We would like to thank Dr. Johnathan Williams for his advice on MATLAB data processing.

The method reported was followed in a study that received ethical approval from the Bournemouth University Research Ethics Committee (Reference 15005).
1. Participants
<ol>
	<li>Recruit healthy adults (aged from 23 to 63 years, mean &#177; S.D.; 42.0 &#177; 13.4, body mass 70.4 &#177; 15.3 kg, height 175.5 &#177; 9.8 cm; 15 males, 15 females) to participate in the study. Thirty participants were recruited for this study.</li>
	<li>Ensure that there is no self-reported history of dizziness, balance problems or walking difficulties in the participants.</li>
	<li>Ensure that participants did not suffer from any known neuromuscular injury or condition affecting balance or walking.</li>
</ol>
2. Setup and procedures for gait analysis
<ol>
	<li>Use a gait analysis system (Figure 1) comprised of a dual-belt force plate-instrumented treadmill, a 10-camera motion capture system and a virtual environment that provides optic flow.</li>
	<li>Ensure that the participant is wearing very tight non-reflective clothing such as cycling shorts or leggings.</li>
	<li>Using double sided adhesive tapes attach 25 passive reflective markers and place according to the lower body configuration of the Human Body Model (HBM)7 as detailed in Table 1 and Figure 2. The information in this document is taken from the HBM Reference Manual8.</li>
	<li>Use a joint ruler to take measurements of the required knee and ankle widths for the HBM6.</li>
	<li>Secure participant to a safety harness that is fastened to an overhead frame.</li>
	<li>Start a new session in the database and make sure it is active (highlighted).</li>
	<li>Using the subject tab, create a new participant from the Labeling Skeleton button.</li>
	<li>Browse to the &#39;LowerLimb HBM_N2.vst&#39; file and then enter the name of the participant. The new participant appears in the Subjects pane.</li>
	<li>Go to the Tools pane and open the Subject Preparation tab.</li>
	<li>Zero level the forceplates via the Hardware tab. Make sure that no weight is exerted on the force plates.</li>
	<li>Prepare the participant for the ROM trial by having them ready in the middle of the treadmill.</li>
	<li>To ensure the participant can accustom themselves to the self-paced treadmill, ask them to walk at a comfortable speed for 5 min at the beginning of the session9,10.</li>
	<li>Following the acclimatization and without any delay time, ask the participant to walk for a minimum of 5 min10,11.</li>
	<li>Ensure participants are blinded to the timing of the recordings.</li>
	<li>Ensure to start the treadmill and start data recordings by clicking the Start recording button12. This can be done with integrated software (Table of Materials).</li>
	<li>Stop the recording after acquiring the desired amount of data. It is recommended to collect three sets of 25 cycles.</li>
	<li>Open the processing software (Table of Materials) and remove the high-frequency noise on data, by selecting a low-pass filter to the marker data such as a second order Butterworth filter with a cut-off frequency of 6 Hz.</li>
	<li>Go to File, and then select Export to save as a .csv.</li>
	<li>Determine individual strides from vertical force data and use the foot markers to ascertain gait events13.</li>
	<li>Analyze the gait parameters such as kinematic, kinetic and spatial-temporal data in Matlab R2017a (Supplementary File).</li>
</ol>
3. Setup and procedures for muscle strength test
<ol>
	<li>Use the muscle strength testing equipment (multimodal dynamometer) (Figure 3), to measure participants&#39; muscle strength based on Maximum Voluntary Isometric Contraction (MVIC)14.</li>
	<li>Attach the tool/pad number 701 to the dynamometer exercise head.</li>
	<li>Test participant&#39;s right and left knee isometric muscle strength.</li>
	<li>Test participants in a seated position on a chair with a backrest.</li>
	<li>Using the up/down switch, align the dynamometer axis with the knee joint&#39;s anatomical axis of rotation. Place the pad of the tool centrally at the lower part of the shin of the tibia.</li>
	<li>Keep the knee at 90&#176; flexion, the hip in neutral rotation and abduction, and the foot in plantar flexion.</li>
	<li>Place the participant&#39;s hands on their abdomen and stabilize the trunk, hips, and mid-thigh on the chair with Velcro straps.</li>
	<li>Run a practice trial for participants to get accustomed to the testing maneuver.</li>
	<li>Instruct the participant to extend their knee (exert pressure upwards on the pad) followed by flex (exert pressure downwards on the pad) to exert a maximum contraction on the command Go for 3 s.</li>
	<li>Provide verbal prompts and encouragement (&#34;Push&#34; for upwards and &#34;Pull&#34; for downwards) during the strength testing.</li>
	<li>Ensure that participants are aware they can stop the test immediately if they experience any unusual pain or discomfort.</li>
	<li>Allow participants to rest for 2 min.</li>
	<li>Repeat steps 3.1 - 3.12, three times for the left leg and right leg and record the data in newtons (N).</li>
	<li>Save all the data and export as a report for the analysis.</li>
</ol>

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The authors have nothing to disclose.

The contribution of this study is to accurately and comprehensively describe within one protocol the techniques for combined gait analysis and muscle strength testing that have not previously been described together.
In order to achieve accurate results for gait analysis, there are two areas that require maximum attention: 1) marker placements and 2) acclimatization time. The accuracy of the measured data is heavily dependent on the accuracy of the model used. The other key factors that affect...

The discipline of biomechanics primarily involves the study of stress, strain, loads and motion of biological systems - solid and fluid alike. It also involves the modelling of mechanical effects on the structure, size, shape and movement of the body1. For many years, developments in this field have improved our understanding of normal and pathologic gait, mechanics of neuromuscular control, and mechanics of growth and form2.
The main objective of this article is to present a comprehensive methodology on two of the latest technologies available to measure lower limb biomechanics of individuals. The gait analysis system measures and quantifies gait biomechanics by using a self-paced (SP) treadmill in combination with an augmented reality environment, which integrates a SP algorithm to regulate the treadmill&#39;s speed, as described by Sloot et al3. The muscle strength testing equipment is used as an assessment and a treatment tool for upper extremity rehabilitation4. This device can objectively assess a variety of physiological patterns of movement or job simulation tasks in isometric and isotonic modes. It is currently recognized as the gold standard for upper limb strength measurement5 but the evidence related specifically to the lower limb remains unclear. This paper explains the detailed protocol for completing an assessment of gait and isometric strength for the lower extremity.
Within biomechanical analysis, it is useful to combine assessments of functional performance (such as gait analysis) with specific tests of muscular performance. This is because whilst it may be assumed that increased muscle strength improves functional performance, this may not always be apparent6. This understanding is required for the improved future design of rehabilitation protocols and research strategies to assess these approaches.

<table><tbody><tr><td>701 Small lever</td><td>Baltimore Therapeutic Equipment Company (BTE)</td><td>Not Available - Online link provided in description</td><td>The unique attachment designed for the Primus RS to measure Knee Extension/Flexion - &lt;a href=&quot;https://store.btetech.com/collections/primus/products/701-small-lever&quot; target=&quot;_blank&quot;&gt;https://store.btetech.com/collections/primus/products/701-small-lever&lt;/a&gt;</td></tr><tr><td>D-Flow Software - Vresion 3.26</td><td>Motekforce Link</td><td>Not Available - Online link provided in description</td><td>Software used to control GRAIL system - &lt;a href=&quot;https://summitmedsci.co.uk/products/motek-dflow-hbm-software/&quot; target=&quot;_blank&quot;&gt;https://summitmedsci.co.uk/products/motek-dflow-hbm-software/&lt;/a&gt;</td></tr><tr><td>Gait Offline Analysis (GOAT) - Version 2.3</td><td>Motekforce Link</td><td>Not Available - Online link provided in description</td><td>Software used for the analysis of the gait parameters - &lt;a href=&quot;https://www.motekmedical.com/product/grail/&quot; target=&quot;_blank&quot;&gt;https://www.motekmedical.com/product/grail/&lt;/a&gt;</td></tr><tr><td>Gait Real-time Analysis Interactive Lab (GRAIL)</td><td>Motekforce Link</td><td>Not Available - Online link provided in description</td><td>GRAIL system measures and quantifies gait biomechanics by using a virtual reality based self-paced (SP) treadmill - &lt;a href=&quot;https://www.motekmedical.com/product/grail/&quot; target=&quot;_blank&quot;&gt;https://www.motekmedical.com/product/grail/&lt;/a&gt;</td></tr><tr><td>Leg Pad for 701</td><td>Baltimore Therapeutic Equipment Company (BTE)</td><td>Not Available - Online link provided in description</td><td>The unique attachment designed for the Primus RS to measure Knee Extension/Flexion - &lt;a href=&quot;https://store.btetech.com/collections/primus/products/701-802-leg-pad&quot; target=&quot;_blank&quot;&gt;https://store.btetech.com/collections/primus/products/701-802-leg-pad&lt;/a&gt;</td></tr><tr><td>Positioning Chair</td><td>Baltimore Therapeutic Equipment Company (BTE)</td><td>Not Available - Online link provided in description</td><td>Participant Positioning Chair is designed for assessment and treatment of the lower exteremeties. The chair is designed for multiple positions. &lt;a href=&quot;https://www.btetech.com/product/primus/&quot; target=&quot;_blank&quot;&gt;https://www.btetech.com/product/primus/&lt;/a&gt;</td></tr><tr><td>Primus RS</td><td>Baltimore Therapeutic Equipment Company (BTE)</td><td>Not Available - Online link provided in description</td><td>Primus RS equipment captures and reports real time objective data in Isotonic, Isometric, and Isokinetic resistance modes - &lt;a href=&quot;https://www.btetech.com/wp-content/uploads/BTE-Rehabilitation-Equipment-PrimusRS-Brochure-1.pdf&quot; target=&quot;_blank&quot;&gt;https://www.btetech.com/wp-content/uploads/BTE-Rehabilitation-Equipment-PrimusRS-Brochure-1.pdf&lt;/a&gt;</td></tr></tbody></table>

lower limb biomechanical analysis of healthy participants

Biomechanical analysis techniques are useful in the study of human movement. The aim of this study was to introduce a technique for the lower limb biomechanical assessment in healthy participants using commercially available systems. Separate protocols were introduced for the gait analysis and muscle strength testing systems. To ensure maximum accuracy for gait assessment, attention should be given to the marker placements and self-paced treadmill acclimatization time. Similarly, participant positioning, a practice trial, and verbal encouragement are three critical stages in muscle strength testing. The current evidence suggests that the methodology outlined in this article may be effective for the assessment of lower limb biomechanics.

The mean and standard deviation of the spatial-temporal, kinematics, and kinetic gait parameters are given in Table 2. MVIC data for all 30 participants are summarized in Table 3. A typical set of data for the left and right side of one participant showing graphical representation of gait parameters is provided in Figure 4 and Figure 5, respectively.
<p class="jove_content" fo:keep-together.w...

Watch this Scientific Journal Video about Lower Limb Biomechanical Analysis of Healthy Participants at JoVE.com

Lower Limb Biomechanical Analysis of Healthy Participants

This article introduces a comprehensive experimental methodology on two of the latest technologies available to measure the lower limb biomechanics of individuals.

Biomechanical analysis techniques are useful in the study of human movement. The aim of this study was to introduce a technique for the lower limb ...

lower-limb-biomechanical-analysis-of-healthy-participants

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9.0K Views.  Bournemouth University. This article introduces a comprehensive experimental methodology on two of the latest technologies available to measure the lower limb biomechanics of individuals.

Video: Lower Limb Biomechanical Analysis of Healthy Participants

Sit-to-stand-and-walk from 120% Knee Height: A Novel Approach to Assess Dynamic Postural Control Independent of Lead-limb

Individuals with sensorimotor pathology e.g., stroke have difficulty executing the common task of rising from sitting and initiating gait (sit-to-walk: STW). Thus, in clinical rehabilitation separation of sit-to-stand and gait initiation - termed sit-to-stand-and-walk (STSW) - is usual. However, a standardized STSW protocol with a clearly defined analytical approach suitable for pathological assessment has yet to be defined.
Hence, a goal-orientated protocol is defined that is suitable for healthy and compromised individuals by requiring the rising phase to be initiated from 120% knee height with a wide base of support independent of lead limb. Optical capture of three-dimensional (3D) segmental movement trajectories, and force platforms to yield two-dimensional (2D) center-of-pressure (COP) trajectories permit tracking of the horizontal distance between COP and whole-body-center-of-mass (BCOM), the decrease of which increases positional stability but is proposed to represent poor dynamic postural control.
BCOM-COP distance is expressed with and without normalization to subjects&#39; leg length. Whilst COP-BCOM distances vary through STSW, normalized data at the key movement events of seat-off and initial toe-off (TO1) during steps 1 and 2 have low intra and inter subject variability in 5 repeated trials performed by 10 young healthy individuals. Thus, comparing COP-BCOM distance at key events during performance of an STSW paradigm between patients with upper motor neuron injury, or other compromised patient groups, and normative data in young healthy individuals is a novel methodology for evaluation of dynamic postural stability.

Here, we present a novel protocol to measure positional stability at key events during the sit-to-stand-to-walk using the center-of-pressure to the whole-body-center-of-mass distance. This was derived from the force platform and three-dimensional motion-capture technology. The paradigm is reliable and can be utilized for the assessment of neurologically compromised individuals.

Individuals with sensorimotor pathology e.g., stroke have difficulty executing the common task of rising from sitting and initiating gait (sit-to-walk: ...

Behavior

Using Gold-standard Gait Analysis Methods to Assess Experience Effects on Lower-limb Mechanics During Moderate High-heeled Jogging and Running

A limited number of studies have explored lower-limb biomechanics during high-heeled jogging and running, and most studies have failed to clarify the wearing experience of subjects. This protocol describes the differences in lower-limb kinematics and ground reaction force (GRF) between experienced wearers (EW) and inexperienced wearers (IEW) during moderate high-heeled jogging and running. A three-dimensional (3D) motion analysis system with a configured force platform was used to synchronously capture lower-limb joint movements and GRF. 36 young females volunteered to participate in this study and were asked about high-heeled shoe-wearing experience, including frequency, duration, heel types, and heel heights. Eleven who had the experience of 3 to 6 cm heels for a minimum of three days per week (6 h per day) for at least two years and eleven who wore high heels less than twice per month participated. Subjects performed jogging and running at comfortable low and high speeds, respectively, with the right foot completely stepping onto a force platform when passing by along a 10 m walkway. EW and IEW adopted different biomechanical adaptations while jogging and running. IEW exhibited a generally larger range of joint movement, while EW showed a dramatically larger loading rate of GRF during running. Hence, further studies on the lower-limb biomechanics of high-heeled gait should strictly control the wearing experience of the subjects.

This study investigated lower-limb kinematics and ground reaction force (GRF) during moderate high-heeled jogging and running. Subjects were divided into groups of experienced wearers and inexperienced wearers. A three-dimensional motion analysis system with a configured force platform captured lower-limb joint movements and GRF.

A limited number of studies have explored lower-limb biomechanics during high-heeled jogging and running, and most studies have failed to clarify the ...

Oscillation and Reaction Board Techniques for Estimating Inertial Properties of a Below-knee Prosthesis

The purpose of this study was two-fold: 1) demonstrate a technique that can be used to directly estimate the inertial properties of a below-knee prosthesis, and 2) contrast the effects of the proposed technique and that of using intact limb inertial properties on joint kinetic estimates during walking in unilateral, transtibial amputees. An oscillation and reaction board system was validated and shown to be reliable when measuring inertial properties of known geometrical solids. When direct measurements of inertial properties of the prosthesis were used in inverse dynamics modeling of the lower extremity compared with inertial estimates based on an intact shank and foot, joint kinetics at the hip and knee were significantly lower during the swing phase of walking. Differences in joint kinetics during stance, however, were smaller than those observed during swing. Therefore, researchers focusing on the swing phase of walking should consider the impact of prosthesis inertia property estimates on study outcomes. For stance, either one of the two inertial models investigated in our study would likely lead to similar outcomes with an inverse dynamics assessment.

Body segmental inertial properties are required for inverse dynamics modeling. Using an oscillation and reaction board technique, inertial properties of below-knee prostheses were measured. Using direct measures of prosthesis inertia in the inverse dynamics model of the prosthetic leg resulted in lower magnitudes of resultant joint forces and moments.

The purpose of this study was two-fold: 1) demonstrate a technique that can be used to directly estimate the inertial properties of a below-knee ...

Bioengineering

Biomechanical Analysis Methods to Assess Professional Badminton Players' Lunge Performance

Under the condition of simulating a badminton court in the laboratory, this study used the injury mechanism model to analyze the maximal right lunge movements of eight professional badminton players and eight amateur players. The purpose of this protocol is to study the differences in kinematics and joint moment of the right knee and ankle. A motion capture system and force plate were used to capture data of the joint movements of the lower extremity and the vertical ground reaction force (vGRF). Sixteen young men who did not have any sports injuries in the past 6 months took part in the study. The subjects performed a maximal right lunge from the start position with their right foot, stepping on and fully contacting with the force plate, hit the shuttlecock with an underhand stroke to the designated position in the backcourt, and then returned to the start/end position. All subjects wore the same badminton shoes to avoid a difference in impact from different badminton shoes. The amateur players showed a greater range of ankle movement and reverse joint moment on the frontal plane, and a larger internal joint rotation moment on the horizontal plane. The professional badminton players exhibited greater knee moment on the sagittal and frontal planes. Therefore, these factors should be considered in the development of the training program to reduce the risk of sports injuries in knee and ankle joints. This study simulates the real badminton court and calibrates the range of activities of each movement of the subjects so that the subjects complete the experimental action in a natural state with high quality. A limitation of this study is that it does not combine joint load and muscle activity. Another limitation is that the sample size is small and should be expanded in future studies. This research method can be applied to the lower limb biomechanical research of other footwork in the badminton project.

Here, we present a protocol to evaluate the differences in injury mechanisms between professional and amateur players when performing a badminton maximal right lunge movement by analyzing lower limb kinematics.

Under the condition of simulating a badminton court in the laboratory, this study used the injury mechanism model to analyze the maximal right lunge ...

Comparative Analysis of Lower Limb Kinematics between the Initial and Terminal  Phase  of 5km Treadmill Running

Running is beneficial for physical health, but it is also accompanied by many injuries. However, the main factors leading to running injury remain unexplained. This study investigated the effects of long running distance on lower-limb kinematic variables and the lower limb kinematic difference of between the initial (IR) and terminal phase (TR) of 5 km running was compared. Ten amateur runners ran on a treadmill at the speed of 10 km/h. Dynamic kinematic data was collected at the phase of IR (0.5 km) and TR (5 km), respectively. The peak angle, peak angular velocities, and range of motion were recorded in this experiment. The main results demonstrated the following: ankle eversion and knee abduction were increased at TR; ROMs of ankle and knee were increased in the frontal plane at TR than IR; a larger peak angular velocity of ankle dorsiflexion and hip interrotation were found in TR compared to IR. These changes during the long distance running may provide some specific details for exploring potential reasons of running injuries.

This study investigated the biomechanical characteristics of the lower extremity kinematic variables between the initial and terminal phase of 5 km treadmill running. The lower-limb kinematic data of 10 runners were collected using a three-dimensional motion capture system on a treadmill at the initial phase (0.5 km) and the terminal phase (5 km), respectively.

Running is beneficial for physical health, but it is also accompanied by many injuries. However, the main factors leading to running injury remain ...

Lower-Limb Biomechanical Characteristics Associated with Unplanned Gait Termination Under Different Walking Speeds

Gait termination caused by unexpected stimulus is a common occurrence in everyday life. This study presents a protocol to investigate the lower-limb biomechanical changes that occur during unplanned gait termination (UGT) under different walking speeds. Fifteen male participants were asked to perform UGT on a walkway at normal walking speed (NWS) and fast walking speed (FWS), respectively. A motion analysis system and plantar pressure platform were applied to collect lower-limb kinematic and plantar pressure data. Paired-sampled T-test was used to examine the differences in lower-limb kinematics and plantar pressure data between two walking speeds. The results showed larger range of motion in the hip, knee, and ankle joints in the sagittal plane as well as plantar pressure in forefoot and heel regions during UGT at FWS when compared with NWS. With the increase in walking speed, subjects exhibited different lower-limb biomechanical characteristics that show FWS associated with greater potential injury risks.

This study compared the biomechanical characteristics of the lower extremity during unplanned gait termination under different walking speeds. The lower-limb kinematic and kinetic data from fifteen subjects with normal and fast walking speeds were collected using a motion analysis system and plantar pressure platform.

Gait termination caused by unexpected stimulus is a common occurrence in everyday life. This study presents a protocol to investigate the lower-limb ...

Subject-specific Musculoskeletal Model for Studying Bone Strain During Dynamic Motion

Bone stress injuries are common in sports and military trainings. Repetitive large ground impact forces during training could be the cause. It is essential to determine the effect of high ground impact forces on lower-body bone deformation to better understand the mechanisms of bone stress injuries. Conventional strain gauge measurement has been used to study in vivo tibia deformation. This method is associated with limitations including invasiveness of the procedure, involvement of few human subjects, and limited strain data from small bone surface areas. The current study intends to introduce a novel approach to study tibia bone strain under high impact loading conditions. A subject-specific musculoskeletal model was created to represent a healthy male (19 years, 80 kg, 1,800 mm). A flexible finite element tibia model was created based on a computed tomography (CT) scan of the subject&#39;s right tibia. Laboratory motion capture was performed to obtain kinematics and ground reaction forces of drop-landings from different heights (26, 39, 52 cm). Multibody dynamic computer simulations combined with a modal analysis of the flexible tibia were performed to quantify tibia strain during drop-landings. Calculated tibia strain data were in good agreement with previous in vivo studies. It is evident that this non-invasive approach can be applied to study tibia bone strain during high impact activities for a large cohort, which will lead to a better understanding of injury mechanism of tibia stress fractures.

During landing, lower-body bones experience large mechanical loads and are deformed. It is essential to measure bone deformation to better understand the mechanisms of bone stress injuries associated with impacts. A novel approach integrating subject-specific musculoskeletal modeling and finite element analysis is used to measure tibial strain during dynamic movements.

Bone stress injuries are common in sports and military trainings. Repetitive large ground impact forces during training could be the cause. It is ...

The Lower Body Positive Pressure Treadmill for Knee Osteoarthritis Rehabilitation

Here, based on a clinician&rsquo;s point-of-view, we propose a two-model lower body positive pressure (LBPP) protocol (walking and squatting models) in addition to a clinical, functional assessment methodology, including details for further encouragement of the development of non-drug surgical intervention strategies in knee osteoarthritis patients. However, we only present the effect of LBPP training in improvement of pain and knee function in one patient through three-dimensional gait analysis. The exact, long-term effects of this approach should be explored in future studies.

Here, based on a clinician&#8217;s point-of-view, we propose a two-model lower body positive pressure (LBPP) protocol (walking and squatting models) in addition to a clinical, functional assessment methodology, including details for further encouragement of the development of non-drug surgical intervention strategies in knee osteoarthritis patients. However, we only present the effect of LBPP training in improvement of pain and knee function in one patient through three-dimensional gait analysis. The exact, long-term effects of this approach should be explored in future studies.

Here, based on a clinician&rsquo;s point-of-view, we propose a two-model lower body positive pressure (LBPP) protocol (walking and squatting models) in ...

Influence of Step-Width Manipulation on Running Biomechanics

Step width is a critical factor influencing lower limb biomechanics during running, significantly affecting stability, performance, and injury risk. Understanding these effects is essential for optimizing running performance and minimizing injury risk. This study evaluated the effects of varying step widths on lower limb biomechanics at different running speeds. Thirteen healthy Chinese males (aged 20-24) participated in the study, running at speeds of 3.0 m/s and 3.7 m/s using six distinct step widths: the preferred step width and five variations (reductions of 13% and 6.5%, and increases of 6.5%, 13%, and 25%, based on leg length). Data were collected using a motion capture system and force plates and analyzed through repeated measures ANOVA and correlation tests. The results indicated that wider step widths significantly reduced peak knee abduction moments and hip adduction angles, whereas narrower step widths increased knee joint loading. These findings have important implications for clinicians and runners, suggesting that careful step width selection can help reduce injury risk and enhance running efficiency. This study contributes a new dataset that lays the foundation for future research into the relationship between step width and running biomechanics and serves as a reference for training and rehabilitation practices.

The present protocol outlines an experimental setup designed to investigate the influence of step width manipulation on running biomechanics using a motion capture system. The objective is to expand relevant datasets and examine the effects of varying step widths on the kinematic chain of the human lower limb.

Step width is a critical factor influencing lower limb biomechanics during running, significantly affecting stability, performance, and injury risk. ...

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.

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 ...