This study aims to evaluate how accurate and reliable two wearable sensor systems (inertial measurement units or IMUs) and a goniometer are in measuring cervical spine (neck) motion. Healthy adult volunteers will be asked to perform simple head movements in different directions while being assessed using the devices. The goal is to compare how closely these tools agree with each other and how consistently they record motion across repeated tests. This information will help determine whether the sensors are suitable for use in clinical settings to assess neck movement in future patient populations.

This interventional validation study will assess the concurrent validity and test-retest reliability of two inertial measurement unit (IMU) systems (Xsens DOT and Trigno Avanti) and a universal goniometer in measuring multi-planar cervical motion. A within-subject design will be used, with participants performing standardized active cervical range of motion (AROM) tasks in flexion, extension, lateral flexion, and rotation. All measurements will be conducted in a biomechanics lab setting under controlled conditions.

Each participant will undergo three testing sessions:

Familiarization session (optional)

Test session 1

Test session 2

Primary outcomes will include:

Peak angular displacement in each movement plane

Inter-device agreement (validity)

Intra-device test-retest consistency (reliability)

Sensor placement will follow anatomical landmarks based on previous biomechanical research. The IMUs and goniometer will be used simultaneously to compare measurements. Data analysis will involve intraclass correlation coefficients (ICC), standard error of measurement (SEM), and Bland-Altman plots for agreement analysis.

The study will recruit 20-30 healthy adults aged 18-40 with no current or past neck injury. The results will inform future clinical applications of wearable sensors in cervical spine assessment, particularly for populations with neck pain or neuromusculoskeletal disorders.

Ethical approval has been granted by the Cyprus National Bioethics Committee (Approval: ΕΕΒΚ ΕΠ 2025.01.231), and all participants will provide written informed consent.

Inclusion Criteria:

• Healthy adults aged 18 to 40 years
• Able to understand and follow instructions
• Provided informed consent

Exclusion Criteria:

• History of cervical spine pathology, trauma, or surgery
• Presence of neck pain, musculoskeletal, neurological, or vestibular disorders
• Use of medications affecting sensorimotor function
• Pregnancy
• Any condition that may interfere with safe participation or data accuracy

De-identified individual participant data (IPD), including cervical range of motion measurements and sensor-derived outputs, will be made available upon reasonable request for secondary analysis. Data will be shared via a secure university repository or data-sharing platform following study completion and publication.

De-identified individual participant data (IPD) and supporting documents will be available beginning 6 months after publication of the main findings and will remain accessible for a minimum of 5 years.

Access to the IPD and supporting materials will be granted to qualified researchers affiliated with academic or research institutions for non-commercial use. Requests should be submitted to the principal investigator and will be evaluated based on the scientific merit of the proposal. Data will be shared via secure transfer through institutional repositories or encrypted platforms.