Mobility Exercises for Gait (MEG Neuroplasticity Project)

To assess the activity of the motor cortices, the child will produce an isometric knee extension force to match a target that is between 5-30% of his/her maximum voluntary force. The children will be instructed to perform the target matching task as rapidly and as accurately as possible. The MEG experiment will involve the child performing ~120 isometric target matching trials.

To assess the activity of the somatosensory cortices, a tactile stimulation will be applied to the bottom of the foot at the first metatarsal using a small airbladder. For each child, 120 paired-pulse trials will be collected using an inter-stimulus interval of 500 ms, and an inter-pair interval that randomly varied between 4.5 and 4.8 s.

The childs 10-meter preferred and fast-as-possible walking speeds will be evaluated. The children will complete three trials at each speed, and the mean of the respective trials will be the key metric. During these tests, the child will walk across a GaitRITE digital mat (CIR Systems, Sparta, NJ) that will quantify the walking speed, step length, step width and cadence.

The child's walking endurance will be assessed by asking them to walk as far as possible for a one-minute time period. Cones will be placed at the ends of a 40-m hallway and the child will be asked to walk back and forth during the time period. During the walk the child will wear a heart-rate monitor and wireless accelerometers that are positioned on the lower back and feet. The heart-rate monitor will be used as an indirect measure of the child's physical fitness, while the accelerometers will be used assess the child's dynamic balance.

The resting state activity of the brain will also be collected. This will involve the child sitting quietly with his/her eyes closed for 5 minutes.

The child will be asked to perform a series of mobility tasks such as stepping over shoe-box, changing their gait speed, walking up stairs, turning head while walking, etc. These series of standardized test will be used to assess the child's gait adaptability.

A Biodex System 3 dynamometer will be used to assess the isometric strength and power production of the right and left knee joint musculature separately. Standard alignment of the knee joint axis with the dynamometer and set-up will be implemented. Separate knee extensor and flexor isometric strength tests will initially be measured from three maximal trials with the knee flexed at 90 degrees. This will be followed by the child performing maximal knee extensor/flexion concentric contractions with the dynamometer set at 30 deg/sec, 60 deg/sec and 120 deg/sec. The peak torque generated from the five contractions performed in each of the respective sets will be used as an outcome variable.

Survey that evaluates the child's self-reported physical activity, strength and pain. The PROMIS will be completed at baseline and at the 3 and 6 months after therapy. A physical therapist will perform the 3 and 6 month follow-up assessments at the family's home.

A survey to be completed by the child's parent/primary caregiver to gather information about the child's current level of participation in home, school and community environments. The survey will provide information regarding frequency of various activities performed, level of involvement during these activities and the parent/caregivers level of desire to see change in the child's involvement in activities. The PEM-CY will be completed at baseline and at the 3 and 6 months after therapy. A physical therapist will perform the 3 and 6 month follow-up assessments at the family's home.

The child will wear an activity tracker at their waist while they are at home, in the community and at school. The activity tracker will be worn for 2 weekdays and 2 weekend days. The average across this time period will be used to assess the activity levels of the child outside of the laboratory setting. These measurements will be performed at baseline and after completing the therapy protocol

This tests is similar to how a medical doctor performs a tendon tap to assess a child's reflexes. The only difference is the methods that will be employed in this study can quantify the magnitude of the reflex. The H-reflex will be elicited by simulating the tibial or median nerve with a constant current electrical simulator. the muscular activity generated by the stimulus will be measured with EMG. The peak amplitude of the H-reflex seen in the EMG signal will be determined by gradually increasing the stimulus until the amplitude of the reflex no longer increases. Changes in the amplitude before the therapy and after will be used as an indirect assessment of spinal cord plasticity.