Funding for this research was provided by:
Ministerstwo Nauki i Szkolnictwa Wyższego (DS-258 project of Jozef Pilsudski University of Physical Education)
Received: 19 May 2020
Accepted: 12 October 2020
First Online: 7 November 2020
Ethics approval and consent to participate
: The study was accepted by the Senate Research Ethics Committee at University of Physical Education in Warsaw (SKE 01–03/2016). The protocol was explained to all participants. The legal guardians of the participants gave their written consent to participate in the study. The patients’ data were regarded as confidential.
: We confirm that the informed consent form has been signed by guardians of the participants.
: The authors declare that they have no competing interests.