Local dynamic stability during treadmill walking can detect children with developmental coordination disorder.

OBJECTIVE: Developmental coordination disorder (DCD) is an innate impairment of motor coordination that affects basic locomotion and balance. This study investigated local dynamic stability of trunk accelerations during treadmill walking as an objective evaluation of gait stability and the sensitivity and specificity of this measure to discriminate children with DCD from typically developing children. METHOD: Eight children with DCD and ten age- and gender-matched typically developing children (TD) walked four minutes on a treadmill. Trunk accelerations in vertical, medio-lateral and anterior-posterior directions were recorded with a sternum mounted accelerometer at 256Hz. Short term local dynamic stability (λs), root mean square (RMS) and relative root mean square (RMSR) were calculated from measures of orthogonal trunk accelerations. Receiver operating characteristic curve (ROC) analysis was performed to discriminate between groups based on short term local dynamic stability. RESULTS: λs was significantly greater in children with DCD in the main movement direction (AP) (DCD: 1.69±0.17 λs; TD:1.41±0.17 λs; p=0.005), indicating reduced local dynamic stability. RMS and RMSR accelerations showed no difference between children with DCD and TD children in any direction. The ROC analysis of λs in separate directions and in two dimensions showed an excellent accuracy of discriminating between children with DCD and TD children. Anterior-posterior direction in combination with medio-lateral or vertical showed best performance with an area under the curve (AUC) of 0.91. CONCLUSION: We have shown that children with developmental coordination disorder have general reduced local dynamic stability and that the short term Lyapunov exponent has good power of discrimination between DCD and TD.

Impaired postural control in children with developmental coordination disorder is related to less efficient central as well as peripheral control.

BACKGROUND: Developmental coordination disorder (DCD) is a neurodevelopmental impairment that affects approximately 6% of children in primary school age. Children with DCD are characterized by impaired postural control. It has yet to be determined what effect peripheral and central neuromuscular control has on their balance control. OBJECTIVE: The aim of this study was to investigate the underlying mechanisms to impaired postural control in children with DCD using the rambling-trembling decomposition of the center of pressure (CoP). METHOD: Nine children with DCD (9.0±0.5years, 7 boys, 2 girls) and 10 age- and gender-matched typically developing children (TD) with normal motor proficiency (9.1±0.4years, 7 boys and 3 girls) performed 3×30s bipedal standing on a force plate in six sensory conditions following the sensory organization procedure. Sway length was measured and rambling-trembling decomposition of CoP was calculated in medio-lateral (ML) and anterior-posterior (AP) direction. RESULTS: Both rambling and trembling were larger for the children with DCD in AP (p=0.031; p=0.050) and ML direction (p=0.025; p=0.007), respectively. ML rambling trajectories did not differ in any conditions with fixed support surface. In ML direction children with DCD had a lower relative contribution of rambling to total sway (p=0.013). CONCLUSION: This study showed that impaired postural control in children with DCD is associated with less efficient supraspinal control represented by increased rambling, but also by reduced spinal feedback control or peripheral control manifested as increased trembling.

Body weight-supported training in Becker and limb girdle 2I muscular dystrophy.

INTRODUCTION: We studied the functional effects of combined strength and aerobic anti-gravity training in severely affected patients with Becker and Limb-Girdle muscular dystrophies. METHODS: Eight patients performed 10-week progressive combined strength (squats, calf raises, lunges) and aerobic (walk/run, jogging in place or high knee-lift) training 3 times/week in a lower-body positive pressure environment. Closed-kinetic-chain leg muscle strength, isometric knee strength, rate of force development (RFD), and reaction time were evaluated. RESULTS: Baseline data indicated an intact neural activation pattern but showed compromised muscle contractile properties. Training (compliance 91%) improved functional leg muscle strength. Squat series performance increased 30%, calf raises 45%, and lunges 23%. CONCLUSIONS: Anti-gravity training improved closed-kinetic-chain leg muscle strength despite no changes in isometric knee extension strength and absolute RFD. The improved closed-kinetic-chain performance may relate to neural adaptation involving motor learning and/or improved muscle strength of other muscles than the weak knee extensors. Muscle Nerve 54: 239-243, 2016.