Model

Through this experiment, I intend to show that there are a series of oscillations that occur during normal movement. Further study could correlate the oscillations to specific muscles or neurological impulses, but this paper will go so far as to begin to identify the fluctuations as the subjects attempt to balance on one foot.

Because our bodies did not develop for standing on one foot, it is a position which can easily be seen to be unstable. There are few muscles and tendons which help with lateral stability and those that do exist are relatively weak. From the data I collected, the results I wished to see stood out most clearly when the subjects stood on one foot. Not only were the oscillations the greatest in this position due to their instability, I was able to infer a correlation between when the subjects had their eyes open compared to when they were closed.

Figure 1

Data Analysis

I took the data I had gathered at 100 Hz and isolated each maneuver. Each time one of the subjects stood on one foot, there was a quick shift in the center of mass and then back in the direction of the foot he or she was standing on. I began the analysis by treating the zero crossing in the direction of the foot which was being stood on as t = 0. The end of the maneuver was considered to be when the subject’s center of mass crossed the zero point once again.

After I parsed the data into the different sections, each was put through a fast fourier transform. With only one sample per maneuver, this was not highly defined, but peaks existed on the graph which could be considered to be each impulse of the fourier transform.

I then sorted out each peak from the surrounding data and was left with a series of impulses such as this:

Figure 2

I analyzed each set of data for the three subjects and compared how the frequencies compared between having their eyes open and having their eyes closed. There was an increase in the number of frequencies when the subject’s eyes were closed. In keeping with the general hypothesis of this experiment, it is fair to assume that additional body movements are used to increase balance when vision is impaired. Arm, head and torso movements could see and increase in frequency as the body’s reflexes try to retain balance.

However, there was an overlap at several frequencies to a resolution for each test. The magnitude changes, but the frequency remains the same. These are the major oscillations that I predicted would be seen in the data. Each of these could potentially be tied to a specific joint or muscle.

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This work is licensed by Shane Hudak under a Creative Commons Attribution License (CC-BY 2.0), and is an Open Educational Resource.

Last edited by Shane Hudak on May 15, 2008 7:24 pm -0500.