Pre- And post-exercise electrocardiogram pattern modifications in apparently healthy school adolescents in Cameroon

Background: Physical Education and Sport (PES) is compulsory in Cameroonian education system. Cardiac accidents and sudden cardiac deaths (SCD) have been reported during PES examinations. This study aimed to contribute in the prevention of these cardiac accidents by studying pre- and post-exercise electrocardiogram (ECG) pattern modifications in apparently healthy school adolescents. Methods: One hundred school adolescents without apparent heart disease [aged 18 ± 2 years; body mass index (BMI): 21.9 ± 2.3] were included. Participants performed two intermittent sprint-endurance tests. The test consisted in walking 2000 m as warm-up, followed by sprint and endurance races. A 12-leads ECG was performed before and in 5 min after the tests. ECG patterns changes were studied with particular attention to abnormalities that could be associated with risk of SCD. Results: At rest, ECG patterns variants consisted of bradycardia (30%), sinus arrhythmia (9%), posterior hemi post-block (2%), and early repolarization (3%). which disappeared after exercise in all participants. QTc (ms) and heart rate (HR) increased after exercise (p < 0.001); and RR (ms) decreased post-exercise (p < 0.001). Other changes includes the appearance of the T-waves reversed in precordial leads (V2–V4) (p < 0.001), ventricular (6%), atrial and other supraventricular premature beats (2%) in the post-exercise ECG. Left ventricular hypertrophy (2%), right auricular enlargement (2%), short PR (2%) appeared at the end of the tests. Conclusion: This study suggests that an intermittent exercise can induce cardiac abnormalities able to provoke cardiac accidents and SCD in apparently healthy school adolescents.