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The generation of centripetal force when walking in a circle: insight from the distribution of ground reaction forces recorded by plantar insoles.

Turcato AM, Godi M, Giordano A, Schieppati M, Nardone A - J Neuroeng Rehabil (2015)

Bottom Line: During curved walking, a greater loading of the lateral heel occurred for Foot-Out than Foot-In and LIN foot.On the contrary, a smaller lateral loading of the heel was found for Foot-In than LIN foot.At the metatarsal heads, an opposite behaviour was seen, since lateral loading decreased for Foot-Out and increased for Foot-In.

View Article: PubMed Central - PubMed

Affiliation: Posture and Movement Laboratory, Division of Physical Medicine and Rehabilitation, Scientific Institute of Veruno, Fondazione Salvatore Maugeri (IRCCS), Veruno, NO, Italy. turcato.anna@gmail.com.

ABSTRACT

Background: Turning involves complex reorientation of the body and is accompanied by asymmetric motion of the lower limbs. We investigated the distribution of the forces under the two feet, and its relation to the trajectory features and body medio-lateral displacement during curved walking.

Methods: Twenty-six healthy young participants walked under three different randomized conditions: in a straight line (LIN), in a circular clockwise path and in a circular counter-clockwise path. Both feet were instrumented with Pedar-X insoles. An accelerometer was fixed to the trunk to measure the medio-lateral inclination of the body. We analyzed walking speed, stance duration as a percent of gait cycle (%GC), the vertical component of the ground reaction force (vGRF) of both feet during the entire stance, and trunk inclination.

Results: Gait speed was faster during LIN than curved walking, but not affected by the direction of the curved trajectory. Trunk inclination was negligible during LIN, while the trunk was inclined toward the center of the path during curved trajectories. Stance duration of LIN foot and foot inside the curved trajectory (Foot-In) was longer than for foot outside the trajectory (Foot-Out). vGRF at heel strike was larger in LIN than in curved walking. At mid-stance, vGRF for both Foot-In and Foot-Out was higher than for LIN foot. At toe off, vGRF for both Foot-In and Foot-Out was lower than for LIN foot; in addition, Foot-In had lower vGRF than Foot-Out. During curved walking, a greater loading of the lateral heel occurred for Foot-Out than Foot-In and LIN foot. On the contrary, a smaller lateral loading of the heel was found for Foot-In than LIN foot. At the metatarsal heads, an opposite behaviour was seen, since lateral loading decreased for Foot-Out and increased for Foot-In.

Conclusions: The lower gait speed during curved walking is shaped by the control of trunk inclination and the production of asymmetric loading of heel and metatarsal heads, hence by the different contribution of the feet in producing the body inclination towards the centre of the trajectory.

No MeSH data available.


Description through the asymmetry index (AI), of the shifts of vGRF subserving the controlled production of the centripetal force during curved walking. Black points indicate the AI during counter-clockwise trajectories; the white points indicate AI during linear trajectories. Note in the Foot-Out the displacement from medial to lateral position of vGRF at the heel and from lateral to medial position of vGRF at the metatarsal heads with respect to linear walking. The reverse occurs in the Foot-In.
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Fig7: Description through the asymmetry index (AI), of the shifts of vGRF subserving the controlled production of the centripetal force during curved walking. Black points indicate the AI during counter-clockwise trajectories; the white points indicate AI during linear trajectories. Note in the Foot-Out the displacement from medial to lateral position of vGRF at the heel and from lateral to medial position of vGRF at the metatarsal heads with respect to linear walking. The reverse occurs in the Foot-In.

Mentions: The subdivision of the foot print into eight regions (four for each longitudinal half) allowed to further explore the mechanisms subserving the controlled production of centripetal force during curved walking. For simplicity, we discuss here in detail only the most salient features of vGRF during the load-acceptance phase and the late stance phase (see FigureĀ 7). Undoubtedly, the measurement of vGRF per se under the feet cannot provide the generation of centripetal force, which is a horizontal force that is not measured by the insoles. However, the instantaneous position of the point of application of this vertical force during turning, and its displacement with respect to what happens during linear walking, can give insight in the production of the gap between the center of mass and this application point. This distance created between center of mass and center of pressure in the medio-lateral plane produces a disequilibrium torque driven by gravity that is responsible for accelerating the body toward the center of the trajectory, very much as a similar torque during linear walking produces a disequilibrium in the sagittal plane that accelerates the body forward [50, 51].Figure 7


The generation of centripetal force when walking in a circle: insight from the distribution of ground reaction forces recorded by plantar insoles.

Turcato AM, Godi M, Giordano A, Schieppati M, Nardone A - J Neuroeng Rehabil (2015)

Description through the asymmetry index (AI), of the shifts of vGRF subserving the controlled production of the centripetal force during curved walking. Black points indicate the AI during counter-clockwise trajectories; the white points indicate AI during linear trajectories. Note in the Foot-Out the displacement from medial to lateral position of vGRF at the heel and from lateral to medial position of vGRF at the metatarsal heads with respect to linear walking. The reverse occurs in the Foot-In.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4325939&req=5

Fig7: Description through the asymmetry index (AI), of the shifts of vGRF subserving the controlled production of the centripetal force during curved walking. Black points indicate the AI during counter-clockwise trajectories; the white points indicate AI during linear trajectories. Note in the Foot-Out the displacement from medial to lateral position of vGRF at the heel and from lateral to medial position of vGRF at the metatarsal heads with respect to linear walking. The reverse occurs in the Foot-In.
Mentions: The subdivision of the foot print into eight regions (four for each longitudinal half) allowed to further explore the mechanisms subserving the controlled production of centripetal force during curved walking. For simplicity, we discuss here in detail only the most salient features of vGRF during the load-acceptance phase and the late stance phase (see FigureĀ 7). Undoubtedly, the measurement of vGRF per se under the feet cannot provide the generation of centripetal force, which is a horizontal force that is not measured by the insoles. However, the instantaneous position of the point of application of this vertical force during turning, and its displacement with respect to what happens during linear walking, can give insight in the production of the gap between the center of mass and this application point. This distance created between center of mass and center of pressure in the medio-lateral plane produces a disequilibrium torque driven by gravity that is responsible for accelerating the body toward the center of the trajectory, very much as a similar torque during linear walking produces a disequilibrium in the sagittal plane that accelerates the body forward [50, 51].Figure 7

Bottom Line: During curved walking, a greater loading of the lateral heel occurred for Foot-Out than Foot-In and LIN foot.On the contrary, a smaller lateral loading of the heel was found for Foot-In than LIN foot.At the metatarsal heads, an opposite behaviour was seen, since lateral loading decreased for Foot-Out and increased for Foot-In.

View Article: PubMed Central - PubMed

Affiliation: Posture and Movement Laboratory, Division of Physical Medicine and Rehabilitation, Scientific Institute of Veruno, Fondazione Salvatore Maugeri (IRCCS), Veruno, NO, Italy. turcato.anna@gmail.com.

ABSTRACT

Background: Turning involves complex reorientation of the body and is accompanied by asymmetric motion of the lower limbs. We investigated the distribution of the forces under the two feet, and its relation to the trajectory features and body medio-lateral displacement during curved walking.

Methods: Twenty-six healthy young participants walked under three different randomized conditions: in a straight line (LIN), in a circular clockwise path and in a circular counter-clockwise path. Both feet were instrumented with Pedar-X insoles. An accelerometer was fixed to the trunk to measure the medio-lateral inclination of the body. We analyzed walking speed, stance duration as a percent of gait cycle (%GC), the vertical component of the ground reaction force (vGRF) of both feet during the entire stance, and trunk inclination.

Results: Gait speed was faster during LIN than curved walking, but not affected by the direction of the curved trajectory. Trunk inclination was negligible during LIN, while the trunk was inclined toward the center of the path during curved trajectories. Stance duration of LIN foot and foot inside the curved trajectory (Foot-In) was longer than for foot outside the trajectory (Foot-Out). vGRF at heel strike was larger in LIN than in curved walking. At mid-stance, vGRF for both Foot-In and Foot-Out was higher than for LIN foot. At toe off, vGRF for both Foot-In and Foot-Out was lower than for LIN foot; in addition, Foot-In had lower vGRF than Foot-Out. During curved walking, a greater loading of the lateral heel occurred for Foot-Out than Foot-In and LIN foot. On the contrary, a smaller lateral loading of the heel was found for Foot-In than LIN foot. At the metatarsal heads, an opposite behaviour was seen, since lateral loading decreased for Foot-Out and increased for Foot-In.

Conclusions: The lower gait speed during curved walking is shaped by the control of trunk inclination and the production of asymmetric loading of heel and metatarsal heads, hence by the different contribution of the feet in producing the body inclination towards the centre of the trajectory.

No MeSH data available.