Hansraj's 2014 calculation model suggests that estimated cervical-spine moment rises as the head tilts forward. The figures are not direct sensor measurements or a pain diagnosis; ONK uses AirPods data only for posture awareness.
Hansraj's calculation model (2014, PMID 25393825) reports that estimated cervical-spine moment rises with forward head tilt and gives an equivalent value of about 27 kg at 60°. This is not a direct measurement in an individual or a prediction of pain or disease. ONK uses AirPods head-tilt data to offer a reminder at your chosen threshold; it does not diagnose or automatically correct posture.
At 30°, ~40 lbs load rests on your neck. Maintaining this posture daily accelerates cervical disc wear.
Using advanced 6-axis motion sensors and Apple's CoreMotion framework:
Gyroscope and accelerometer feeds calculate your head angle relative to gravity in real time.
When excessive tilt persists for >20s, a subtle audio cue nudges your gaze back up gently.
Sensor streams never leave your device. Processed locally on iOS with zero cloud telemetry.
AirPods Pro (1st & 2nd gen), AirPods Max, and AirPods 3 / 4 support spatial CoreMotion head tracking.
A 3-minute cervical decompression routine daily provides meaningful relief from desk and smartphone strain. You can use our live timer on the Exercises page.
No. ONK is not a medical device. It provides posture awareness and gentle habit coaching. Always consult a physician for clinical spinal conditions.
Hansraj, K. K., MD (2014). Assessment of Stresses in the Cervical Spine Caused by Posture and Position of the Head. Surgical Technology International, 25, 277-279. PMID: 25393825.
View Official PubMed Medical Study (PMID: 25393825) ↗ONK is built exclusively for iOS 26+ and watchOS 26+.
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