Coordination

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

Katie Energetics, JournalArticle, Publications , , ,

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.

KM Peters, VE Kelly, T Chang, MC Weismann, S Westcott McCoy, KM Steele (2018) “Muscle recruitment and coordination during upper-extremity functional tests.” Journal of Electromyography and Kinesiology

Keshia JournalArticle, Publications ,

Journal article in Journal of Electromyography and Kinesiology:

In collaboration with Rehabilitation Medicine here at the University of Washington, we evaluated muscle use of 20 unimpaired participants during three upper-extremity functional tests. An interactive supplement can be found HERE.

Recruitment and cocontration plots of eight upper-extremity muscles during the Jebsen Taylor Hand Function Test.Background: Performance-based tests, such as the Jebsen Taylor Hand Function Test or Chedoke Arm and Hand Activity Inventory, are commonly used to assess functional performance after neurologic injury. However, the muscle activity required to execute these tasks is not well understood, even for unimpaired individuals. The purpose of this study was to evaluate unimpaired muscle recruitment and coordination of the dominant and non-dominant limbs during common clinical tests.

Methods: Electromyography (EMG) recordings from eight arm muscles were monitored bilaterally for twenty unimpaired participants while completing these tests. Average signal magnitudes, activation times, and cocontraction levels were calculated from the filtered EMG data, normalized by maximum voluntary isometric contractions (MVICs).

Results: Overall, performance of these functional tests required low levels of muscle activity, with average EMG magnitudes less than 6.5% MVIC for all tests and muscles, except the extensor digitorum, which had higher activations across all tasks (11.7 ± 2.7% MVIC, dominant arm). When averaged across participants, cocontraction was between 25 and 62% for all tests and muscle pairs.

Conclusion: Tasks evaluated by speed of completion, rather than functional quality of movement demonstrated higher levels of muscle recruitment. These results provide baseline measurements that can be used to evaluate muscle-specific deficits after neurologic injury and track recovery using common clinical tests.