Trunk and hip muscle activation patterns are different during walking in young children with and without cerebral palsy

Abstract

Background: Poor control of postural muscles is a primary impairment in people with cerebral palsy (CP).

Objective: The purpose of this study was to investigate differences in the timing characteristics of trunk and hip muscle activity during walking in young children with CP compared with children with typical development (TD).

Methods: Thirty-one children (16 with TD, 15 with CP) with an average of 28.5 months of walking experience participated in this observational study. Electromyographic data were collected from 16 trunk and hip muscles as participants walked at a self-selected pace. A custom-written computer program determined onset and offset of activity. Activation and coactivation data were analyzed for group differences.

Results: The children with CP had greater total activation and coactivation for all muscles except the external oblique muscle and differences in the timing of activation for all muscles compared with the TD group. The implications of the observed muscle activation patterns are discussed in reference to existing postural control literature.

Limitations: The potential influence of recording activity from adjacent deep trunk muscles is discussed, as well as the influence of the use of an assistive device by some children with CP.

Conclusions: Young children with CP demonstrate excessive, nonreciprocal trunk and hip muscle activation during walking compared with children with TD. Future studies should investigate the efficacy of treatments to reduce excessive muscle activity and improve coordination of postural muscles in CP.

Figures

Figure 1.

Mean total percent activation of trunk and hip muscles for children with cerebral palsy (CP) and children with typical development (TD). Bars represent upper and lower bounds of 95% confidence intervals. Asterisks indicate muscles that were significantly higher in the CP group compared with the TD group. TZ=trapezius, ES=erector spinae, RA=rectus abdominis, EO=external oblique, GMx=gluteus maximus, GMd=gluteus medius, RF=rectus femoris, and ST=semitendinosus.

Figure 2.

Histograms for number of active muscles at each point in the gait cycle (1% increments) in children with typical development (TD) and children with cerebral palsy (CP). Left and right sides were counted individually, for a maximum of 32 in the TD group and 30 in the CP group. Thick vertical lines indicate toe-off, the transition from stance phase to swing phase (57% of the gait cycle in the TD group, 59% of the gait cycle in the CP group). Asterisks indicate periods of activity where the CP group had significantly more active muscles than the TD group. TZ=trapezius, ES=erector spinae, RA=rectus abdominis, EO=external oblique, GMx=gluteus maximus, GMd=gluteus medius, RF=rectus femoris, and ST=semitendinosus.

Figure 3.

Muscle activity during the gait cycle in children with typical development (TD) and children with cerebral palsy (CP). Dashed vertical lines indicate toe-off, the transition from stance phase to swing phase (57% of the gait cycle in the TD group, 59% of the gait cycle in the CP group). TZ=trapezius, ES=erector spinae, RA=rectus abdominis, EO=external oblique, GMx=gluteus maximus, GMd=gluteus medius, RF=rectus femoris, and ST=semitendinosus.