Relationship between changes in motor capacity and objectively measured motor performance in ambulatory children with spastic cerebral palsy.

Background: Different interventions are offered to children with cerebral palsy (CP) to improve the activity domain of the international classification of functioning (ICF). In therapy settings, the focus is mostly on motor capacity, but the ultimate goal is to improve motor performance. We therefore examined if changes in motor capacity outcomes are accompanied by changes in objectively measured motor performance after a 3-month intensive treatment period in ambulatory children with CP.

Methods: A secondary analysis on prospective clinical trial data was performed using multivariate linear regression. Sixty-five children (37 boys and 28 girls) with spastic CP, mean age 7 years and 3 months, Gross Motor Function Classification System (GMFCS) levels I-III were involved in a distinct 3-month intensive treatment period. Motor capacity (Gross Motor Function Measure [GMFM], functional muscle strength [FMS], and walking speed [WS]) and motor performance (using three Actigraph-GT3X+-derived outcome measures) were measured at baseline, 12 and 24 weeks.

Results: No significant associations were found for any of the change scores (∆ ) between motor capacity and motor performance after a 12-week intensive treatment period. After 24 weeks, ∆ FMS (p = .042) and ∆ WS (p = .036) were significantly associated with changes in motor performance outcome measure percentage of time spent sedentary (∆ %sedentary). In this model, 16% of variance of ∆ %sedentary was explained by changes in motor capacity (p = .030).

Conclusions: Changes in motor capacity are mostly not accompanied by changes in objectively measured motor performance after an intensive treatment period for ambulatory children with CP. These findings should be taken into account during goal setting and are important to manage expectations of both short- and longer term effects of treatment programmes.