Non-specific chronic neck pain (NCNP) is commonly seen in office workers. Individuals with NCNP not only demonstrate impaired neck movement control and muscle activation, but also show abnormal scapular kinematics and muscle activation timing. Office workers with NCNP also show higher activity of upper trapezius during computer typing and have difficulty relaxing upper trapezius after typing. These changes related to scapula may increase strain over neck. In addition to the altered neuromuscular control, recent studies found neuroplasticity changes in the central nervous system on patients of chronic musculoskeletal disorders. Therefore, few studies found shifts and alterations of motor cortex representation of neck muscles in individuals with NCNP, which was correlated with delayed muscle activation of deep neck flexors muscle in functional activities. However, no studies have explored that whether this corticospinal adaptation also happens over scapular muscles, especially after a computer typing task. The objectives of this proposal are to investigate the differences in corticospinal and neuromuscular control of shoulder complex between office workers with and without NCNP. Thirty-five individuals with NCNP and 35 healthy controls will be recruited. Twenty young healthy subjects will be also recruited for a pilot study to test the reliability of all the measures. Scapular kinematics and muscle activation will be tested during arm elevation. Corticospinal parameters of trapezius and serratus anterior will be tested with transcranial magnetic stimulation (TMS), including active motor threshold, motor evoked potential, cortical silent period, short interval intracortical facilitation, short interval intracortical inhibition and cortical mapping. Corticospinal parameters, except cortical mapping, will be measured again after a 30-minute computer typing task. Scapular muscle activation will be also recorded during the typing task.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
OTHER
Masking
SINGLE
Enrollment
51
The subject sits in front of a computer screen and perform computer typing tasks for 30 minutes. The same computer table and chair were used for all subjects. The height of the table and screen, and the distance of the keyboard from the subject were adjusted according to their familiar and comfortable position.
Rest for 30 minutes
National Yang-Ming University
Taipei, Taiwan
Neurophysiological measures - Active motor threshold
Active motor threshold (AMT) will be described with the percentage (%) of maximum stimulator output (MSO).
Time frame: Change from baseline AMT after 30-minute computer typing task or 30-minute rest
Neurophysiological measures - Motor evoked potential
Motor evoked potential (MEP) will be described with millivolt (mV).
Time frame: Change from baseline MEP after 30-minute computer typing task or 30-minute rest
Neurophysiological measures - Cortical silent period
Cortical silent period (CSP) will be measured with millisecond (ms)
Time frame: Change from baseline CSP after 30-minute computer typing task or 30-minute rest
Neurophysiological measures - Short interval cortical inhibition
Short interval cortical inhibition (SICI) will be defined as percentage (%) of conditioning responses vs testing responses while the inter-stimulus interval is below 5 ms
Time frame: Change from baseline SICI after 30-minute computer typing task or 30-minute rest
Neurophysiological measures - Short interval cortical facilitation
Short interval cortical facilitation (SICF) will be defined as percentage (%) of conditioning responses vs testing responses while the inter-stimulus interval is above 5 ms
Time frame: Change from baseline SICF after 30-minute computer typing task or 30-minute rest
Neurophysiological measures - Area of cortical mapping
Area of cortical mapping will be described with square millimeter (mm2)
Time frame: Before 30-minute computer typing task
Neurophysiological measures - Volume of cortical mapping
Volume of cortical mapping will be calculated with multiplying summation of motor evoke potentials on the map (mV) by the area of the map (mm2) with the unit of mV\*mm2
Time frame: Before 30-minute computer typing task
Neurophysiological measures - Center of gravity of cortical mapping
Center of gravity of cortical mapping will be described in a x-y coordinate system (mm).
Time frame: Before 30-minute computer typing task
Neurophysiological measures - Area of cortical mapping
Area of cortical mapping will be described with square millimeter (mm2)
Time frame: Change from baseline area of cortical mapping after 30-minute rest (pilot subjects)
Neurophysiological measures - Volume of cortical mapping
Volume of cortical mapping will be calculated with multiplying summation of motor evoke potentials on the map (mV) by the area of the map (mm2) with the unit of mV\*mm2
Time frame: Change from baseline volume of cortical mapping after 30-minute rest (pilot subjects)
Neurophysiological measures - Center of gravity of cortical mapping
Center of gravity of cortical mapping will be described in a x-y coordinate system (mm).
Time frame: Change from baseline center of gravity of cortical mapping of cortical mapping after 30-minute rest (pilot subjects)
Scapular kinematics during arm elevation
Scapular kinematics, including anterior/posterior tilt, upward/downward rotation, and internal/external rotation in scapula plane elevation at 30°, 60°, 90°, and 120°, and will be described with degree (°).
Time frame: Before 30-minute computer typing task
Scapular kinematics during performing the computer task
The average of scapular kinematics, including anterior/posterior tilt, upward/downward rotation, and internal/external rotation will be calculated with a window of 10 seconds and will be described with degree (°).
Time frame: Change from baseline during the 30-minute computer typing task at 5, 10, 15, 20, 25, 30 minutes of the task
Scapular muscles activation during arm elevation
The root mean square of electromyography (EMG) data of the upper trapezius, lower trapezius, and serratus anterior will be normalized by the maximum voluntary contraction amplitude (percentage of maximal voluntary contraction, %) and calculated over three 30° increments of motion during arm elevation from 30° to 120°, including 30° - 60°, 60° - 90°, and 90° - 120°.
Time frame: Before 30-minute computer typing task
Scapular muscles activation during performing the computer task
The root mean square of electromyography (EMG) data of the upper trapezius, lower trapezius, and serratus anterior will be calculated with a window of 10 seconds and will be normalized by the maximum voluntary contraction amplitude (percentage of maximal voluntary contraction, %).
Time frame: Change from baseline during the 30-minute computer typing task at 5, 10, 15, 20, 25, 30 minutes of the task
Craniovertebral angle
Craniovertebral angle will be measured as the included angle between the tragus, C7 spinous process and the horizontal line and will be described with degree (°)
Time frame: Before 30-minute computer typing task
Craniovertebral angle
Craniovertebral angle will be measured as the included angle between the tragus, C7 spinous process and the horizontal line and will be described with degree (°)
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Time frame: Change from baseline during the 30-minute computer typing task at 5, 10, 15, 20, 25, 30 minutes of the task
Scapular kinematics during arm elevation
Scapular kinematics, including anterior/posterior tilt, upward/downward rotation, and internal/external rotation in scapula plane elevation at 30°, 60°, 90°, and 120°, and will be described with degree (°).
Time frame: Change from baseline scapular kinematics after 30-minute rest (pilot subjects)
Scapular muscles activation during arm elevation
The root mean square of electromyography (EMG) data of the upper trapezius, lower trapezius, and serratus anterior will be normalized by the maximum voluntary contraction amplitude (percentage of maximal voluntary contraction, %) and calculated over three 30° increments of motion during arm elevation from 30° to 120°, including 30° - 60°, 60° - 90°, and 90° - 120°.
Time frame: Change from baseline scapular muscles activation after 30-minute rest (pilot subjects)
Craniovertebral angle
Craniovertebral angle will be measured as the included angle between the tragus, C7 spinous process and the horizontal line and will be described with degree (°)
Time frame: Change from baseline craniovertebral angle after 30-minute rest (pilot subjects)