How Hexoskin Measures and Converts Respiratory Data
Hexoskin’s breathing data comes from thoracic and abdominal RIP bands, which track chest and abdomen movement during respiration. Signals are combined and converted into volumes using a default coefficient (13.28 ml/unit), with an option to adjust based on user weight. This produces parameters like breathing rate, tidal volume, and minute ventilation. For highest accuracy, Hexoskin recommends calibration with a spirometer.
Hexoskin’s respiratory data is derived from the raw signals captured by the shirt’s two Respiratory Inductance Plethysmography (RIP) bands — one positioned on the chest and the other on the abdomen. These sensors detect the expansion and contraction of the thorax and abdomen during breathing, producing “arbitrary values” proportional to respiratory movements. The thoracic and abdominal signals are then combined using specific weights to generate a single composite respiration signal. From this, Hexoskin calculates various respiratory parameters, including breathing rate, inspiration and expiration onset, tidal volume, and minute ventilation.
By default, the raw respiration signal is converted to volume using the formula:
Ventilation Data (ml) = Total Weighted Bands Movement (in arbitrary units) x 13.28 ml/unit
This default conversion coefficient (13.28 ml/unit) was established through an internal validation study.
"Adjusted" Respiratory Data
Once your records are synchronized, complete respiratory data — including “adjusted” values — becomes available. Adjusted ventilation data accounts for the user’s weight to further personalize the conversion factor:
Adjusted Ventilation Data (ml) = Ventilation Data (ml) * (Weight in kg / 65)
Ventilation Data Calibration
For even greater accuracy in ventilation measurements, Hexoskin recommends calibrating the ventilation data using a spirometer. Detailed calibration instructions are available in our support article: Calibrating Hexoskin Ventilation Data Using a Spirometer.