The goal of this interventional study is to learn about the biomechanical factors underlying the beneficial changes in children with cerebral palsy after using individually-adapted stand-on ride-on power mobility devices (PMD).

The main questions we aim to answer are:

• How does the use of stand-on PMDs affect static balance in children with cerebral palsy?
• How does the use of stand-on PMDs affect dynamic balance and mobility function in children with cerebral palsy?

Children ages 4-6 years old with cerebral palsy (GMFCS levels II and III) will:

• Use individually-adapted stand-on PMDs for three months.
• Undergo tests to measure static balance, dynamic balance, and mobility function before and after the intervention.
• Receive a full biomechanical assessment (kinematics, kinetics, muscle activity, gait spatiotemporal characteristics).

Researchers will compare pre-intervention and post-intervention measurements to quantify improvements in balance, muscle activation, and mobility.

Inclusion Criteria:

1. Diagnosis of spastic diplegia CP, GMFCS level III;
2. Between 4 and 6 years old (age band selected based on the benefits of early intervention and the age-limitation imposed from the size constraints of the PMDs (toy cars) selected for the intervention);
3. Able to stand and to walk short distances (at least 10 meters) with or without external assistance;
4. Physician medical clearance to participate; and
5. Exhibit sufficient cooperation and attention so that simple verbal instructions can be followed.

Exclusion Criteria:

1. Have notable orthopedic conditions (e.g., lower extremity amputation; recent hip surgeries or soft tissue lengthening);
2. Inadequate vision to complete study's procedures safely;
3. Serious/unstable cardiac conditions that prevent engagement in the Evaluation Sessions; and
4. Any other factor that might hinder full participation in the study or confound interpretation of the results.

Further discussion is needed given vulnerable population.

In this phase of the study, masking cannot be done as all participants will receive the intervention.