**5. Conclusions**

The adolescents participating in this study show medium/high levels of health-related physical fitness, with the girls obtaining slightly higher results. The participants' adherence to MD is classified as medium/high since 60% of the participants are in the middle level and almost 25% are in the high level.

The results found showed significant correlations between MD and the endurance test in the girls and the boys. A high adherence to MD also correlates with better results in endurance and agility speed tests in the boys.

This research shows the importance of developing and maintaining an adequate physical fitness and, together with a medium or high level of adherence to MD, it culminates in a better health-related quality of life in adolescents. Both the boys and the girls that showed a medium and high adherence to MD had the highest scores in the health-related physical fitness tests [50].

These results agree with those obtained in the Spanish and Portuguese adolescent population, since a high adherence to MD is related to higher levels of perceived quality of life, within which a good level of physical fitness is found. Moreover, a high adherence to MD is associated with a significant improvement in physical health and with lower obesity, a fact that is consistent with recent results [42].

Finally, this research appeals for the development of public health programmes, awareness campaigns, and the creation of PA and healthy eating environments for children and adolescents [64]. Not only an adequate diet is sufficient [65], but a minimum of daily physical activity practice is necessary to avoid the appearance of diseases derived from a sedentary lifestyle [40] and consequently, a poor quality of life [66].

**Author Contributions:** T.G., F.R. and A.J.S.-O. designed the study. P.G.-L. and T.G. collected the data. R.D. realised statistical work. P.G.-L., R.D., and A.J.S.-O. interpreted data. P.G.-L., R.D., and A.J.S.-O. drafted the manuscript. All the authors contributed to developing, editing, and approving the final version of the paper.

**Funding:** This work was supported by the fifth Research Programme 2013-2016 (PPI2015-IV.5 / PP2016-EBRV) of the University of Seville, Seville, Spain and the University of Iceland Research Fund, Reykjavik, Iceland.

**Acknowledgments:** The authors thank the participants and schools in the study.

**Conflicts of Interest:** The authors declare no conflicts of interest.
