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The influence of gait speed on co-activation in unilateral spastic cerebral palsy children
Raphaël Gross1, Fabien Leboeuf, Jean Benoit Hardouin
1Laboratoire d'analyse du Mouvement, Pôle Médecine Physique et Réadaptation, hôpital Saint Jacques, CHU Nantes, Nantes, France. raphael.gross@chu-nantes.fr
Insights
Children with unilateral cerebral palsy show increased muscle co-activation during gait, especially in the involved limb, as walking speed increases. This suggests altered motor control contributes to gait challenges in pediatric cerebral palsy.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Pediatric Rehabilitation
Background:
- Muscle co-activation is crucial for joint stability during walking.
- Excessive co-activation can impede movement and elevate energy costs.
- Gait speed and upper motor neuron lesions exacerbate co-activation.
Purpose of the Study:
- To investigate the pathological component of muscle co-activation in children with unilateral cerebral palsy.
- To analyze how gait speed influences co-activation in affected limbs.
Main Methods:
- Compared gait parameters and electromyography (EMG) in 10 children with unilateral cerebral palsy and 10 typically developing children.
- Recorded EMG activity of key leg muscles (rectus femoris, vastus medialis, semi-tendinosus, tibialis anterior, soleus) across different walking speeds.
- Calculated co-activation index for antagonistic muscle pairs and analyzed using mixed linear models.
Main Results:
- Children with unilateral cerebral palsy exhibited a significantly greater effect of walking speed on co-activation in their involved limbs compared to controls.
- This speed-dependent co-activation increase was observed across all studied muscle couples in the affected limbs.
- Unlike typically developing children, the rectus femoris/semi-tendinosus co-activation in children with cerebral palsy did not show reduced sensitivity to gait speed.
Conclusions:
- A pathological component in muscle activation likely drives the heightened co-activation response to gait speed in the involved limbs of children with cerebral palsy.
- Altered motor control mechanisms may underlie the increased sensitivity of specific muscle couples, like rectus femoris/semi-tendinosus, to walking speed.
Background:
Physiological co-activation of antagonistic muscles during gait allows stability of loaded joints. Excessive co-activation restrains motion and increases energy expenditure. Co-activation is increased by gait speed and in the case of upper motor neuron lesions. This study aimed to assess the pathological component of co-activation in children with unilateral cerebral palsy.
Methods:
10 children with unilateral cerebral palsy and 10 typically developing children walked at spontaneous, slow and fast speeds. The spatio-temporal parameters and electromyographic activity of the rectus femoris, vastus medialis, semi-tendinosus, tibialis anterior and soleus of both lower limbs were recorded. A co-activation index was computed from the EMG envelopes. A mixed linear model was used to assess the effect of walking speed on the index of the antagonistic muscle couples (rectus femoris/semi-tendinosus, vastus medialis/semi-tendinosus and tibialis anterior/soleus) in the different limbs.
Findings:
A greater effect of walking speed on co-activation was found in the involved limbs of children with cerebral palsy for all muscle couples, compared with their uninvolved limbs and the limbs of typically developing children. In typically developing children, but not in children with cerebral palsy, the effect of gait speed on the co-activation index was lower in the rectus femoris/semi-tendinosus than in the other agonist/antagonist muscle couples.
Interpretations:
In children with cerebral palsy, a pathological component of muscle activation might be responsible for the greater increase in co-activation with gait speed in the involved limb. Altered motor control could explain why the co-activation in the rectus femoris/semi-tendinosus couple becomes more sensitive to speed.
