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.