Funding for this research was provided by:
Univerzita Karlova v Praze (UNCE/HUM/032)
Received: 29 August 2020
Accepted: 12 March 2021
First Online: 30 March 2021
: The study protocol was approved by the Bioethics Committee for Scientific Research, at the Academy of Physical Education in Katowice, Poland, (3/2019) according to the ethical standards ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. All participants gave their informed consent prior to their inclusion in the study.
: Not applicable.
: The authors declare that they have no conflict of interest.