Adaptation of Plantar Pressure Distribution after wearing X10D® Shoes for 8 weeks

Jan Swager van Dok: 
Physiotherapie Postmarkt Grenchen, Kirchstrasse 1, 2540 Grenchen, Switzerland

Heiner Baur:
Bern University of Applied Sciences, Health, Physiotherapy, Murtenstrasse 10, 3008 Bern, Switzerland

Jan Cabri:
Norwegian School of Sports Sciences, Department of Physical Performance, P.O. Box 4014 Ullevål Stadion, 0806 Oslo, Norway

Anja Hirschmüller:
University Hospital Freiburg, Department of Orthopaedics and Traumatology, Hugstetter Strasse 49, 79106 Freiburg, Germany

BACKGROUND | INTRODUCTION

It seems that more and more people in the modern society suffer from foot and body posture related complaints due to sedentary lifestyle. Nowadays humans tend to walk slower and more passively, resulting in a wide gait with smaller steps and more abducted forefoot positioning during stance. In order to provide a possible remedy for the above explained chain of musculoskeletal malfunctions, the X10D® shoe was developed.

The objective of the X10D® shoe sole is to restore regular motion sequence. The intention of the construction of the sole is to invite the user to efficiently relearn, particularly in the mid-foot area, a more lateral foot pressure distribution during walking. As there is a relation between insufficient foot muscle activity and inadequate posture, the X10D® may help in achieving a more upright body posture.

AIMS | RESEARCH QUESTIONS

The aim of the study was therefore to analyze plantar pressure distribution of the new X10D® shoe design in comparison to a “reference shoe” and barefoot walking.

METHODS | MATERIAL AND METHODS

Eight women, (mean age 31±7.3 years) and eight men (mean age: 37±8.8) walked with three shoe conditions: shoe with a specially designed midsole (X10D®), a reference shoe and simulated barefoot. The participants walked for three minutes on a treadmill with a speed of 1.25 m*s -1 in all three conditions. Pressure distribution was measured using the Pedar-X insole system (Novel, Munich, Germany). After initial measurements, all participants used the X10D® for eight weeks during daily life activities. After this period all conditions were measured for a second time. Peak pressures [kPa] in the total foot and in specific foot areas (rearfoot, midfoot (medial & lateral) and forefoot) served as outcome measures.

RESULTS

After eight weeks of accommodation to the X10D®, significantly higher peak pressures were measured for the lateral midfoot with the X10D® and barefoot compared to the reference shoe. Also after 8 weeks, the X10D®-condition resulted in reduced peak pressures with values between the reference shoe and barefoot for the total foot, the rear-, mid- and forefoot.

DISCUSSION

The intended goal of the X10D® shoe is to alter foot pressure distribution. The function and construction of the sole of the X10D® invites the user to bring the center of pressure during walking shortly after heel-strike more to the lateral side of the shoe. It has been shown that in people with uncontrolled overpronation and flatfeet, the center of pressure proceeds more on the medial side of the foot during walking [1].

The modification of the “roll-over process” may restore uncontrolled over-pronation and muscle control of the longitudinal arch of the foot. This study also showed that foot pressure distribution alteration can be observed by wearing X10D® shoes. After eight weeks of accommodation to the new shoe design, a distinct change in pressure distribution compared to normal shoes was detected. The pressure distribution changed towards barefoot characteristics, especially when looking at the midfoot area.

In normal feet there must be a rotational equilibrium in the subtalar joint, which maintains a position midway between neutral and maximal pronation[2]. This position ensures a range of pronation available for shock absorption, increases the available motion of the forefoot and allows the foot to adapt to ground surfaces. Flatfeet and over-pronation are caused by medial deviation of the subtalar joint. In medial deviation, the sub-talar joint axis is medially translated, or internally rotated, compared with normal subtalar joint axis location[5]. In case of this internally rotated joint axis, the foot pressure distribution is shifted more to the medial side of the foot sole. The present result, i.e. higher peak pressure in the lateral midfoot, might be explained by the mechanism mentioned above, whereby the increased pressure at the lateral side is the result of a new position of the subtalar joint.

Mechanical subtalar correction is a possible therapeutic approach in order to relieve lower limb injuries and back problems if excessive pronation is present. Traditionally, functional foot orthoses (FFO) have been used for correcting excessive pronation. Subsequently, proximal posture is thought to be improved and stress to lower limb and pelvis structures might be reduced. This therapeutic approach with FFO is based on theoretical argumentation supported by some evidence [3]. The potential mechanism of pain relief and improvement of body alignment by the use of FFO are still largely unknown and still a controversial issue [4]. Wearing the X10D® may offer an alternative and active functional therapy approach for these complaints. In this present study healthy participants were involved. Prospective studies are needed to prove this approach for people with flatfeet and uncontrolled pronation as well as inappropriate body alignment.

References
[1] Ledoux (2002) Gait & Posture [2] Kirby (1989) J Am Podiatr Med Assoc[3] Barwick (2012) Foot (Edinb)[4] Collins (2007) Foot Ankle Int
Acknowledgements
This poster was presented at the WCPT Congress 2015, Singapore.

Funding
This study was partly funded by the GVB Shoetech AG Zofingen Switzerland.

Ethics
The study was evaluated by the Local Ethics Committee of the Canton Solothurn (15.04.2013/mw). It was classified as a “low risk” study requiring no explicit examination by the Committee.