Changes in short-term and ultra-short term heart rate, respiratory rate, and time-domain heart rate variability parameters during sympathetic nervous system activity stimulation in elite modern pentathlonists: a pilot study - Gąsior, Jakub S.; Hoffmann, Bartosz; Silva, Luiz Eduardo Virgilio da; Małek, Łukasz; Flatt, Andrew A.; Baranowski, Rafał; Werner, Bożena (Diagnostics, 2020)