Department of Neuroscience, Roehampton University, London, UK.
Evid Based Complement Alternat Med. 2013;2013:743504. doi: 10.1155/2013/743504. Epub 2013 Apr 23.
Slow breathing increases cardiac-vagal baroreflex sensitivity (BRS), improves oxygen saturation, lowers blood pressure, and reduces anxiety. Within the yoga tradition slow breathing is often paired with a contraction of the glottis muscles. This resistance breath "ujjayi" is performed at various rates and ratios of inspiration/expiration. To test whether ujjayi had additional positive effects to slow breathing, we compared BRS and ventilatory control under different breathing patterns (equal/unequal inspiration/expiration at 6 breath/min, with/without ujjayi), in 17 yoga-naive young healthy participants. BRS increased with slow breathing techniques with or without expiratory ujjayi (P < 0.05 or higher) except with inspiratory + expiratory ujjayi. The maximal increase in BRS and decrease in blood pressure were found in slow breathing with equal inspiration and expiration. This corresponded with a significant improvement in oxygen saturation without increase in heart rate and ventilation. Ujjayi showed similar increase in oxygen saturation but slightly lesser improvement in baroreflex sensitivity with no change in blood pressure. The slow breathing with equal inspiration and expiration seems the best technique for improving baroreflex sensitivity in yoga-naive subjects. The effects of ujjayi seems dependent on increased intrathoracic pressure that requires greater effort than normal slow breathing.
缓慢呼吸可增加心脏迷走神经血压反射敏感性（BRS），提高血氧饱和度，降低血压，并减轻焦虑。在瑜伽传统中，缓慢呼吸通常与声门肌肉的收缩相结合。这种阻力呼吸“乌加依”以各种吸气/呼气的速率和比例进行。为了测试乌加依是否对缓慢呼吸有额外的积极影响，我们比较了不同呼吸模式（6 次/分钟的等呼和不等呼，有/无乌加依）下的 BRS 和通气控制，共有 17 名未经瑜伽训练的年轻健康参与者参与。除了吸气+呼气乌加依外，无论是否伴有呼气乌加依，缓慢呼吸技术都能提高 BRS（P<0.05 或更高）（P<0.05 或更高）。BRS 的最大增加和血压的降低出现在等呼和等呼的缓慢呼吸中。这与血氧饱和度的显著改善相对应，而心率和通气没有增加。乌加依在血氧饱和度上表现出相似的增加，但在血压没有变化的情况下，对血压反射敏感性的改善稍小。对于未经瑜伽训练的受试者，等呼和等呼的缓慢呼吸似乎是提高血压反射敏感性的最佳技术。乌加依的作用似乎取决于增加的胸腔内压力，这需要比正常缓慢呼吸更大的努力。
