Abstract
Background: Athletes with intense exercise may exhibit electrocardiogram (ECG) changes in three groups: normal, borderline, and abnormal. There are many factors involved in these changes.
Objectives: (1) To describe the electrocardiographic characteristics of athletes with high intensity exercise. (2) To find out some factors related to the changes on the electrocardiogram in the above study subjects.
Methods: A cross-sectional descriptive study conducted on 130 athletes in 6 sports in the highintensity exercise subgroup. Each ECG of athlete was recorded and analyzed for standard parameters and then classified into one of three groups: normal, borderline, and abnormal according to international recommendations for electrographic interpretation in athletes. Finally, analyse some factors affecting abnormal ECG change.
Results: The most normal ECG changes in the study group of athletes were: early repolarization (63.1%), sinus bradycardia with a frequency >30 beats/min (61.5%), sinus arrhythm (54.6%), isolated left ventricular hypertrophy (35.4%), incomplete right bundle branch block (18.5%). The rate of early repolarization was greater in the group doing exercise >21 h/week than in the group doing exercise ≤21 h/week (85.7% vs 54.7%, p=0.002). The rate of sinus bradycardia was more common in men than in women (68.1% vs 46.2%, p=0.018. In addition, the rate of isolated left ventricular hypertrophy was higher in the active greater dynamic exercise athletes than in the greater static exercise group (49% vs 27.2%, p=0.012). The group of athletes who practiced and competed for >21 hours/week had an abnormal electrocardiogram change 6.34 times higher than the group that exercised ≤21h/week (95%CI= 1.492-26.978, p=0.012). Compare with the group of athletes competing at the international level, the group of athletes competing at the regional level had a lower abnormal ECG change, approximately 0.063 times (95%CI 0.005-0.782, p=
0.031). When age increasing by 1 year, the possibility of abnormal ECG changes increased by 1,069 times (95% CI = 1,003 - 1.139, p = 0.039).
Conclusion: In athletes with high-intensity exertion, normal ECG changes are: early repolarization, sinus bradycardia with a rate >30 bpm, sinus arrhythm, isolated left ventricular hypertrophy, incomplete right bundle branch block. Abnormal ECG changes are: negative T wave inversion and pre-excitation syndrome. Training and competition duration >21 hours/week and increasing age rise the incidence of abnormal electrocardiographic changes in athletes.