Aacharya Chetan, Telles Shirley, Sharma Sachin Kumar
Department of Yoga, University of Patanjali, Haridwar, Uttarakhand, India.
Patanjali Research Foundation, Haridwar, Uttarakhand, India.
Int J Yoga. 2024 Jan-Apr;17(1):29-36. doi: 10.4103/ijoy.ijoy_197_23. Epub 2024 May 13.
Volitionally modifying respiration leads to changes in middle cerebral arterial (MCA) blood flow. The effect of changes in breath rate on MCA blood flow has not been reported.
To determine the effect of slow (bumblebee yoga breathing) and fast (high frequency yoga breathing) yoga breathing techniques on MCA blood flow and vagally mediated heart rate variability.
Thirty participants (mean age ± standard deviation, 27.3 ± 4.2 years) were assessed on 2 separate days practicing either high frequency yoga breathing (HFYB, breath frequency 54.2/min) or slow frequency bumblebee yoga breathing (BBYB, breath frequency 3.8/min) in random order to determine the effects of changes in breath frequency on MCA hemodynamics. Assessments included transcranial Doppler sonography, vagally mediated heart rate variability (VmHRV), and respiration.
Both HFYB and BBYB (i) reduced MCA flow velocities, i.e., peak systolic, end diastolic, and mean flow velocities, and (ii) increased MCA pulsatility indices. There was an increase in VmHRV during BBYB based on increased power in high frequency (HF) and low frequency (LF). LF reflects VmHRV for slow breath frequencies. In BBYB the average breath rate was 3.8 breaths/min. In contrast, VmHRV decreased during HFYB (based on reduced HF power; repeated measures analysis of variance, < 0.05, all cases).
Hence, irrespective of the differences in breath frequency, both HFYB and BBYB appear to reduce MCA flow velocities and increase the resistance to blood flow bilaterally, although the VmHRV changed in opposite directions. MCA velocity and pulsatility changes are speculated to be associated with low global neural activity during yoga breathing.
自主调节呼吸会导致大脑中动脉（MCA）血流发生变化。呼吸频率变化对MCA血流的影响尚未见报道。
确定慢速（蜂鸣式瑜伽呼吸）和快速（高频瑜伽呼吸）瑜伽呼吸技巧对MCA血流及迷走神经介导的心率变异性的影响。
30名参与者（平均年龄±标准差，27.3±4.2岁）在2个不同日期接受评估，随机顺序练习高频瑜伽呼吸（HFYB，呼吸频率54.2次/分钟）或慢速蜂鸣式瑜伽呼吸（BBYB，呼吸频率3.8次/分钟），以确定呼吸频率变化对MCA血流动力学的影响。评估包括经颅多普勒超声、迷走神经介导的心率变异性（VmHRV）和呼吸。
HFYB和BBYB均（i）降低了MCA血流速度，即收缩期峰值、舒张期末期和平均血流速度，且（ii）增加了MCA搏动指数。基于高频（HF）和低频（LF）功率增加，BBYB期间VmHRV增加。LF反映慢呼吸频率时的VmHRV。在BBYB中，平均呼吸频率为3.8次/分钟。相比之下，HFYB期间VmHRV降低（基于HF功率降低；重复测量方差分析，P<0.05，所有情况）。
因此，尽管VmHRV呈相反方向变化，但无论呼吸频率存在差异，HFYB和BBYB似乎均会降低MCA血流速度并增加双侧血流阻力。推测MCA速度和搏动性变化与瑜伽呼吸期间较低的整体神经活动有关。
