Received: 18 April 2019
Accepted: 19 November 2019
First Online: 9 December 2019
Ethics Approval and Consent to Participate
: Informed consent of all the participants in the study was obtained. The protocol of the study was approved by the Committee of Institutional Ethics (University of Valladolid) and agreed with the Declaration of Helsinki for Human Research of 1974 (last modified in 2000).
: Not applicable.
: The authors, David Delgado, Juan Orriols, and Carlos Saborido, declare that they have no competing interests.