes. Amsterdam UMC, together with other Dutch centres, examined 775 elite athletes, both men and women, across 48 different sports. Their hearts were assessed using cardiac magnetic resonance (CMR) and compared with those of 249 non-athletes.

Rethinking the Strength-Sport Heart

The study found that sport type says too little about the cardiac phenotype of an individual athlete. The most striking finding was that 75% of the examined strength athletes had hearts that were "normal" in shape and proportions, without clear thickening of the heart muscle. When thickening of the heart muscle was present in elite athletes, it was usually accompanied by enlarged heart chambers. This pattern was not specific to one sport type. Van Diepen: "The distinction between a 'thickened' strength-sport heart and a 'dilated' endurance-sport heart is therefore far less clear than we long assumed."

Sport Type Not Decisive

According to sports cardiologist Harald Jørstad, these findings are important because several heart conditions can also manifest as a thickened or dilated heart. "In athletes, the question is often whether an abnormal heart shape is caused by exercise or by disease. This study shows that relying solely on sport type to assess an athlete's heart carries risks," says Jørstad. A remarkable heart shape may then be incorrectly dismissed as "normal for this sport." Van Diepen: "The clinician should first look at the heart muscle, the chambers, and the relationships between them, and combine that with symptoms, family history, and training data. Sport type should not take centre stage." The study also showed that ejection fraction had no association with sport type, suggesting that reduced pumping function should not be attributed to a specific sport.

Towards Personalised Sports Cardiology

The findings underscore that evaluating the athlete's heart requires a personalised approach. Cardiac images of athletes should be compared with robust reference values. Other data, including symptoms, blood pressure, and training load, also play a role. This can help better distinguish between a healthy athlete's heart and early signs of cardiac disease, thereby preventing both unnecessary sport restrictions and missed diagnoses.

The findings were published in the European Journal of Preventive Cardiology and were presented by Maarten van Diepen at the ESC Congress 2026 in Munich. The ELITE study was supported by Amsterdam Movement Sciences, the Dutch National Olympic Committee*National Sports Federation, and the Heart to Handle Foundation. The work was conducted within the FIT-HEART consortium, which is supported by the Dutch Heart Foundation.

This article is copied from Amsterdam UMC Vandaag.