• 한국운동역학회지
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• 제26권4호
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• pp.407-412
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• 2016

Objective: The aim of this study was to analyze the net joint moment and joint power of the lower extremity during squat in female patients with genu varum. Method: Eight female patients with genu varum were asked to do regular squats, and their net joint moment and joint power were compared to those of another eight female participants with straight legs. Their video recordings and ground reaction force data were analyzed to be used as a theoretical evidence of squatting effectively for female patients with genu varum. Results: Squats had a higher impact on internal knee joint rotation and ankle joint flexion moments in the genu varum group than in the straight leg group due to their weak and short hip joint muscles. Conclusion: There is a need to develop a squat movement that is appropriate for women with genu varum in order to distribute overload efficiently among the hip, knee, and ankle joints and to strengthen the muscles in a balanced way.

• 한국정밀공학회지
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• 제25권11호
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• pp.107-118
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• 2008

In this study, lower extremity joint kinematics and kinetics and lumbar lordosis were investigated for two different symmetrical lifting techniques(squat and stoop) using the three-dimensional motion analysis. Twenty-six male volunteers lifted boxes weighing 5, 10 and 15kg by both squat and stoop lifting techniques. There were not significant differences in maximum lumbar joint moments between the two techniques. The hip and ankle contributed the most part of the support moments during squat lifting, and the knee flexion moment played an important role in stoop lifting. The hip, ankle and lumbar joints generated power and only the khee joint absorbed power in the squat lifting. The knee and ankle joints absorbed power, the hip and lumbar joints generated power in the stoop lifting. The bi-articular antagonist muscles' co-contraction around the knee joint during the squat lifting and the eccentric co-contraction of the gastrocnemius and semitendinosus were found to be important for straightening up during the stoop lifting. At the time of lordotic curvature appearance in the squat lifting, there were significant correlations in all three lower extremity joint moments with the lumbar joint. Differently, only the hip moment had significant correlation with the lumbar joint in the stoop lifting. In conclusion, the knee extension which is prominent kinematics during the squat tilling was produced by the contributions of the kinetic factors from the hip and ankle joints(extensor moment and power generation) and the lumbar extension which is prominent kinematics during the stoop lifting could be produced by the contributions of the knee joint kinetic factors(flexor moment, power absorption, bi-articular muscle function).

• 한국운동역학회지
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• 제21권2호
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• pp.189-196
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• 2011

The purpose of this study was to verify the difference in biomechanical variation and pattern of the lower limb between planned and unexpected termination, which is related to the prevention of fatal fall in the elderly. Therefore, selected twenty subjects for each group which composed of females(age: $73.5{\pm}4.63$ year, height: $153.2{\pm}6.46$ cm, body mass: $58.98{\pm}5.82$ kg) and women(age: $23.4{\pm}2.5$ year, height: $164.65{\pm}3.9$ cm, body mass: $58.47{\pm}5.53$ kg) in their twenties. As a result, lower limb's extension moment and power were increased significantly in statistics(p<.05). Also, knee joint power showed instant changes from concentric contraction to eccentric contraction and hip joint power from eccentric contraction to concentric contraction. During unexpected termination there were dramatical increase in eccentric contraction and power(p<.05). In both planned and unexpected termination, ankle joint moment were higher in young group, but the moment of the hip joint were higher in the elderly group(p<.05). In contrast to younger group, there were no changes in knee extension moment in elderly group(p<.05). but showed relatively higher hip joint extension moment and power(p<.05).

• 한국운동역학회지
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• 제34권2호
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• pp.45-52
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• 2024

Objective: The purpose of this study was to measure the morphological characteristics of the foot and biomechanical variables of the lower extremity joints during vertical jump and investigate the relationship between foot morphology and biomechanics of vertical jump. Method: 24 men in their 20s (age: 22.42 ± 1.41 yrs, height: 173.37 ± 4.61 cm, weight: 72.02 ± 6.21 kg, foot length: 251.70 ± 8.68 mm) participated in the study. Morphological characteristics of the foot included the length of the first toe, the length of the second toe, and the horizontal length from the center of ankle joint to the achilles tendon (Plantar Flexion Moment Arm [PFMA]). Biomechanical variables were measured for plantar flexor strength of the ankle joint and peak angular velocity, moment, and power of the lower extremity joint during vertical jump. Results: There was a significant correlation between the length of the first toe and plantar flexion strength at 30°/s [r=.440, p=.016], the angular velocity of the metatarsophalangeal [MTP] joint [r=-.369, p=.038] while significant correlations between PFMA and the angular velocities of the knee joint [r=.369, p=.038] and ankle joint [r=.420, p=.021] were found. There were also significant correlations between the length of the first toe and the maximum moment of the hip joint [r=.379, p=.034], and the length of the second toe and the power of the hip joint [r=-.391, p=.029]. Finally, significant correlations between PFMA and the power of the ankle joint [r=.424, p=.019] and MTP joint [r=.367, p=.039] were found. Conclusion: Based on the results of this study, the length of the toe and PFMA would be related to the function of the lower extremity joint. Therefore, this should be considered when designing the functional structure of a shoe. Furthermore, this relationship can be applied to intensive training for the plantar flexors and toe flexors to improve power in athletic performance.

• 한국운동역학회지
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• 제17권2호
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• pp.187-196
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• 2007

The purpose of this study was to find the most effective movement pattern from three different types of preparatory movement(squat, countermovement and hopping) in sideward responsive propulsion task, which had the time constraint to complete the performance. 7 healthy subjects participated in left and right side movement task by an external signal, which required the subject to perform the task as fast as possible. Mechanical output and joint kinetics focusing on the lower extremities were analyzed. The results were as follows. In spite of the shortest duration in propulsive phase, the hopping condition showed no difference with other conditions in the work output done and take-off velocity. It resulted from the greatest power output generated during the propulsive phase. A significant difference was found for joint moment and joint power according to the movement conditions. The joint moment and joint power for the countermovement and hopping conditions were larger than those in the squat condition. This was speculated to be due to the extra power that could be generated by the pre-stretch of muscle in preparation for the propulsion. The hopping condition which had substantially more pre-stretch load in the preparatory eccentric phase produced considerably more power than countermovement condition in the propulsive concentric phase. Furthermore during the hopping a large amount of joint moment and joint power could be produced in a shorter time. Therefore it was deemed that the hopping movement is an effective type of preparatory movement which takes much more advantage of the pre-stretch than any other movement.

• The Journal of Korean Physical Therapy
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• 제11권1호
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• pp.55-61
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• 1999

The purpose of this study was to compare the moment and power of affected Side and those of unaffected side during gait in hemiplegic patients after stroke. Force plate ana kinetic gait analysis was used. The following is resulted from this study. 1. In the hip joint, moment values had not difference between affected side and unaffected side. Power values had difference between affected and unafected side. 2. In the knee joint, moment values and power values had difference between affected side and unaffected side. 3. In the ankle feint, moment and power values had not, difference between affected side and unaffected side.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1431-1432
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• 2011

• 한국운동역학회지
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• 제29권4호
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• pp.255-261
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• 2019

Objective: The purpose of this study was to investigate differences of shock attenuation strategies between double-leg and single-leg landing on sagittal plane using statistical parametric mapping. Method: Nine healthy female professional soccer players (age: 24.0±2.5 yrs, height: 164.9±3.3 cm, weight: 55.7±6.6 kg, career: 11.2±1.4 yrs) were participated in this study. The subjects performed 10 times of double-leg and single-leg landing from the box of 30 cm height onto force plates respectively. The ground reaction force, angle, moment, angular velocity, and power of the ankle, knee, and hip joint on sagittal plane was calculated from initial contact to maximum knee flexion during landing phase. Statistical parametric mapping was used to compare the biomechanical variables of double-leg and single-leg landing of the dominant leg throughout the landing phase. Each mean difference of variables was analyzed using a paired t-test and alpha level was set to 0.05. Results: For the biomechanical variables, significantly increased vertical ground reaction force, plantarflexion moment of the ankle joint, negative ankle joint power and extension moment of the hip joint were found in single-leg landing compared to double-leg landing (p<.05). In addition, the flexion angle and angular velocity of the knee and hip joint in double-leg landing were observed significantly greater than single-leg landing, respectively (p<.05). Conclusion: These findings suggested that negative joint power and plantarflexion moment of the ankle joint can contribute to shock absorption during single-leg landing and may be the factors for preventing the musculoskeletal injuries of the lower extremity by an external force.

• 한국운동역학회지
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• 제26권4호
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• pp.433-441
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• 2016

Objective: The purpose of this study was to understand the injury mechanism and to provide quantitative data to use in prevention or posture correction training by conducting kinematic and kinetic analyses of risk factors of lower extremity joint injury depending on the change of direction at different angles after a landing motion. Method: This study included 11 men in their twenties (age: $24.6{\pm}1.7years$, height: $176.6{\pm}4.4cm$, weight: $71.3{\pm}8.0kg$) who were right-leg dominant. By using seven infrared cameras (Oqus 300, Qualisys, Sweden), one force platform (AMTI, USA), and an accelerometer (Noraxon, USA), single-leg drop landing was performed at a height of 30 cm. The joint range of motion (ROM) of the lower extremity, peak joint moment, peak joint power, peak vertical ground reaction force (GRF), and peak vertical acceleration were measured. For statistical analysis, one-way repeated-measures analysis of variance was conducted at a significance level of ${\alpha}$ <.05. Results: Ankle and knee joint ROM in the sagittal plane significantly differed, respectively (F = 3.145, p = .024; F = 14.183, p = .000), depending on the change of direction. However, no significant differences were observed in the ROM of ankle and knee joint in the transverse plane. Significant differences in peak joint moment were also observed but no statistically significant differences were found in negative joint power between the conditions. Peak vertical GRF was high in landing (LAD) and after landing, left $45^{\circ}$ cutting (LLC), with a significant difference (F = 9.363, p = .000). The peak vertical acceleration was relatively high in LAD and LLC compared with other conditions, but the difference was not significant. Conclusion: We conclude that moving in the left direction may expose athletes to greater injury risk in terms of joint kinetics than moving in the right direction. However, further investigation of joint injury mechanisms in sports would be required to confirm these findings.

• 대한물리치료과학회지
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• 제10권1호
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• pp.90-101
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• 2003

Gait analysis can provide a better understanding of how the alignment of the lower limb and foot can contribute to force observed at the knee. Anatomic and mechanical factors that affect loading in the knee pint can contribute to pathologic change seen at the knee in degenerative pint disease and should be considered in treatment plan. The purpose of this study is to present the gait analysis data and to determine whether there is any relationships between alignment of the lower limb, foot progression angle and knee pint moments in elderly healthy women with 3-dimensional motion analyzer. The results were as follows; 1. Cadence showed 114.8 steps/min, gait speed showed 1.05 m/s, time per a stride showed 1.06 sec, time per a step showed 0.53 sec, single-supporting phase was 0.41 sec, double-supporting phase was 0.24 sec, stride length was 1.04 m, Step length was 0.56 m. 2. According to the parameters of kinematics, the maximal knee flexion angle through swing phase showed left $46.82^{\circ}$, right $40.19^{\circ}$ and the maximal knee extension angle showed left $-1.32^{\circ}$, right $2.01^{\circ}$. knee varus showed left $26.90^{\circ}$, right $30.93^{\circ}$. 3. Moment, one of kinetic parameters of knee pint the maximal flexion moment showed left 0.363. Nm/kg, right 0.464 Nm/kg and maximal extension moment showed left 0.389 Nm/kg, right 0.463 Nm/kg. The maximal. adduction moment showed left 0.332 Nm/kg, right 0.379 Nm/kg and the maximal internal rotatory moment showed left 0.13 Nm/kg, right 0.140 Nm/kg. 4. On sagittal plane, the maximal power of knee joint showed left 0.571 J/kg, right 0.629 J/kg. On coronal plane, the maximal power of knee joint showed left 0.11 J/kg, right 0.12 J/kg. On transverse plane, the maximal power of knee joint showed left 0.058 J/kg, right 0.072 J/kg. 5. The subject who had varus alignment of the lower extremity had statistically higher in knee adduction moment in mid stance phase. 6. The subject who had large foot progression angle had statistically lower in knee adduction moment in late stance phase. A relationship was observed between the alignment of the lower extremity and the adduction moment of the knee joint during stance phase. Hence, we need some research to figure, out the change of adduction moment according to the sort of knee joint osteoarthritis and the normal geriatrics as well. And we also require more effective, specific therapeutic program by making use of those background of researches.