Yoga Nidra relaxation produced favorable changes in heart rate variability, with no significant differences whether performed alone or preceded by a bout of Hatha yoga.
RCT (n=20)
counter-balanced
No
Does Yoga Nidra relaxation preceded by Hatha yoga improve acute heart rate variability compared to Yoga Nidra relaxation alone in adults?
Yoga Nidra relaxation produces favorable acute changes in heart rate variability, shifting autonomic balance toward parasympathetic dominance, regardless of whether it is preceded by Hatha yoga.
OBJECTIVE: The measurement of heart rate variability (HRV) is often applied as an index of autonomic nervous system (ANS) balance and, therefore, myocardial stability. Previous studies have suggested that relaxation or mind-body exercise can influence ANS balance positively as measured by HRV but may act via different mechanisms. No studies, to the authors' knowledge, have examined the acute response in HRV to interventions combining relaxation and mind-body exercise. The objective of this study was to compare the acute HRV responses to Yoga Nidra relaxation alone versus Yoga Nidra relaxation preceded by Hatha yoga. DESIGN: This was a randomized counter-balanced trial. SETTING: The trial was conducted in a university exercise physiology laboratory. SUBJECTS: Subjects included 20 women and men (29.15±6.98 years of age, with a range of 18-47 years). INTERVENTIONS: Participants completed a yoga plus relaxation (YR) session and a relaxation only (R) session. RESULTS: The YR condition produced significant changes from baseline in heart rate (HR; beats per minute bpm, p<0.001) and indices of HRV: R-R (ms, p<0.001), pNN50 (%, p=0.009), low frequency (LF; %, p=0.008) and high frequency (HF; %, p=0.035). The R condition produced significant changes from baseline in heart rate (bpm, p<0.001) as well as indices of HRV: R-R (ms, p<0.001), HF (ms(2), p=0.004), LF (%, p=0.005), HF (%, p=0.008) and LF:HF ratio (%, p=0.008). There were no significant differences between conditions at baseline nor for the changes from baseline for any of the variables. CONCLUSIONS: These changes demonstrate a favorable shift in autonomic balance to the parasympathetic branch of the ANS for both conditions, and that Yoga Nidra relaxation produces favorable changes in measures of HRV whether alone or preceded by a bout of Hatha yoga.
Markil et al. (2012) reported an RCT. Yoga Nidra relaxation preceded by Hatha yoga vs. Yoga Nidra relaxation alone was evaluated on Acute heart rate variability (HRV) responses. Yoga Nidra relaxation produced favorable changes in heart rate variability, with no significant differences whether performed alone or preceded by a bout of Hatha yoga.