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

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

2. Joint Movements 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 kinematic variables of the studied joints when using Enquist footwear vs traditionalshoes. • ? • =

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. 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 • APAS (Arial Performance Analysis System) motion analysis program • 4 JVC GR-DVR 9800 digital camera (200 Hzfrequency) • Applied statistical method • The original, equipment recordedand the calculated relative values and variables in respect of the two shoetypes, were compared by student’st-test.

8. Recording and processing the video material • For a more defined resolution a modified test model was used; we focused on the knee and ankle joints as well as the thigh, lower leg and leg as segments. • 2 cameras were focused on the ankle joint, recording any changes during the stance phase providing lateral and frontal views at 200 Hz frequency. • 2 cameras recorded the kinematic characteristics of the thigh-knee-lower leg-ankle-leg system also providing lateral and frontal views. • Errors of manual digitalisation were reduced by placing reflective markers on the appropriate anatomical points and these were lit by reflectors from underneath the cameras; this way we could use the automatic digitalisation function of the program during processing.

9. Reflective marking of the modified testmodel The markers were placed on the right side lower limb on anatomical points 1-10.

10. Digitally recorded stance phase Normal shoes Enquist • The digitalised register of the anatomical points and segments applied in the process. • marker 1: metatarsal head V • marker 4: lateral malleolus • marker 5: calcaneus • marker 9: lateral femoral epicondyle • marker 10: halfway point between the lateral femoral epicondyle and the greater trochanter • On the phase figures the differences are almost unnoticeable, they become visible after processing the position-joint angle-, angular velocity- and turning motion-time functions.

11. Angular region of the knee and ankle joints under the stance phase P  0,05 P  0,05 Significant difference was found in the range of motion under stance phase for both the knee and the ankle joints. The range of motion for the knee is greater when using Enquist footwear, whilst for the ankle it is smaller for a stance phase of identical duration.

12. Ankle joint angular velocity in the stance phase P  0,05 P  0,05 P  0,05 P  0,05 P  0,05 The speed of angular rotation occurring in the ankle joint is smaller on average when wearing Enquist footwear and this difference is also statistically significant. Even greater difference was found in the case of the maximum angular velocity also in the heel strike and launching phases. At the moment of heel strike significantly greater momentary angular velocity was found in the case of normal shoes with a rigid sole structure, which can be explained by the passive “slamming” of the leg.

13. Turning moment of the lower leg P  0,05 P  0,05 The turning moment of the lower leg in respect of both its average and maximum value is significantly smaller when wearing Enquist.

14. Reject the null hypothesis Based on the findings of the video analyses the set null hypothesis was rejected. During walking we found significant differences in the kinematic variables of the studied joints when wearing Enquist footwear and traditional shoes.

15. Summary • In Enquist footwear the range of movement of the ankle joint is smaller, whilst that of the knee joint is greater than in traditional shoes. • When walking in Enquist footwear, due to the angular rotation velocity of the ankle joint, the loading on the ankle and other connecting joints is less than in traditional shoes. • When walking in Enquist footwear, the turning moment of the shin is less than in traditional shoes, which reduces the loading on the ankle and knee.

16. Indications • health prevention • relief of the passive locomotor system (lower limb, spine) • ankle, knee and hip joint rehabilitation, relearning walking • treatment of lower limb pains, alleviation of symptoms

17. Thank you for your attention.