• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.175-187
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• 2006

The purpose of this study was to find the relationship between Achilles tendon angle, angular velocity from 2D cinematography utilized to easily analyze the functions of shoes, ankle joint moment, knee joint moment, and hip joint moment from 3D cinematography utilized to predict the injury. Also, this study was to provide the optimal standard to analyze the injury related to the shoes. Subjects in this study were 30 university male students and 18 conditions (2 types of running speed, 3 of midsole hardness, 3 of midsole height) were measured using cinematography and force platform. The results were as following. 1) Hip joint abduction moment was effected by many variables such as running speed, midsole height, maximum achilles tendon angle, ground reaction force. 2) Knee joint rotational moment in running was approximately 1/10 - 1/4 times of the injury critical value and eversion moment was approximately 1/4 - 1/2 times of the injury critical value. 3) Ankle joint pronation moment in running was 1/3 - 1/2 times of the injury critical value. 4) Knee joint rotational moment was found to be irrelevant with maximum achilles tendon angle or angular velocity. 5) Pronation from running was thought to be relevant to rather eversion moment activity than rotational moment activity of knee joint. 6) Plantar flexion abductor of ankle showed significant relationship with the ground reaction force variable. 7) When the loading rate for ground reaction force in passive region increased, extensor tended to be exposed to the injury. Main variables in biomechanical analysis of shoes were impact absorption and pronation. Among these variables, pronation factor was reported to be relevant with knee injury from long duration exercise. Achilles tendon angle factor was utilized frequently to evaluate this. However, as the results of this study showed, the relationship between these variables and injury relating variable of knee moment was so important. Studies without consideration on this finding should be reconsidered and reconfirmed.

• Journal of the Ergonomics Society of Korea
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• v.20 no.1
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• pp.63-72
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• 2001

Rearfoot control can be defined as the relative ability of a shoe to limit the amount of subtalar joint pronation immediately following footstrike. A normal amount of pronation provides a means of decreasing peak forces experienced by the leg, but excessive pronation of the foot can be arised its injures. The purpose of this study is to compare amount of pronation according to a difference between medial and later hardness of shoe midsole for better design of running shops. The experiment is examined for 7 running shoes. 8 males. to measure the Achilles tendon angle and rearfoot angle using high speed camera. The results is conducted that the changes of Achilles tendon angle significantly differ at each test shoe with increased running speed. And, a difference between medial and lateral hardness of midsole affects rearfoot motion of runner. The displacements of maximal Achilles tendon angle described a amount of pronation motion is decreased when medial hardness of midsole is large more than lateral.

• Korean Journal of Applied Biomechanics
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• v.15 no.2
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• pp.69-81
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• 2005

In this study using two-dimensional system of the analysis of image, when normal males in their twenties who have normal foot and step with heel first are walking and running, they who are wearing running shoes or barefoot are testing and comparing the exchange factors of heel control. There are following results of this test by verifying them with T-Test. 1) When they are running, there are two big different gap which is $6.05^{\circ}$ between barefoot and wearing the running shoes. The former is $174.79^{\circ}{\pm}6.31$ and the latter is $180.84^{\circ}{\pm}4.69$. But it is not statistically significant. The angle of first step with heel is $100.42^{\circ}{\pm}3.95$ with barefoot and $93.97^{\circ}{\pm}094$ with wearing the running shoes. In this case, it is statistically significant(p<.01) 2) When they are running, the angle of the Achilles' tendon has different gap which is $5.24^{\circ}$ between barefoot and wearing the running shoes. The former is $179.70^{\circ}{\pm}4.23$ and the latter is $184.94^{\circ}{\pm}4.09$. It is not statistically significant. The angle of minimal step with heel is $96.30^{\circ}{\pm}3.07$ with barefoot and $90.84^{\circ}{\pm}0.44$ with wearing the running shoes. In this case, it is statistically significant(p<.01). 3) In the angle of the Achilles' tendon and the angle of first step with heel, when they are walking, the angle of the Achilles' tendon has different gap which is $1.81^{\circ}$ between barefoot and wearing the running shoes. The former is $6.39^{\circ}{\pm}0.83$ and the latter is $8.20^{\circ}{\pm}1.85$. It is not statistically significant. The angle of first step with heel is $2.32^{\circ}{\pm}0.51$ with barefoot and $3.22^{\circ}{\pm}1.44$ with wearing the running shoes. It is not statistically significant. 4) In the angle of the take-off of Achilles' tendon, when they are walking, the angle of the take-off of Achilles' tendon has different gap which is $3.88^{\circ}$ between barefoot and wearing the running shoes. The former is $177.62^{\circ}{\pm}8.78$ and the latter is $173.74^{\circ}{\pm}16.31$. It is statistically significant(p<.05). Therefore, they are running, the angle of the take-off of Achilles' tendon is $178.37^{\circ}{\pm}19.28$ with barefoot and $171.26^{\circ}{\pm}12.18$ with wearing the running shoes. It is statistically significant(p<.05).

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.51-59
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• 2007

These studies show that I applied to functional insole (a specific A company) for minimizing shocks and sprain people's ankle arising from running. How to an effect on human body which studied a kinematics and kinetics from 10 college students during experiments. This study imposes several conditions by barefoot, normal running shoes and put functional insole shoes ran under average $2.0{\pm}0.24\;m$/sec by motion analysis and ground reaction force that used to specific A company. First of all, motion analysis was caused by achilles tendon angle, angle of the lower leg, angle of the knee, initial sole angle and barefoot angle. The result of comparative analysis can be summarized as below. Motion analysis showed that statically approximates other results from achilles tendon angle (p<.01), initial ankle angle(p<.05), initial sole angle(p<.001) and barefoot angle(p<.001). Ground reaction force also showed that statically approximates other results from impact peak timing (p<.001), Maximum loading rate(p<.001), Maximum loading rate timing (p<.001) and impulse of first 20 percent (p<.001). Above experiment values known that there was statically difference between Motion analysis and Ground reaction force under absorbing of the functional insole shoes which was not have an effect on our body for kinetics and kinematics.

• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.161-173
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• 2003

This study was performed to investigate the kinematic and kinetic differences between functional walking shoe(FWS) and general sports shoe(GSS). The subjects for this study were 4 male adults who had the walking pattern of rearfoot strike with normal feet. The movement of one lower leg was measured using force platform and 3 video cameras while the subjects walked at the velocity of 2/1.5 m/s. The findings of this study were as follows 1. The angle of lower leg-ground and angle of knee with FWS was greater than with GSS at the moment of strike the floor and the moment of second peak ground reaction force. The decreasing rate of angle of ankle was smaller in FWS from the strike phase to the second peak ground reaction force. These mean upright walking and round walking along the shoe surface. 2. The maximal Increased angle of Achilles tendon and the minimal decreased angle of rearfoot were smaller in FWS very significantly(p<0.001). Thus FWS prevent the excessive pronation of ankle and have good of rear-foot control. 3. The vortical ground reaction force and the rate of it to the BW were smaller in FWS statistically(p<0.001). The loading rate was smaller in FWS, too, and thess represent the reduction of load on ankle joint and prevention of injuries on it.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.105-114
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• 2007

The purpose of this study was to compare the biomechanical difference of barefoot and two types taekwondo footwear. which will provide scientific data to coaches and players, to further prevent injuries and to improve each players skills. How to an effect on human body which studied a kinematics and kinetics from 8 college students during experiments. This study imposes several conditions by barefoot and two types of taekwondo footwear ran under average $2.56{\pm}0.21\;m$/sec by motion analysis, ground reaction force and electromyography that used to specific A company. First of all, motion analysis was caused by achilles tendon angle, angle of the lower leg, angle of the knee. The result of comparative analysis can be summarized as below. Motion analysis showed that statically approximates other results from achilles tendon angle (p<.01), initial ankle angle(p<.05), initial sole angle(p<.001) and barefoot angle(p<.001). Ground reaction force also showed that statically approximates other results from impact peak timing (p.001), Maximum loading rate(p<.001), Maximum loading rate timing (p<.001) and impulse of first 20 percent (p<.001). showed that averagely was distinguished from other factors, and did not show about that.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.67-82
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• 2004

The purpose of this study was to evaluate the function and the safety of an additional weight shoe developed for the improvement of aerobic capacity, and to improve some problems found by subject's test for an additional weight shoe. The subjects employed for this study were 10 college students. 4 video cameras, AMTI force platform and Pedar insole pressure distribution measurement device were used to analyze foot motions. The results of the study were as follows: 1 The initial achilles tendon angle and initial rearfoot pronation angle of an additional weight shoe during walking were 183.7 deg and 2.33 deg, respectively, and smaller than a barefoot condition. Maximum achilles tendon angle and the angular displacement of achilles tendon angle were 185.35 deg and 4.21 deg respectively, and smaller than barefoot condition. Thus rearfoot stability variables were within the permission value for safety. 2. Maximal anterior posterior ground reaction force of additional weight shoe was appeared to be 1.01-1.2 B.W., and was bigger than a barefoot condition. The time to MAPGRF of an additional weight shoe was longer than a barefoot condition. Maximal vertical ground reaction force of additional weight shoe was appeared to be 2.3-2.7 B.W., and was bigger than a barefoot condition in propulsive force region. But A barefoot condition was bigger in braking force region. The time to MVGRF of an additional weight shoe was longer than a barefoot condition. 3. Regional peak pressure was bigger in medial region than in lateral region in contrast to conventional running shoes. The instant of regional peak pressure was M1-M2-M7-M4-M6-M5 -M3, and differed form conventional running shoes. Regional Impulse was shown to be abnormal patterns. There were no evidences that an additional weight shoe would have function and safety problems through the analysis of rearfoot control and ground reaction force during walking. However, There appeared to have small problem in pressure distribution. It was considered that it would be possible to redesign the inner geometry. This study could not find out safety on human body and exercise effects because of short term research period. Therefore long term study on subject's test would be necessary in the future study.

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.291-296
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• 2002

The midsole hardness of athletic footwear affects capability of absorbing impact shock and controls rearfoot movement during running and walking. The prior studies were focused on examining the proper hardness of footwear for rearfoot movement or to finding effective hardness for absorbing impact shock. The displacements of maximal Achilles tendon angle described a amount of pronation motion is decreased when medial hardness of midsole is large more than lateral. Increasing hardness of footwear midsole are effected to reduce maximum and intial pronation angle, but declined the ability of impact shock during heelstrike. For determination of effectiveness hardness of midsole, therefore, the study that makes a compromise between rearfoot movement and absorbing impact during footstrike must be performed. The purpose of this study is to examine quantitative values of rearfoot control and absorbing impact shock with different hardness of medial and lateral midsole on heel portion. The results are useful to define biomechanical hardness of midsole for developing running shoes. As variable for impact shock, accelerations onto shank and knee are measured during 4 running speeds (5, 7, 9, 11km/h). Also, maximum and $10\%$ pronation angle (Achilles tendon angle) were measured using high-speed camera.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.99-109
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• 2007

The purpose of the study is to examine the effect of the spring shoe through the comparison of spring shoe to general shoe. For this, 12 healthy females in the age from 20 to 30 years participated in the E.M.G. experiment with testing kinematic variables. Results indicated that there was significant differences in angle of ankel between the general and spring shoe. Specifically, the spring shoe showed a bigger angle of take on and a smaller angle of take off in walking than the general shoe. This mesns that the spring shoe does not have a significant effect to produce efficient and smooth walking. In addition, the spring shoes revealed a bigger rear-foot angle than the general shoe in the evaluation of rear-foot control function. This means that the rear-foot control function of the spring shoe is low compared to trhe general shoe. Meanwhile, there is no significant differences in angle of knee and angle of Achilles tendon between both shoes. In an analysis of E.M.G., the significant differences were found in gastrocnemius muscle, anterior tibial musculi, musculi rectus femoris, biceps muscle of thigh between both the general and spring shoe groups by the section. In the case of gastrocnemius muscle, the spring shoe showed a low muscle production of anterior tibial musculi than the general shoe. This is a result from structural nature of the sole of a foot of the spring shoe. The spring shoe performs a rolling movement through slightly large pronation toward front-foot from rear-foot in supprt time before taking-off of toe and the power for this movement is mainly produced from musculi rectus femoris.

• Journal of Korean Orthopaedic Sports Medicine
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• v.1 no.2
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• pp.138-142
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• 2002

Purpose: To evaluate the results and prognosis of operative repair to acute rupture of achilles tend on associated sports injury. Materials and Methods: 21 cases were surgically treated and average follow-up period was 1 year and eight months. The forth decade was most common with $55\%$ and soccer was most common in sports with 5 cases. End-to-end suture of ruptured achilles tendon was performed, and paratendinous structure was wrapped sufficiently. Postoperatively. ankle was plantarflexed for 6 weeks with longleg cast. And then 2 weeks interval, short leg cast with equinous position was conversed to functional position. About 10 weeks after operation, ankle was recovered to right angle. Hooker scale was used to evaluate the results. Results: Compared to normal side, heel-floor distance of ruptures side was decreased 0.7 cm in average, and 0.8 cm was deceased after 20 times weight loaded dorsiflexion. Mid-calf circumference was deceased 0.3 cm, and active dorsiflexion and plantar flexion of ankle was decreased each 3 and 5degree. 16 cases showed ‘excellent’result and 5 cases showed ‘satisfactory’. There was no complication, such as re-rupture or infection at operation site. Conclusion: After end-to-end operative repair to achilles tendon, sufficient wrapping of paratendinous structure is efficient for healing and prevention of postoperative adhesion. And serial dorsiflex-ion cast change is considered to be a successful treatment for preventing residual equinus deformity.