Key result
National-level triathlete status is linked to ~34% lower resting heart rate vs. sedentary controls.
Why the study?
High-intensity endurance training induces specific cardiac adaptations often observed via ECG changes, prompting investigation into ECG abnormalities in national-level Australian triathletes compared to sedentary controls.
Does high-intensity endurance training induce electrocardiographic and structural cardiac adaptations in national-level triathletes compared to sedentary controls?
Cross-Sectional (n=29)
No
Does high-intensity endurance training induce electrocardiographic and structural cardiac adaptations in national-level triathletes compared to sedentary controls?
National-level triathletes exhibit significant electrocardiographic and structural cardiac adaptations, including resting bradycardia and increased left ventricular mass, highlighting the need to distinguish physiological from pathological changes.
Background: High-intensity endurance training induces specific cardiac adaptations, often observed through electrocardiographic (ECG) changes. This study investigated the prevalence of ECG abnormalities in national-level Australian triathletes compared to sedentary controls. Methods: A cross-sectional observational study was conducted involving 22 triathletes and 7 sedentary controls. Standard 12-lead ECGs assessed resting heart rate, ECG intervals, and axis deviation. Peak oxygen consumption was evaluated in triathletes to correlate with ECG indices and left ventricular mass, derived via echocardiography. Results: Triathletes exhibited significantly lower resting heart rates (53.8 vs. 72.1 bpm, −34%, p = 0.04), shorter QRS durations (0.088 vs. 0.107 ms, −21.6%, p = 0.01), and longer QT intervals (0.429 vs. 0.358 ms, +16.6%, p = 0.01) compared to controls. Sinus bradycardia was present in 68.2% of triathletes, with varying severity. First-degree atrioventricular block was identified in 13.6% of athletes, and left ventricular hypertrophy was confirmed in 18 triathletes via echocardiography. A significant positive relationship was identified between VO2peak and left ventricular mass (r = 0.68, p = 0.003). Conclusions: National-level triathletes exhibited ECG and structural cardiac adaptations consistent with high-intensity endurance training. Echocardiography is recommended for the accurate identification of LVH. These findings highlight the need for comprehensive cardiac evaluation in athletes to distinguish between physiological and pathological adaptations.
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Climstein et al. (2025) conducted a cross-sectional in Healthy (National-level triathletes vs sedentary controls) (n=29). High-intensity endurance training (Triathlete status) vs. Sedentary lifestyle was evaluated on Resting heart rate (-34%, p=0.04). National-level triathletes exhibited significantly lower resting heart rates (53.8 vs. 72.1 bpm, p=0.04) and structural cardiac adaptations compared to sedentary controls.
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