Polar H10 Resonance Breathing: SYMPATHETIC Adds HRV and ECG

Most breathing apps count your breaths. SYMPATHETIC, a free iPhone app spotlighted by the5krunner, reads a Polar H10 chest strap while you breathe at about six breaths a minute and shows heart rate, HRV, and a single-lead ECG trace as you go. For athletes who already own an H10 and use slow breathing to cool down, it turns a habit into something you can see, with no account and no subscription.

Why This Category Matters

Resonance breathing means slow, paced breathing, often near six breaths per minute, to enlarge the natural rise and fall of heart rate with each breath. Research has linked slow, controlled breathing with greater parasympathetic influence on the heart, and the best pace varies between people. That variation is why seeing your own heart’s response matters more than following a fixed timer.

The app was built by Lucas Camillo, a longevity researcher and medical student at the University of Cambridge, who uses resonance breathing in his own recovery routine. The article is his developer-written feature, edited by the5krunner, so it describes the app rather than testing it independently. It is part of the5krunner’s Indie Spotlight series, which has also covered Apple Watch recovery apps such as Cinder.

What Makes It Different

According to the article, the app works “either as a quiet breathing guide or as a closer look at the heart.” The breathing guide runs without any sensor. With an H10 connected, it adds heart rate, beat-to-beat HRV, a combined heart-and-breath view, and an ECG trace you can scroll, zoom, and export.

A guided assessment compares breathing settings. In the article’s worked example, 5.5 and 5.3 breaths per minute produced a median heart rate of about 71 to 72 bpm and almost identical HRV, so the assessment kept the starting pace. The article doesn’t explain exactly how the app chooses a pace beyond comparing settings.

The Catch / Who It’s For

The limits are specific. The Polar H10 is the only supported sensor, so Apple Watch and other heart rate straps won’t work. The app needs iOS 18 or later. ECG and heart rate data don’t go to Apple Health, only breathing time as Mindful Minutes, and recordings stay on the phone unless exported. The article gives no validation data for the app’s measurements.

The article also makes a point that applies to any HRV app: breathing itself changes HRV, so readings taken during a session should be kept apart from morning or overnight recovery readings. And anything unusual on an ECG trace is, in the article’s words, “a question for a doctor.”

Source: the5krunner

Content created with AI assistance and reviewed for accuracy.