View Full Version : Using oscillations to measure leg stiffness.

06-13-2006, 04:53 AM

I am looking for any citations or comments on using vertical leg
oscillations to measure leg stiffness.

I have been using an Excel/VB version of the Spring Mass model to understand
the relation between running kinetics and gait parameters. The model
requires the leg stiffness (kN/m).

I estimate stiffness by measuring the frequency of small vertical (~3 cm)
oscillations while standing on one leg when the knee is flexed to the
approximate angle it has during mid-stance (k=m*(2*PI*f)^2)

Is this a reasonable method for measuring leg stiffness? I obtain values in
the area of 18+/-2 kN/m?

Is there any research that compares this simple method with the approach
that uses the vertical GRF and COM displacement?

Ted Andresen
Math Department
St. Petersburg College
St. Petersburg, Florida
Will factor polynomials for food.