A number of studies have documented the effects of singing on cardio-respiratory health. For example, one study reports that choir group singing improves heart rate variability, which is a significant predictor of cardiovascular health. Notably, decreased heart rate variability is linked to hypertension, heart failure and work stress, while increased heart rate variability indicates a healthy balance between the sympathetic and the parasympathetic systems.
Toning is one form of singing that involves the vocalization of open vowel sounds; it can be performed alone and without training. The present study seeks to examine the effects of toning on the cardio-respiratory system to determine whether similar benefits can be reproduced. A significant finding in this study is the reduced breathing frequency characterized by deeper breathing, moderately increased minute ventilation (i.e., inhaling and exhaling), and a robust increase in tidal volume (i.e., amount of carbon dioxide that leaves the body). Those results reflect an optimum cardio-respiratory pattern indicative of a relaxed state.
More specifically, the respiratory pattern generated during toning coincides with slow-deep breathing, which is a breathing manipulation that is used in meditation. Slow-deep breathing is associated with increased subjective feelings of relaxation and decreased anxiety. More importantly, those effects appear to be accessible to anyone as this self-regulatory breathing dynamic can emerge spontaneously, without prior training.
Reference:
Bernardi, N.F., Snow, S., Peretz, I., Perez, H.D., Sabet-Kassouf, N., & Lehmann, A. (2017). Cardiorespiratory optimization during improvised singing and toning. Scientific Reports, 7.