https://www.npr.org/sections/health-shots/2022/09/20/ [login to see] /daily-breath-training-can-work-as-well-as-medicine-to-reduce-high-blood-pressure
It's well known that weightlifting can strengthen our biceps and quads. Now, there's accumulating evidence that strengthening the muscles we use to breathe is beneficial too. New research shows that a daily dose of muscle training for the diaphragm and other breathing muscles helps promote heart health and reduces high blood pressure.
"The muscles we use to breathe atrophy, just like the rest of our muscles tend to do as we get older," explains researcher Daniel Craighead, an integrative physiologist at the University of Colorado Boulder. To test what happens when these muscles are given a good workout, he and his colleagues recruited healthy volunteers ages 18 to 82 to try a daily five-minute technique using a resistance-breathing training device called PowerBreathe. The hand-held machine — one of several on the market — looks like an inhaler. When people breathe into it, the device provides resistance, making it harder to inhale.