Acute cardiovascular responses to slow and deep breathing in normotensive men and women

Slow and deep breathing is recommended as an effective treatment for hypertension using the RESPeRATE device. However, the acute cardiovascular responses to slow and deep breathing, including the potential mechanisms underlying its antihypertensive effect are not fully understood. This study characterised the acute cardiovascular responses to three differing, 10-minute bouts of slow and deep breathing. Twelve participants completed four conditions in a randomised order: 1) RESPeRATE, 2) dynamic slow and deep breathing frequency, 3) fixed breathing frequency of 6 breaths.min-1, 4) spontaneous breathing. Comparing mean values for all variables obscured the cardiovascular perturbations created by slow and deep breathing. However, intra- and inter-breath differences (minimum vs. maximum) in arterial blood pressure were significantly larger during slow and deep breathing compared with spontaneous breathing. The amplitude of systolic blood pressure oscillations increased by up to 10.2% (11.4 mmHg) during inspiration and 8.4% (10.0 mmHg) during expiration (spontaneous breathing; 2.9% (3.4 mmHg) and 3.4% (4.2 mmHg) respectively). Cardiovascular responses were maximised at ~6 breaths.min-1, but further research is needed to identify the optimal breathing frequency to induce maximal cardiovascular perturbations.