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Introduction to the Russo-Japanese revolution in stabilometry

DOI:10.17784/mtprehabjournal.2018.16.584
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Pierre-Marie Gagey
Pierre-Marie Gagey
Pierre-Marie Gagey
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We knew that the postural system was concerned with the venous return circulation and the stabilization of the body, but we did not know that the stabilometric signal was modified by the interference of these two functions. A new signal analysis is being made.
SHORT COMMUNICATION
Manual Therapy, Posturology & Rehabilitation Journal. ISSN 2236-5435. Copyright © 2017. This is an Open Access article
distributed under the terms of the Creative Commons Attribution Non-Commercial License which permits unrestricted non-
commercial use, distribution, and reproduction in any medium provided article is properly cited.
Introduction to the Russo-Japanese revolution in stabilometry.
Pierre-Marie Gagey1
ABSTRACT
We knew that the postural system was concerned with the venous return circulation and the stabilization of the body, but we did
not know that the stabilometric signal was modified by the interference of these two functions. A new signal analysis is being made.
Keywords: Posturology; Stabilometry; Stability; Circulation; Signal analysis;
Corresponding author: Pierre-Marie Gagey; Institute of Posturology, 20 rue du Rendez-vous, 75012 Paris, France. e-mail: pmgagey@gmail.com
1 Institute of Posturology, 20 rue du Rendez-vous, 75012 Paris, France.
Financial support: The author declare no nancial support.
Submission date 02 March 2018; Acceptance date 03 May 2018; Publication date 02 July 2018
http://dx.doi.org/10.17784/mtprehabjournal.2018.16.584
BACKGROUND
Since the studies by Inamura et al. were published(1–3), we
know that the postural system is also concerned with control
of the venous return circulaon (Figure 1).
The discovery of Inamura et al. did not change our approach
to stabilometry, which we pursued it from a purely mechanical
perspecve, in relaonship to the subject’s stability, without
being able to determine how to integrate this discovery into
our reecons. At that me, venous return was not a focus of
our interests; we were trying to gure out how to calculate the
posion of the center of gravity from the posion of the center
of pressure, which mobilized a large number of teams for
decades unl in 2016(4–15). Recently, V. Usachev and V. Belyaev
took on long-term stabilometric recordings (7 minutes).
They showed migraons, about every minute, of the average
point around which the center of pressure stabilizes during
this minute (Figure 2).
These displacements of the pressure zones on the plantar
sole, and, consequently, on Lejars’ venous sole(17,18) evoke
phenomena implicated in venous return, which remain to
be conrmed. But, on the other hand, the migraons, every
minute, of the mean point around which the center of pressure
stabilizes during that minute, have immediate consequences
on our concepon of stabilometric signal analysis. We can no
longer speak of X-means and Y-means, except in the mode
of approximate values because there are indeed a series of
dierent X-means and Y-means, and the X-mean and Y-mean
Figure 1 - Stabilogram/Plethysmogram Comparison; Inamura’s “one-minute wave”.
Note: A: Nine 1-minute recordings. Only the forward/backward stabilogram is shown, in phase opposion to the contours of the leg. B: Enlargement of a
part of A to show the connuity of the volume wave between the leg and thorax. This subject’s wave frequency is between 0.012 and 0.022 Hz. (Figure
reworked aer Inamura et al., 1990).
2
Russo-Japanese revolution in stabilometry MTP&RehabJournal 2018, 16: 584
that are computed on short recordings represent only singular
elements of this series. According to the video images, the
dierence would be more important between the Y-means
than between the X-means, which is in accordance with the
stascally known extents of the deviaons of the Y-means,
48 cm, and of the X-means, 2 cm, described in Normes 85(19).
We can no longer speak of measuring stability, since there
is no longer ONE mean equilibrium posion; remember that
stability is the property of a body that automacally returns
to the vicinity of ITS equilibrium posion, when it is displaced
from it.
CAN WE STILL TALK ABOUT “STABILOMETRY”?
The Russians and the Japanese already proposed
“stabilometric” parameters that take into account the
complexity of the signal coming from the force plaorms,
because that signal accounts for stability phenomena, along
with hemodynamic phenomena(20).
CONFLICT OF INTERESTING
The author declare no conict of interest.
REFERENCES
1. Inamura K, Mano T, Iwaze S, editors. One minute wave of body sway
related to muscle pumping during stac standing in human. ISPGR; 1990;
München: Georg Thieme (Stugart).
2. Inamura K, Mano Y, Iwaze S, Yamamoto K, editors. Changes in funconing
mechanisms of one minute wave in body uid volume during head-up
and head-down lngs in humans. Posture and gait: control mechanisms;
1992; Portland: University of Oregon Books.
3. Inamura K, Mano T, Iwaze S. Role of postural sway as a compensatory
mechanism for gravitaonal stress on the cardiovascular system. Gait
Posture. 1999; 9 (suppl. 1):S5.
4. Spaepen A, Vranken M, Willems E. Comparison of the movements of the
center of gravity and of the center of pressure in stabilometric studies.
Agressologie. 1977;18(2):109-13.
5. Shimba T. An esmaon of center of gravity from force plaorm data. J
Biomech. 1984;17(1):53-60.
6. Levine O, J M. An iterave model for the esmaon of the trajectory of the
center of gravity from bilateral reacve force measurements in standing
sway. Gait Posture. 1996;4:89-99.
7. King D, Zatsiorsky V. Extracting gravity line displacement from
stabilographic recordings. Gait & Posture. 1997;6(1):27-38.
8. Caron J, Faure B, Brenière Y. Esmang the centre of gravity of the body
on the basis of the centre of pressure in standing posture. J Biomech.
1997;11-12:1169-71.
9. Brenière Y. Why we walk the way we do? J Motor Behavior. 1996;28(4):291-8.
10. Zatsiorsky V, D K. An algorithm for determining gravity line locaon from
posturographic recordings. J Biomechanics. 1998;31:161-4.
11. Morasso P, Spada G, Capra R. Compung the COM from the COP in postural
sway movements. Human Movement Science. 1999;18:759-67.
12. Barbier F, Allard P, Guelton K, Colobert B, Godillon-Maquinghen A.
Esmaon of the 3-D center of mass excursion from force-plate data
during standing. IEEE Trans Neural Syst Rehabil Eng. 2003;11(1):31-7.
13. Hugon M, Ouaknine. M, editors. L’équilibration posturale se réalise
par relaxaon entretenue de commandes automasées. Ecience et
Déciences du Contrôle Postural; 2004; Dijon.
14. Gagey B, Bourdeaux O, Gagey P. From the center of pressure to the center
of gravity, a new algorithm for a step forward in stabilometry. MTPRehab
Journal. 2015;13:264-70.
15. Gagey B. Soluon théorique et calcul praque de l’équaon du pendule
simple inversé dite de Winter. 2016 [Available from: http://ada-
posturologie.fr/Programme_Bernard.pdf.
16. Belyaev V. Film of a seven minutes stabilometric recording 2017 [Available
from: hp://ada-posturologie.fr/signal.htm.
17. Lejars F. Les veines de la plante du pied. Archives de Physiologie. 1890;5.
pages
18. Bourceret. Circulation locale. Procédé d’injection des veines. Note
présentée à l’Académie des Sciences 1885.
19. A.F.P. Normes 85: ADAP; 1985.
20. Usachev V, Belyaev V, Kononov A, Gagey P. The SKG area is not an
informave parameter of stability. Man. Ther., Posturology Rehabil. J. In
press.
Figure 2 - One-minute movement summaries of a 7-minute stabilometric recording
Note: (From the video made by V. Belyaev(16)). A: Contour of the surface that will be occupied during the recording session by the pressure center displacements
by the end of the 7-minute recording. (To give a general overview of the framework of these movements). B: Tracing of the summarized movement of the
stabilizaon zone of the center of pressure during minute 1 (Freeze frame at the end of the rst minute). C: Tracing of the summarized movement of the
stabilizaon zone of the center of pressure during minute 2 (Freeze frame at the end of the second minute). D: Tracing of the summarized movement of the
stabilizaon zone of the center of pressure during minute 4: note the clear shi from the preceding zones (Freeze frame at the end of the fourth minute).
E: Global summary of the 7-minute recording of the nal frozen frame of the video.
... The publications of Inamura and his colleagues, have had no echo among posturologists until the long-term stabilometric recordings made by Belayev and Usachev (4) showing instead that the postural oscillations of one minute could be accompanied at each oscillation, by a migration of the center of pressure. This questioned the conventional concepts, in the analysis of the stabilometric signal, of the mean position of the center of pressure and consequently the measures of deviation from the average position of the center of pressure which were used to evaluate the stability of the subject (5) . These migrations of the center of pressure then suggested the hypothesis that they participated in the ejection of the blood contained in the venous sole of Lejars (5,6) . ...
... This questioned the conventional concepts, in the analysis of the stabilometric signal, of the mean position of the center of pressure and consequently the measures of deviation from the average position of the center of pressure which were used to evaluate the stability of the subject (5) . These migrations of the center of pressure then suggested the hypothesis that they participated in the ejection of the blood contained in the venous sole of Lejars (5,6) . Clumsy hypothesis because since 2010 an anatomical work (7) had shown that this venous sole of Lejars was an artifact. ...
... It continues with the effect of the contraction of the leg muscles, all the more efficient as the rhythm of these contractions increases. The stretching of the tissues of the posterior compartment of the leg also causes an increase of the venous flow, which suggests an effectiveness of the anterior tibialis, with no available guarantee from these experiments The inaugural work of Inamura et al. (1)(2)(3) is thus largely confirmed: the postural system plays an important role in the venous return circulation and the repercussion of this function on the stabilometric observations must be at last studied (5) . ...
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