Heart-focused breathing technique and attitude breathing technique effects on heart rate variability in young healthy subjects.

Heart rate variability (HRV) is controlled mainly by the autonomic nervous system (ANS). The aim of our prospective study was to investigate whether respiratory control influences changes in ANS activity, as reflected by HRV parameters. The analyzed parameters were compared in different sessions and by anxiety or depression score. The root mean square of the mean squared differences of successive NN intervals (rMSSD) and the high frequency power (HF) was lower in anxious females. As compared with rest, in sessions that involved respiratory control, the standard deviation of NN intervals (SDNN) and low frequency power (LF) were higher, whereas the ratio between very low frequency (VLF) and total power (TP) had lower values. LF/HF expressed the highest variation in all analyzed groups, increasing in all situations compared to the rest, without differences between sexes. Normalized coherence (NCoh) peaked during heart-focused breathing and was lowest at rest. NCoh increased during respiratory control in anxious females. The NCoh-LF/HF correlation was observed in all sessions in subjects without anxiety. Respiratory control improved HRV parameters and cardiorespiratory coherence, with significant differences between sexes and individuals with and without anxiety.