Estimation, analysis and comparison of the PR and RR intervals under exercise conditions and recovery

Very little works have been done on PR intervals, undoubtedly because this signal is difficult to extract and process, as in exercise tests where T-P fusion occurs during higher heart rates, what makes this problem still interesting. The common approach for the estimation of PR interval during both exercise and recovery is to determine the latency using the detection of the maximum of cross correlation function. This work aims to present a new method of time delay estimation with unknown signal based on an iterative maximum-likelihood approach which generalizes the well known Woody\´s method. This leads to a new approach to determine the PR intervals taking into account the presence of the T wave that is modeled. This work exhibits the existence of an abrupt change of slopes of PR and RR intervals at the same time occurrence and a phenomenon of "overshoot" during the recovery for athletes.