Effect of Wearing Running Shoes on Lower Limb Kinematics by Using OpenSim Simulation Software
Round 1
Reviewer 1 Report
The authors reported on the kinematics difference between flat-foot subjects with and without running shoes. They revealed there was a difference in ankle angle with and without shoes, which contributed to the decrease of the angle. I think the experiment design is proper, but the description of the results should be added more. The followings are the points to be addressed.
Why does the difference in hip, knee, and ankle angles arise between left and right? It is related to the subject's dominant foot?
In lines 74-75, the authors describe "it is indicated that ... can yield positive long-term effects". How does figure 4 indicate this?
In line 76, the authors mention that FE and AA were higher. What comparison was done? I agree that FE was higher absolute values than AA and RR in figure 4, but I don't understand what is high for AA.
In line 96, I cannot understand "According to Figure 9, ..." because there is no experimental comparison between the flat-foot group and the normal group in this study.
On lines 98-101, how is the Medio-Lateral motion of COM related to the balance? Even if there is literature, please describe the relationship briefly.
For minor corrections,
In the sentence before eq.(1), the same x_i is used for different data. Is it correct?
At line 65, % is missing.
Author Response
Reviewer #1:
Suggestion 1.) Why does the difference in hip, knee, and ankle angles arise between left and right? It is related to the subject's dominant foot?
Response: No, it is not related to subject’s dominant foot. The main reason for the difference in right and leg joint angle pattern is due to the gait patterns. For example, if the patient right leg starts with heel strike, the left leg will heel strike at the swing phase. The below figure will help us to understand the difference between right and left.
Source: https://musculoskeletalkey.com/normal-gait/
Suggestion 2.) In lines 74-75, the authors describe "it is indicated that ... can yield positive long-term effects". How does figure 4 indicate this?
Response: Thanks for pointing out this suggestion. The following correction has been made in the manuscript.
The following excerpt has been added to the “3.1 Kinematic Analysis” section of the manuscript.
As from Figure 4, it is indicated that the patient with flatfoot exhibits higher FE.
Suggestion 3.) In line 76, the authors mention that FE and AA were higher. What comparison was done? I agree that FE was higher absolute values than AA and RR in figure 4, but I don't understand what is high for AA.
Response: Thanks for pointing out this suggestion. The following correction has been made in the manuscript.
The following excerpt has been added to the “3.1 Kinematic Analysis” section of the manuscript.
Compared to left and right flat-foot hip kinematics, Flexion/Extension shows higher in both with shoe and without shoe cases. The absolute values of the Hip AA were observed higher in the right compared to left.
Suggestion 4.) In line 96, I cannot understand "According to Figure 9, ..." because there is no experimental comparison between the flat-foot group and the normal group in this study.
Response: Thanks for pointing out this suggestion. The following correction has been made in the manuscript.
The following excerpt has been added to the “3.1 Kinematic Analysis” section of the manuscript.
According to Figure 9, It is clear that the flat-foot group with shoes had a larger variability in the COM compared to without shoe (barefoot) group.
Suggestion 5.) On lines 98-101, how is the Medio-Lateral motion of COM related to the balance? Even if there is literature, please describe the relationship briefly.
Response: Thanks for pointing out this suggestion. Medio-Lateral COM relationship with balance control is detailed in the below study and it has been already cited as the [16] reference in the manuscript also for the line 98-101.
- Chou, L.S.; Kaufman, K.R.; Hahn, M.E.; Brey, R.H. Medio-lateral motion of the center of mass during obstacle crossing distinguishes elderly individuals with imbalance. Gait & posture 2003, 18, 125–133
Suggestion 6.) In the sentence before eq.(1), the same x_i is used for different data. Is it correct?
Response: Thanks for pointing out this suggestion. The following correction has been made in the manuscript.
The following excerpt has been added to the “3.1 Kinematic Analysis” section of the manuscript.
The IK estimates a weighted least square equation to minimize length between model marker data (xi) and surface reflective marker data ()in each time interval
Suggestion 7.) At line 65, % is missing
Response: Thanks for pointing out this suggestion. The suggested correction has been made in the manuscript.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The instrumentation, data analysis, statistics (paragraph 2.2, 2.4, 2.5) are insufficiently described or represented.
I think the results from analyses for one complete gait cycle presented in the Figure 3, 5 and 7 could be more detailed.
Also, the conclusions are too short.
Author Response
Reviewer #2:
Comments.) The instrumentation, data analysis, statistics (paragraph 2.2, 2.4, 2.5) are insufficiently described or represented. I think the results from analyses for one complete gait cycle presented in the Figure 3, 5 and 7 could be more detailed. Also, the conclusions are too short.
Response: Thank you very much for your suggestion and inputs. The following correction has been made in the manuscript.
Instrumentation
Following the Navicular drop test and resting calcaneal position test, the 3D gait analysis was performed. Subjects were asked to perform a bilateral stance posture assessment for model creation and processing prior to gait acquisition. As a result, all subjects were instructed to walk barefoot at a self-selected and comfortable pace across an 8-meter walkway, replicating their daily gait. A starting point was established to standardize gait initiation. Twelve Vicon motion capturing camera (Vicon MX, Oxford, UK, 200 Hz Sampling Frequency) were used to record the kinematics data. For motion capture, the 35 reflective markers were affixed over the anatomical landmarks as shown in the Figure 1. Each participant was asked to walk with and without shoe (Running shoe made of TPU) and the data was obtained for 5 successive trials. The trial was discarded if the subjects failed to produce their daily gait and the new trial was conducted for the study. Trials which are clear with all the marker data were selected for further processing.
Data Analysis
The Mokka (Motion Kinematics and Kinetics Analyser) software was used to distinguish the on-set and off-set from the C3D file and convert to TRC files. Mokka can also be used for extracting the Ground reaction force (GRF) and EMG data associated with the subject. The duration time of one cycle gait was normalized to percentage to facilitate the timing comparison timing between groups and subjects.
Statistics
The data were statistically processed with the Matlab 2022 software (MathWorks, USA). The statistics analysis was performed for the lower limb kinematics for gait with and without running shoes. The results are present at mean values and standard deviation (SD) with a confidence level of 95%.
3.1. Kinematic Analysis
The Ankle, Hip and Knee angles of each lower limb (Left/Right) were analysed for one complete gait cycle and are presented in the Figure 3, 5 and 7. Hip Kinematics of the Flatfoot subject with its Maximum joint angle characteristics are visualized in Figure 3 and 4. As from the above Figure 3, there is no significant difference in Hip kinematics with and without shoe. As from Figure 4, it is indicated that the patients with flatfoot exhibit higher FE compared to other range of motions. Compared to left and right flat-foot hip kinematics, Flexion/Extension shows higher in both with shoe and without shoe cases. The absolute values of the Hip AA were observed higher in the right compared to left. Hip rotation shows higher differences in joint angles with a decrease of -187.4% and increase of -4.9% in the right and left flatfoot during gait phase [15].
Knee Angle of the Flatfoot subjects and its Maximum joint angle with and withoutshoe characteristics are depicted in Figure 5 and 6.
As from the above Figure 5 and 6, there is no significant difference between with and without shoe conditions in flatfoot subjects. Knee kinematics of flatfoot subjects with and without shoe group were in similar fashion [15]. The percent of change between with and without shoe group of Knee was found to be a decrease of 12.4% and a increase of 0.4% in the right and left knee.
Ankle Angle of the Flatfoot subjects and its Maximum joint angle with and without shoe characteristics are depicted in Figure 7 and 8.
As from the above Figure 7 and 8, it is clearly shown that the Ankle kinematics of Flatfoot with and without shoes were distinctly separable. Less ankle dorsiflexion angle was observed while using shoe for one complete gait cycle. The percent of change between with and without shoe group was found to be a decrease of 41.96% and 35.2% in the right and left ankle angle. It is clearly evident that while wearing shoes, the DOF and ankle kinematics were reduced, indicating lesser pressure was required to initiate the movement than normal walking. Hence, the ankle plays a major role in Flatfoot kinematics and the orthosis will help in balance control for flatfoot subjects and also help in reducing ankle pronation deformity.
- Discussion
Flatfoot is a condition that causes several injuries, such as pain due to the alternation in the gait patterns, speed, balance, and control. This will consequently result in risk of falling and decreasing the mobility functions. Hence, this presented study was to compare kinematics analysis of gait with and without running shoes and the Medio-Lateral relationship to balance in flatfoot subjects. The kinematics results indicate that flatfoot disorder alters the lower body kinematics, balance, and control. Flatfoot subjects have lesser ankle dorsiflexion and knee extension peak, leading to lack of mobility. It also indicates that flatfoot groups have a different range of motion (ROM) similar to previous literature [4, 15 ]. It is shown that the above kinematic variables can be customized and improvised for normal gait by wearing shoes. Based on this study, the pronation deformity will improve when wearing shoes and it can reduce the ankle angle. [4, 15 ,16 ]. The hip and knee flexion results need to be absorbed at the foot level usually during the dynamic impact. Running shoes acts a cushion and balance support for flatfoot subjects. This can be improvised by providing compensation counterparts within the shoe to absorb the abnormal changes in the gait. Additionally, the Medio-Lateral COM and its role in balance control were detailed in this study [16]. The counter balance in the frontal plane is essential for flatfoot subjects to reduce the risk of falling. The above needs are addressed by wearing shoes. Further, The presented data can be cross-validated with normal subjects to differentiate the lower limb kinematics. Plantar pressure characteristics can also be recorded to understand the pressure distribution variations in the foot region. Also, the balance compensation strategy for flatfoot subjects needs to be developed. In this way, the presented data will be helpful in the development of foot orthosis for flatfoot subjects suitable for dynamic activities.
- Conclusions
The main goal of the current study was to quantify the kinematics variables and COM relationship in flat foot subjects with and without running shoes. The shoe and barefoot groups were significantly different in the kinematics of lower limb joints. Running shoes can alter the kinematics variables of the lower limbs in flat foot subjects. Hence, in order to protect, restore, and reduce the side effects of the complete foot and posture, wearing suitable shoes can be a fine option for flat foot disorder. Also, the presented study describes the parameters essential for balance and control. Further attempts are needed to evaluate the specific modification strategy of subjects with flatfoot, which could use different running shoes with visual input. In addition, the correlation between kinematics and kinetics variables in the evaluation of running shoes will be helpful to find pathological aspects.
The following excerpt has been added to the “3.1 Kinematic Analysis” section of the manuscript.
In line 81, The characteristics of the Kinematic and COM plots are discussed in detail. As from the above Figure 3, there is no significant difference in Hip kinematics with and without shoe. As from Figure 4, it is indicated that the patients with flatfoot exhibit higher FE compared to other range of motions. Compared to left and right flat-foot hip kinematics, Flexion/Extension shows higher in both with shoe and without shoe cases. The absolute values of the Hip AA were observed higher in the right compared to left. Hip rotation shows higher differences in joint angles with a decrease in -187.4% and increase in -4.9% in the right and left flatfoot during gait phase [15].
Author Response File: Author Response.pdf
Reviewer 3 Report
The article entitled "Effect of wearing running shoes on lower limb kinematics by using OpenSim simulation software" is basically an interesting data analysis. The capturing of gait data and the subsequent data treatment seems excellent.
However, unfortunately, the authors do not present any new results or new practical applications from their data.
For instance, in the conclusion, they write:
"Running shoes can alter the kinematics variables of the lower limbs in flat foot subjects therefore, wearing suitable shoes can fine option to reduce the side effects of flat foot disorder."
This is nothing new and this is why "...over-the-counter insole to restore foot mechanics and reduce discomfort is a common therapy", as the authors claim in the abstract.
What is also missing is a comparative analysis of these data with those obtained from non-flat-foot subjects.
In any case, for an acceptable article, there must be a problem to be solved, i.e. the data obtained by the authors must be used to diagnose or treat a condition/problem, and this has not been shown in that article.
For that reason, I cannot recommend it for publication.
Author Response
Reviewer #3:
Comments.) The article entitled "Effect of wearing running shoes on lower limb kinematics by using OpenSim simulation software" is basically an interesting data analysis. The capturing of gait data and the subsequent data treatment seems excellent. However, unfortunately, the authors do not present any new results or new practical applications from their data.
For instance, in the conclusion, they write: "Running shoes can alter the kinematics variables of the lower limbs in flat foot subjects therefore, wearing suitable shoes can fine option to reduce the side effects of flat foot disorder."
This is nothing new and this is why "...over-the-counter insole to restore foot mechanics and reduce discomfort is a common therapy", as the authors claim in the abstract. What is also missing is a comparative analysis of these data with those obtained from non-flat-foot subjects.
In any case, for an acceptable article, there must be a problem to be solved, i.e. the data obtained by the authors must be used to diagnose or treat a condition/problem, and this has not been shown in that article. For that reason, I cannot recommend it for publication.
Response: Thank you very much for your suggestion and inputs.
Goal: The goal of the current study is (1) to examine the flat-foot gait kinematics with and without running shoe and (2) to compare the balance control relationship between with shoe and without shoe group for flatfoot subjects in different directions.
Proposed Solution: We analyse the effects of running shoes to find how we can reduce the side effects of flatfoot subjects by wearing running shoes.
Flatfoot is also associated with several factors. 3D Gait biomechanical investigation is essential for early detection of the foot disorders. Also, the over counter insoles are widely used for the diagnosis purposes. In order to protect the complete foot functions and posture, shoes would be a perfect option in order to preserve and restore the gait by enhancing the compensation mechanism. Based on our research, we found that the ankle dorsiflexion, Hip Abduction -Adduction, internal/ external rotation joint angles and COM variability would be an indicator for altering the flatfoot gait patterns. Hence, we find this work would add value to the clinical way by emphasizing the role of running shoes for flatfoot subjects in order to reduce the side effects of the flatfoot.
The following correction has been made in the manuscript.
3.1. Kinematic Analysis
The Ankle, Hip and Knee angles of each lower limb (Left/Right) were analysed for one complete gait cycle and are presented in the Figure 3, 5 and 7. Hip Kinematics of the Flatfoot subject with its Maximum joint angle characteristics are visualized in Figure 3 and 4. As from the above Figure 3, there is no significant difference in Hip kinematics with and without shoe. As from Figure 4, it is indicated that the patients with flatfoot exhibit higher FE compared to other range of motions. Compared to left and right flat-foot hip kinematics, Flexion/Extension shows higher in both with shoe and without shoe cases. The absolute values of the Hip AA were observed higher in the right compared to left. Hip rotation shows higher differences in joint angles with a decrease of -187.4% and increase of -4.9% in the right and left flatfoot during gait phase [15].
Knee Angle of the Flatfoot subjects and its Maximum joint angle with and without shoe characteristics are depicted in Figure 5 and 6.
As from the above Figure 5 and 6, there is no significant difference between with and without shoe conditions in flatfoot subjects. Knee kinematics of flatfoot subjects with and without shoe group were in similar fashion [15]. The percent of change between with and without shoe group of Knee was found to be a decrease of 12.4% and a increase of 0.4% in the right and left knee.
Ankle Angle of the Flatfoot subjects and its Maximum joint angle with and without shoe characteristics are depicted in Figure 7 and 8.
As from the above Figure 7 and 8, it is clearly shown that the Ankle kinematics of Flatfoot with and without shoes were distinctly separable. Less ankle dorsiflexion angle was observed while using shoe for one complete gait cycle. The percent of change between with and without shoe group was found to be a decrease of 41.96% and 35.2% in the right and left ankle angle. It is clearly evident that while wearing shoes, the DOF and ankle kinematics were reduced, indicating lesser pressure was required to initiate the movement than normal walking. Hence, the ankle plays a major role in Flatfoot kinematics and the orthosis will help in balance control for flatfoot subjects and also help in reducing ankle pronation deformity.
- Discussion
Flatfoot is a condition that causes several injuries, such as pain due to the alternation in the gait patterns, speed, balance, and control. This will consequently result in risk of falling and decreasing the mobility functions. Hence, this presented study was to compare kinematics analysis of gait with and without running shoes and the Medio-Lateral relationship to balance in flatfoot subjects. The kinematics results indicate that flatfoot disorder alters the lower body kinematics, balance, and control. Flatfoot subjects have lesser ankle dorsiflexion and knee extension peak, leading to lack of mobility. It also indicates that flatfoot groups have a different range of motion (ROM) similar to previous literature [4, 15 ]. It is shown that the above kinematic variables can be customized and improvised for normal gait by wearing shoes. Based on this study, the pronation deformity will improve when wearing shoes and it can reduce the ankle angle. [4, 15 ,16 ]. The hip and knee flexion results need to be absorbed at the foot level usually during the dynamic impact. Running shoes acts a cushion and balance support for flatfoot subjects. This can be improvised by providing compensation counterparts within the shoe to absorb the abnormal changes in the gait. Additionally, the Medio-Lateral COM and its role in balance control were detailed in this study [16]. The counter balance in the frontal plane is essential for flatfoot subjects to reduce the risk of falling. The above needs are addressed by wearing shoes. Further, The presented data can be cross-validated with normal subjects to differentiate the lower limb kinematics. Plantar pressure characteristics can also be recorded to understand the pressure distribution variations in the foot region. Also, the balance compensation strategy for flatfoot subjects needs to be developed. In this way, the presented data will be helpful in the development of foot orthosis for flatfoot subjects suitable for dynamic activities.
- Conclusions
The main goal of the current study was to quantify the kinematics variables and COM relationship in flat foot subjects with and without running shoes. The shoe and barefoot groups were significantly different in the kinematics of lower limb joints. Running shoes can alter the kinematics variables of the lower limbs in flat foot subjects. Hence, in order to protect, restore, and reduce the side effects of the complete foot and posture, wearing suitable shoes can be a fine option for flat foot disorder. Also, the presented study describes the parameters essential for balance and control. Further attempts are needed to evaluate the specific modification strategy of subjects with flatfoot, which could use different running shoes with visual input. In addition, the correlation between kinematics and kinetics variables in the evaluation of running shoes will be helpful to find pathological aspects.
The following excerpt has been added to the “Current State of Art” section of the manuscript.
Goal: The goal of the current study is (1) to examine the flat-foot gait kinematics with and without running shoe and (2) to compare the balance control relationship between with shoe and without shoe group for flatfoot subjects in different directions.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The revised manuscript has solved most of my concerns, but I still raise a point to be addressed before publication.
The authors modified "According to Figure 9, ..." as highlighted on lines 107-108 in the revised version, while the indication is not clear for me from the figure. Which part of the figure represents larger variability with shoe than that without shoe? (size of standard deviation? or mean curve behaivior?) I also recommend to separate what the figure represents and what is known in literature.
Author Response
Suggestion 1.) The authors modified "According to Figure 9, ..." as highlighted on lines 107-108 in the revised version, while the indication is not clear for me from the figure. Which part of the figure represents larger variability with shoe than that without shoe? (size of standard deviation? or mean curve behaviour?) I also recommend to separate what the figure represents and what is known in literature.
Response: Size of standard deviation
Explanation: The standard deviation of kinematics variables indicates that variability for shoe conditions was higher than without shoe conditions therefore, wearing shoes may increase kinematics variability.
Reviewer 2 Report
the manuscript has been sufficiently improved to warrant publication in Actuators
Author Response
Thanks for your valuable suggestion and inputs. We appreciate your time and efforts for providing comments on our manuscript.
Reviewer 3 Report
The authors have carefully considered the reviewer comments. The second version of the manuscript has been improved greatly. Some issues which raised my concerns have been resolved. For that reason, I can now recommend the paper for publication.
Author Response
Thanks for your valuable suggestion and input. We appreciate your time and efforts in providing comments on our manuscript.
