ProActionClinic a mené plusieurs années de recherches et de synthèse de nombreux travaux scientifiques et a mis au point le coussin extensit.

Extensit est la bases d’une nouvelle stratégie d’approche des troubles posturaux et des maux de dos qui y sont probablement liés.



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Recent works have put into an evidence new concepts on global postural strategy and  treatment.

« In upright posture, the trunk load passes the sacroiliac joints (SIJ). The orientation of the SIJ surfaces, however, is more or less in line with the direction of loading, which induces high shear forces between sacrum and coxal bones.[1] [2] The SIJ have a strong passive, viscoelastic ligamentous system for providing stability. These ligaments are vulnerable for creep during constant trunk  load and need to be protected against high SIJ shear forces.[3] From a biomechanical point of view, an active muscle corset that increases the compression force between the coxal bones and the sacrum could protect the ligamentous system and support the transfer of trunk load to the legs and vice versa »[4]

« Effective stabilization of the sacroiliac joints (SIJ) is essential, since spinal loading is transferred via the SIJ to the coxal bones, and further to the legs.(…) reduction of the vertical SIJ shear force resulted in further increase of SIJ compression force by 400%, due to activation of the transversely oriented M. transversus abdominis and pelvic floor muscles. The M. transversus abdominis crosses the SIJ and clamps the sacrum between the coxal bones. Moreover, the pelvic floor muscles oppose lateral movement of the coxal bones, which stabilizes the position of the sacrum between the coxal bones (the pelvic arc). »[5]

Dysfunction of these physiological phenomenons can lead to global altered postural strategy.

Instead of transcient, transversely oriented muscular activation  clamping the sacrum between the coxal bones can become permanent. Unprepared for this role, Transversus abd. and pelvic floor soon get tired and as a result, have to modify their properties and configuration. At that time, these muscles will impose a permanent and excessive compression force on sacroiliac joints and, on an other part, their protective action against shear will be delayed in case of need : weight loading for ex..[6] [7] Unstabilized shear can lead to altered mechanotransduction in extracellular matrix, essential in normal conditions for  homeostasis of the joint. [8] [9] [10] [11] [12] [13]

Increased permanent activation of Transversus abd. and pelvic floor definitely induces increased permanent abdominal pressure which in turn increase diaphragm pressure and finally decrease diaphragm  respiratory excursion and even modify its position and postural function. [14] [15] [16] [17] [18]As a compensation, respiratory accessory muscles will be also activated, leading to an over-activated « muscular serie » (i.e. scalene, trapezius, sterno-cl.mast, intercostal m., diaphragm, transv.abd and pelvic floor)  reporting tension on the whole vertebral column, unilateraly or bilateraly.[19] [20] [21] [22] [23] [24]

Other postural muscles take part to this over-activation : para-lumbar muscles which provoke  undesirable compressive effects[25] and iliopsoas which induce knee flexum and shortening of hamstrings.[26]

In conclusion, one can figure out that global altered postural strategy can be treated by iliosacral joint counter-shear.

That’s the way extensit pad acts : progressive iliosacral joint counter-shear (effective after 10 (minimal) to 20 minutes (optimal)  can reverse altered postural strategy above described.

The Extensit pad induces a posture allowing a gradual, gentle, painless stretching and with programmable duration.
The patient may remain clothed, removing the belt. Supine, the sacrum is maintained by the nose of the pad,  vertebral column is extended, so the two ilium bones  gently go down  which induce iliosacral joint counter- shear.

And especially : this counter- shear is bilateral.

Please note that due to « muscular serie »,  induced  muscular relaxation following counter-shear can also benefit to cervical mobility (rotation)  and to hip mobility which can involve better knee extension due to simultaneous psoas muscles stretching.


Extensit cushion can be used in complement with  other medical treatment : see scientific studies and  speak to your therapist !


[1] Andersson E. A, Oddsson L. I. E, Grundstrom H, Nilsson J, Thorstensson A.  EMG activities of the quadratus lumborum and erector spinae muscles during flexion–relaxation and other motor tasks. Clin. Biomech. 11:392–400, 1996.

[2] Brand R. A, Crowninshield R. D, Wittstock C. E, Pedersen D. R, Clark C. R, van Krieken F. M. A model of lower extremity muscular anatomy J. Biomech. 104:304–310, 1982.

[3] McGill S. M, Brown S. Creep response of the lumbar spine to prolonged full flexion. Clin. Biomech. 7:1975–1983, 1992.

[4] van Wingerden JP, Vleeming A, Buyruk HM, Raissadat K. Stabilization of the sacroiliac joint in vivo: verification of muscular contribution to force closure of the pelvis. Eur Spine J. 2004 May;13(3):199-205.

[5] Pel J.M, Spoor C. W,  Pool-Goudzwaard A. L, Hoek van Dijke G. A, Snijders C. J. Biomechanical Analysis of Reducing Sacroiliac Joint Shear Load by Optimization of Pelvic Muscle and Ligament Forces. Ann Biomed Eng. 2008 March; 36(3): 415–424.

[6] Richardson CA, Snijders CJ, Hides JA, Damen L, Pas MS, Storm J. The relation between the transversus abdominis muscles, sacroiliac joint mechanics, and low back pain. Spine. 2002 Feb 15;27(4):399-405.

[7] Hungerford B, Gilleard W, Hodges P. Evidence of altered lumbopelvic muscle recruitment in the presence of sacroiliac joint pain. Spine. 2003 Jul 15;28(14):1593-600.

[8] Lane Smith R, Trindade MC, Ikenoue T, Mohtai M, Das P, Carter DR, et al. Effects of shear stress on articular chondrocyte metabolism. Biorheology. 2000;37(1-2):95-107.

[9] Chiquet M1Renedo ASHuber FFlück M. How do fibroblasts translate mechanical signals into changes in extracellular matrix production? Matrix Biol. 2003 Mar; 22(1):73-80.

[10] Silver FH, Siperko LM.Mechanosensing and mechanochemical transduction: how is mechanical energy sensed and converted into chemical energy in an extracellular matrix? Crit Rev Biomed Eng. 2003;31(4):255-331.

[11] Chiquet M, Tunç-Civelek V, Sarasa-Renedo A. Gene regulation by mechanotransduction in fibroblasts. Appl Physiol Nutr Metab. 2007 Oct;32(5):967-73.

[12] Chiquet M, Gelman L, Lutz R, Maier S. From mechanotransduction to extracellular matrix gene expression in fibroblasts. Biochim Biophys Acta. 2009 May;1793(5):911-20.

[13] Chan MWHinz BMcCulloch CA . Mechanical induction of gene expression in connective tissue cells. Methods Cell Biol. 2010;98:178-205.

[14]Kolar P, Neuwirth J, Sanda J, Suchanek V, Svata Z, Vojejnik J, et al. Analysis of diaphragm movement, during tidal breathing and during its activation while breath holding, using MRI synchronized with spirometry.Physiol Res. 2009;58: 383–92.

[15]Kolar P, Sulc J, Kyncl M, et al. Stabilizing function of the diaphragm: dynamic MRI and synchronized spirometric assessment. J Appl Physiol. 2010;109:1064–1071.

[16]Kolar P, Sulc J, Kyncl M, Sanda J, Cakrt O, Andel R, et al. Postural function of the diaphragm in persons with and without chronic low back pain. J Orthop Sports Phys Ther. 2012;42(4):352–62.

[17] Frank CKobesova AKolar P. Dynamic neuromuscular stabilization & sports rehabilitation. Int J Sports Phys Ther. 2013 Feb;8(1):62-73.

[18] Vostatek PNovák DRychnovský TRychnovská S. Diaphragm postural function analysis using magnetic resonance imaging.  PLoS One. 2013;8(3):e56724.

[19] Amarenco G et al. Cough anal reflex: strict relationship between intravesical pressure and pelvic floor muscle electromyographic activity during cough. Urodynamic and electrophysiological study. J Urol. 2005 Oct;174(4 Pt 1):1502-3.

[20] O'Sullivan PB, Beales DJ, Beetham JA, Cripps J, Graf F, Lin IB, et al. Altered motor control strategies in subjects with sacroiliac joint pain during the active straight-leg-raise test. Spine. 2002 Jan 1;27(1):E1-8.

[21] Beales DJ, O'Sullivan PB, Briffa NK. Motor control patterns during an active straight leg raise in chronic pelvic girdle pain subjects. Spine (Phila Pa 1976). 2009 Apr 20;34(9):861-70.

[22] Beales DJ, O'Sullivan PB, Briffa NK. Motor control patterns during an active straight leg raise in pain-free subjects. Spine (Phila Pa 1976). 2009 Jan 1;34(1):E1-8.

[23] Pelosi P, Quintel M, Malbrain ML. Effect of intra-abdominal pressure on respiratory mechanics.  Acta Clin Belg Suppl. 2007;(1):78-88.

[24] Macklem PT, Macklem DM, De Troyer A. A model of inspiratory muscle mechanics J. Appl. Physiol. 1983.55(2): 547-557.

[25] Moseley G,  Nicholas M, Hodges P.W. Does anticipation of back pain predispose to back trouble? Brain 2004 127(10):2339-2347

[26] Rhie TYSung KHPark MSLee KMChung CY J. Hamstring and psoas length of crouch  gait in cerebral palsy: a comparison with induced crouch gait in age- and sex-matched controls. J Neuroeng Rehabil. 2013 Jan 30;10:10.







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