Attention-neuromuscular training for improving dynamic postural control in children with developmental coordination disorder

Abstract

Developmental coordination disorder (DCD) is a common neurodevelopmental motor disorder in school-age children. It is characterized by clumsiness in motor skills which significantly interferes with children’s daily activities and academic performance. Impaired postural control (balance) is one of the major motor deficits but research on dynamic (reactive and adaptive) balance performances in these children is lacking. Recent evidence has suggested that both cognitive (attention) and neuromuscular deficits may be contributing factors to inferior balance performance in people with disabilities. Hence, this thesis is the first investigation into the reactive and adaptive balance deficits and the associated cognitive and neuromuscular problems in children with DCD. A novel attention-neuromuscular perturbation-enhanced training program is then proposed.

In the first two cross-sectional studies, reactive and adaptive balance responses were assessed by a Motor Control Test (MCT) and an Adaptation Test (ADT), respectively. Leg muscle activation times were measured by surface electromyography (EMG), and attention levels were assessed by electroencephalography (EEG). These outcomes were compared between children with DCD and those typically developing (TD). Results revealed that the reactive balance responses in children with DCD were direction-specific, with longer latency in backward (p=0.048) but shorter latency in forward (p=0.024) MCT platform translations. Children with DCD were also less attentive during and after backward (p=0.042) and forward (p=0.031) platform translations. No significant differences in leg muscle activation latencies were found (p>0.05). Furthermore, while the TD group showed faster balance responses in the second trial compared to the first trial in ADT toes-up (p=0.005) and toes-down (p=0.001) platform inclinations, children with DCD failed to demonstrate similar postural adaptations.

In the third and fourth studies, randomised controlled trials were conducted to compare the effects of perturbation-enhanced neuromuscular training (NMT) with EEG-biofeedback attention training (AT), NMT alone, AT alone and controls on reactive and adaptive balance responses, associated leg muscle activation times and attention levels. Interventions were delivered twice weekly for 12 weeks. Outcome measures were taken before, after, and 3 months after training. At post-intervention, NMT-AT, NMT, and AT groups yielded faster reactive postural responses compared to the control group (p<0.001). In addition, only children in the NMT-AT and AT groups significantly improved in attention levels before or during platform translations (p<0.017). NMT failed to improve adaptive balance responses at post-intervention, but reduced ADT toes-down sway energy score at the 3-month follow-up (p=0.004). No changes in leg muscle activations were noted.

In summary, this thesis is the first to explore the reactive and adaptative balance responses and test a novel intervention NMT-AT in children with DCD. Direction-specific balance responses, inattention during postural disturbances, and failure to adapt in reactive balance tasks are noted in children with DCD. NMT-AT, NMT, and AT are comparable in improving reactive balance performance, with AT providing extra benefit in improving attention during postural control tasks. However, short-term NMT fails to induce postural adaptations. Rehabilitation for children with DCD should thus focus on reactive balance training and incorporate attention training. Further studies may explore other interventions to facilitate adaptative balance responses in these children.