Electrocardiographic monitoring in sport using a portable device

  ABSTRACT Exercise can affect the cardiac size, mass, structure, and function, often referred to as the athlete’s heart. Athlete’s heart is a constellation of structural and functional changes that occur in the heart of people who regularly train. Cardiovascular monitoring has become the essence of sports because it enables preventive intervention on heart condition which could lead to sudden cardiac death when combined with a high level of physical effort. Thus, the aim of the thesis is to monitor the cardiovascular activity of sprinters during athletics training and competition. The major features of an electrocardiogram (ECG) include the P wave, the PR interval, the QRS complex, the QT interval, the ST segment, and the T wave. The P wave corresponds to atrial depolarization; the PR interval represents the delay between atrial and ventricular depolarization; the QRS complex correspond to ventricular depolarization; during the ST segment, all the ventricular myocardium is depolarized; the QT interval represents the duration of ventricular activation; and the T wave reflects ventricular repolarization. To achieve the objective of the study the ECG features and their changes during the development of the athlete training have been analysed. For monitoring, nowadays there are numerous devices, both wearable and portable, which perform short cardiac tests. The instrument used in this study is the Single Lead KardiaMobile from Alivecor, which is part of a range of mobile ECG recorders of clinical quality. Data are a collection of 200 ECGs acquired on 10 young subjects practicing athletics, during two different workouts (strength and speed) and a competition. In these three scenarios, several phases can be distinguished: pre-warm-up, post-warm-up, post the first exercise, post the second exercise, 5 minutes, 10 minutes, and 15 minutes of rest after exercise. Data were pre-processed and analysed in MATLAB® environment. For a detailed image of the subjects, an analysis of the cardiac characteristics extracted from the KardiaMobile signals was conducted. The extracted features from each acquired ECG signal were the duration of the waves (ms) and the intervals (ms) and have been presented as the mean value and standard deviation of the 10 subjects. Statistical analyses were performed using the two-sample t-test to verify the statistical difference between different phases (p < 0.05). The obtained results show that the values of the duration of the P wave and the PR interval after the exercise are lowering to return to the baseline in the recovery phase, as if they follow the heart rate, which is something unexpected. The same happens to the QT interval, the ST interval and the duration of the T wave, as reported in literature. Indeed, QT interval changes with heart rate and as expected for these features the p-value is less than 0.05 in the post exercise phases because the T wave is stretching. The study suggests that the analysis conducted is an excellent tool to assess heart changes while subjects are practicing sport. Hence, this cardiovascular monitoring activity should be promoted to counteract and prevent sudden cardiac death in athletes. However, the study should be deepened in future to improve its limits and to become more reliable in the athlete population. Moreover, a future development of this thesis could be a physiological study of the P wave undergoing a stress test.