Motor Control

AK Clarke, AJ Ries, MH Schwartz, KM Steele (2026) Influence of body weight support on motor control in typically developing children and children with cerebral palsy

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Journal Article in Journal of Biomechanics

Despite reduced activation of key support muscles and kinematic changes, BWS has minimal impact on synergies for individuals with CP and TD peers

Aim: Body weight support (BWS) is often provided during rehabilitation interventions or activities of daily living with assistive devices for children with cerebral palsy (CP). How individuals alter their muscle activity and coordination in response to BWS provides insight into neuromuscular control and may inform the design of future interventions.

Methods: Children with CP (n = 12) and typically developing (TD) peers (n = 8) walked on a treadmill with 1%, 20%, 40%, and 60% BWS while electromyographic (EMG) data was recorded from 7 lower limb muscles. We computed muscle synergies from the EMG data using non-negative matrix factorization.

Results: As BWS increased, activity of support muscles like the gluteus maximus and gluteus medius decreased for both CP and TD groups. Children with CP had significantly reduced synergy complexity compared to TD peers (total variance accounted for by one synergy, tVAF1 = 76.3 for CP versus 67.4 for TD averaged across all conditions). However, synergy complexity did not change with BWS for either group.

Interpretation: Although BWS may assist mobility by reducing demand on support muscles, it does not directly modulate motor control.

Neuromechanics & Mobility Lab presents at ASB 2025

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The Neuromechanics & Mobility Lab had a fantastic showing at the 2025 American Society of Biomechanics (ASB) Annual Meeting in Pittsburgh, PA! From student awards to impactful presentations, our team contributed to advancing the science of human movement and rehabilitation engineering.

We’re proud to celebrate Ally Clarke, who received a Student Travel Award for her abstract titled “Influence of Bodyweight Support on Motor Control in Children with Cerebral Palsy.” Her work was recognized by the ASB community for its contribution to pediatric motor control research. Congratulations, Ally!

Lab members presented posters across multiple themes. Madeleine McCreary explored toddler muscle activation during joystick driving in her poster “Kicking it off: Does toddler leg muscle activation while driving change with posture?” Mackenzie Pitts shared insights on “Mechanisms of split-belt treadmill adaptation in children with cerebral palsy.” Ally Clarke presented her award-winning work on bodyweight support and motor control, and Katie Landwehr-Prakel showcased her research on “Muscle activity during walker-based exoskeleton use in children with cerebral palsy.”

Beyond the science, our team engaged in workshops, debates, and networking events that emphasized advocacy, inclusion, and the integration of lived experiences into biomechanics research. The ASB 2025 program featured sessions on AI in biomechanics, wearable tech, and neuromechanics – all aligning with our lab’s mission to enhance mobility and participation.

Thank you to ASB and the biomechanics community for an inspiring week. We’re already looking forward to connecting again at the World Congress of Biomechanics (WCB) in Vancouver in 2026!

  • Four people standing together on a rooftop at sunset with a scenic view of the Pittsburgh city skyline, yellow bridges, and river in the background during ASB 2025
  • Four individuals standing in front of a research poster at ASB 2025, representing the University of Washington.
  • Group of individuals standing and discussing research in front of scientific posters at ASB 2025, with charts and graphs visible on the posters
  • Researcher presenting findings to an attendee in front of scientific posters at ASB 2025, showcasing graphs and charts related to biomechanics research.
  • Two individuals standing in front of three research posters on cerebral palsy at ASB 2025

Congratulations – Ally Clarke receives ASB Student Travel Award!

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A young woman with blonde hair is wearing a green sweater and blue jeans while standing in front of a blossoming tree.

We’re excited to share that Ally Clarke has been selected to receive a Student Travel Award from the American Society of Biomechanics (ASB) to attend the 2025 ASB Annual Meeting in Pittsburgh, PA. This award supports students who have authored abstracts accepted for presentation. Ally’s abstract Influence of Bodyweight Support on Motor Control in Children with Cerebral Palsy was selected for presentation at the meeting, and we’re proud to see her work recognized and supported by the biomechanics community.

Congratulations, Ally!

CR DeVol, SR Shrivastav, VM Landrum, KF Bjornson, D Roge, CT Moritz, KM Steele (2025) “Effects of spinal stimulation and short-burst treadmill training on gait biomechanics in children with cerebral palsy”

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Journal article in Gait & Posture

Children with cerebral palsy (CP) have an injury to the central nervous system around the time of birth that affects the development of the brain and spinal cord. This injury leads to changes in gait neuromechanics, including muscle activity and joint kinematics. Transcutaneous spinal cord stimulation (tSCS) is a novel neuromodulation technique that may improve movement and coordination in children with CP when paired with targeted physical therapy.

Example kinematics and muscles activity at each assessment timepoint for P03’s more-affected side. A) Sagittal-plane hip, knee, and ankle kinematics over the gait cycle. Horizontal colored lines indicate where there were significant changes in kinematics over each phase of the study based on statistical parametric mapping (p Aim: How does the combination of tSCS and short-burst interval locomotor treadmill training (SBLTT) affect individual gait neuromechanics in children with CP?

Methods: Four children with CP (4–13 years old), received 24 sessions each of SBLTT only and SBLTT with tSCS (tSCS+SBLTT). Clinical assessments of spasticity and passive range of motion (PROM), as well as biomechanical assessments of joint kinematics, musculotendon lengths, and muscle activity were recorded during overground, barefoot walking. Assessments were taken before and after each intervention, and 8-weeks later.

Results: The combination of tSCS+SBLTT led to greater increases in hip and knee extension than SBLTT only for three participants. Three children also became more plantarflexed at the ankle during stance after tSCS+SBLTT compared to SBLTT only. While tSCS+SBLTT reduced spasticity, these changes were only weakly correlated with changes in musculotendon lengths during gait or PROM, with the largest correlation between change in gastrocnemius operating musculotendon length during fast walking and gastrocnemius spasticity (R2 = 0.26) and change in plantarflexor PROM and gastrocnemius spasticity (R2 = 0.23).

Interpretation: Children with CP used a more upright, less crouched posture during gait after tSCS+SBLTT. Large reductions in spasticity after tSCS+SBLTT were only weakly correlated with changes in kinematics and PROM. Understanding the mechanisms by which tSCS may affect gait for children with CP is critical to optimize and inform the use of tSCS for clinical care.

AM Spomer, BC Conner, MH Schwartz, ZF Lerner, KM Steele (2024) “Multi-session adaptation to audiovisual and sensorimotor biofeedback is heterogeneous among adolescents with cerebral palsy”

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Journal Article in PLoS ONE

There is growing interest in the use of biofeedback-augmented gait training in cerebral palsy (CP). Audiovisual, sensorimotor, and immersive biofeedback paradigms are commonly used to elicit short-term gait improvements; however, outcomes remain variable. Because biofeedback training requires that individuals have the capacity to both adapt their gait in response to feedback and retain improvements across sessions, changes in either capacity may affect outcomes. Yet, neither has been explored extensively in CP.

Experimental protocol used to evaluate multi-session adaptation to multimodal biofeedback. Participants completed a four-day protocol using combined audiovisual and sensorimotor biofeedback. Audiovisual biofeedback on soleus activity was provided unilaterally on the more-affected limb whereas sensorimotor biofeedback was administered bilaterally using a resistive ankle exoskeleton. Each session was separated into baseline (1 minute), biofeedback (2, 10-minute bouts), and washout (1 minute) phases. The nominal torque value of the ankle exoskeleton was set at 0.1 Nm/kg during the first bout of the first session and incrementally adjusted by 0.025 Nm/kg over the subsequent bouts, according to the schedule shown. Overground walking data were collected pre- and post-intervention. A licensed physical therapist also performed a full physical examination at the pre-intervention session. Motion capture data were collected during at the pre- and post-intervention sessions and electromyography (EMG) data were collected bilaterally from the vastus lateralis, semitendinosus, soleus, and tibialis anterior across all sessions.Aim: The aim of this study was to evaluate the extent to which individuals with CP adapt gait and retain improvements during multi-session practice with a multimodal biofeedback paradigm, designed to promote plantarflexor recruitment. Secondarily, we compared overground walking performance before and after biofeedback sessions to understand if any observed in-session improvements were transferred. 

Methods: In this study, we evaluated the extent to which adolescents with CP (7M/1F; 14 years (12.5,15.26)) could adapt gait and retain improvements across four, 20-minute sessions using combined audiovisual and sensorimotor biofeedback. Both systems were designed to target plantarflexor activity. Audiovisual biofeedback displayed real-time soleus activity and sensorimotor biofeedback was provided using a bilateral resistive ankle exoskeleton. We quantified the time-course of change in muscle activity within and across sessions and overground walking function before and after the four sessions.

Results: All individuals were able to significantly increase soleus activity from baseline using multimodal biofeedback (p < 0.031) but demonstrated heterogeneous adaptation strategies. In-session soleus adaptation had a moderate positive correlation with short-term retention of the adapted gait patterns (0.40 ≤ ρ ≤ 0.81), but generally weak correlations with baseline walking function (GMFCS Level) and motor control complexity (ρ ≤ 0.43). The latter indicates that adaptation capacity may be a critical and unique metric underlying response to biofeedback. Notably, in-session gains did not correspond to significant improvements in overground walking function (p > 0.11).

Interpretation: This work suggests that individuals with CP have the capacity to adapt their gait using biofeedback, but responses are highly variable. Characterizing the factors driving adaptation to biofeedback may be a promising avenue to understand the heterogeneity of existing biofeedback training outcomes and inform future system optimization for integration into clinical care.