[Determination of an expected plantar pressure threshold: dimensionless approach use to reduce the variability of the plantar pressures].
OBJECTIVE
The aim of this study was to verify that the determination of walking velocities proportional to the leg lengths of the subjects together with the dimensionless expression of the results enable us to decrease the variability and to determine a plantar pressure threshold.


METHODS
Fifteen male subjects performed two walking tests on a treadmill at imposed velocities (V1 and V3) and similar velocities (V27 and V37). Similar velocities (Vsim =Nfr(g.Li)(0.5)) were determined from two fractions of the Froude number (Nfr), the gravitational acceleration (g) and the length of the lower limb (Li) of the subjects. An in-shoe plantar pressure measurement system allowed the pressure peaks to be recorded. The peak of pressure (p) was reported to the step length (a) and the weight of the subject (mg) for the dimensionless pressure peaks (Dim(P)=p.a2/mg) to be expressed. The coefficients of variability (CoV) and extends of the dimensionless pressure peaks (Epp) have been studied at the different imposed walking velocities.


RESULTS
The CoV and Epp of the dimensionless pressure peaks recorded at V27 and V37 (similar velocities) are from 2 to 9% and 3 to 22% lower than those observed at V1 and V3, respectively.


CONCLUSIONS
The analysis of the pressure peaks CoV and Epp shows that the method should allow a data bank usable to detect the effects of a disability on the plantar pressures to be elaborated. Indeed, our results enable us to define a plantar pressure pattern with a variability lower than those reported in most scientific articles.
Laboratoire d'études de la motricité humaine, FSSEP, 9, rue de l'Université, 59790 Ronchin, France.
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Bisiaux
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Moretto
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Lensel
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Thévenon
D000328:Adult; D001696:Biomechanical Phenomena; D005528:Foot / Q000502:physiology*; D006801:Humans; D008297:Male; D011312:Pressure