Effect of 4 Weeks Resonance Frequency Breathing on Glucose Metabolism and Autonomic Tone in Healthy Adults

Abstract

Backgruound: The autonomic nervous system plays a crucial role in the brain's communication with metabolically important peripheral organs, modulating insulin sensitivity and secretion. Increased sympathetic tone is a common feature in prediabetes and diabetes. The parasympathetic nervous system activity might be improvable through resonance frequency breathing (RFB) with heart rate variability biofeedback (HRV-BF) training.

Methods: We here investigated the effect of a 4-week mobile RFB-HRV-BF intervention on glucose metabolism and HRV of 30 healthy adults (17 females; mean age 25.77±3.64 years; mean body mass index 22.65±2.95 kg/m2). Before and after the intervention, glucose metabolism was assessed by 75 g oral glucose tolerance tests (with blood sampling every 30 minutes over 2 hours) and HRV was measured through electrocardiography.

Results: RFB-HRV-BF training did not influence glucose metabolism in healthy adults but reduced fasting as well as 2-hour-postload glucose in participants categorized as more insulin resistant before the intervention. In addition, RFB-HRV-BF training was associated with an increase in the time and frequency domain HRV parameters standard deviation of all NN-intervals, root mean square successive differences, HRV high-frequency and HRV low-frequency after 4 weeks of intervention.

Conclusion: Our findings introduce RFB-HRV-BF training as an effective tool to modulate the autonomic nervous system with a shift towards the parasympathetic tone. Along with the observed decrease in glycemia in those with lower insulin sensitivity, RFB-HRV-BF training emerges as a promising non-pharmacological approach to improve glucose metabolism which has to be further investigated in prediabetes and diabetes.

Keywords: Blood glucose; Breathing exercises; Parasympathetic nervous system; Vagus nerve; Young adult.

Fig. 1.

Study outline. (A) Consolidated Standards of Reporting Trials (CONSORT) flow diagram. (B) Study design of resonance frequency breathing with heart rate variability biofeedback intervention.

Fig. 2.

Changes in autonomic function showing in heart rate variability-parameters standard deviation of all NN-intervals (SDNN) and root mean square successive differences (RMSSD) during baseline and 4 weeks of intervention with resonance frequency breathing with heart rate variability biofeedback in healthy adults (n=30). Data presented as mean±standard deviation. ln, logarithm naturalis+1; ms, millisecond; RSB, resting sitting position with spontaneous breathing; W1, intervention week 1; W2, intervention week 2; W3, intervention week 3; W4, intervention week 4. ^aP≤0.001, significant difference between resting sitting position with spontaneous breathing and intervention week.

Fig. 3.

Box-and-Whisker plots of heart rate and heart rate variability (HRV)-parameters before and after 4 weeks intervention of resonance frequency breathing with heart rate variability biofeedback in healthy adults (n=30). Data presented as mean±standard deviation. ln, logarithm naturalis+1; ms, millisecond; SDNN, standard deviation of all NN-intervals; RMSSD, root mean square successive differences; LF, power in low-frequency range 0.04–0.15 Hz; HF, power in high-frequency range 0.15–0.4 Hz. ^aP≤0.05, significant difference between pre- and post-intervention value, ^bP≤0.01, significant difference between pre- and post-intervention value.

Fig. 4.

Changes in (A) blood glucose, (B) insulin, (C) C-peptide, and (D) cortisol after oral glucose tolerance test before and after 4 weeks of intervention with resonance frequency breathing with heart rate variability biofeedback in healthy adults (n=30). Data presented as mean±standard deviation.