Citation
Chaddha A, Modaff D, Hooper-Lane C, Feldstein DA. Device and non-device-guided slow breathing to reduce blood pressure: A systematic review and meta-analysis. Complement Ther Med. 2019 Aug;45:179-184. doi: 10.1016/j.ctim.2019.03.005. Epub 2019 Mar 15. PMID: 31331557.
4 FUNDAMENTALS
1. Essential Background Material
This meta-analysis aimed to analyze if slow breathing reduces blood pressure in hypertensive and prehypertensive patients based on randomized controlled trials.
Hypertension is a significant risk factor for cardiovascular disease, which is the leading cause of death in the U.S. For instance, if systolic blood pressure rises from 115 mmHg to 135 mmHg, your risk of cardiovascular disease doubles.
Slow breathing has consistently been shown to reduce blood pressure. In particular, an FDA-approved device called RESPeRATE, which slowly reduces breathing rate down to below ten breaths per minute, has been studied extensively. It consistently lowers blood pressure in hypertensive patients. Due to the ample evidence, the American Heart Association has even given device-guided slow breathing a “class IIA” rating for reducing blood pressure.
However, although many individual studies provide support for slow breathing, meta-analyses and systematic reviews have been inconclusive. For instance, one showed that no positive effects are found when industry-funded studies are excluded. Others have had small sample sizes or excluded non-device guided slow breathing.
Thus, this meta-analysis aimed to fill that gap by providing a concise yet comprehensive summary of studies that have examined slow breathing (device and non-device guided) and hypertension using strict inclusion criteria and randomized controlled trials (RCTs).
2. What Did this Research Do?
The authors searched several public databases (e.g., Web of Science, MEDLINE) from their inception until mid-2015. They used a combination of search terms like “hypertension OR prehypertension” and “slow breathing OR device-guided breathing” to identify papers relevant to the meta-analysis.
In the identified papers, slow breathing was defined as anything below ten breaths per minute. They included studies of people with both hypertension and prehypertension. The subjects had to perform slow breathing at least three times a week for at least 5 minutes each session. The follow-up period had to be at least 4 weeks, and changes in blood pressure had to be reported.
The authors started with 1,984 studies, but only 17 met their criteria for inclusion in the meta-analysis. Although this was a reasonably strict search, it certainly wasn’t perfect, and there are some important caveats.
Of the 17 studies selected, five were abstracts only. Additionally, only two had slow breathing without a device. The other fifteen were device-guided slow breathing using the RESPeRATE, and the maker of the device sponsored six of these.
Thus, there was still a high risk of publication bias in these studies.
(Note that this current meta-analysis was self-funded. So, that gives us some hope that the authors had no conflict of interest with this review.)
3. What Were the Major Findings?
Despite these limitations, the pooled results were impressive. The average decrease in systolic blood pressure (SBP) across all seventeen studies was 5.62 mmHg. The two non-device slow breathing studies had an even more significant drop of 7.69 mmHg. For diastolic blood pressure, the mean decrease was 2.67 mmHg for the device-guided slow breathing.
They also examined how the intensity of the slow breathing practice affected results—the conclusion: the longer subjects practiced, the more significant their reduction in blood pressure. For example, for slow breathing <100 min a week, the decrease in SBP was 3.01 mmHg, for 100-200 min, it was 6.44 mmHg, and for >200 min, it was 14.00 mmHg.
4. Why Do These Results Matter?
The significance of these findings is that modest reductions in blood pressure lower the chances of strokes, coronary events, heart failure, cardiovascular deaths, and total deaths. This is especially important for diabetics who are at higher risk of developing hypertension and heart disease.
Moreover, the improvements from slow breathing were similar to those seen with antihypertensive medications. Those medications have been shown to improve long-term outcomes in hypertensive and prehypertensive patients. Therefore, slow breathing could potentially provide similar positive results if practiced consistently over a long period.
1 BIG TAKEAWAY
Slow breathing reduces systolic blood pressure by 5.62 mmHg and diastolic blood pressure by 2.67 mmHg. The more time you practice per week, the greater the blood pressure reductions. This is a go-to reference for anything slow breathing and hypertension-related.
1 PRACTICAL APPLICATION
Many of the studies cited used a device that gradually guided people’s breath to slower rates.
We can mimic this with The Breathing Zone App. This app lets you set a target breathing rate (I suggest 5-6 breaths per minute) and a starting breathing rate (say 7-10 breaths per minute). Then, it will gradually guide your breathing from your starting rate to your target rate so that it feels more manageable and effortless.
Moreover, their “Breathing Zone” setting also starts with a 1:1 ratio and gradually makes your exhales longer until you reach a 1:2 ratio (exhales twice as long as inhales). This was also the approach used by most of the studies cited in this meta-analysis.
You could use this app for ~20 minutes a day to be in the sweet spot of blood pressure reduction found in this meta-analysis.