Understanding the Endurance Athlete’s Heart

by Katerina Paul • 23.01.2025
Ski Classics Engadin La Diagonela Pontresina - Zuoz (SUI) heart health
Endurance sports like cross-country skiing place unique demands on the human body, and the heart—as the engine of athletic performance—is no exception.
Endurance sports like cross-country skiing place unique demands on the human body, and the heart—as the engine of athletic performance—is no exception.

The Pro@Heart study, a 20-year collaborative effort between Australian and Belgian researchers, offers a unique opportunity to assess the long-term health effects of elite level endurance exercise. By closely studying athletes’ physical characteristics and following their health over time, this research seeks to find out if individual heart features are linked to positive or negative long-term health effects. Unlike earlier studies that looked at athletes at just one moment in time, this long-term design aims to uncover whether these outcomes are caused by exercise itself or pre-existing conditions. With the study now nearing its 10-year mark, it offers an exciting glimpse into its progress and the insights still to come.

Cross-Country Skiers and Cardiac Health

Cross-country skiing is one of the most physically demanding endurance sports, requiring exceptional cardiovascular fitness. However, even among elite skiers, the risk of cardiac conditions like atrial fibrillation (AF) is a growing concern. Ski Classics athlete Emilie Fleten recently experienced AF during the Drei Zinnen Ski Marathon, forcing her to slow down mid-race.

Fleten is not alone. Biathlete Ingrid Landmark Tandrevold and several other skiing stars—including Sivert Bakken, Martin Johnsrud Sundby, and Marit Bjørgen—have faced similar challenges. These situations highlight the importance of understanding exercise-induced cardiac remodeling (EICR) and its potential risks for elite athletes in endurance sports like cross-country skiing.

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What is Exercise-Induced Cardiac Remodeling (EICR)?

EICR refers to the changes in the heart’s structure, function, and electrical system that happen due to the intense demands of endurance exercise. These changes help athletes sustain long periods of physical activity, often leading to larger hearts with better stroke volume and cardiac output. While usually beneficial, the Pro@Heart study aims to find out why some athletes face issues like arrhythmias or other heart conditions.

Key Determinants of Cardiac Remodeling

One of the study’s focal points is the variability in how athletes’ hearts adapt to training. Factors influencing EICR include:

  1. Training Load: Athletes participating in dynamic sports like cross-country skiing, biathlon, cycling, and rowing tend to exhibit significant cardiac adaptations. However, even among athletes with similar training regimens, responses can differ. Long-term training intensity, total hours, and sudden changes in exercise load all play a role in shaping cardiac structure. Interestingly, higher lifetime training volumes have been linked to conditions such as atrial fibrillation (AF) and myocardial fibrosis according to De Bosscher, Dausin, Janssens, et al. (2022).
  2. Genetics: When differences in cardiac adaptation can’t be fully explained by training load, genetic predispositions may offer insights. For instance, genetic factors might influence susceptibility to exercise-induced arrhythmogenic right ventricular cardiomyopathy (ARVC), a rare but serious condition in some endurance athletes.

Balancing Performance and Risk

Despite the well-documented health benefits of regular exercise, including improved cardiovascular health, reduced obesity, and increased longevity, endurance athletes are not immune to cardiac risks. The Pro@Heart study, De Bosscher R, Dausin C, Janssens K, et al. (2022), emphasises that high training volumes can increase the risk of arrhythmias, particularly atrial fibrillation. A 2009 meta-analysis found that endurance athletes are over five times more likely to develop AF than non-athletes. However, these risks must be weighed against the undeniable benefits, including enhanced VO2 max and overall cardiovascular fitness.

The Long Road Ahead

The Pro@Heart study takes a unique long-term approach, following athletes over 5, 10, 15, and 20 years to better understand how endurance exercise affects heart health. This extensive research aims to answer important questions about the long-term effects of exercise-induced cardiac remodeling (EICR), what drives individual differences, and how athletes can train effectively while managing potential risks.

Reference

De Bosscher R, Dausin C, Janssens K, et al. Rationale and design of the PROspective ATHletic Heart (Pro@Heart) study: long-term assessment of the determinants of cardiac remodelling and its clinical consequences in endurance athletes. BMJ Open Sport & Exercise Medicine 2022;8:e001309. doi:10.1136/ bmjsem-2022-001309

If you would like to follow along for updates on the study or further information, visit the Pro@Heart website

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