Pathological and physiological muscle co-activation during active elbow extension in children with unilateral

A Sarcher1, M Raison2, F Leboeuf3

  • 1Motion Analysis Laboratory, Physical Medicine and Rehabilitation, Saint Jacques Hospital, University Hospital of Nantes, Nantes, France; Laboratory of Medical Information Processing (LaTIM), INSERM UMR 1101, Brest, France.

Insights

Children with cerebral palsy (CP) exhibit abnormal muscle co-activation during elbow extension, varying with movement speed and phase. This co-activation is linked to spasticity and reduced range of motion.

Area of Science:

  • Neurology
  • Biomechanics
  • Pediatrics

Background:

  • Cerebral palsy (CP) often involves motor control deficits.
  • Understanding muscle co-activation patterns is crucial for assessing upper limb function in children with CP.

Purpose of the Study:

  • To investigate the roles and mechanisms of co-activation in flexor/extensor muscle pairs during elbow extension in children with CP.
  • To differentiate co-activation patterns between typically developing (TD) children and those with unilateral spastic CP.

Main Methods:

  • Surface electromyography (sEMG) and 3D motion analysis were used to record muscle activity and joint kinematics during elbow extension/flexion in 13 TD and 13 children with CP.
  • Co-activation of brachioradialis/triceps and biceps/triceps muscle pairs was calculated during acceleration and deceleration phases of extension.
  • Statistical analyses included linear mixed effects models and Spearman rank correlations.

Main Results:

  • Children with CP showed strong, speed-dependent co-activation in both muscle pairs during the acceleration phase, unlike TD children.
  • During deceleration, co-activation increased with speed in both groups, but was greater in children with CP for the brachioradialis/triceps pair.
  • In children with CP, brachioradialis/triceps co-activation during deceleration was negatively correlated with extension range and positively correlated with flexor spasticity.

Conclusions:

  • Abnormal co-activation patterns occur throughout elbow extension in children with CP, varying by movement phase and specific flexor muscles.
  • Co-activation in children with CP presents both physiological and pathological characteristics, highlighting the complexity of motor control in this population.
Abstract