# Toward a Symbolic AI Approach to the WHO/ACSM Physical Activity & Sedentary Behavior Guidelines
## 3 Results
### Evaluation of HeLiFit and HeLiFit-Rule  
**Validation. ** We checked the logical consistency of classes, object properties and datatype properties inferences [55]. To achieve this, we applied directly the HermiT reasoner [55] (version 1.4.3) that is made available through Protege. The results proved that _HeLiFit_ if free of logical inconsistencies or other errors that can be detected by the reasoner. **Evaluation. ** After validating the ontology for consistency, we proceeded with the evaluation of its appropriateness and usefulness with respect to the use cases of _Frailty and Sedentary Behaviour_ and _Mental Health and Well-being_, in application scenario concerned with _Digital Coaching in the Healthcare Domain_. As a first step, the _HeLiFit_ ontology was reviewed, during several sessions, by domain experts from the GATEKEEPER consortium, including Sport Medical Doctors and Mental Health Specialists, over the course of several sessions. During these sessions, the design rationale of the ontology, concepts and properties were explained, along with how to use _HeLiFit_ to express the set of rules formalizing the recommendations. The domain experts found that the model is indeed consistent with a doctor's approach, when this provides advice to patients aiming to boost physical activity and reduce sedentary behavior. To evaluate the _usefulness_ of _HeLiFit-Rule_, the domain expert proposed several standard patient profiles, to be assessed using _HeLiFit-Rule_ as a decision support tool. Specifically, we constructed four exemplar user profiles, named _Sedentary_ (Figure 12), _Moderate_ (Figure 13), _Vigorous_ (Figure 14) and _High_ (Figure 15). Below we show the results obtained by applying our set of rules to these profiles. In particular, for the _Sedentary_ profile, we show in Figure 12 that [PERSON], 54 years old, over a time window of a week, performed 1.5 h of walking (aerobic activities). Figure 12: Sedentary profile. \begin{table}
\begin{tabular}{l c l c} \hline \hline  & \multicolumn{2}{c}{**Metrics**} \\ \hline Axiom & 770 & Logical axiom count & 308 \\ Declaration axiom count & 289 & Class count & 250 \\ Object property count & 12 & Data property count & 5 \\ Individual count & 23 & Annotation property count & 1 \\ DL expressivity & ALHI(D) & SubClassOf & 246 \\ SubObjectPropertyOf & 2 & InverseObjectPropertiesf & 3 \\ ObjectPropertyDomain & 10 & ObjectPropertyRange & 10 \\ SubDataPropertyOf & 2 & DataPropertyDomain & 6 \\ DataPropertyRange & 6 & ClassAssertion & 23 \\ AnnotationAssertion & 173 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: HeLiFit metrics. Although she is compliant with the _duration_ parameter, as 1.5 h is greater than the required 70 min, when it comes to _intensity_, this activity corresponds to a total of 4700 steps, which implies a very low speed. In this case, rule 5 (see Appendix A) is activated to detect this behavior and to classify [PERSON] as _Sedentary_. In addition, [PERSON] did not perform any muscle strengthening activity, hence, rule 17 (see Appendix A) is also triggered. As a result, the following recommendations are issued as reported in the output's section of Figure 12.  
For _moderate_ behavior, as illustrated in Figure 13, we consider [PERSON], who is 40 years old and has performed, over a time window of one week, 80 min of aerobic physical activity. This level of activity is compliant with the WHO guidelines and, as a result, rule 13 is activated to issue a congratulatory message to [PERSON]. However, he has performed muscle-strengthening only once, instead of the required two sessions a week, and therefore rule 15 is activated, which issues the following recommendations as reported in the output's section of Figure 13. For the _Vigorous_ profile, we consider [PERSON] (Figure 14), who is 25 years old. He has performed 105 min of vigorous aerobic physical activity, which is compliant with the WHO requirements. For this reason, a congratulatory message is issued by rule 12.