3.2 Spectral Analysis by Impulse Response on Walking 
The homeostasis is maintained in the human body. While 
walking, the movement of the left knee controls that of right 
knee, and visa versa. This is a feedback control loop of two 
variables. The computational impulse of two times the standard 
deviation (S.D.) of fluctuation of each subject's knee movement 
was applied as white noise in this study. When the impulse is 
given to left knee movement, it is transmitted and its response 
appears on the right knee movement, and visa versa. 
3.2.1 In case of the patients who have a damaged left back: 
before therapy, the value and the duration of the impulse 
response of the right knee is larger than that of the left knee. 
After a month therapy, both values and duration of the impulse 
responses of the right and left knee became smaller and similar 
to each other (Figure 6). 
After two months therapy, both values of the impulse responses 
of the right and left knee became similar to each other. This 
suggests that the left knee has no longer burdened and showed 
better walking stability. 
3.2.2 In case of the patient with a sprained right foot: before 
therapy, the value of the impulse response of left knee was 
larger than that of the right knee. After two months therapy, 
both values of the impulse responses of the right and left knee 
became similar to each other (Figure 7). This suggests that the 
left knee has no longer burdened and showed better walking 
stability. 
The value and duration of the impulse response curves have 
showed which knee is stronger and to what degree. In the case 
of the right knee is strong against the impulse, and the response 
value of left knee is small, the impulse seems to be absorbed 
and isn’t transmitted to the left knee, and visa versa. 
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Figure 6. Spectral Analysis by Impulse Response on Walking by Patient who has a Damaged Left Back 
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before therapy after therapy 
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Figure 7. Spectral Analysis by Impulse Response on Walking by Patient who has a Sprained Right Foot 
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