Name: evaluating the function of the foot core system in the elderly
Uploaded: 2022-03-11T14:30:00
Description: Watch this Scientific Journal Video about Evaluating the Function of the Foot Core System in the Elderly at JoVE.com

The authors acknowledge the funding of the Breeding Program of Shanghai Tenth People&#39;s Hospital (YNCR2C022).

This study was conducted at the Sports Medicine and Rehabilitation Centre, Shanghai University of Sport, and has been approved by the ethics committee of the Shanghai University of Sport (No. 102772020RT001). Before the test, the participants were given details about the experimental purpose and procedures; all participants signed the informed consent.
1. Participant selection
<ol>
	<li>Include participants who (1) are aged over 60 years old; (2) can maintain standing positi...

The presented protocol is used to measure the characteristics of the foot in the elderly, which provides a comprehensive assessment to investigate foot core stability, including the passive, active, and neural subsystems. This new paradigm illuminates the foot function that interacts to stabilize the foot and sustain sensorimotor function in daily activities33. In previous studies, the researchers paid more attention to exploring foot deformity; toe flexion strength; diminished plantar sensory; an...

The human foot is a highly complex structure, consisting of bones, muscles, and tendons that attach to the foot. As a segment of the lower extremity, the foot constantly provides direct source contact with the supporting surface and hence contributes to weight-bearing tasks1. Based on the complex biomechanical interplay between muscles and passive structures, the foot contributes to shock absorption, adjusts for irregular surfaces, and generates momentum. Evidence shows that the foot contributes meaningfully to postural stability, walking, and running2,3,4.
According to a new paradigm proposed by McKeon5 in 2015, the foot core is rooted in the functional interdependence of the passive, active, and neural subsystems, which combine into the foot core system controlling foot motion and stability. In this paradigm, the foot bony anatomy forms the functional half dome, which includes the longitudinal arches and transverse metatarsal arches and flexibly adapts to load changes6. This half dome and passive structures, including the ligaments and joint capsules, constitute the passive subsystem. Additionally, the active subsystem consists of foot intrinsic muscles, extrinsic muscles, and tendons. The intrinsic muscles act as local stabilizers responsible for supporting the foot arches, load dependence, and modulation7,8, while the extrinsic muscles generate foot motion as global movers. For the neural subsystem, several kinds of sensory receptors (e.g., capsuloligamentous and cutaneous receptors) in the plantar fascia, ligaments, joint capsules, muscles, and tendons contribute to foot dome deformation, gait, and balance9,10.
Several researchers have speculated that the foot contributes to daily activities in two main ways. One is by mechanical support via the functional arch and the modulation among lower limb muscles. The other is the input of plantar sensory information about the position11. Based on the foot core system, deficits in this system, including foot posture, the strength of intrinsic and extrinsic foot muscles, and sensation sensibility, may predispose to the weakness of mobility and balance9,11,12,13.
However, with advancing age, alterations to the aspect, biomechanics, structure, and function of the foot commonly occur, including foot or toe deformities, weakness of foot or toe strength, plantar pressure distribution, and reduced plantar tactile sensitivity14,15,16,17. The presence of toe deformity and the severity of hallux valgus are associated with mobility and fall risk in the elderly11,18. Moreover, the strength of toe flexor muscles, which used to be overlooked, contributes to balance in elderly people19. Meanwhile, the elderly are also at higher risks to have foot conditions associated with pathologies such as diabetes, peripheral arterial disease, neuropathy, and osteoarthritis20,21.
The assessment, examination, and health care of the foot, especially in the elderly, have attracted increasing attention14,21. However, there is a limited study to explore the comprehensive evaluation for the function of the foot core system. Numerous studies aimed to explore foot pathological problems in the elderly, such as pain and nail, skin, bone/joint, and neurovascular disorders21,22,23. The role of the foot in mechanical support and sensory input during daily activities and as a functional core system needs to be recognized and evaluated, which was ignored in previous studies. Especially, the foot active components, including the intrinsic and extrinsic muscles, works as the local stabilizers and global movers and contribute to the foot stability and behavior in static posture and dynamic movement5.
The toe flexion strength is singularly reported to represent foot muscle strength, and it&#39;s also utilized to explore the relationship between foot function and other health situations, such as balance, and mobility24,25,26. Inherently, the foot muscle strength is limited to distinguishing the action of intrinsic and extrinsic muscles. Moreover, several tests, including the paper grip test and an intrinsic positive test, were criticized as non-quantitative tests that have poor reliability and validity7,27. Recently, a new evaluation of foot doming strength was reported to quantify the intrinsic foot muscle strength and it has been shown to have a good validity28. By measuring the doming (short-foot movement) strength, it contributes to directly quantifying the function of intrinsic muscle.
Therefore, a protocol is proposed here aiming to explore the characteristics of the foot in the elderly based on the foot core system, especially the function of the active subsystem. This protocol provides a comprehensive assessment to investigate foot core stability, including the passive, active, and neural subsystem, in the elderly. Moreover, alterations in foot core function have been reported in several health situations, such as plantar fasciitis, flat foot, and diabetes24,29,30. In the future studies, it might help to evaluate the foot function among different populations in a multidimensional measurement.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Diagnostic Ultrasound System</td>
			<td>Mindray</td>
			<td></td>
			<td>It is used in clinical ultrasonic diagnostic examination.</td>
		</tr>
		<tr>
			<td>ergoFet dynamometer</td>
			<td>ergoFet</td>
			<td></td>
			<td>It is an accurate, portable, push/pull force gauge, which is designed to be a stand-alone gauge for capturing individual force measurements under any 
			job condition.</td>
		</tr>
		<tr>
			<td>Height vernier caliper</td>
			<td></td>
			<td></td>
			<td>It is an accurate measure tool for height.</td>
		</tr>
		<tr>
			<td>LabVIEW</td>
			<td></td>
			<td></td>
			<td>It is a customed program software for strength analysis.</td>
		</tr>
		<tr>
			<td>Semmes-Weinstein monofilaments</td>
			<td>Baseline</td>
			<td></td>
			<td>It consists of 20 pieces, and each SWM haves an index number ranging from 1.65 to 6.65, that is related with a calibrated breaking force.</td>
		</tr>
		<tr>
			<td>Two-Point Discriminator</td>
			<td>Touch Test</td>
			<td></td>
			<td>It is a set of two aluminum discs, each containing a series of prongs spaced between 1 to 15 mm apart.</td>
		</tr>
	</tbody>
</table>

evaluating the function of the foot core system in the elderly

As a complex structure to link the body and the ground, the foot contributes to postural control in human static and dynamic activities. The foot core is rooted in the functional interdependence of the passive, active, and neural subsystems, which combine into the foot core system controlling foot motion and stability. The foot arch (passive subsystem), responsible for load, is considered the functional core of the foot, and its stability is necessary for normal foot functions. The functional abnormalities of the foot have been widely reported in the elderly, such as weakness of toe flexor muscles, abnormal foot postures, and decreased plantar sensory sensitivity. In this paper, a comprehensive approach is introduced for evaluating the foot function based on foot core subsystems. The strength and morphology of the foot intrinsic and extrinsic muscles were used to evaluate the foot muscle (active subsystem) function. The doming strength test was applied to determine the function of foot intrinsic muscles, while the toe flexion strength test focused more on the function of extrinsic muscles. The navicular drop test and foot posture index were applied to evaluate foot arch (passive subsystem) function. For the neural subsystem, the plantar light touch threshold test and two-point discrimination test were used to assess plantar tactile sensitivity at nine regions of the foot. This study provides new insights into the foot core function in the elderly and other populations.

In this study, 84 participants were included for measurement. The young&#160;group included 42 university students with an average age of 22.4 &#177; 2.9 years and height of 1.60 &#177; 0.05 m. The elderly group included 42 community-dwelling elderly with an average age of 68.9 &#177; 3.3 years and height of 1.59 &#177; 0.05 m.
Representative active subsystem results 
The morphology and strength of foot muscles are used to determine the function of the active subsystem. M...

Watch this Scientific Journal Video about Evaluating the Function of the Foot Core System in the Elderly at JoVE.com

Evaluating the Function of the Foot Core System in the Elderly

The functional core stability of the foot contributes to the human static posture and dynamic activities. This paper proposes a comprehensive evaluation for the function of the foot core system, which combines three subsystems. It may provide increased awareness and multifaceted protocol to explore the foot function among different populations.

As a complex structure to link the body and the ground, the foot contributes to postural control in human static and dynamic activities. The foot core is ...

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