Cardiorespiratory optimization during improvised singing and toning

Abstract

We evaluated the effect of different forms of singing on cardiorespiratory physiology, and we aimed at disentangling the role of breathing from that of vocal production. Cardiorespiratory recordings were obtained from 20 healthy adults at rest and during: a) singing of familiar slow songs as in the standard form of Western culture; b) improvised vocalization of free vowel sounds, known as toning. To disentangle the role of breathing from that of vocal production, we compared the vocal conditions with matched breathing-only conditions. Toning significantly improved heart rate variability, ventilatory efficiency and slowed respiration to almost exactly six breaths per minute (p < 0.001), a pattern that is known to optimize cardiovascular function and that coincides with the period of endogenous circulatory rhythms. Singing songs also positively impacted cardiorespiratory function, although to a lesser extent. The breathing pattern imposed upon participants in the absence of vocal production was sufficient to generate the physiological benefits. The effects of toning are similar to what has been previously described as a result of engaging in formal breathing exercises. Toning and singing may offer an engaging and cost effective tool to trigger beneficial respiratory patterns and the related cardiovascular benefits.

Figure 1

Respiratory data. Respiration slows down relative to baseline during song singing and even more so during toning, reaching ~6 breaths/minute (0.1 Hz). Singing is accompanied by an increase in both tidal volume and minute ventilation relative to baseline. Toning accentuate even further the increase in tidal volume while only moderately increasing ventilation compared to baseline, suggesting respiratory optimization. * Statistically significant difference compared to baseline; # significant difference between the vocal and the matched paced breathing condition; Ω significant difference between song singing and toning. ^{*, #, Ω}p < 0.05; ^{**, ##, ΩΩ}p < 0.01; ^{***, ###, ΩΩΩ}p < 0.001. Bars indicate mean ± SEM.

Figure 2

Cardiovascular data. Heart rate increases during vocal production, similarly for song singing and toning. Overall heart rate variability (SDNN) increases in all conditions relative to baseline, significantly more during toning compared to singing, and significantly more during silent breathing compared to the matched vocal conditions. For LF and HF heart rate variability see text. All conventions as in Fig. 1.