Materials and methods
The study was approved by the Senate Ethics
Committee of the Josef Pilsudski University of Physical
Education in Warsaw. All participants were informed
about the aim and course of the study, and
about the possibility of immediate resignation without
giving the cause. All subjects gave their written consent.
Fourteen Second Division female volleyball
players from the AZS AWF Warszawa (age 21.8
± 1.6 years, body height 177.0 ± 6.0 cm, body mass