2.2.4. Evaluating the Cardiac Rehabilitation Sessions

Previous sections describe real-time monitoring of heart rate stream within a wearable device based on fuzzy logic. Once the rehabilitation session has been finished by the patient, evaluating the further session at the end to provide a feedback is fairly intuitive.

Based on the degree of a fuzzy term *V<sup>r</sup>* and its temporal window *T<sup>r</sup>* , we compute an accumulative degree in the complete data stream *S* ¯*hr* by Equation (9).

$$\begin{aligned} low(S\_{\hat{l}\hat{r}}) &= \sum low \cup T\_{low}(l\bar{r}\_i) \\ node(s\_{\hat{l}\hat{r}}) &= \sum adequate \cup T\_{adaptive}(l\bar{r}\_i) \\ high(S\_{\hat{l}\hat{r}}) &= \sum light \cup T\_{high}(l\bar{r}\_i) \end{aligned} \tag{9}$$

Under this approach, the accumulative degrees are calculated as the average degree of the terms in the heart rate stream ahead, providing upright and interpretable analytical data for the session. For example, the accumulative value of the term *adequate* has been used to fill a 4-star scale in the mobile application of this work in order to provide an evaluation of the rehabilitation session for the patient.
