Heart rate variability during controlled respiration after endurance training

Abstract

Heart rate variability (HRV) during spontaneous respiration (SR) and controlled respiration 6 (CR6) and 15(CR15) times per minute of 28 highly qualified athletes before and after 7-week endurance training was studied. There were no considerable changes in HR (min.-1) at the beginning of CR6, however, the reaction of HR during CR15 was characterized by noticeable rise: from 71.4(63.9;77.5) to 82.0 (72.2;89.3), р < 0.01; and after endurance training HR (min.-1) it sharply fell to 64.3 (60.8;68.3), р < 0.01 during SR; its reaction to CR6 and CR15 turned to be rather lower, yet, the reaction to CR15 with insignificant degree of probability still exceeded the one during SR та CR6. The latter may indicate a more adequate HR response to hyperventilation, which occurs when the tests are performed. HRV indices before and after training during CR6 do not differ between one another. The increase in endurance was reflected in response of HF (ms2) of HRV that was not practically influenced by controlled respiration. That differed them from the data at the beginning of the training where there was significant decrease in HF (ms2) to 967.2(479.6;2540.2) during CR15 in comparison with SR (2035.7(756.3;6037.3)) and CR6 (2560.9(1361.6; 5098.0)) (р<0.05). There was significant decrease in LF/HF (р<0.01) during CB15 in response to increase in endurance. VLF (ms2) indices during SR at the beginning and in the end of tests do not differ; and the reaction to CR6 does not lead to changes in VLF (ms2). The reaction to CR15 at the beginning does not differ from SR and CR6 indices. At the end of the training there was a significant decrease in VLF (ms2) during CR15 348.0(196.0;590.5) comparing to both SR 765.2(299.3;1108.9) and CR6 637.6(470.9;930.3), р<0.01.