| Abstract [eng] |
Endurance training is generally associated with cardiovascular benefits, including improved cardiac output, reduced resting heart rate, and enhanced metabolic efficiency. However, both insufficient and excessive training levels have been linked to increased cardiovascular risk, raising the question of where beneficial adaptation ends and harmful stress begins. This master's thesis investigates the physiological and pathological cardiovascular effects of endurance training, with a particular focus on athletes' awareness of these effects. The study combines a systematic literature review with a cross-sectional online survey of 307 active endurance athletes. The questionnaire was distributed in Germany and Lithuania in English and German via sports clubs, universities, and online platforms. The survey results reveal that no universal training threshold exists beyond which endurance exercise becomes cardiovascular harmful. Risk depends on the interaction of training volume, frequency, age, sex, and individual health literacy. Athletes aged 18 to 29 years reported the highest rates of acute symptoms with very high statistical significance (p = 2.14×10⁻¹⁰), suggesting acute overreaching as a primary risk driver in this cohort. Training frequencies of 3 to 6 days per week were associated with the most favorable outcomes, consistent with a U-shaped dose-response relationship. Contrary to prevailing literature, female participants reported chest pain more frequently than male participants (p = 0.02), contributing to growing evidence that female cardiovascular risk in endurance sport may be systematically underestimated. Knowledge of heart rate zone training was associated with significantly lower symptom prevalence, demonstrating the protective effect of structured training control. However, a substantial proportion of zone-aware athletes did not actively implement it, indicating a persistent health literacy gap. A critical finding concerns risk awareness. Only 3% of participants identified coronary artery calcification as an endurance-associated risk, and fewer than a quarter recognized sudden cardiac death. This study provides population-level evidence that the most clinically significant cardiovascular risks of endurance training are largely absent from athlete awareness, underscoring the need for targeted health education in endurance sport communities. |
