• The Journal of Korea Robotics Society
• /
• v.17 no.3
• /
• pp.296-302
• /
• 2022

This paper proposes a center of plantar foot pressure (CoP) trajectory estimation method based on Gaussian process regression, with the aim to show robust results regardless of the regions and numbers of FSRs of the insole sensor. This method can bring an interpolation between the measurement points inside the wearable insole sensor, and two experiments are conducted for performance evaluation. For this purpose, the input data used in the experiment are generated in three types (13 FSRs, 8 FSRs, 5 FSRs) according to the regions and numbers of FSRs. First, the estimation results of the CoP trajectory are compared using Gaussian process regression and weighted mean. As a result of each method, the estimation results of the two methods were similar in the case of 13 FSRs data. On the other hand, in the case of the 8 and 5 FSRs data, the weighted mean varies depending on the regions and numbers of FSRs, but the estimation results of Gaussian process regression showed similar results in spite of reducing the regions and numbers. Second, the estimation results of the CoP trajectory based on Gaussian process regression during several gait cycles are analyzed. In five gait cycles, the previous cycle and the current estimation results are compared, and it was confirmed that similar trajectories appeared in all. In this way, the method of estimating the CoP trajectory based on Gaussian process regression showed robust results, and stability was confirmed by yielding similar results in several gait cycles.

• The Journal of Korean Physical Therapy
• /
• v.22 no.1
• /
• pp.47-51
• /
• 2010

Purpose: The purpose of this study was to determine whether there are any differences, with and without a toe spreader (TS), in dynamic foot pressure distribution in children with spastic diplegic cerebral palsy. Methods: Dynamic foot pressure recording using the RSscan system were obtained during walking in 12 participants (male=7, female=5) with and without TS. Mean force was measured for four different plantar regions; great toe, forefoot, midfoot, hindfoot. Displacement of center of pressure (COP), velocity of COP displacement and stance time were also measured during gait. Results: TS walking exhibited statistically significant decrease of mean force under great toe and forefoot (p<0.05), compared with a barefoot walking. Also, TS walking exhibited statistically significant increase of antero-posterior displacement of COP (p>0.05). Conclusion: These findings indicate the potential clinical utility of toe spreader to correct dynamic foot pressure during stance phase in children with spastic diplegic cerebral palsy.

• Korean Journal of Applied Biomechanics
• /
• v.31 no.3
• /
• pp.189-198
• /
• 2021

Objective: The aim of this study is to investigate the effect of biomechanical variables on gait according to indoor and outdoor environmental conditions in elderly women at risk of falling. Method: 26 elderly women aged 70 years or older, and consisted of 13 elderly people with a walking speed of less 1.0 m/s and 13 people in the fall risk group as normal groups. Depending on the purpose of the study, physical examination and psychological questionnaire were prepared, and then walking was performed in an indoor/outdoor environment, and the gait pattern, muscle activity, and plantar pressure results were compared and analyzed in the elderly females through a 2 group × 2 environment 2-way repeted ANOVA analysis. Results: The gait variable showed an interaction effect the cadence. The muscle variables showed interaction effects in the rectus femoris and tibialis anterior muscles, and the interaction effects of the plantar pressure variables were confirmed in the forefoot and midfoot of the contact area, and the midfoot of the mean pressure. Conclusion: These results indicate that both groups are exposed to falls risk when gait in an outdoor environment, but the fall risk group has a higher risk of falls in both the gait pattern, muscle activity, and plantar pressure variables. The results of this study are considered to be helpful as basic data and development of exercise programs to prevent falls.

• Korean Journal of Applied Biomechanics
• /
• v.20 no.4
• /
• pp.469-477
• /
• 2010

The purpose of this study was to evaluate the effects of insole-equipped ankle-foot-orthoses (AFO) on gait. 10 healthy males who had no history of injury in the lower extremity participated in this study as the subjects. The foot of each subject was first scanned, and the insole fit to the plantar was made using BDI-PCO(Pedcad Gmbh, Germany). The subject then was made to walk on a treadmill under four experimental conditions: 1) normal walking, 2) walking wearing AFO, 3) walking wearing AFO equipped with the insole, 4) walking wearing pneumatic-ankle-foot-orthosis (pAFO) equipped with the insole. During walking, foot pressure data such as maximum force, contacting area, peak pressure, and mean pressure was collected using Pedar-X system (Novel Gmbh, Germany) and EMG activity of lower limb muscles such as gastrocnemius medial head, gastrocnemius lateral head, and soleus was recorded using MP150 EMG module (BIOPAC System Inc., USA). Collected data was then analyzed using paired t-test in order to investigate the effects of the insole. As a result of the analysis, when insole was equipped, overall contacting area was increased while both the highest peak pressure and the mean pressure were significantly decreased, and EMG activity of the lower limb muscles was decreased. On the contrary, the cases of wearing AFO showed the decreased contacting area and the increased pressures. Therefore, the AFO equipped with a proper insole fit well to the foot can help comfortable walking by spreading the pressure over the entire plantar.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.12
• /
• pp.224-229
• /
• 2019

This study was undertaken to provide correct posture guidance and reference material for sports injury and injury prevention programs, by analyzing body alignment and plantar pressure distribution in high school baseball players. Totally, 32 subjects were enrolled for the study. Body alignment was measured from the trunk imbalance, kyphotic angle, lordotic angle, pelvic tilt, and pelvic torsion. Foot pressure was measured from the left maximum pressure, right maximum pressure, left weight, and right weight. The mean and standard deviation of the measured factors were calculated and tabulated, and the correlation between body alignment and foot pressure distribution was analyzed using Pearson's correlation analysis. All statistical significance levels were set at 0.05. Body alignment and foot pressure distribution show a positive correlation between the lordotic angle of lumbar spine and the left maximum pressure. There was no correlation between trunk imbalance, kyphotic angle, lordotic angle, pelvic tilt, pelvic torsion, and the left·right weight distribution and the left·right maximum pressure of each foot. Results of this study determined that the increase of the lordotic angle of lumbar spine results in more force on one side of the foot, thereby increasing the maximum pressure. We believe our data could be a reference for exercise programs on physical alignment and plantar pressure distribution of athletes.

• Korean Journal of Applied Biomechanics
• /
• v.18 no.1
• /
• pp.159-168
• /
• 2008

The purpose of this study was to analyze the variables of plantar pressure distribution, the COG between Flying Sit Spin(FSS) and Flying Camel Spin(FCS) during a Figure Skating. In order to investigate the two types of spin mechanism in the Korea national of elite women Figure skaters(N=4), this study investigated the phase time, CA(contact area), MF(maximum force) Mean Force, and PP(peak pressure) Mean Force. The data was collected using PEDAR Mobile System which is the pressure distribution measuring devices. The obtained conclusions were as follow: During the two types of spins(FSS and FCS), the FCS is higher than the FSS on the MF(20%BW), PP(20%BW) variables during P4 phase, but the FSS is larger than the FCS in the CA, MF, and PP during P1, P2, P3 phase. Consequently, depend on the COP and the COG locations about the vertical ground reaction vector, the FCS comparatively excelled control of speed feedback than the FSS in the P4 phase.

• Journal of Korean Foot and Ankle Society
• /
• v.8 no.1
• /
• pp.16-21
• /
• 2004

Purpose: To investigate the characteristics of the patients and therapeutic shoes for diabetic patients. Materials and Methods: Forty two diabetic patients who had their own therapeutic shoes which were prescribed somewhere else were studied from March 2003 to December 2003. There were 27 males and 15 females, and the mean age was 62.1 years (range, 49-72 years). Duration of diabetes was average 14 years (range, $6{\sim}30$ years), all had type 2 diabetes. Sensation was examined with 5.07 nylon monofilament. The route of purchasing the shoes, compliance to the prescribed shoes were investigated by interview. The shape of shoe, stiffness of upper, conformity of insole to the shape of the foot were recorded. In-shoe plantar pressure was measured in 15 patients. Results: Eighteen patients were insensate to the monofilament. Seven patients did not wear the therapeutic shoes, and only 18 of 35 patients were wearing the therapeutic shoes more than 6 hours a day. The shoes of 17 patients were prescribed by medical doctor and the rest were purchased by the recommendation of acquaintances or advertisement. Ulcer recurred in four of five patients to whom the shoe was prescribed by medical doctor and the cause of three recurrences were evident by just observing the foot and shoe. The therapeutic shoes were made from 11 different makers. Eight shoes were adequate for diabetic patients with respect to the material, shape of insole, type of shoe. In-shoe plantar pressure was examined in 15 patients and was less than 300 kPa in all patients. Conclusion: The therapeutic shoes for the diabetic patients need to be prescribed by medical doctor for selective patients with neuropathy or previous history of ulcer and follow-up examination is important to monitor the compliance of the patients and adequacy of the shoes.

• Korean Journal of Applied Biomechanics
• /
• v.30 no.1
• /
• pp.7-16
• /
• 2020

Objective: It is to find factors related to stability through analysis of plantar pressure factors according to the level of instability when performing Snatch. Method: Foot pressure analysis was performed while 10 weightlifters performed 80% of the highest level of Snatch, and motion was classified and analyzed in 3 grades according to the level of instability. Results: First, in Bad Motion, the movement distance of the pressure center in the direction of ML and AP was larger significantly in Phase 2. Second, in Phase 2, the number of zero-crossing in the AP direction was larger statistically significantly in Good Motion. Third, in the bad motion in Phase 3, the number of zero-crossing in the ML direction showed a significantly larger value. Fourth, in Phase 4, it was found that the more stable the lock out motion, the greater the activity of foot controlling in the left and right directions. Fifth, Phase 3, the greater the Maximum/Mean foot pressure value, the more stable the pulling action. Sixth, in Phase 2, the foot pressure was concentrated with a wide distribution in the midfoot and rearfoot. Seventh, the triggering number of the forefoot region was small in the last pull phase. Eighth, the number of triggers in the toe area was significantly higher during Good Motion in Phase 4. Conclusion: Summarizing the factors of instability in Snatch, there was no significant difference in Phase 1 for each condition. In order to enhance the stability in Phase 2, the sensory control ability in the AP direction is required, and focusing the foot pressing motion with a wide distribution in the middle and rear parts increases the instability. In Phase 3, it was found that the more unstable, the more sensory control activity was performed in the ML direction, the stronger the forefoot pressing action should be performed for a stable Snatch. In Phase 4, It is important that the feet sensory control activity in ML directions and the control ability of the toes in order to have stable Lock out motion.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.3
• /
• pp.1-7
• /
• 2005

Excessive pronation and impact force during running are related to various running injuries. To prevent these injuries, three type of running shoes are used, such as cushioning, stability, and motion control. Although there were may studies about the effect of midsole hardness on impact force, no study to investigate biomechanical effect of motion control running shoes. The purpose of this study was to determine biomechanical difference between cushioning and motion control shoes during treadmill running. Specifically, plantar and rearfoot motion, impact force and loading rate, and insole pressure distribution were quantified and compared. Twenty male healthy runners experienced at treadmill running participated in this study. When they ran on treadmill at 3.83 m/s. Kinematic data were collected using a Motion Analysis eight video camera system at 240 Hz. Impact force and pressure distribution data under the heel of right foot were collected with a Pedar pressure insole system with 26 sensors at 360 Hz. Mean value of ten consecutive steps was calculated for kinematics and kinetics. A dependent paired t-test was used to compare the running shoes effect (p=0.05). For most kinematics, motion control running shoes reduced the range of rearfoot motion compared to cushioning shoes. Runners wearing motion control shoe showed less eversion angle during standing less inversion angle at heel strike, and slower eversion velocity. For kinetics, cushioning shoes has the effect to reduce impact on foot obviously. Runners wearing cushioning shoes showed less impact force and loading rate, and less peak insole pressure. For both shoes, there was greater load on the medial part of heel compared to lateral part. For pressure distribution, runners with cushioning shoes showed lower, especially on the medial heel.

• The Journal of Korean Physical Therapy
• /
• v.21 no.2
• /
• pp.97-101
• /
• 2009

Purpose: This study examined how the direction of carrying a load affects the foot stability and kinesiology while walking. Methods: The heel rotation, Hallux stiffness, foot balance, metatarsal load, toe out angle, subtalar joint flexibility were measured in 40 adults (men and women) who carried a load back and forth, walking on a 2-meter-long board. The measurement was carried out three times and the mean of the measurements was used to compare the difference between the front, back and the condition without a load. Results: While walking, heel rotation and hallux stiffness occurred most when a front load was applied compared to a back load or no load condition (p<0.05). A metatarsal load also appeared to be the highest with the frond load, but there was no significant difference in the balance of the whole foot. Both the toe out angle and subtalar joint flexibility appeared to increase significantly (p<0.05). Conclusion: Applying the front load causes subtalar joint instability and increases the plantar foot pressure imbalance during walking.