This one is still on the workbench. It runs on my own watches every day, but it isn’t in the Connect IQ store yet, and some of what’s below will change before it is.

Slow, steady breathing does something you can measure: your heart rate starts to rise as you breathe in and fall as you breathe out, in a smooth, regular wave. That pattern is called heart rhythm coherence. This app paces your breathing on the watch and tells you, live, how coherent your rhythm is.

How a session works

  • Breathe with the pacer: four seconds in, six seconds out, about six breaths a minute, with gentle vibrations so you can close your eyes.
  • Watch the colour: a ring around the screen goes red, yellow or green as your coherence builds. The watch only buzzes when you reach green or drop back to red, and stays quiet while you’re doing well.
  • Pick a length: 5, 10, 15 or 20 minutes, or a free session.
  • See how it went: a summary of time in each colour, your average and best coherence, and RMSSD, a common measure of heart-rate variability, plus a graph of the whole session.
  • Keep the record: every session is saved to Garmin Connect as a breathwork activity with its own coherence and RMSSD charts, and to a history on the watch.

It’s designed to be dead simple: something you can do in a parked car on a break, without a chest strap.

The interesting part

Coherence comes from the gaps between individual heartbeats, not from your heart rate. Every few seconds the app takes the last 64 seconds of beats, cleans out obvious glitches, and looks for how much of the variation sits at your breathing rate compared with everything else. The more your rhythm follows your breath, the higher the score.

The catch is getting those beats. Garmin’s wrist sensor sometimes stops sending individual beat timings while still reporting your heart rate. In one early test it went silent for over two minutes of a three-and-a-half-minute calibration. Garmin describes this as a device limitation, so much of the work has been finding out what makes it worse: moving your wrist, releasing the sensor at the wrong moment, even the watch’s own vibrations. One vibration pattern I tried shook the wrist enough to interrupt the beats and had to go.

Made for real use

Lately the work has been about living with it:

  • Night display: after sunset the session screens dim, so it’s comfortable in a dark bedroom.
  • Falling asleep is fine: a session left untouched is saved after five minutes and the app closes, and free sessions end on their own after an hour.
  • Vibrations you can choose: two patterns and three strengths.

What’s next

  • More breathing paces, including box breathing and 4-7-8, each with its own shape on screen
  • A resonance scan to find the breathing pace that suits you best
  • A simpler start screen, a new name and logo, and support for more Garmin watches
  • Then the Connect IQ store

It’s a training aid for relaxation, not a medical device.