Association between smartphone use and head-down tilt posture has not yet been quantitatively evaluated in natural settings. This study aimed to objectively assess the angle and duration of head-down tilt posture of smartphone users during a typical working day via naturalistic data collection. Thirty-one college students conducted their typical school activities while their head posture and smartphone-app usage records were collected simultaneously for 8 hours. Participants spent 125.9 minutes (median usage duration) on their smartphones with significantly larger head-down tilt (p < .05) than when they were not using the phone. Head tilt angle greater than 30° was found to be more common when using the phone, while head tilt less than 20° was more common when they were not using the phone. Study findings provide empirical evidence that supports an association between the duration of smartphone use and the intensity of head-down tilt posture. Practitioner Summary: Head postures of young smartphone users were quantified for 8 hours continuously during a typical workday using a wearable sensor. Participants spent more time in larger head-down tilt postures (greater than 30°) when they were using their smartphones as compared to when they were not using them.
Keywords: Text neck; looking down posture; mobile phone; texting.