Abstract: Objective To study the general rule in the power spectrum percentage of balance when normal people standing and the differences of the power spectrum percentage between normal people and the stroke patients. Methods 30 normal people and 30 stroke patients was tested with Active Balancer EAB-100 (Sakai Iryo) open- and close-eye. The whole path length, circumference area and the percentages of power spectrum on the X, Y and Z axes were recorded. The correlation and the differences were analyzed. Results The percentages of power spectrum were not statistically correlated (P>0.05) with age, height, weight or gender. There was significant difference between two groups in the percentage of power spectrum (P<0.05). On the frequency spectrum, the ratio rised on the low and middle frequency part, especially within 0.2~2 Hz, but the ratio decreased on the high frequency part (2~10 Hz) (P<0.05). Conclusion The percentage of power spectrum can be an important reference in assessing the stroke patients' balancing functions.

Key words: power spectrum, percentage, stroke, balance function