Funding for this research was provided by:
Ministerstwo Nauki i Szkolnictwa Wyższego (N404 075337)
Received: 11 July 2019
Accepted: 9 November 2019
First Online: 19 November 2019
Compliance with ethical standards
: The authors have no conflict of interest to declare.
: The study protocol was approved (18 February 2009) by the Senate Committee for Scientific Research Ethics at University School of Physical Education in Wrocław. The study was conducted in accordance with the recommendations of the Declaration of Helsinki. All persons gave written consent to participate in the study.
: Informed consent was obtained from all individual participants included in the study.