Received: 10 December 2019
Accepted: 13 March 2020
First Online: 2 April 2020
Ethics approval and consent to participate
: Children’s participation in the study was subject to research participation consent given by their parents or guardians. Information regarding the objectives and content of the study were presented using an information booklet and telephone calls were made to communicate additional information to all parents and guardians. Ethical approval for the study (reference number 53/2012) was granted by the Institutional Research Ethics Committee, Faculty of Physical Culture, Palacký University Olomouc. The study design followed the ethical principles of the 1964 Declaration of Helsinki and their official amendments.
: Not applicable.
: The authors declare that they have no competing interests.