Manual Therapy, Posturology & Rehabilitation Journal
http://mtprehabjournal.com/article/doi/10.17784/mtprehabjournal.2015.13.264
Technical Note

# From the center of pressure to the center of gravity, a new algorithm for a step forward in stabilometry

Downloads: 0
Views: 431

## Abstract

Introduction: For more than thirty years, in clinical stabilometry, we have been using the center of pressure (CoP) to calculate stabilometric parameters. That was a mistake because the CoP signal comprises two series of information, one on the position of the center of gravity (CoG), and the other on the acceleration of the CoG. Objective: A step forward must be taken in order to separate these variables clearly using the CoG instead of the CoP to calculate stabilometric parameters. A lot of methods have been proposed to obtain the CoG from the CoP, yet none of them is used. We present a new algorithm for the same purpose. Method: A new mathematical way for solving the differential equation of DA Winter is proposed, which can use the "edge effects" due to known boundary conditions of the variables. Result: Solving the Winter's equation has two interests: Clinicians may think about what is observed through a model, and inter-subjects comparisons are better thanks to Winter's coefficient. Conclusion: During its next session, the international Committee for standardization of clinical stabilometry must choose one method to obtain the CoG from the CoP, before this choice is made, this new method must be known, well known and well understood because it could be the best choice.

## Keywords

Clinical Stabilometry, Standardization, Center of Pressure, Center of Gravity

## References

1. Murray M, Seireg A, RC Scholz. Center of gravity, center of pressure, and supportive forces during human activities. J Appl Physiol. 1967;23:831-8.

2. Thomas D, Whitney R. Postural movements during normal standing in man. J Anat. 1959;93:524-39.

3. Gurfinkel V. Physical foundations of stabilography. Agressologie. 1973;14(C):9-14.

4. Gagey P, Bizzo G, Debruille O, Lacroix D. The one Hertz phenomenon. In: Igarashi M BF, editor. Vestibular and visual control on posture and locomotor equilibrium. Basel: Karger; 1985. p. 89-92.

5. Collins J, Luca Cd. Open-loop and closed-loop control of posture: a random-walk analysis of center-of-pressure trajectories. Exp Brain Res. 1993;95:308-18.

6. Winter D, Eng P. Human balance and posture control during standing and walking. Gait & Posture. 1995;3(4):193-214.

7. Gagey B. Subroutine to calculate the position of the center of mass from the position of the center of pressure. 2010 [updated 19/02/2015; cited 2015 19/02/2015]; Institut de Posturologie:[Software]. Available from: http://ada-posturologie.fr/Programme_Bernard-a.htm.

8. Houel N, Dornier N, Gagey P, Gagey B, Stubbe L. Évaluation de la précision et de la concordance de l’équation permettant de prédire la position du centre de gravité à partir du centre de pression dans le cadre de l’analyse posturale: Étude préliminaire. In: France Ardr-vP, editor. XXIIe Journées de Posturologie clinique; 24/25 Janvier 2015; Paris. Paris: Association Connaissance et ´`Évolution, 20 rue du rendez-vous 75012 Paris France; 2015. p. 53.

9. Dudde R, Müller G, Bourdeaux O, Gagey B, Weber B, Gagey P. Dialogue médecins/entraîneurs autour d’une plateforme de forces. Science et Sports. 2015 (In Press). Original Publication.

10. Gage W, Winter D, Frank J, Adkin A. Kinematic and kinetic validity of the inverted pendulum model in quiet standing. Gait & Posture. 2004;19(2):124-32.

11. Winter D, Patla A, Prince F. Stiffness control of balance during quiet standing. Gait and Posture. 1997;5(2):154-5.

12. Gagey B. Etude sur le coefficient de l’équation de Winter. 2013 [cited 2013 06/10//2013]; Available from: http://ada-posturologie.fr/Winter_coefficient_k2.pdf.

Links & Downloads

Share this page
Page Sections