Newer Garmin units should be able to detect respiration rate from almost any connected HRM. Mine works with both a Wahoo Tickr X and Sosche Rhythm+. From what I’ve read, there are tiny changes in your heart beat that correspond to breaths, which is what Garmin uses to determine respiration rate. I haven’t really seen anything on the accuracy, though. While I find the data interesting, I’m not sure what to do with it, though.
Here are the Garmin Connect plots from The Owl +3 this morning (30-second hard start followed by 10 min just below threshold). Overall the respiration plot at the bottom follows what I recall. The 30-second hard starts weren’t long enough to cause me to hit VO2-type respiration rates, so the rate was steady for essentially the whole combined interval. The dips mid-interval were when I took drinks. Cool to see, but not sure that it informs anything about how to train.
