Validity and reliability of smartphone orientation measurement to quantify dynamic balance function

Area of Science:

• Neuromotor assessment
• Biomechanics
• Mobile health technology

Background:

• Postural control is often impaired after head trauma, necessitating reliable balance assessment.
• Current neuromotor assessments may not fully capture dynamic balance deficits.
• Smartphone technology offers a potential platform for accessible and objective neuromotor evaluation.

Purpose of the Study:

• To develop and validate a novel smartphone-based protocol for assessing dynamic balance decrements after head trauma.
• To screen for impaired balance in individuals with a history of head injury.
• To provide an objective measure of neuromotor function.

Main Methods:

• Compared smartphone orientation detection algorithms with a motion capture system using pendulum and human stepping tasks.
• Examined the test-retest reliability of a stepping-in-place protocol under varying sensory conditions (eyes open, no vision, head shake).
• Extracted temporal and spatial variability metrics from thigh orientation data.

Main Results:

• Smartphone sensors accurately measured movement timing and amplitude, validating their use.
• Sensor firmware and Android OS versions impacted measurement quality.
• The stepping-in-place protocol demonstrated high test-retest reliability for key temporal and spatial variables.

Conclusions:

• The developed smartphone application is a valid and reliable tool for measuring leg movement characteristics during dynamic balance activities.
• This technology can provide an objective method for assessing neuromotor function post-head trauma.
• The protocol has potential applications for other populations experiencing balance dysfunction.