Adaptive reactions of heart rate regulation for functional tests with breath holding

Synchronization of biorhythms in living organisms is of particular interest to researchers from the standpoint of adaptation theory. The purpose of the work was to identify the characteristics of the response of regulatory influences on the heart rhythm during tests with arbitrary breath holding during inhalation and exhalation. Materials and methods. The study involved 21 students aged 20.64 ± 1.14 years, body weight 67.19 ± 12.98 kg, height 172.29 ± 7.63 cm, of which 9 were boys and 12 girls. The study involved five-time sequential recording of ECG made by “Varicard 3.0” hardware - software complex in the subject’s sitting position after a five-minute rest: 1 – initial state; 2 – voluntary holding of breath while inhaling; 3 – state of rest; 4 – voluntary breath holding while exhaling; 5 – state of rest. Mathematical analysis of the heart rhythm was carried out with the use of “Varicard 3.0” hardware and software complex; the analysis took into account statistical parameters of the heart rhythm (HR; Meаn; SDNN; CV; RMSSD; pNN50; Mo; AMo50,; SI), indicators of spectral frequency analysis (TP ; HF; LF; VLF; LF/HF; VLF/HF; IC). Results. HRV decreased during the breath holding period, while at rest it increased in all types of groups (according to Shlyk N.I., 2009). Differences: in type I group after a breath-hold test during the rest period, eutonia was observed according to spectral analysis (HF = LF). Statistical and time analysis data in this group demonstrated an increase in the contribution of the parasympathetic component to HRV (RMSSD, pNN50, SDNN, CV), creating the prerequisites for increased heart rate variability. In type II group, after breath-holding tests, a slight decrease in sympathetic activity was observed. At the same time, a tense pattern of autonomic regulation was observed during the exhalation breath-hold test, which may indicate a reduced functional state of the regulatory systems. Type III group was characterized by a sharp increase in sympathetic activation in the test with breath holding during inhalation, followed by a soft correction during breath holding during exhalation, which can be regarded as an adequate response of the body to the load. At rest after the test, the regulation pattern returned to the original state with a moderate predominance of parasympathetic activity and with a more favorable level of heart rate variability for the body. Conclusion. Adaptive reactions of the HRV are manifested by the increase in sympathetic activation, which is subsequently replaced by a compensatory activation of the parasympathetic division of the ANS during normal breathing. Despite the unidirectional nature, the severity of the reactions varies depending on the group ranking adopted by us.