The effects of yoga and quiet rest on subjective levels of anxiety and physiological correlates: a 2-way crossover randomized trial

Abstract

Background: Rest or acute exercise can decrease state anxiety, with some evidence showing exercise to prevent laboratory-induced elevations in anxiety. No study has examined whether yoga provides short-term protection against laboratory-induced anxiety. The aim of this study was to examine the effectiveness of an acute YogaFit session on state anxiety and measures of heart rate variability (HRV) to determine whether yoga provides short-term protection against emotional picture stimuli.

Methods: A randomized repeated-measures crossover clinical trial was performed. Forty healthy, female college students completed a 30 min session of YogaFit and a time-matched seated rest condition on separate days. After each condition, participants viewed 30 min of emotional picture stimuli. State anxiety, heart rate and time-domain and frequency-domain measures of HRV were assessed baseline, post- condition, and post-exposure to emotional stimuli. Data were analysed using a condition x time (2 × 3) repeated-measures ANOVA.

Results: Post-hoc comparisons indicate the following: (1) state anxiety significantly decreased from baseline to post-condition for both yoga and rest (p = 0.001) but returned to baseline values following exposure to emotional stimuli (p < 0.001) for both conditions; (2) heart rate decreased post-condition to post-exposure (p = 0.020) and baseline to post-exposure (p = 0.033) for both conditions; (3) time-domain measure of HRV showed a significant increase in HRV between baseline and post-condition (p = 0 .019), post-condition and post-exposure (p = 0 .007), and between baseline and post-exposure (p < 0.001).

Conclusions: Both YogaFit and seated rest were effective at acutely reducing state anxiety post-condition, but not at preventing an induced anxiety response post-exposure. Following exposure to the emotionally stimulating pictures, there was a shift from the high frequency-domain to the low frequency-domain and an increase in the time-domain measure of HRV for both the YogaFit and the quiet rest condition.

Trial registration: Retrospectively registered 2/16/2018, clinicaltrials.gov, Identifier: NCT03458702 .

Keywords: Affect; Autonomic function; Emotion; Heart rate variability; Quiet rest.

Conflict of interest statement

Ethics approval and consent to participate

All procedures performed were in accordance with the ethical standards of the 1964 Helsinki declaration and its later amendments and with the Texas Tech University Human Protection Program. All procedures performed in this study were approved through the Institutional Review Board processes at Texas Tech University and all participants signed the consent form approved by the Institutional Review Board before pre-screening.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1

The Consort Flow Diagram

Fig. 2

(i) State anxiety scores at baseline, post-condition, and post-exposure for the yoga and rest conditions. No significant difference between the yoga and rest conditions. (ii) Combined state anxiety scores at baseline, post-condition and post-exposure. Significant decrease, **p = 0.001, between baseline and post-condition and significant increase, ***p < 0 .001, between post-condition and post-exposure. (iii) Heart rate (HR) at baseline, post-condition and post-exposure for the yoga and rest conditions. Significant interaction between condition & time, ***p < 0 .001. (iv) Combined HR for both conditions at baseline, post-condition and post-exposure. Significant decrease between post-condition and post-exposure, *p = 0 .020 and between baseline and post-exposure, * p = 0 .033. Note symbols or abbreviations on graphs: N.S.- not significant, *p < 0.05, **p = 0 .001, and ***p < 0 .001. Error bars = SEM

Fig. 3

(i) Root Mean Square of Successive Differences in RR Intervals (RMSSD) at baseline, post-condition and post-exposure for the yoga and rest conditions. Significant condition x time interaction, * p = 0 .042. (ii) Combined RMSSD at baseline, post-condition and post-exposure. Significant increase between baseline and post-condition (p = 0 .019), post-condition and post-exposure (*p = 0 .007), and between baseline and post-exposure,*** p < 0 .001. (iii) Low-frequency power in normalized units (LFN) at baseline, post-condition and post-exposure for the yoga and rest conditions. No significant difference between the yoga and rest conditions. (iv) Combined LFN at baseline, post-condition and post-exposure. Significant increase,* p = 0 .008, between post-condition and post-exposure. Note symbols or abbreviations on graphs: N.S.- not significant, *p < 0 .05, **p = 0 .001, and ***p < 0 .001. Error bars = SEM