Effect of seat surface inclination on postural stability and forward reaching efficiency in children with spastic cerebral palsy.
Tip the seat slightly forward so kids with spastic CP sit steadier and reach faster.
01Research in Context
What this study did
The team tilted a seat three ways: flat, a little forward, or a little back.
Kids with spastic CP and typically-developing peers reached for toys while the researchers tracked how much their bodies swayed.
Force plates under the seat measured every tiny wobble.
What they found
When the seat tipped forward the children sat steadier and grabbed toys faster.
When it tipped backward the kids with CP rocked side-to-side more, making reaches slower.
The same tilt hurt balance for both groups, but the CP group showed the bigger change.
How this fits with other research
Cimolin et al. (2011) and Capodaglio et al. (2011) saw adults with Prader-Willi sway more front-to-back while standing still.
Rong-Ju et al. now show kids with CP sway more side-to-side when the seat tilts back.
Together the papers map direction-specific balance problems: PWS adults struggle forward-backward; CP children struggle left-right.
Galli et al. (2011) and Rigoldi et al. (2013) link extra sway in Ehlers-Danlos to weak, floppy muscles.
The CP findings echo this: posterior tilt forces the same weak muscles to work harder, so sway grows.
Why it matters
If you seat a child with spastic CP, slide a thin wedge under the front of the chair.
A slight forward tilt gives the child a stable base for writing, eating, or play tasks without extra equipment.
Check that the hips do not slide; a non-slip mat can help.
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Join Free →Slide a 5-degree wedge under the front of the chair and time one reach task—note if the child finishes faster with less trunk wobble.
02At a glance
03Original abstract
The purpose of this study was to examine the effect of seat surface inclination on postural stability and forward reaching efficiency in 10 children with spastic cerebral palsy (CP) and 16 typically developing (TD) children. The children performed a static sitting and a forward reaching task while sitting on a height- and inclination-adjustable stool at flat, three anterior-inclined, and three posterior-inclined positions. Postural stability was expressed as normalized (with body weight) peak vertical ground reaction force, center of pressure displacement in the anterior/posterior directions (COP_AP), in the medial/lateral directions (COP_ML), and sway ratio (COP_AP/COP_ML). Reaching efficiency was expressed as reaction time and movement time of arm reaching forward to a target. The results showed that seat inclination affected children's postural stability and the effects were comparable for CP and TD children in all measures except for COP_ML. Children with CP presented much larger COP_ML than TD children at the posterior-inclined positions relative to the flat and the anterior-inclined positions. Seat inclination affected reaching efficiency for both groups of children equally. Efficiency was better at the anterior positions than the posterior positions. Anterior-inclined positions improved postural stability and reaching efficiency. Posterior positions posed greater postural challenge and the challenge was tougher for children with CP.
Research in developmental disabilities, 2009 · doi:10.1016/j.ridd.2009.07.002