• 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.

• The Journal of Korean Physical Therapy
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• v.27 no.2
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• pp.89-95
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• 2015

Purpose: The purpose of this study is to determine the effects of visual information on movement time and each angular velocity of trunk and lower extremity joints while healthy adults are in sitting and squat motion. Methods: Participants consisted of 20 healthy male and female adults; movement time and each angular velocity of trunk, pelvis, hip, knee and ankle of sitting and squat motion according to common vision, visual task and visual block were analyzed using a three dimensional motion analysis system. Results: Each angular velocity of the trunk, pelvis, hip, knee and ankle in phase 2 of the sitting showed significant difference according to the types of visual information (p<0.05). Movement time and each angular velocity of pelvis and hip in phase 2 of squat motion showed significant difference according to the types of visual information (p<0.05). According to the common vision, each angular velocity of knee and ankle in phase 1 was significantly fast in sitting (p<0.05). According to the common vision, each angular velocity of trunk, pelvis, hip, knee, and ankle in phase 2 was significantly fast in sitting (p<0.05). Conclusion: Visual information affects the angular velocity of the motion in a simple action such as sitting, and that in more complicated squat motion affects both the angular velocity and the movement time. In addition, according to the common vision, visual task and visual block, as angular velocities of all joints were faster in sitting than squat motion.

• PNF and Movement
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• v.17 no.3
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• pp.463-469
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• 2019

Purpose: This study investigated the effect of plantar-flexor muscle fatigue on the force sense and joint reposition sense of ankle joints in the healthy adults. Methods: Fifteen healthy subjects (male: 9, female: 6) participated in this study. A digital dynamometer was used to measure the force sense error while a wireless motion capture device was used to measure the joint reposition sense error. To induce plantar-flexor muscle fatigue for a dominant lower extremity, the subjects were asked to perform plantar flexion until exhaustion while barefoot. The differences in force sense error and joint reposition sense error for the ankle joint were measured immediately. The Wilcoxon test was used to compare these values before and after inducing plantar-flexor muscle fatigue. Results: The force sense error and joint reposition sense error of ankle joints after inducing plantar-flexor muscle fatigue increased significantly compared to the values before inducing muscle fatigue. Conclusion: This study suggests that plantar-flexor muscle fatigue could degrade the force sense and joint reposition sense in ankle joints. In addition, it could deteriorate ankle proprioception.

• Korean Journal of Applied Biomechanics
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• v.33 no.3
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• pp.110-117
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• 2023

Objective: The purpose of this study was to find out kinematic and kinetic differences the lower extremity joint according to the landing type during vertical jump movement after jump landing, and to present an efficient landing method to reduce the incidence of injury in youth players. Method: Total of 24 Youth players under Korean Sport and Olympic Committee, who used either heel contact landing (HCG) or toe contact landing (TCG) participated in this study (HCG (12): CG height: 168.7 ± 9.7 cm, weight: 60.9 ± 11.6 kg, age: 14.1 ± 0.9 yrs., career: 4.3 ± 2.9 yrs., TCG height: 174.8 ± 4.9 cm, weight: 66.9 ± 9.9 kg, age 13.9 ± 0.8 yrs., career: 4.7 ± 2.0 yrs.). Participants were asked to perform jump landing consecutively followed by vertical jump. A 3-dimensional motion analysis with 19 infrared cameras and 2 force plates was performed in this study. To find out the significance between two landing styles independent t-test was performed and significance level was set at .05. Results: HCG showed a significantly higher dorsi flexion, extension and flexion angle at ankle, knee and hip joints, respectively compared with those of TCG (p<.05). Also, HCG revealed reduced RoM at ankle joint while it showed increased RoM at knee joint compared to TCG (p<.05). In addition, HGC showed greater peak force, a loading rate, and impulse than those of TCG (p<.05). Finally, greater planta flexion moment was revealed in TCG compared to HCG at ankle joint. For the knee joint HCG showed extension and flexion moment in E1 and E2, respectively, while TCG showed opposite results. Conclusion: Compared to toe contact landing, the heel contact landing is not expected to have an advantage in terms of absorbing and dispersing the impact of contact with the ground to the joint. If these movements continuously used, performance may deteriorate, including injuries, so it is believed that education on safe landing methods is needed for young athletes whose musculoskeletal growth is not fully mature.

• Journal of Convergence for Information Technology
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• v.10 no.4
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• pp.160-167
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• 2020

This study analyzes the effects of changes in running velocity and slope on the biomechanical factors of the lower limb joints. For this purpose, 15 adult males in their 20s ran according to changes in running speed (2.7, 3.3 m/s) and slope ( -9°, -6°, 0°, 6°, 9°) on the treadmill, and their running characteristics (stride length, stride frequency). The range of motion of the lower limb joint and the vertical ground reaction force were greater in UR (p <.05), and the moment of the lower limb joint, braking force, thrust and load factor was large in DR (p <.05). In joint power, the ankle joint was greater in DR, and hip joint was greater in the UR (p <.05). These results show that the injuries of the ankle joint will be greater than other cases when running DR at a speed of 3.3 m/s.

• Korean Journal of Applied Biomechanics
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• v.29 no.3
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• pp.145-155
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• 2019

Objective: The purpose of this study was to compare the physical characteristics (bone mineral density, joint muscle strength) and running biomechanics between older adults and young adult runners to understand the changes of running strategy by aging. Method: Bone mineral density (Dual Energy X-ray Absorptiometry, USA) of lower lower extremity and muscle strength (Cybex Humac Norm [DEXA], CSMI, USA) were measured to identify the physical characteristics of 10 elderly (age: $67.70{\pm}3.30yrs$, height: $1.68{\pm}0.04m$, mass: $67.70{\pm}3.80kg$) and 10 young adults (age: $21.20{\pm}0.42yrs$, height: $1.73{\pm}0.06m$, mass: $72.11{\pm}4.15kg$). Running data was collected by using an instrumented treadmill (Bertec, USA) and 7 infrared cameras (Oqus 300, Qualisys, Sweden). Two-way repeated ANOVA analysis was used to analyze results at a significant level of .05 with Bonferroni post hoc analysis. Results: Compared to the young adult group, the elderly group showed statistically significant difference in physical characteristics and in running characteristics. Elderly runners showed lower BMD and muscle strength compared with young runners (p<.05). In the running parameters, elderly runners tend to show shorter contact time and stride length compared with young runners (p<.05). In the joint angles, elderly runners showed smaller range of ankle motion compared with young runners (p<.05). Finally, elderly runners showed lower level of joint moment, joint power, and GRF compared with young runners in each running speed (p<.05). Conclusion: The running behavior of the elderly performed periodic running was similar to many variables of young adults. However, there were noticeable differences found in the ankle joints and most kinetic variables compared with young adult runners. This discrepancy may propose that elderly runners should consider appropriate running distance and intensity in the program.

• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.189-195
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• 2017

Objective: The aim of this study was to examine the effect of foot landing type (forefoot vs. rearfoot landing) on kinematics, kinetics, and energy absorption of hip, knee, and ankle joints. Method: Twenty-five healthy men performed single-leg landings with two different foot landing types: forefoot and rearfoot landing. A motion-capture system equipped with eight infrared cameras and a synchronized force plate embedded in the floor was used. Three-dimensional kinematic and kinetic parameters were compared using paired two-tailed Student's t-tests at a significance level of .05. Results: On initial contact, a greater knee flexion angle was shown during rearfoot landing (p < .001), but the lower knee flexion angle was found at peak vertical ground reaction force (GRF) (p < .001). On initial contact, ankles showed plantarflexion, inversion, and external rotation during forefoot landing, while dorsiflexion, eversion, and internal rotation were shown during rearfoot landing (p < .001, all). At peak vertical GRF, the knee extension moment and ankle plantarflexion moment were lower in rearfoot landing than in forefoot landing (p = .003 and p < .001, respectively). From initial contact to peak vertical GRF, the negative work of the hip, knee, and ankle joint was significantly reduced during rearfoot landing (p < .001, all). The contribution to the total work of the ankle joint was the greatest during forefoot landing, whereas the contribution to the total work of the hip joint was the greatest during rearfoot landing. Conclusion: These results suggest that the energy absorption strategy was changed during rearfoot landing compared with forefoot landing according to lower-extremity joint kinematics and kinetics.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.10 no.1
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• pp.87-95
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• 2015

Background : Charcot Marie Tooth disease can cause muscle weakness and foot deformity. Ankle pain induced by foot deformity affect patients' gait pattern and quality of life. Objectives : The purpose of this study is to evaluate the traditional Korean medicine treatment for ankle pain induced with Charcot-Marie Tooth Disease, especially Chuna manual therapy on ankle joints. Methods : One patient was treated with acupuncture, phamacopuncture, herbal medication and chuna manual therapy on ankle joints. To evaluate the pain of ankle, lower back and lower extremity, visual analog scale(VAS) was measured. Results : After treatment for 5 week, the pain of ankle joint was declined from VAS 6 to VAS 2. Conclusions : Traditional Korean medicine treatment including acupuncture, pharmacopuncture, herbal medication and Chuna manual therapy is effective for ankle pain with foot deformity. But further studies are required to prove the effectiveness of Chuna manual therapy on ankle joints.

• Korean Journal of Applied Biomechanics
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• v.28 no.4
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• pp.227-236
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• 2018

Objective: The purpose of this study was to investigate the effects of a 12-week combined exercise program on gait parameters in elderly women with osteoarthritis. Method: The subjects of this study were 11 elderly women (age: $67.09{\pm}2.47$, height: $157.35{\pm}4.30cm$, weight: $62.49{\pm}6.36kg$) with knee osteoarthritis. The combined exercise program of this study was divided into aerobic exercise and lower extremity strengthening exercises. The exercises were performed for 60 minutes per session, three times a week, for a total of 12 weeks. The maximum joint moments of the hip, knee, and ankle joints with walking were obtained with 8-3D cameras (MX-T20, Vicon, USA) and 2-force plate (AMTI OR6-7-400, AMTI, USA). SPSS Windows version 23.0 was used for statistical analysis. A paired t-test was used for pre-post comparison. An alpha level of .05 was utilized in all tests. Results: The maximum extension moment was significantly higher in the hip joint after P1 on the X axis. The maximum joint moment of P3 in extension was statistically significantly lower after intervention. On the Z axis, the maximum joint moment was significantly lower after the exercise intervention at P3. There was a statistically significant increase in the extension moment of the left and right knee joints in the X axis after exercise intervention. In the right ankle joint, P1 (plantar flexion moment) showed a statistically significant high moment after exercise intervention. Conclusion: These results suggest that combined exercise, including lower limb and aerobic exercise, may have a positive effect on mobility and walking moments in patients with osteoarthritis of the knee.

• Korean Journal of Applied Biomechanics
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• v.25 no.3
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• pp.311-322
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• 2015

Objective : The purpose of this study was to investigate the effects of landing height and knee joint muscle fatigue on the movement of the lower extremity during cutting after landing. Method : Subjects included 29 adults (age: $20.83{\pm}1.56years$, height: $172.42{\pm}9.51cm$, weight: $65.07{\pm}10.18kg$). The subjects were asked to stand on their dominant lower limb on jump stands that were 30 and 40 cm in height and jump from each stand to land with the dominant lower limb on a force plate making a side step cutting move at a $45^{\circ}$ angle with the non-dominant lower limb. The fatigue level at 30% of the knee extension peak torque using an isokinetic dynamometer. Results : The results showed that the difference of landing height increased maximum range of motion and angular velocity of hip, knee, and ankle joints in the sagittal plane, and in the angular velocity of motion of the hip joint in the sagittal plane. The maximum range of motion of the knee joint in the sagittal plane and the frontal plane decreased on landing from both heights after the fatigue exercise. The angular velocity of the hip joint in the sagittal plane, and the maximum range of motion of the hip joint in the transverse plane decreased for both landing heights after the fatigue exercise. The angular velocity of the hip joint in the frontal plane decreased for the 30 cm landing height after the fatigue exercise. On the other hand, the angular velocity and maximum range of motion of the ankle joint in the sagittal plane for both landing heights, and the angular velocity and maximum range of motion of the ankle joint in the frontal plane increased on landing from the 40 cm height after the fatigue exercise. Conclusion : Different landing heights of 30 and 40 cm and 30% fatigue of peak torque of knee extensor found a forefoot and stiff landing strategy, when cutting after landing. These results might be due to decline in the shock absorption capability of the knee joint and the movement capability related to cutting while increasing the contribution of the ankle joint, which may cause increased ankle joint injuries.