Immediate heart rate variability parameter changes, provoked by different relaxation techniques, decreased after 6-month yoga intervention

It is known that yoga practice recalls parasympathetic activity. There are studies analyzing yoga and heart rate variability (HRV) relation, although there is still lack of data, especially when studying how long acute yoga effects can remain. The purpose of the study was to compare HRV parameter changes while shifting from one yoga relaxation technique to another after 2, 4 and 6 months of regular yoga practice. The research team designed an experimental study that used yoga practice as intervention. The study took place at the Lithuanian University of Health Sciences in Kaunas, Lithuania. Participants were 35 women who were practicing yoga for more than 6 months. Participants had yoga practice for 6 months 2 times per week. Changes were measured when shifting from rest (Pr) to yoga nidra (Yn), then to ujjayi breathing (Ub) and rest (Fr) for 5 min after 2, 4 and 6 months of yoga practice. Electrocardiogram heart rate variability parameters RR, LF, HF and LF/HF changes were measured. Results suggest that practicing yoga for six months can influence HRV factors, nevertheless, after four months this impact is becoming less significant. Moreover, practicing breathing technique ujjayi has a bigger impact on HRV than yoga nidra relaxation.