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Old 03-20-2013, 07:59 AM   #67
Alex Megann
Dojo: Southampton Aikikai
Location: Southampton
Join Date: Sep 2004
Posts: 338
Re: A Consideration of Aikido Practice within the Context of Internal Training

Erick Mead wrote: View Post
Furitama and tekubifuri operate at ~10 Hz -- which happens to be the natural or resonant frequency (or its first harmonic) of the human body. Most interestingly in the context of neurodynamics is that this is in the middle of the alpha wave activity frequency band (8-12Hz) which is indicative of undifferentiated awareness -- a highly martial concern-- and also mu waves which are sensorimotor rhythms at 8-13Hz.
Hi Erick,

Does the human body (which is basically a collection of more or less loosely coupled, and more or less damped, oscillators) have a "resonant frequency"? Do you have a reference for this?

I can imagine that the lungs might act as cavity resonators, and I believe that the fluid-filled viscera indeed have a resonance at around this frequency (and hence would respond strongly to furitama), but if you bring in the arms, legs and head (as do most of us) it all gets rather complicated.

In my opinion it would be more interesting to ask what the transmission speed would be for mechanical disturbances from the wrists to the spine and from the spine to the feet (and hence derive a a characteristic time for each), and to compare this with the reaction time of the relevant parts of the neuromuscular system.

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