Limits...
Alteration of the foot center of pressure trajectory by an unstable shoe design.

Khoury M, Haim A, Herman A, Rozen N, Wolf A - J Foot Ankle Res (2015)

Bottom Line: A counterintuitive but significant correlation was found between stride to stride variability and the instability of the biomechanical elements.Moreover, there was significant correlation between the instability of the elements and the perturbations found in the COP trajectory.The linear model describing this correlation was found to be statistically significant.

View Article: PubMed Central - PubMed

Affiliation: Biorobotics and Biomechanics Lab (BRML), Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, 32000 Israel.

ABSTRACT

Background: Unstable sole designs have been used as functional or therapeutic tools for improving body stability during locomotion. It has been suggested that the narrow base of support under the feet generate perturbations that challenge the instability of different joints during motion, thereby forcing the body to modify its movement in order to maintain a stable gait. The purpose of the present study was to explore the correlation between the stability of the footwear-device and the magnitude of perturbation conveyed during gait.

Methods: Various levels of dynamic instability were achieved using a novel foot-worn platform with two adjustable convex rubber elements attached to its sole. A total of 20 healthy male adults underwent direct in-shoe pressure measurements while walking with the footwear device. Foot center of pressure (COP) and stride to stride variability measures were extracted to examine the correlation between the magnitude of the instability and the imposed perturbations during gait.

Results: A counterintuitive but significant correlation was found between stride to stride variability and the instability of the biomechanical elements. Moreover, there was significant correlation between the instability of the elements and the perturbations found in the COP trajectory. The linear model describing this correlation was found to be statistically significant.

Conclusion: There was significantly negative correlation between the level of instability induced by the shoe design and the amount of perturbations conveyed during gait. This suggests that the external perturbation must remain within a certain range limit. Exceeding this limit can negatively affect the treatment and probably lead to opposite results.

No MeSH data available.


Related in: MedlinePlus

Mean COP M-L location vs biomechanical elements height, according to gait stage. The points represent mean COP for each element (height) at each gait stage. The linear models show that as the height increases (level of instability), the COP moves medially. This effect is similar for every gait stage. COP center of pressure, M-L mediolateral, LR loading response, MS mid-stance, TS terminal stance, PS preswing
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Fig2: Mean COP M-L location vs biomechanical elements height, according to gait stage. The points represent mean COP for each element (height) at each gait stage. The linear models show that as the height increases (level of instability), the COP moves medially. This effect is similar for every gait stage. COP center of pressure, M-L mediolateral, LR loading response, MS mid-stance, TS terminal stance, PS preswing

Mentions: Mean values and standard deviations of the mean COP measured with four different levels of convexity are presented in Table 1. The COP trajectory throughout the stance shifted medially as the stage of instability induced by the biomechanical element was increased. A linear model for the shift as a function of element height and gait stage was COP = A + B × Conv. The intercept (A) changed with gait stage being 56.28, 53.09, 46.09 and 40.89 mm for stages LR, MS, TS and PS, respectively. The Slope was −0.21 mm (±0.09) for each mm of height of the biomechanical elements. This means that for each mm of height the COP shifted medially by 0.21 mm. This was found to be statistically significant (p = 0.001). The model fit the data well ( = 0.796, overall model p = 0.001). In all the gait stages, the effect of the stage of instability on COP position was similar, i.e. the interaction terms were not statistically significant and were excluded from the model. The linear model for each gait stage and the COP position are presented in Fig. 2.Table 1


Alteration of the foot center of pressure trajectory by an unstable shoe design.

Khoury M, Haim A, Herman A, Rozen N, Wolf A - J Foot Ankle Res (2015)

Mean COP M-L location vs biomechanical elements height, according to gait stage. The points represent mean COP for each element (height) at each gait stage. The linear models show that as the height increases (level of instability), the COP moves medially. This effect is similar for every gait stage. COP center of pressure, M-L mediolateral, LR loading response, MS mid-stance, TS terminal stance, PS preswing
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4666148&req=5

Fig2: Mean COP M-L location vs biomechanical elements height, according to gait stage. The points represent mean COP for each element (height) at each gait stage. The linear models show that as the height increases (level of instability), the COP moves medially. This effect is similar for every gait stage. COP center of pressure, M-L mediolateral, LR loading response, MS mid-stance, TS terminal stance, PS preswing
Mentions: Mean values and standard deviations of the mean COP measured with four different levels of convexity are presented in Table 1. The COP trajectory throughout the stance shifted medially as the stage of instability induced by the biomechanical element was increased. A linear model for the shift as a function of element height and gait stage was COP = A + B × Conv. The intercept (A) changed with gait stage being 56.28, 53.09, 46.09 and 40.89 mm for stages LR, MS, TS and PS, respectively. The Slope was −0.21 mm (±0.09) for each mm of height of the biomechanical elements. This means that for each mm of height the COP shifted medially by 0.21 mm. This was found to be statistically significant (p = 0.001). The model fit the data well ( = 0.796, overall model p = 0.001). In all the gait stages, the effect of the stage of instability on COP position was similar, i.e. the interaction terms were not statistically significant and were excluded from the model. The linear model for each gait stage and the COP position are presented in Fig. 2.Table 1

Bottom Line: A counterintuitive but significant correlation was found between stride to stride variability and the instability of the biomechanical elements.Moreover, there was significant correlation between the instability of the elements and the perturbations found in the COP trajectory.The linear model describing this correlation was found to be statistically significant.

View Article: PubMed Central - PubMed

Affiliation: Biorobotics and Biomechanics Lab (BRML), Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa, 32000 Israel.

ABSTRACT

Background: Unstable sole designs have been used as functional or therapeutic tools for improving body stability during locomotion. It has been suggested that the narrow base of support under the feet generate perturbations that challenge the instability of different joints during motion, thereby forcing the body to modify its movement in order to maintain a stable gait. The purpose of the present study was to explore the correlation between the stability of the footwear-device and the magnitude of perturbation conveyed during gait.

Methods: Various levels of dynamic instability were achieved using a novel foot-worn platform with two adjustable convex rubber elements attached to its sole. A total of 20 healthy male adults underwent direct in-shoe pressure measurements while walking with the footwear device. Foot center of pressure (COP) and stride to stride variability measures were extracted to examine the correlation between the magnitude of the instability and the imposed perturbations during gait.

Results: A counterintuitive but significant correlation was found between stride to stride variability and the instability of the biomechanical elements. Moreover, there was significant correlation between the instability of the elements and the perturbations found in the COP trajectory. The linear model describing this correlation was found to be statistically significant.

Conclusion: There was significantly negative correlation between the level of instability induced by the shoe design and the amount of perturbations conveyed during gait. This suggests that the external perturbation must remain within a certain range limit. Exceeding this limit can negatively affect the treatment and probably lead to opposite results.

No MeSH data available.


Related in: MedlinePlus