Device-guided slow breathing reduces blood pressure and sympathetic activity in young normotensive individuals of both sexes.

Abstract

Slow breathing (SLOWB) is recommended for use as an adjuvant treatment for hypertension. However, the extent to which blood pressure (BP) responses to SLOWB differ between men and women are not well-established. Therefore, we tested the hypothesis that an acute bout of SLOWB would induce larger decreases in BP in males than females, given that males typically have higher resting BP. We also examined autonomic contributors to reduced BP during SLOWB, that is, muscle sympathetic nerve activity (MSNA), and spontaneous cardiovagal (sequence method) and vascular sympathetic baroreflex sensitivity (BRS). We tested normotensive females (n=10, age: 22±2y, BMI: 22±2kg/m2) and males (n=12, 23±3y, 26±4kg/m2). Subjects were tested at baseline and during the last 5-min of a 15-min RESPeRATE-guided SLOWB session. Overall, SLOWB reduced systolic BP (SBP) by 3.2±0.8 mmHg (main effect, p<.01). Females had lower SBP (main effect, p=.02); we observed no interaction between sex and SLOWB. SLOWB also reduced MSNA burst incidence by -5.0±1.4 bursts/100hb (main effect, p<.01). Although females tended to have lower burst incidence (main effect, p=.1), there was no interaction between sex and SLOWB. Cardiovagal BRS improved during SLOWB (21.0 vs 36.0 ms/mmHg, p=.03) with no effect of sex. Despite lower overall BP in females, our data support a lack of basement effect on SLOWB-induced reductions in BP, as SLOWB was equally effective in reducing BP in males and females. Our findings support the efficacy of the RESPeRATE device for reducing BP in both sexes, even in young, normotensive individuals.