Objective
To investigate differences of the postural control in unstable sitting position between elderly and young adults. Method: Twenty five healthy elderly and twenty five healthy young adults were included. The evaluation system for postural control consisted of unstable plate, frame, safety harness, monitor and computer. Subjects sat on an unstable plate with arms crossed. Using two tilt sensor and postural control software in unstable platform measured the center of pressure (COP) of subject. COP sway (COP was maintained on the center circle and the distance from the central location for 30 sec) time and mean absolute deviation (MAD), COP maintaining (COP was maintained on the desired target in anterior, posterior, left or right directions during 30 sec) time and MAD, COP moving time (the time required to move the COP to desired target location away from center), COP sine curve maintaining (COP was maintained on the circle on moving sine curve during 30 sec) time and MAD were recorded in both groups. Each subject performed three trials and the mean value of the trials was used for analysis. Results: In static evaluation, there was no significant difference in COP sway between two groups. In dynamic evaluations, elderly showed significantly decreased maintaining time in all four directions, decreased sine curve trace and increased moving time in all eight directions (p＜ 0.001). Conclusion: Elderly revealed significantly impaired dynamic sitting postural control, regardless of directions. It might be related to decreased movement and proprioception of trunk. (J Korean Acad Rehab Med 2010; 34: 59-65)

Objective
To investigate differences in the dynamic postural control in unstable sitting position between children with spastic diplegic cerebral palsy (CP) and normally developing children. Method: Sixteen children with spastic diplegic CP who could sit alone and walk independently and sixteen age- matched normally developing children were included. The evaluation system for postural control consisted of unstable platform, force plate, frame, safety harness, monitor and computer. Force plate on unstable platform measured center of pressure (COP) of the subject. COP sway, COP maintaining time and COP moving time were recorded in both groups. In diplegic CP group, Gross Motor Function Measure (GMFM) was evaluated. Results: In COP sway, the distance away from central location was significantly increased and time maintaining on circle at center decreased significantly in diplegic CP group (p＜0.05). The children with diplegic CP showed significant decrease in maintaining time and significant increase in moving time in all directions. COP sway was significantly correlated with GMFM. Conclusion: Postural control in children with spastic diplegic CP walking independently was revealed to be significantly worse compared to normal age-matched children. Further studies are necessary to find out whether the training for seated postural control could improve the motor function. (J Korean Acad Rehab Med 2009; 33: 552-556)