*1.2. Related Works*

In the literature, we highlighted recent works and reviews where the effectiveness of smart health monitoring systems is described and summarized [15,22,23]. In recent years, some works have been carried out in which information and communication technologies and/or wearable device have enabled the telemonitoring of these patients. These are the most representative of the following works.

In [24], a home-based CR with telemonitoring guidance is evaluated. It includes *individual coaching by telephone weekly* after uploading training data. In [25], a home-based walking training program is presented. The approach includes a health device with four electrodes. At the end of the sessions, the data are transmitted using a mobile device to a monitoring center, which provides indicators of adherence and evaluation. In [26], a combination of e-textiles, wireless sensor networks, and a transmission board provide monitoring of several physiological parameters, such as the electrocardiogram (ECG), heart rate, and body temperature for *future healthcare environments*. In [13], the cardiac and aortic data are collected by wearable t-shirts with embedded electrodes. Then, they are processed by a mobile device to acquire biosignals. In addition, fuzzy logic is presented as an effective modeling tool with monitoring of the vital signs by means of fuzzy rules. In [27], a mobile application uploads the sessions from a wearable device to enable the coaching of health personnel. The wearable device is presented as a data collector without providing a real-time feedback of sessions. In [28], Fitbit wearable sensor devices, and personalized coaching with SMS are proposed. In the same way, an ad hoc application was not embedded in the wearable device. Finally, in [29], the heart rate was measured by the index finger on a built-in camera for one minute at each exercise stage in order to evaluate the quality of the session.

In this way, previous works have foregrounded the relevance and efficacy of integrating cardiac rehabilitation programs (CRPs) into home-based solutions, but with the limitations of non-programmable heart rate sensors or burdensome devices in the early stages of implantation. However recently, a new generation of smart-watches and wrist-worn devices has improved the

quality of measures in heart rate (HR), achieving a median error below 5% in laboratory-based activities [30]. Moreover, smart-watches and wrist-worn devices are expected to *be a boon to mHealth technologies* in physical activity sensing thanks to the recent tools and operating systems which enable application development [31].

Based on this context, in this work, we describe real-time monitoring and evaluation of cardiac rehabilitation sessions (CRSs) at home using wearable wrist-worn devices with heart rate sensors. The highlights of this approach are:

