The effect of Enquist footwear on the locomotor system. Part I.

1. The effect of Enquist footwear on the locomotor system. Part I.

2. Ground Reaction Forces comparative biomechanical test Dr. Levente Rácz Phd., Prof. Dr. Károly Bretz, Dr. Lukas Trzaskoma Phd., Sándor Sáfár, Renátó Gál, Zsolt Gréger Semmelweis University Faculty of Physical Education and Sport Laboratory of Biomechanics

3. The objective of the test • To examine with a biomechanical approach the impact of the Enquist footwear on the lower limbs. • To show the effects resulting from the special sole structure of the Enquist footwear. • To verify the differences resulting from the use of the Enquist vs traditional footwear.

4. Hypothesis According to scientific research methods, we have set a null hypothesis in our comperative test. If the null hypothesis is not rejected by statistical methods it suggests there is no difference between two footwears with different sole structure, if it is rejected it suggests the existence of statistically verifiable differences.

5. Null hypothesis • As there has not yet been any testing of this type, we start from the following null hypotheses: • During walking there is no difference in the temporal structure of gait phases when using Enquist footwear vs traditional shoes. • The ground reaction forces change similarly in the Enquist footwear and in traditional shoes. • ? • =

6. The conditions of the study Test candidates During the test we recorded data from 20 healthy individuals of average build and with average physical fitness. Our test processed the gait results of these candidates (40 steps). Age: 28.8 ± 8.8, height: 172.2 ± 6, weight: 66.15 ± 11.1. Tested footwear The tests were carried out for all candidates in their most frequently worn shoes with a traditional normal sole (marking: N) as well as in an Enquist footwear with a special sole structure (marking: E).

7. The conditions of the test Equipment used Kistler Force Plate System (2 force plates three-dimensional ground reaction analysis, Bioware 2812D processing program, sampling frequency 1000 Hz). Applied statistical method The equipment recorded the original and the calculated relative values and variables, in respect of the two shoetypes. These were compared by student’st-test.

8. Recording and processing data • The force plates were positioned at ground level in the longitudal axis of gait after one another, so that the stance phase of the right and the left leg of the walking cycle were recorded separately. • The first platform was reached by the test candidates after 4-5 steps at an average walking speed, theyproceeded to the second platform without any change in velocity, then maintaining their speed, they made at least 3 further steps.

9. FV1 FV2 FV3 FH1 TFH1 TFH2 FH2 TFV1 TFV2 TFV3 TÖSSZ TKÉTLÁB Force components parallel to the direction of gait, thus the horizontal, as well as perpendicular to the support, thus the vertical force components were recorded against time with 1000 Hz frequency. The significant peak force values and the time factors of the horizontal and vertical force-time curves were compared during the analysis.

10. The length of the stance phase and the time of the double-support TTWO LEGS TTOTAL

11. Analysis of horizontal ground reaction time data TFH1 TFH2

12. Analysis of vertical ground reaction time data TFV1 TFV2 TFV3

13. Studying the temporal structure of walking The recorded data was normalised in relation to the full stance period, to exclude variations resulting from anthropometric and running speed differences of the test candidates. There was no statistically verifiable difference in the temporal variables for any of the measured data.

14. The null hypothesis is not rejected • There was no difference in the duration of the stance phase, which indicates gait of near identical velocity in the two shoes with differing sole structures; furthermore this fact provides a legitimate basis for carrying out further statistical comparisons. • There was no statistically verifiable difference when comparing footwear with normal and that with the special Enquist sole structure, neither in the rise time of vertical or horizontal peak forces, nor in the duration of the double support. • The Enquist footwear does not influence the temporal structure of either the support or the swing phase. • Results of the study • The Enquist footwear does not change the temporal variables of heel support, rolling, launching, double support and swing phases of gait.

15. Ground reaction force data during walking The ground reaction force data (vertical and horizontal) was normalised in relation to body weight to exclude variations resulting from anthropometric differences of the test candidates.

16. Analysis of vertical ground reaction force data FV1 FV3 FV2

17. Vertical ground reaction force data P  0,05 In respect of the peak force (FV1N-FV1E) developing in the vertical forces at the beginning of the stance phase (breaking) we observed significant differences. When wearing Enquist footwear, the peak force is smaller, which represents a smaller loading on the passive locomotor system at the time of “impact” with the ground.

18. Analysis of horizontal ground reaction force data FH1 FH2

19. Horizontal ground reaction force data P  0,05 In the case of the horizontal forces, the peak force (FH2N-FH2E) developing in the launching phase (acceleration) when using Enquist footwear is significantly smaller, which, besides identical temporal variables, represents a more economic progress for the wearer of the Enquist.

20. Reject the null hypothesis • Based on the results of the ground reaction forces analysis we rejected the set null hypothesis. • Fundamental and significant differences were found at the beginning of the stance phase (heel support) of gait, where the vertical peak force, which is responsible for most of the load on the passive locomotor system, showed a significantly lower value when wearing Enquist footwear, while the force component parallel with the direction of the walk did not differ at all. • We also found significant differences in the launching phase of gait, where the horizontal peak force, besides identical temporal variables, is significantly smaller when wearing Enquist footwear, which supports this phase of walking.

21. Summary The temporal variables of the gait phases do not show a difference between Enquist footwear and in traditional shoes. It can be stated that the Enquist footwear does not effect a persons accustomed gait rhythm, thus there is no need to learn a new way of walking in them.

22. Summary • Walking in the Enquist footwear gait is easier on the joints than in traditional shoes. • Indications • health prevention • prevention and treatment of arthrosis, alleviation of symptoms • all conditions, where relief of the joints of the lower limbs or the spine is required

23. Summary • The Enquist footwear supports the launching phase of gait, which makes walking easier. • Indications • rehabilitation of lower limbs • stiffened ankle/knee joints • learning to walk with a lower limb prosthesis • supporting and making walking easier for neurological conditions

24. Thank you for your attention.