Slow breathing has unequal effects on prehypertensives from different ethnic/racial groups

Abstract

In this study, we investigated whether slow breathing reduces blood pressure (BP) in individuals at risk of developing hypertension and if slow breathing has the same effect on Caucasian, African, Arabian and Indian subjects. Also we assessed ethnic/racial differences in low frequency (LF) power and high frequency (HF) power of heart rate variability (HRV). A total of 40 Caucasian men from Ukraine, 39 West African men mostly from Nigeria, 38 Arabic men from Palestine and Israel and 41 South Asian men from India studying at V. N. Karazin Kharkiv National University were recruited in this study. The subjects were further classified into normotensive and prehypertensive groups. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), LF power, HF power of HRV were recorded at spontaneous breathing and at paced breathing of 10 and 6 breaths per minute. It was found that slowing respiratory rate to 6 breaths per minute reduces SBP in prehypertensive Caucasians, Arabs, Indians, but not in Africans. At 6 breaths per minute, natural logarithm of HF (LnHF) power indicating cardiovagal activity was less in normotensive Arabs than in Caucasians, Africans and Indians possibly suggesting an increased risk of developing hypertension; while prehypertensive Africans demonstrated LnHF power higher than Arabs and Indians. When covariates like age and body mass index (BMI) were considered, prehypertensive Africans demonstrated LnHF power higher than in Caucasians also. It is suggested that in prehypertensive Africans the control of autonomic nervous activity is reset to a higher level of parasympathetic outflow.

Effect of slow breathing on the blood pressure and the Valsalva ration in prehypertensive Indian students

“…The current study, showing an increase in the Valsalva ratio and a decrease in the systolic blood pressure in prehypertensive subjects during slow breathing, extends our previous observations of the effects of slow breathing on the blood pressure and HRV (Shekh, 2017).…”

“…We proceeded from the assumption that LF HRV power represents sympathoinhibitory arm of baroreflex (Shekh, 2018). In congruence with previous reports, in the current study the LnLF power was increased during slow breathing in both groups (Pitzalis et al, 1998;Wang, 2013;Shekh, 2017). It is proposed that this evaluation of LnLF power represents an increase in inhibitory influences exerted on the sympathetic nervous system.…”

“…Unlike the SBP, the heart rate and the DBP did not drop in any group during slow breathing in agreement with most of previous reports (Bernardi et al, 2002;Joseph et al, 2005;Raupach et al, 2008;Shekh, 2017). Even more, the HR was significantly increased in both groups.…”

“…In congruence with previous researches, in the current study the lowering of the respiratory rate to 6 breaths/min led to a significant reduction of systolic blood pressure in the prehypertensive group. The decrease of the SBP by means of the respiratory modulation was shown in patients with chronic heart failure (Bernardi et al, 2002), essential hypertension (Joseph et al, 2005), in hypoxic patients with chronic obstructive pulmonary disease (COPD) (Raupach et al, 2008), and in young men from different ethnic/racial populations developing hypertension (Shekh, 2017). Table 3.…”