1. Faculty of Physical Education, University School of Physical Education, Wrocław, Poland;
2. Faculty of Physiotherapy, University School of Physical Education, Wrocław, Poland;
3. Department of Anthropology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland;
4. Department of Kinesiology and Health Education, University of Texas, Austin, TX, USA