• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.771-778
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• 2009

We aimed to determine the effect of heel height on foot pressure by comparing and analyzing data on foot pressure in shoes with different heel heights. Qn the basis of a previous study, we selected 3cm and 7cm as the shoe heel heights preferred by female college students. We divided 10 female students into forefoot and hindfoot to measure vertical force, maximum pressure, and average pressure. The average pressure on the forefoot was higher and that on the hindfoot was lower in the case of 7cm high-heeled shoes. The maximum pressure on the forefoot was significantly higher in the case of the 7cm heel height (p<.05). The vertical force, maximum pressure, and average pressure on the hindfoot were also significantly higher in the case of the 7cm heel height (p<.05). The results showed that wearing 7cm high-heeled shoes exerted greater maximum pressure on the forefoot and greater vertical force, maximum pressure, and average pressure on the Hndfoot. This leads to increase in confining pressure caused by high pressure distribution over the forefoot and increase in the pressure on the hindfoot, which may cause deformation of toes and heel pain over a long period. Therefore, female college students who wish to wear high heels are recommended to wear 3cm high-heeled shoes rather than 7cm high-heeled shoes.

• Interaction and multiscale mechanics
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• v.5 no.1
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• pp.75-90
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• 2012

This paper investigates the effects of sports ground materials on the transfer characteristics of the landing impact force using a coupled foot-shoe-ground interaction model. The impact force resulting from the collision between the sports shoe and the ground is partially dissipated, but the remaining portion transfers to the human body via the lower extremity. However, since the landing impact force is strongly influenced by the sports ground material we consider four different sports grounds, asphalt, urethane, clay and wood. We use a fully coupled 3-D foot-shoe-ground interaction model and we construct the multi-layered composite ground models. Through the numerical simulation, the landing impact characteristics such as the ground reaction force (GRF), the acceleration transfer and the frequency response characteristics are investigated for four different sports grounds. It was found that the risk of injury, associated with the landing impact, was reduced as the ground material changes from asphalt to wood, from the fact that both the peak vertical acceleration and the central frequency monotonically decrease from asphalt to wood. As well, it was found that most of the impact acceleration and frequency was dissipated at the heel, then not much changed from the ankle to the knee.

• Journal of the Ergonomics Society of Korea
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• v.29 no.5
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• pp.789-795
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• 2010

This study aimed to investigate the effect of differing heel height on static balance and muscle activation of ankle joint during standing. Twenty-one young females volunteered to participate in this study. To measure balance function and EMG activity of tibialis anterior and gastrocnemius muscles, the subjects were asked to perform 1-min standing with eyes open and closed state under 3 different heel heights: barefoot, 3cm, and 7cm each. During the standing, postural sway distance and area, and EMG activity of tibialis anterior and gastrocnemius muscles were significantly augmented with increasing heel height (p<0.05). For comparison between eyes open and closed in terms of postural sway area and EMG activity of tibialis anterior muscle, barefoot and 7cm height conditions respectively showed significant differences as well. The findings indicate that high-heeled shoes may have disadvantages in maintaining balance function because of extra-muscular effort of ankle joint. This study provides useful information that will inform future studies on how heel height affects muscle activity around the ankle joint in aspects of static and dynamic balance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.260-263
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• 2005

In this study, we analyzed the plantar shear stress and pressure of diabetic foot patients during walking by using in-shoe local shear force and plantar pressure measurement system. Twelve normal subjects and three diabetic foot patients with diabetic neuropathy in lateral heel were participated in this study. The center of pressure in diabetic foot patients moved more medially and directed toward 1st, 2nd metatarsal heads and hallux during late stance period, making pressure at the medial heel and 2nd metatarsal head significantly higher than in the normal. Shear stress at the heel were changed significantly in early stance and the magnitude of shear stresses in each metatarsal head were also changed. Further studies would be very helpful to design foot orthoses in patients with diabetic neuropathy or other diseases.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.111-119
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• 2007

The purpose of this study was to investigate muscle activity and gait pattern in lower limb depending on the outsole of heel rockers. Fifteen healthy men volunteered for this experiment. Each subject performed totally three trails with two pairs of different heel rocker shoes and a pair of normal running shoes at speed of 1.33m/s for 1 minute during walking on a treadmill. Kinematic data gathered in 100Hz was recorded and analyzed by using the 3D motion capture system to measure the trunk tilt and joint angle of the right lower limb. And the lower extremity muscle activities were simultaneously recorded in 1000Hz and assessed by using EMG. The statistical analysis was the one-way ANOVA with the repeated measures to compare among the three kinds of shoes. The level of statistical significance for all tests was 0.05. Joint angle of lower limb was showed statistically significant different in MST(hip joint), LHS(ankle joint), and RTO(knee and ankle joint). Muscle activity of rectus femoris and biceps femoris was statistically increased in both heel rocker shoes during gait cycle on treadmill. The maximum peak time of tibialis anterior in the negative heel rocker showed the delay of approximately 23.8%time than normal shoes. Gait pattern variability of the negative heel rocker was increased in the first half of the stance phase and the variability of the positive heel rocker was increased in the terminal stance phase. In Conclusion, stability was decreased in between joints of lower limb on positive heel rocker than negative heel rocker. This study found that there were different joint angle, muscle activity, gait pattern and coordinate system of the lower limb in each kind of shoes. These unstability affected the lower extremity and the whole body. A further study has to be continued with study of rehabilitation and exercise for a long-term.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.196-203
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• 2004

In this study, a new gait phase detection system using both FSR(Force Sensing Resister) sensors and a gyrosensor was developed to detect various gait patterns. FSR sensors were put in self-designed shoe insoles and a gyrosensor was attached to the posterior aspect of a shoe. An algorithm was also developed to determine eight different gait transitions among four gait phases: heel-strike, foot-flat, heel-off and swing. The developed system was compared with the conventional gait phase detection system using only FSR sensors in various gait experiments such as level walking, fore-foot walking and stair walking. In fore-foot walking and stair walking, the developed system showed much better accuracy and reliability to detect gait phases. The developed gait phase detection system using both FSR sensors and a gyrosensor will be helpful not only to determine pathological gait phases but to apply prosthetics, orthotics and functional electrical stimulation to patients with gait disorders.

• Korean Journal of Applied Biomechanics
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• v.29 no.3
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• pp.167-172
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• 2019

Objective: The aim of this study was to investigate the effect of midsole hardness of running shoe on muscle fatigue and impact force during distance running. Method: Ten healthy college recreational runners who were performing distance running at least three times a week participated in this experiment. They were asked to run for 15 minutes in the treadmill at 10 km/h with running shoes having three different types of midsole hardness (Soft, Medium, Hard). EMG signal and insole pressure were collected during the first and last one minute for each running trials. Data were analyzed using a one-way analysis of variance (ANOVA) with repeated measures. Results: Midsole hardness did not affect the consistency of stride length. For the median frequency of the EMG signal, only VL was affected by midsole hardness; that of medium was greater than other midsoles (p<.05). The loading rate of impact forces increased by midsole hardness (p<.01). Conclusion: Although soft midsole could attenuate impact forces at heel contact, it might have a negative effect on the fatigue of muscle which could decelerate the body after heel contact. Therefore, it is necessary to select the optimum hardness of midsole carefully for both reduction impact forces and muscle fatigue.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.59-66
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• 2018

The utilized coefficient of friction (UCOF) as a ratio of the shear force to the normal force on the ground during walking is used to identify the point at which slip is likely to occur. Shoe walking will change the utilized coefficient of friction by shoe design such as sole thickness and hardness, heel shape, and outsole pattern. In this study, subjects are 21 adults (10 female, 11 male, age: $25.2{\pm}2.3yrs$, height: $165.6{\pm}7.2cm$), analysis variables were walking speed, GRF, when the UCOF is maximal, and Tangent of CoP-CoM angle, and correlation analysis with the utilized friction coefficient (UCOF). As a result, First, for the shod walking the time point which UCOF is maximum about heel strike was faster and the magnitude was larger than for barefoot walking. Second, the correlation between the tangent of CoP-CoM and UCOF of right foot was higher at the left heel striking point (UCOF2_h) which occurred in the post propulsion phase than at the right heel striking point (UCOF1_h). This suggests that the right foot UCOF is related to the braking phase of left foot( which is the propulsion phase of right foot) rather than the braking phase of right foot.

• Fashion & Textile Research Journal
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• v.10 no.1
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• pp.83-91
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• 2008

This study was designed to figure out the changes in elderly women's foot size and shape by aging, to propose size specification for elderly women's shoes, and to produce regression equations using representative measurements items to estimate other measurements usually hard to get. Subjects were 118 women of 30-59 years and the 227 elderly women over 60 years. Martin's anthropometry was done on the right foot of each subject for 25 items. And 11 indirect measurement items were measured on both foot printing sole outline and picture in profile taken by digital camera. For statistical analysis on the anthropometric measurements by SPSS program, analysis of variance, post-hoc test(SNK-test), crosstabulation, multiple correlation analysis, regression analysis were performed. The results of the study are as follows. Firstly, it was found that the foot figures of elderly women over 60 years were smaller in girth and width than those of below 60 years. In addition, it was revealed that a big toe and a little toe of elderly women showed a tendency concentrating to the central axis of feet. The foot index of elderly was smaller in width and girth. Secondly, foot size distribution table of elderly group showed wider size ranges and covered smaller sizes than the below the age of 60, meaning wide variation in foot size of elderly women. Thirdly, the multiple correlation analysis showed high correlation of foot length/girth to other measurements, suggesting these two items could be used as representative items for elderly women's shoe size specification as other age groups. Regression equations were produced using foot length/girth to estimate other measurements, suggesting such items could be estimated effectively and utilized in on/off-line shoe manufacturing shop as heel to big toe length, heel to little toe length, exterior malleouls width, instep girth, ankle girth, etc. These results imply prudent features of elderly women's foot as diversity of foot shape and wide size specification range should be applied for ergonomic shoe design for them.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1266-1273
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• 2013

The purpose of this study was to analysis the effect of form of outsole - complex function double rocker sole(CDR) vs. negative-heel rocker sole (NR) - on energy consumption and heart rate intensity during gait. 11 women, who had no medical history on musculoskeletal disease and surgery within 3 years prior to study, were participated. The walking energy cost per time (WECt) during 35minutes, heart rate intensity, and total calorie consumption were compared by using pair t-test. The WECt and total calorie consumption were found to be significantly higher(p<.05) in CDR than NR. However, there was no difference in HRi. Based on the present study, CDR shoe may have significant implications in shoe prescription for people who want to increase energy consumption.