title: Slowed muscle force production and sensory organization deficits contribute to altered postural control strategies in children with developmental coordination disorder.
abstract: This study aimed to (1) compare the postural control strategies, sensory organization of balance control, and lower limb muscle performance of children with and without developmental coordination disorder (DCD) and (2) determine the association between postural control strategies, sensory organization parameters and knee muscle performance indices among children with DCD. Fifty-eight DCD-affected children and 46 typically developing children participated in the study. Postural control strategies and sensory organization were evaluated with the sensory organization test (SOT). Knee muscle strength and time to produce maximum muscle torque (at 180°/s) were assessed using an isokinetic machine. Analysis of variance was used to compare the outcome variables between groups, and multiple regression analysis was used to examine the relationships between postural control strategies, sensory organization parameters, and isokinetic indices in children with DCD. The DCD group had significantly lower strategy scores (SOT conditions 5 and 6), lower visual and vestibular ratios, and took a longer time to reach peak torque in the knee flexor muscles than the control group (p>0.05). After accounting for age, sex, and body mass index, the vestibular ratio explained 35.8% of the variance in the strategy score of SOT condition 5 (p<0.05). Moreover, the visual ratio, vestibular ratio, and time to peak torque of the knee flexors were all significant predictors (p<0.05) of the strategy score during SOT condition 6, accounting for 14, 19.7, and 19.8% of its variance, respectively. The children with DCD demonstrated deficits in postural control strategy, sensory organization and prolonged duration of muscle force development. Slowed knee muscle force production combined with poor visual and vestibular functioning may result in greater use of hip strategy by children with DCD in sensory challenging environments.
authors.affiliation: Institute of Human Performance, The University of Hong Kong, Hong Kong. smfong@hku.hk
authors.forename: Shirley S M
authors.initials: SS
authors.lastname: Fong
authors.forename: Shamay S M
authors.initials: SS
authors.lastname: Ng
authors.forename: Beverley P H L
authors.initials: BP
authors.lastname: Yiu
mesh_terms: D016022:Case-Control Studies; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D009048:Motor Skills / Q000502:physiology; D019957:Motor Skills Disorders / Q000503:physiopathology*; D009119:Muscle Contraction / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012678:Sensation Disorders / Q000503:physiopathology*; D014722:Vestibule, Labyrinth / Q000502:physiology
keywords: Balance; Clumsy children; Motor strategy; Muscle contraction time; Sensory inputs