The goal of this study is to see if gentle electrical stimulation can help children with cerebral palsy (CP) walk more easily. This stimulation, called neuromuscular electrical stimulation (NMES), sends small pulses to muscles to help them activate. Researchers will test different ways of using NMES to find out which method works best.

Participants will walk on a treadmill at a comfortable speed while NMES is applied to leg muscles. The study will compare different stimulation settings to see which one helps the most.

Children with cerebral palsy (CP) can have trouble with daily tasks such as walking. This raises their risk of disability as they age into their teens. Current treatments are not very effective. In this study, children with CP will walk on a treadmill while receiving neuromuscular electrical stimulation (NMES) on their lower limb muscles, using surface electrodes, while their gait dynamics are assessed, using Inertial Measurement Unit (IMU) sensors. Our proposed study aims to gather preliminary evidence to support the potential efficacy of NMES assistance to muscles across all lower limb joints during walking, i.e., multi-joint NMES assistance. Additionally, we aim to investigate the optimal level of intensity. We intend to quantify neuroprosthetic, i.e., immediate effects during NMES assistance on gait kinematics. 40 children between the ages of 7 to 18 who are diagnosed with spastic diplegic cerebral palsy and GMFCS level I-III, and 25 healthy adults will be recruited for this study. The study consists of one pilot session and two assessment sessions. During the pilot session, participants will walk on the treadmill at their self-selected speed while two IMU sensors measure their shank velocity and acceleration. No stimulation will be applied to the subjects during the pilot session, as we aim to only validate and improve the software that triggers the stimulation during the gait, i.e., our gait phase detection system. During assessment sessions, subjects will walk on a treadmill with and without NMES assistance at their self-selected walking speed. The assessment sessions consist of multiple NMES conditions. Each condition lasts about 1 minute and will be repeated 3 times, with 30 seconds rest between trials for each condition and 5 minutes between each condition. The total walking time will not exceed 30 minutes. Each visit will last about 3 hours. The first session will also include a consent process, which will add an extra 30 minutes. The assessment sessions will begin with a no-stimulation condition and will be followed by multiple NMES conditions consisting of NMES assistance to various lower limb muscle combinations.

*Inclusion Criteria*

CP Group:

• Age 7-18
• Diagnosis of spastic diplegic cerebral palsy (CP)
• GMFCS level I-III (be able to walk with or without assistive devices)
• MIGR < 40% femoral head covering in acetabulum
• Crouch, equinus, or jump gait
• At least 0° passive dorsiflexion range of motion (ROM)
• Sufficient visuoperceptual, cognitive, and communication skills
• Seizure-free or well-controlled seizures
• No other neurological or musculoskeletal disorders (e.g. dystonia, severe scoliosis, hip instability
• Ability to travel to the University of Nebraska at Omaha two times
• Ability to communicate pain or discomfort
• Ability to obtain child assent and obtain parent/guardian consent

Healthy adults (control) group:

• Adults aged 20 to 40
• Adults with good physical health
• Adults with the ability to follow verbal instructions
• Adults with the ability to walk on a treadmill for 15 minutes
• No orthopedic surgery on the lower limb within the past 3 months

*Exclusion Criteria*

CP Group:

• Diagnosis of athetoid or ataxic cerebral palsy (CP)
• Scoliosis with primary curve > 49%
• Spinal fusions extending into the pelvis
• Lower Extremity (LE) joint instability or dislocation
• Severe tactile hypersensitivity
• LE botulinum injections in the past 6 mo
• Implanted medical device contraindicative of functional electrical stimulation (FES)
• Pregnancy
• Severe LE spasticity (Modified Ashworth Scale score of 4 or greater)
• History of pulmonary disease limiting exercise tolerance (Asthma Control Test screen)
• History of cardiac disease (American Heart Association, AH,) screen)
• Excessive LE joint pain during walking
• Severely limited range of joint motion/ irreversible muscle contractures, i.e.> 10° knee flexion, >15° hip flexion contractures, or >5° plantarflexion contractures
• LE surgery or significant injury within 1 yr.

Healthy adults (control) group:

• Adults with any chronic illnesses or medical conditions that could impact their health.
• Adults with significant behavioral or emotional issues that could indicate developmental disorders or psychological conditions.
• Adults with diagnosed developmental disorders (e.g., autism, ADHD, learning disabilities)
• Adults with surgery on their lower limb within the past 3 months.