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I want to compare the much-talked about Cheeta running prosthesis to a the normal running process in terms of force and energy, but I don't know where to start. How would you start the comparison? A mathematical model would be much appreciated.

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This is probably too complicated an issue address accurately here. see – Mark Eichenlaub Dec 21 '10 at 11:21
You need to know what you wanna compare. – TROLLKILLER Dec 21 '10 at 11:51
Perhaps, if the OP rewords the question a little, we can give qualitative reasons towards why it is more efficient then a regular leg. But we really can't address it quantitatively. – Malabarba Dec 21 '10 at 13:54

As mentioned in comments, the question isn't very well-defined, but I'll seed some ideas for basis of comparison.


  • Put a series of pressure transducers on the sole of a shoe & on the bottom of the Cheeta
    • Measure the distribution/duration of force.
    • Compare the amount of force that gets translated into forward momentum.
    • Compare the duration of force, see if one exerts horizontal force longer.
  • Measure the strength of various muscles on both runners, look for discrepancy in muscles used.
  • Measure displacement of the body of the Cheeta, calculate stress, compare to stress in joints.


  • Compare runner's speeds under different loading conditions (50 lbs. backpack, etc.)
  • Compare runner's speeds up/down hills.
  • Hook runners up to oxygen consumption monitors, measure VO2max, calculate energy expenditure while running.

Just some ideas, any of which would provide interesting basis for comparison in terms of "force and energy."

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