Objectives: To compare the effectiveness of Tai Chi-muscle power training (TC-MPT), Tai Chi (TC) alone, muscle power training (MPT) alone, and usual care (as a control) for improving the limits of stability (LOS) of balance control in children with developmental coordination disorder (DCD) and to explore the relationship among LOS, falls, and functional performance in this population.

Design: A randomized controlled trial. Sample: 156 children with DCD. Interventions: TC-MPT, TC alone, MPT alone, or usual care for 12 weeks. Major outcomes: Outcomes will be evaluated at baseline, post-intervention, and a 3-month follow-up. An LOS test will give a dynamic LOS score, an isokinetic test will quantify leg muscle force production speed, Movement Assessment Battery for Children-2 will be used to assess functional motor performance, and fall history will be obtained via interviews.

Anticipated results and significance: The TC-MPT group is predicted to display the best LOS balance performance, which is associated with reduced fall incidents and improved functional performance. This novel training regime could be readily adopted into school or clinical settings to improve physical well-being in children with DCD, an outcome with positive socioeconomic implications.

Children with developmental coordination disorder (DCD), who comprise about 6% of the primary school population, display marked movement and balance difficulties. Reduced limits of stability (LOS), the maximum spatial area in which a standing person can lean, in these children is a major concern because it predisposes them to falls and affects their motor development.

The investigator's recent studies demonstrate the underlying causes of impaired LOS in children with DCD to include suboptimal volitional control of the center of gravity (COG) and reduced leg muscle force production speed. Tai chi (TC) is a particularly suitable exercise for improving COG control, yet the speed of movement is too slow to improve muscle power. Hence, muscle power training (MPT), which can hasten leg muscle force production, in conjunction with TC (TC-MPT) may be an ideal therapy for improving LOS, preventing falls, and improving functional performance in children with DCD.

In the proposed study, the investigators will pioneer the treatment of both COG control and leg muscular deficit in children with DCD by incorporating MPT into TC. It is hypothesized that the LOS of balance control in these children can best be improved by treating both their COG control and muscular deficits. This hypothesis is supported by the prediction that TC-MPT is superior to either TC or MPT alone in improving LOS balance performance. Furthermore, improved LOS is associated with fewer fall incidents and better functional performance in children with DCD.

Objectives: To compare the effectiveness of TC-MPT, TC alone, MPT alone, and usual care (as a control) for improving the LOS of balance control in children with DCD and to explore the relationship among LOS, falls, and functional performance in this population.

Design: A randomized controlled trial. Sample: 156 children with DCD. Interventions: TC-MPT, TC alone, MPT alone, or usual care for 12 weeks. Major outcomes: Outcomes will be evaluated at baseline, post-intervention, and a 3-month follow-up. An LOS test will give a dynamic LOS score, an isokinetic test will quantify leg muscle force production speed, Movement Assessment Battery for Children-2 will be used to assess functional motor performance, and fall history will be obtained via interviews.

Anticipated results and significance: The TC-MPT group is predicted to display the best LOS balance performance, which is associated with reduced fall incidents and improved functional performance. This novel training regime could be readily adopted into school or clinical settings to improve physical well-being in children with DCD, an outcome with positive socioeconomic implications.

Inclusion Criteria:

9- to 12-years-old

Classified as DCD according to the Diagnostic and Statistical Manual of Mental Disorders V (DSM-5)

A percentile score of < 5th percentile on the MABC-2

A total score of < 55 (for children aged 8 to 9 years 11 months) or < 57 (for children aged 10 or above) on the DCD questionnaire 2007 (Chinese version)

Attending a mainstream primary school (i.e., intelligence level within the normal range)

Exclusion Criteria:

Any known significant congenital, cognitive, psychiatric (other than comorbid attention deficit hyperactivity disorder [ADHD] or autism spectrum disorder [ASD]), neurological, sensory, musculoskeletal, or cardiopulmonary disorder that may affect motor performance

Receiving active treatment such as physiotherapy

Demonstrating excessive disruptive behavior during the assessments

Those unable to follow instructions properly