The natural frequency of the foot-surface cushion during the stance phase of running

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Journal of Biomechancis in press:

http://www.jbiomech.com/article/S0021-9290(10)00607-X/abstract

The natural frequency of the foot-surface cushion during the stance phase of running

Wangdo Kim, John Tan, Antonio Veloso, Veronica Vleck, Arkady S. Voloshin

Found this, looked interesting and would not mind a read of the full text.

But in reading the abstract something jumped out.

Why would you use a inverted pendulum model for running when a spring mass model is the norm.

Also the journal key words are leg stiffness as we have discussed leg stiffness is based on spring mass models so somewhat

 

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Just a quick post Mike, I haven't read the paper yet. I think that spring-mass and inverted-pendulum are effectively the same model. That is, the inverted-pendulum model is just and example of the spring-mass model with a very, very high Kleg. In other words, the spring-mass model considers the leg to be relatively more compliant than the inverted-pendulum model, but theoretically if we plotted GRF's and energetics for every Kleg from infinitely compliant to infinitely stiff, would we not see a gradual transition from those observed with the spring-mass model towards those observed with the inverted-pendulum model as leg stiffness increased toward infinity??

Now, until I've read the paper, I have no idea why they modelled running as a stiff-legged gait.

 

Thanks sir

I agree about the stiff spring-mass model in walking from our discussions last year. Perhaps the paper will shed some light on the matter of why a stiff spring-mass model was used.

 

Right Ive had a read and the authors state their main aim.

So I see what they say but I still don´t get why the knee was removed, In my way of thinking the flexion -extension moment at the knee would effect the cushioning at the ground foot interface ?