By William M. Austin, DC

Feet perform a number of simultaneous tasks: support, balance and propel the body; absorb shock and adapt to walking stresses; and provide the stability necessary for daily activities. And central to all of these tasks is the integrity of their 3-arched structure.

This structure is actually a complex of 3 bony arches (the plantar vault) that distribute the weight of the entire body (Fig. 1).1 Each arch consists of several bones bound together by tough, yet somewhat elastic ligaments and tendons. These strong connective tissues ensure that the structure is flexible, yet able to tolerate both sustained stress and sudden forces. If any one of these 3 arches is compromised, biomechanical stresses accumulate in the other arches and symptoms develop throughout the body.

Figure 1


Biomechanical Stress

Whenever the arches in the feet are compromised, two kinds of muscle dysfunctions can result.

First, it is well known that whenever the Golgi Tendon Organs (GTO)—mechanoreceptors found within the musculotendinous junction—are activated by excessive stretch, the contractibility of the muscle is inhibited. Therefore, whenever any joint in the body is misaligned, the optimal pulley system of the muscles crossing that joint is adversely affected (inhibited) neurologically and cannot function to its full potential.

Second, and not so well known, are the type III mechanoreceptors within the extra spinal ligaments that, like the GTO, inhibit the contractibility of the muscles innervated by those cord levels when they undergo excessive stretch.

The Three Arches and Their Related Muscles

Most of the intrinsic and extrinsic muscles of the foot are innervated by the Tibial Nerve and/or its extensions, the Lateral and Medial Plantar Nerve representing cord levels L3, L4, L5, S1, S2 and S3. As previously mentioned, excessive muscle stretching—in this case in the 3 arches of the feet—can eventually inhibit the contracting abilities of the affected muscles. This neurological inhibition can also affect all the associated muscles innervated by those same cord levels, i.e., the iliopsoas, the hip adductors and the quadriceps and hamstrings.

Manual Muscle Testing

Manual muscle testing often reveals sub-optimal strength and/or imbalances in otherwise normal healthy muscles. The following simple steps will help to determine which muscles are affected:

  1. TEST bilaterally the iliopsoas, gluteus medius/minimus and quadriceps muscles. Note the relative strength of each.
  2. ADJUST bilaterally the navicular (medial arch), cuboid (lateral arch) and metatarsal heads (transverse arch).
  3. RETEST the muscles as in Step 1. Note the increase of the relative strength.

Note: When there is plastic deformation or ligamentous laxity the osseous alignment of the joints must be supported. Otherwise, every time the patient stands up, the neurologic inhibition via the GTO and type III mechanoreceptors will negatively affect optimal function. This effect can be alleviated using custom-made functional orthotics (Fig. 2), which:

  • Figure 2.  InMotion® adds strength and stamina with Celliant® technology for improved performance.unnamed-2
  • Create a symmetrical foundation by blocking pronation or supporting supination2–5
  • Provide heel strike shock absorption—the natural shock absorbing capacity of the foot/ankle complex is reduced with either pronation or supination6,7
  • Inhibit serial biomechanical stress up the Kinetic Chain—the inward rotation of the foot/ankle complex, tibia, and fibula is a contributing factor in frequent ankle sprains and other conditions8,9
  • Enhance neuromuscular re-education—the sensory information from the mechanoreceptors of the foot play a major role in balance, gait, reciprocal inhibition and innervation of muscles, and posture.10–12

Choosing the Correct Style of Orthotics

Since most people have more than one pair of shoes, an orthotics Combo is recommended for all-day support (Fig. 3). A Combo consists of one pair of functional orthotics for shoes with laces and one pair for shoes without laces.

Figure 3 Foot Levelers’ InMotion® and XP3® Combounnamed-1

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Cannot be combined with other offers and cannot be used on past orders. Offer in USD. Offer has no cash value.

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  1. The relationship between foot arch measurements and walking parameters in children. Gill SV, Keimig S, Kelty-Stephen D, Hung YC, DeSilva JM. BMC Pediatr. 2016 Jan 23;16(1):15. doi: 10.1186/s12887-016-0554-5.
  2. Postural Re-Education of Scoliosis – State of the Art (Mini-review). Borysov M, Moramarco M, Sy N, Lee SG. Curr Pediatr Rev. 2016;12(1):12-6.
  3. Management of idiopathic and nonidiopathic flatfoot. Frances JM, Feldman DS. Instr Course Lect. 2015;64:429-40.
  4. The influence of foot orthoses on foot mobility magnitude and arch height index in adults with flexible flat feet. Sheykhi-Dolagh R, Saeedi H, Farahmand B, Kamyab M, Kamali M, Gholizadeh H, Derayatifar AA, Curran S. Prosthet Orthot Int. 2015 Jun;39(3):190-6. Epub 2014 Mar 6.
  5. Effect of soft and semirigid ankle orthoses on Star Excursion Balance Test performance in patients with functional ankle instability. Hadadi M, Mousavi ME, Fardipour S, Vameghi R, Mazaheri M. J Sci Med Sport. 2014 Jul;17(4):430-3. doi: 10.1016/j.jsams.2013.05.017. Epub 2013 Jun 28.
  6. Effect of different orthotic concepts as first line treatment of plantar fasciitis. Walther M, Kratschmer B, Verschl J, Volkering C, Altenberger S, Kriegelstein S, Hilgers M. Foot Ankle Surg. 2013 Jun;19(2):103-7. doi: 10.1016/j.fas.2012.12.008. Epub 2013 Feb 19.
  7. Mechanics of the foot Part 1: a continuum framework for evaluating soft tissue stiffening in the pathologic foot. Fernandez JW, Ul Haque MZ, Hunter PJ, Mithraratne K. Int J Numer Method Biomed Eng. 2012 Oct;28(10):1056-70. doi: 10.1002/cnm.2494. Epub 2012 Jun 25.
  8. Association between foot type and lower extremity injuries: systematic literature review with meta-analysis. Tong JW, Kong PW J Orthop Sports Phys Ther. 2013 Oct;43(10):700-14. doi: 10.2519/jospt.2013.4225. Epub 2013 Aug 30.
  9. Outcome after complex trauma of the foot. Kinner B, Tietz S, Müller F, Prantl L, Nerlich M, Roll C. J Trauma. 2011 Jan;70(1):159-68; discussion 168. doi: 10.1097/TA.0b013e3181fef5eb.
  10. Plantar Pressure Distribution Pattern during Mid-Stance Phase of the Gait in Patients with Chronic Non-Specific Low Back Pain. Anukoolkarn K, Vongsirinavarat M, Bovonsunthonchai S, Vachalathiti R. J Med Assoc Thai. 2015 Sep;98(9):896-901.
  11. Identification of Foot Pathologies Based on Plantar Pressure Asymmetry. Wafai L, Zayegh A, Woulfe J, Aziz SM, Begg R. Sensors (Basel). 2015 Aug 18;15(8):20392-408.
  12. Determination of plantar pressure in people who use orthoses of the foot. López-López D, Ortiz-González LM, Saleta-Canosa JL, de los Ángeles Bouza-Prego M, García-Sánchez MM, Tajes FA. Gac Med Mex. 2015 May-Jun;151(3):318-22. Spanish.