Daily 'breath training' works as well as medicine to reduce high blood pressure
npr.org
npr.org
US$40 and up. My wife has high blood pressure, but I don't. However, as a distance runner, this part interested me, so perhaps I'll get one or two:
"Craighead, whose personal marathon best is 2 hours, 21 minutes, says he has incorporated IMST as part of his own training."
If you’re so out of shape that your breathing through your mouth entirely, I imagine you would see some of these similar benefits through that one change in habit.
The correlation could go the other way though. I lost 30 lbs and find I no longer breathe through my mouth the way I used to.
Strengthening the breathing muscles is what improves the blood pressure, according to the article.
Now I'm going to get one of these things!
Strengthening the muscles you use to breathe make it easier to do and thus puts your body in a relaxed state more often.
You don't need a device to do this. You can also do any popular deep breathing exercise like Wim Hof, square breathing, 4/7/8 breathing, or restricting airflow with thumbs in nostrils. A device may be more effective at training your resistance however.
In yoga there is a practice called Ujjayi Breathing where you restrict airflow in and out of the lungs via the the throat, making a soft sound. This is often combined with meditation or sometimes uses in very energetic situations to calm the breath.