RESUMO
The 800-m (m) run is part of Physical Education classes in Cameroon, after which arrhythmias may occur during recovery. Hence, this study aimed at determining relationship between 800-m run loads on cardiac autonomic recovery among school adolescents. Forty-two male adolescents (aged [17 â± â1] years) performed 800-m. Post-exercise heart rate variability (HRV) was recorded during 5-min (min) (HRV5-min) and 15-min (HRV15-min) in time: Standard deviation of normal to normal (SDNN); Root mean square of successive differences (RMSSD) and frequency domain (LH: Low frequency, HF: High frequency, TP: Total power). Rating of Perceived Exertion (RPE) and blood lactate concentration (BLa) were measured after exercise. In HRV5-min, RPE was associated with SDNN (r â= â-0.44, p â< â0.01) and RMSSD (r â= â-0.38, p â< â0.05). BLa was correlated with SDNN (r â= â-0.38, p â< â0.05) and RMSSD (r â= â-0.56, p â< â0.001) in the time-domain, LF (r â= â-0.64, p â< â0.001), HF (r â= â-0.58, p â< â0.001) and TP (r â= â-0.61, p â< â0.001) in frequency-domain. Moreover, RPE was correlated with LF (r â= â-0.44, p â< â0.01), TP (r â= â-0.49, p â< â0.01) while exercise duration with HF (r â= â-0.38, p â< â0.05). In HRV15-min, BLa was correlated with RMSSD (r â= â-0.53, p â< â0.001) and SDNN (r â= â-0.68, p â< â0.001). RPE was negatively correlated SDNN (r â= â-0.53, p â< â0.01) and RMSSD (r â= â-0.44, p â< â0.01). BLa was associated with HF (r â= â-0.55, p â< â0.001), TP (r â= â-0.50, p â< â0.01) and RPE with LF (r â= â-0.51, p â< â0.01), HF (r â= â-0.50, p â< â0.01), TP (r â= â-0.49, p â< â0.01). In addition, exercise duration was negatively linked to HF (r â= â-0.36, p â< â0.05). This study outlined that in untrained adolescents an increase of 800-m loads is associated with a slow vagal indexes of HRV during the recovery.
RESUMO
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.
