Muscle coactivation during gait in children with and without cerebral palsy.

BACKGROUND: Children with Cerebral Palsy (CP) walk with an uncoordinated gait compared to Typically Developing (TD) children. This behavior may reflect greater muscle co-activation in the lower limb; however, findings are inconsistent, and the determinants of this construct are unclear. RESEARCH OBJECTIVES: (i) Compare lower-limb muscle co-activation during gait in children with, and without CP, and (ii) determine the extent to which muscle co-activation is influenced by electromyography normalization procedures and Gross Motor Function Classification System (GMFCS) class. METHODS: An electromyography system measured muscle activity in the rectus femoris, semitendinosus, gastrocnemius, and tibialis anterior muscles during walking in 46 children (19 CP, 27 TD). Muscle co-activation was calculated for the tibialis anterior-gastrocnemius (TA-G), rectus femoris-gastrocnemius (RF-G), and rectus femoris-semitendinosus (RF-S) pairings, both using root mean squared (RMS)-averaged and dynamically normalized data, during stance and swing. Mann-Whitney U and independent t-tests examined differences in muscle co-activation by group (CP vs. TD) and GMFCS class (CP only), while mean difference 95% bootstrapped confidence intervals compared electromyography normalization procedures. RESULTS: Using dynamically normalized data, the CP group had greater muscle co-activation for the TA-G and RF-G pairs during stance (p < 0.01). Using RMS-averaged data, the CP group had greater muscle co-activation for TA-G (stance and swing, p < 0.01), RF-G (stance, p < 0.05), and RF-S (swing, p < 0.01) pairings. Muscle co-activation calculated with dynamically normalized, compared to RMS-averaged data, were larger in the RF-S and RF-G (stance) pairs, but smaller during swing (RF-G). Children with CP classified as GMFCS II had greater muscle co-activation during stance in the TA-G pair (p < 0.05). SIGNIFICANCE: Greater muscle co-activation observed in children with CP during stance may reflect a less robust gait strategy. Although data normalization procedures influence muscle co-activation ratios, this behavior was observed independent of normalization technique.

Muscle co-contraction and co-activation in cerebral palsy during gait: A scoping review.

BACKGROUND: Cerebral palsy (CP) results from an injury to a developing brain. Muscle activation patterns during walking are disrupted in individuals with CP. Indeed, excessive muscle co-contraction or co-activation (MCo/MCa) is one of the characteristics of pathological gait. Although some researchers have studied MCo/MCa in individuals with CP during gait, inconsistent results limit our understanding of this literature. Increased knowledge of MCo/MCa patterns in individuals with CP may help the development of improved gait management approaches. RESEARCH QUESTION: This review aims to summarize MCo/MCa patterns while walking in individuals with CP across the existing literature and compare them with their healthy peers. METHODS: This study follows the Joanna Briggs Institute (JBI) guidelines and the recommendations presented in PRISMA Extension for Scoping Reviews (PRISMA-ScR). The recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for scoping Reviews statement were respected. The following databases were searched: MEDLINE (Ovid), EMBASE (Ovid), CINAHL Plus with Full Text (Ebsco), SPORTDiscus with Full Text (Ebsco), and Web of Science. RESULTS: Among 2545 identified studies, 21 studies remained after screening. In total, 337 participants with CP and 249 healthy participants were included. Both MCo and MCa terminologies are used for describing simultaneous muscle activation; however, when it is measured by electromyography (EMG), MCa terminology should be preferred to facilitate interpretation. A wide range of MCo/MCa patterns has been found across studies using different methodologies (e.g., gait protocol, computation methods). Finally, most of the included studies confirm that MCo/MCa is increased in individuals with CP during walking compared to controls. SIGNIFICANCE: This review identified missing concepts and common limitations in the literature which could be addressed in future research such as the association between MCo/MCa and gait deviations, and the most appropriate MCo/MCa computation method.

The effect of uneven surfaces on inter-joint coordination during walking in children with cerebral palsy.

Clinical gait analysis on uneven surfaces contributes to the ecological assessment of gait deviations of children with spastic cerebral palsy (CP). Walking on uneven surfaces requires specific motor strategies, which can be assessed by lower-limb kinematic and inter-joint coordination analyses. This study aimed to assess and compare kinematics and inter-joint coordination between children with CP and their typically developing (TD) peers when walking on even and two levels of uneven surfaces (medium and high). A total of 17 children with CP and 17 TD children (11.5 ± 3.5 and 10.4 ± 4.5 years old, respectively) were asked to complete 6-8 gait trials on a 4-m walkway of each surface (n = 3) in randomized blocks while fit with retro-reflective markers on their lower-limbs. Children with CP showed proximal gait adaptations (i.e., hip and knee) on uneven surfaces. Compared with the TD group, the CP group showed decreased hip extension during late stance (49-63%, d = 0.549, p < 0.001), and a more in-phase knee-hip coordination strategy during swing phase (75-84% of gait cycle, d = 1.035, p = 0.029 and 92-100%, d = 1.091, p = 0.030) when walking on an uneven (high), compared to even surface. This study provides a better understanding of kinematic strategies employed by children with spastic CP when facing typical daily life gait challenges. Further studies are needed to evaluate the benefits of integrating uneven surfaces in rehabilitation care.

Lower-limb joint-coordination and coordination variability during gait in children with cerebral palsy.

BACKGROUND: Children with cerebral palsy present with poor motor control, altering their ability to perform tasks such as walking. Continuous relative phase analysis is a popular method to quantify motor control impairments via inter-joint coordination and coordination variability; however, it has not been explored in children with cerebral palsy. METHODS: 45 children with cerebral palsy and 45 typically developing children walked while fit with retroreflective markers. Continuous relative phase analysis for knee-hip and ankle-knee joint pairs quantified inter-joint coordination and coordination variability. The Gait Profile Score estimated gait pathology. Group differences were assessed with unpaired t-tests for coordination amplitude and variability (knee-hip, ankle-knee) across gait events. For the cerebral palsy group, correlations assessed the relation between the gait profile score and coordination metrics. FINDINGS: The cerebral palsy group showed more in-phase patterns for knee-hip coupling compared to the typically developing group (initial contact, loading response, mid-stance, terminal swing) (p ≤ 0.03). The cerebral palsy group showed lower knee-hip coordination variability (mid-stance, mid-swing) (p ≤ 0.037) and lower ankle-knee coordination variability (initial contact, loading response, terminal swing) (p < 0.001). The gait profile score correlated weakly to moderately (r = [0.323-0.472]), and negatively with the knee-hip inter-joint coordination (initial contact, loading response, mid-stance, terminal swing) (p ≤ 0.042). INTERPRETATION: Children with cerebral palsy showed a more in-phase gait strategy during challenging transitional gait cycle phases (beginning and end) and less flexible and adaptable motor behaviors. Moreover, the correlation between in-phase joint patterns and increased gait deviations (gait profile score) reinforces the relevance of coordination analysis to assess motor control impairment.

Gait adaptations of individuals with cerebral palsy on irregular surfaces: A scoping review.

BACKGROUND: Individuals with cerebral palsy (CP) have a reduced ability to perform motor tasks such as walking. During daily walking, they are confronted with environmental constraints such as irregular surfaces (e.g., relief and uneven surfaces) which may require adaptations to maintain stability and avoid falls. Laboratory gait assessments are conventionally conducted under ideal conditions (e.g., regular and even surfaces) and may overlook subtle problems which may only present in challenging walking environments. Increased knowledge of adaptations to successfully navigate irregular surfaces may contribute to a better understanding of everyday walking barriers. RESEARCH QUESTION: This scoping review aims to describe gait adaptations to irregular surfaces in individuals with CP and contrast adaptations with those of healthy individuals. METHODS: This review followed the 6-stage Joanna Briggs Institute methodology and respected the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews statement. The MEDLINE, EMBASE, CINAHL, SPORTDiscus, and Web of Science databases were searched on March 2021. RESULTS: The research strategy identified 1616 studies published between 2014 and 2020, of which 10 were included after abstract and full-text screening. This review reported on 152 individuals with CP (diplegia: n = 117, hemiplegia: n = 35) and 159 healthy individuals. The included studies focused on spatial-temporal, kinematic, kinetic, and muscle activity parameters over relief, inclined, and staircase surfaces. 7/10 studies were conducted in laboratories, often using surfaces that are not representative of the real-world. The results suggest that for individuals with CP, adaptations on irregular surfaces differ from flat surface walking and across CP subtype. Moreover, individuals with CP present with typical and pathology-specific adaptations to irregular surfaces compared to healthy individuals. SIGNIFICANCE: This review highlights the clinical and research interest of focusing future studies on more ecologically valid data collection approaches and provides important recommendations to overcome research gaps in the existing literature.