The Frontier X2 measures breathing rate using a method known as ECG-Derived Respiration (EDR). This technique leverages the natural correlation between cardiac and pulmonary cycles during normal breathing, identifying individual respiratory cycles by analyzing amplitude peaks within the ECG signal.

It’s important to note that the gold standard for measuring breathing rate involves a flow meter that directly captures breath flow — a method not feasible in a compact, wearable device like the FX2. As a result, the EDR method may produce inaccurate respiration rate readings in scenarios where the correlation between heart and lung activity is disrupted. Such scenarios can include intentional breathing patterns, certain cardiopulmonary conditions, or the use of anti-arrhythmia medications. In most cases, breathing rate readings normalize after a brief period of rest.

We are continually working to improve the accuracy of our breathing rate measurements by closely studying the interplay between cardiac and pulmonary responses during exercise.