“…Consequently, a comparison of HRV corresponding to different HR may be biased ( Sacha and Grzeszczak, 2001 ; Nieminen et al, 2007 ; Sacha and Pluta, 2008 ). Mathematical methods removing the HRV dependence on HR (i.e., the HRV correction for prevailing HR) ( Hayano et al, 1990 , 1991 ; Sacha and Grzeszczak, 2001 ; Sacha and Pluta, 2008 ; Sacha et al, 2013b , c ; Monfredi et al, 2014 ; Estévez-Báez et al, 2015 ; van Roon et al, 2016 ) should allow to draw objective conclusions when comparing HRV associated with various HR ( Sacha, 2013 , 2014a , b , c ; Monfredi et al, 2014 ; Billman et al, 2015 ). So far, only one study dealing with normal ranges of HRV employed the HRV correction for HR, however, authors presented normal values only for two time domain HRV markers derived from 10-s ECGs ( van den Berg et al, 2018 ).…”