The influence of breathing exercises on the heart rate variability parameters of female medical students

Abstract

We studied the influence of breathing exercises (BE) with an imposed rhythm on the dynamics of heart rate variability (HRV) parameters in order to study the nature of adaptive processes in the body of girls with different initial levels of total HRV. Heart rate, time indicators: SDNN, mNN, RMSSD, pNN50 - and spectral parameters: TP, HF and HFnu, LF and LFnu, LF/HF - as well as IVR and IN indices were evaluated. According to the level of SDNN, individuals with conditionally low and conditionally high levels of total HRV were identified - groups LV (40 (31; 47) ms) and HV (64 (58; 70) ms). At rest, HRV parameters in HV-girls were significantly higher than in the LV-subgroup. After BE, a significant increase in SDNN and TP was observed in the LV-subgroup, against the background of a decrease in HF and HFnu and an increase in LF and LFnu, and the LF/HF ratio after BE increased by 80%. In HV-girls after BE, an increase of 6% in heart rate was recorded, but not in total HRV parameters: a decrease in HF and HFnu was compensated by an increase in LFnu, as a result, the LF/HF ratio increased significantly by almost 1.5 times compared to the rest level. In LV-girls, the indicators of autonomic balance index (AVR) and stress-index (SI) were higher by 2.6–2.7 than in the HV-subgroup. After BE, a decrease of 24 and 19% in the parameters of AVR and SI was observed in the LV, but not in the HV-subgroup. Thus, the adaptation of the work of the heart to BE occurred in a similar way in LV- and HV-individuals, however, it differed in different adaptive costs of such an effort for LV- and HV-subjects.