• Korean Journal of Applied Biomechanics
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• v.12 no.1
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• pp.89-114
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• 2002

The purpose of this study was to analyze impact absorption function of midsole in cushioned marathon shoes. The foot is made up of a complex interaction of bones, ligaments, and muscles. These structures help the foot alternate between being a mobile, flexible adaptor and a stable rigid lever. The foot is broken down into two functional parts, the forefoot and the rearfoot. Cushioned marathon shoes for high arches have generous cushioning for efficient and high-mileage runners. Cushioned marathon shoes are made for feet that have high arches or no excessive motion and don't roll inward or roll outward. This condition is known as underpronation. Especially, Cushioned marathon shoes are designed to reduce shock and generally have the softest (or most cushioned) midsoles and the least medial support. They are usually built on a semicurved or curved last to encourage foot motion, which is helpful for underpronators (who have rigid, immobile feet). Cushioning marathon shoes recommended for the high-arched runner, whose foot may roll outward (supinate) rather than the natural slight inward roll, or whose feet may be relatively rigid. Cushioning shoes emphasize flexibility and usually are built on a curved or semicurved last to encourage a normal motion of the foot. Cushioning shoes usually offer no medial (inner foot) support. Cushioned marathon shoes have the single-density midsole, which is stable and relatively firm for a cushioned shoe, stays the same. But the forefoot is more rounded, and the rearfoot now includes a new and supportive rearfoot cradle. A foam midsole, perhaps with layers of different densities, to provide cushioning and shock absorption. EVA (ethylene vinyl acetate) and PU (polyurethane), the materials from which these foams usually are made. EVA is slightly softer than PU. EVA and PU may be layered together in a shoe, or a shoe may have more than one density of EVA.

• Archives of Reconstructive Microsurgery
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• v.2 no.1
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• pp.46-52
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• 1993

Soft-tissue deficits over the plantar forefoot, plantar heel, Achilles tendon, and distal parts of lower leg are often troublesome to cover with a simple graft or local flap due to limited mobility of surrounding skin and poor circulation in these area. Soft-tissue reconstruction in these regions should provide tissue components similar to the original lost tissue, supply durability and minimal protective pressure sensation and result in a donor site that is well tolerated and treated. We analysed 7 cases that were treated with the Instep flap due to soft-tissue defects over these regions from July of 1990 to July of 1993. All flaps were viable and successful at follow-up. 1. The age ranged from 9 years to 60 years, and 6 cases were male and 1 case female. 2. The sites of soft-tissue loss were the plantar forefoot(1 case), plantar heel(3 cases), Achilles tendon(2 cases), and distal parts of lower leg(1 case). 3. The causes of soft-tissue loss were simple soft-tissue crushing injury(1 case), crushing injury of the 1st toe(1 case) and posttraumatic infection and necrosis(5 cases). 4. The associated injury were open distal tibio-fibula, fracture(2 cases), medial malleolar fracture of the ankle(1 case), Achilles tendon rupture(2 case) and 1st metatarso-phalangeal disarticulation(1 case). 5. The size of flap was from $3{\times}4cm$ to $5{\times}10cm$(average $4{\times}5.6cm)$. 6. In 7 cases, we were not to find post-operative necrosis and infection, non-viability, limitation of ankle joint, and gait disturbance caused by the Instep flap surgery. 7. This study demonstrates that the Instep flap should be considered as another valuable technique in reconstruction of these regions.

• The Journal of Korean Physical Therapy
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• v.15 no.3
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• pp.1-15
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• 2003

The purpose of this study was to evaluate the change of lower extremity alignment according to plantar surface compliance in standing status. The thirty normal adults (15 men and 15 women) aged between 20 and 29 were assigned to 3 groups: control group, experimental groups (AHPS group, ASPH group). The lower extremity alignment was examined before and after adaptation with corresponding foam types. The results of this study were as follows : 1. As the result of comparing lower extremity alignment before and after test of the control group which any change did not exist in plantar surface compliance, there were not significant differences in the angle A, B, C, D, E of right and left(p>0.05). 2. As the result of comparing lower extremity alignment before and after test of the AHPS group which forefoot part of plantar surface is hard and rear foot part is soft, there were not significant differences in the angle A of right and left(p>0.05). But, there were significantly decreased in the angle B, C, D, E of right and left(p<0.05). 3. As the result of comparing lower extremity alignment before and after test of the ASPH group which forefoot part of plantar surface is soft and rear foot part is hard, there were not significant differences in the angle A of right and left(p>0.05). But, there were significantly increased in the angle B, C, D, E of right and left(p<0.05). 4. As the result of comparing lower extremity alignment of the control group, AHPS group and ASPH group, there were not significant differences in the angle A, B, C, D, E of right and left before test(p>0.05). But, there were significant differences in the angle C, D of right and left after test(p<0.05).

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

• Journal of Korean Foot and Ankle Society
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• v.15 no.3
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• pp.139-143
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• 2011

Purpose: The purpose of this study was to introduce the 'Matrixplasty' for the treatment of a severely incurved toenail with growth plate deformity and to report our results treating this disease entity. Materials and Methods: Between January 2010 and May 2010, 48 consecutive patients (62 cases) underwent treatment of symptomatic incurved toenails with the 'matrixplasty'. The mean period of time at last follow-up was $14.0{\pm}1.3$ months. The recurrence rate and complication rate were evaluated. An American Orthopedic Foot and Ankle Society (AOFAS) forefoot hallux score was assigned and patients were evaluated at pretreatment and the last follow-up meeting. For evaluation of improvement in toenail shape, the center to edge angle of the toenail was measured at pretreatment and last follow-up. Results: All ingrown toenails healed and the nail deformity was corrected within 3 weeks after the procedure. Among the 62 cases, four cases had recurred by the last follow-up. The mean pretreatment AOFAS forefoot hallux score was $73.1{\pm}12.8$, and it improved to $98.7{\pm}1.1$ by the last follow-up (p<0.01). The mean center to edge angle of the toenail improved from $53.3{\pm}12.9$ degrees to $18.2{\pm}7.4$ degrees by the last follow-up (p<0.01). Minor paronychia, which was managed with local wound dressing and oral antibiotics, was identified in eight cases. Conclusion: Matrixplasty showed excellent clinical results in the treatment of severe incurved toenail (pincer nail) and this procedure also showed great improvement of the deformed toenail and its growth plate.

• Physical Therapy Korea
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• v.10 no.1
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• pp.77-95
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• 2003

Many factors affect foot and ankle biomechanics during walking, including gait speed and anthropometric characteristics. However, speed has not been taken into account in foot kinematics and kinetics during walking. This study examined the effect of walking speed on foot joint motion and peak plantar pressure during the walking phase. Eighty healthy subjects (40 men, 40 women) were recruited. Maximal dorsiflexion and excursion were measured at the first metatarsophalangeal joints during walking phase at three different cadences (80, 100, and 120 step/min) using a three dimensional motion analysis system (CMS70P). At the same time, peak plantar pressure was investigated using pressure distribution platforms (MatScan system) under the hallux heads of the first, second, and third metatarsal bones and heel. Maximal dorsiflexion and excursion and excursion at the ankle joint decreased significantly with increasing walking speed. Peak plantar pressure increased significantly under the heads of the first of the first, second, and third metatarsal bones, and heel with increasing walking speed: three was no change under the hallux. There were no significant changes in maximal dorsiflexion or excursion at the first metatarsophalangeal joint. The results show that walking speed should be considered when comparing gait parameters. The results also suggest that slow walking speeds may decrease forefoot peak plantar pressure in patients with peripheral neuropathy who have a high risk of skin breakdown under the forefoot.

• Physical Therapy Korea
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• v.22 no.2
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• pp.41-51
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• 2015

The purposes of this study were 1) to determine the effects of low-dye taping on peak plantar pressure following treadmill walking exercise, 2) to determine whether the biomechanical effectiveness of low-dye taping in peak plantar pressure was still maintained following removal of the tape during treadmill walking, and 3) to determine the trend towards a medial-to-lateral shift in peak plantar pressure in the midfoot region before and after application of low-dye taping. Twenty subjects with flexible flatfoot were recruited using a navicular drop test. The peak plantar pressure data were recorded during five treadmill walking sessions: (1) un-taped, (2) baseline-taped, (3) after a 10-minute treadmill walking exercise, (4) after a 20-minute treadmill walking exercise, and (5) after removal of the taping. The foot was divided into six parts during the data analysis. One-way repeated measures analysis of variance was performed to investigate peak plantar pressure variations in the six foot parts in the five sessions. This study resulted in significantly increased medial forefoot peak plantar pressure compared to the un-taped condition (p=.017, post 10-minute treadmill walking exercise) and (p=.021, post 20-minute treadmill walking exercise). The peak plantar pressure in the lateral forefoot showed that there was a significant decrease after sessions of baseline-taped (p=.006) and 10-minute of treadmill walking exercise (p=.46) compared to the un-taped condition. The tape removal values were similar to the un-taped values in the five sessions. Thus, the findings of the current study may be helpful when researchers and clinicians estimate single taping effects or consider how frequently taping should be replaced for therapeutic purposes. Further studies are required to investigate the evidence in support of biomechanical effectiveness of low-dye taping in the midfoot region.

• PNF and Movement
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• v.15 no.3
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• pp.343-351
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• 2017

Purpose: This study aimed to suggest effective lunge exercise methods for various purposes by comparing differences in the muscle activity of thigh and plantar pressure according to changes in base of support during lunge exercises. Methods: The subjects were 20 college students who agreed to participate in the experiment. They performed three types of lunges-a basic lunge (BL), wide lunge (WL), and narrow lunge (NL). In a static position during each lunge, the muscle activity of the thigh and plantar pressure were measured. Each movement was maintained for 7 seconds, and the muscle activity for the 3 seconds in the middle was measured and analyzed. The plantar pressure was divided into six areas for analysis. The subjects randomly performed the lunges to prevent the influence of an experimental sequence. Each movement was performed three times, and the mean value of the three measurements was analyzed. Results: The analysis of muscle activities in the thigh during the three lunge movements showed statistically significantly higher muscle activity of biceps femoris in WL and NL than BL. Moreover, the analysis of plantar force showed statistically significant differences between BL and WL and WL and NL on the medial-forefoot and medial-midfoot, as well as between BL and WL and BL and NL on the lateral-midfoot. The analysis of plantar contact pressure exhibited statistically significant differences between BL and NL and WL and NL on the medial-forefoot, as well as a statistically significant difference between WL and NL on the medial-midfoot and lateral-hindfoot. Conclusion: This study suggests that changing the base of support during lunges can be useful to suit the purposes of various rehabilitation programs.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.4
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• pp.442-449
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• 2013

This study was to compare a domestic comfort shoes to the popular import(SAS$^{(R)}$) to gain a better understanding in biomechanical characteristics for shoe design for the elderly. For each shoe type, morphologic dimensions, shock absorption, and flexibility were assessed. From subjects(n = 20, $72.4{\pm}5.5$ years, $67.7{\pm}7.9$ kg), mean peak pressure(MPP) and contact area(CA) at the plantar surface were analyzed. The domestic shoes reflecting anatomic contour of the plantar surfaces of Asians resulted in wider CA(by 30.4 $cm^2$), higher shock absorption(by 2.4%) and stiffness(by 0.5 N/mm) than the import. With the domestic shoes, significantly less MPPs were found at the forefoot(by 42~49%) regions(p < .05) and higher CA was noted additionally at hallux and lessor toes(by 26~63%). More anatomically-contoured insole and favorable mechanical characteristics may help reduce the plantar pressures more effectively and more evenly, especially across the central forefoot and midfoot regions of the plantar surface, especially for the design of the comfort shoes for the elderly.

• Journal of Korean Foot and Ankle Society
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• v.2 no.2
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• pp.71-75
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• 1998

The fact that, under similar training activities performed in the same environment, march fractures develop in only a certain percentage of the trainees indicates that intrinsic factors are affecting the prevalence of these fractures. Among these intrinsic factors, the relation between foot arch type and the occurance of march fractures was investigated in this study. From 1997 to 1998, at one infantry medical company of infantry corps in Korea, 15 march fracture patients were detected among infantry soldiers. Quantitative measures of the foot arch (longitudinal) structure of 15(30feet) march fracture patients were established and compared with those of 15(30feet) normal person. The results were as follows. 1. From the lateral X-ray film, three parameters (i.e. calcaneal angle, forefoot angle, height to length ratio)were defined to describe the structure of the longitudinal arch of the foot. 2. The mean value of the calcaneal angle of march fracture group and normal control group showed 16.4 degree, 20.5 degree respectively. The difference between two groups was statistically significant (P>0.006), but those of forefoot angle and height to length ratio were not. 3. In the calcaneal angle twenty-six feet(87%) of march fracture group were lower than 17 degrees but twenty-five feet(83%) of normal control group were more than 17 degrees. That is, march fracture were more prevalent in feet with low calcaneal angle. 4. In the low arch foot, the orthotic device might relieve the energy load carried by the foot, thus reducing the incidence of march fractures, and should be analyzed in further study.