• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.20 no.1
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• pp.35-38
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• 2014

Background: The case study examined the effect of a hip joint traction and hip posterolateral muscles strengthening on knee pain, range of motion, and lower extremity function scale of patients with patellofemoral pain syndrome (PFPS). Although PFPS has previously been attributed to quadriceps dysfunction, more recent research has linked this condition to impairment of the hip musculature and kinematic. Methods: Subject is a 27-years-old female with PFPS. Performed hip joint traction with belt and posterolateral muscles(hip abductors, external rotators) strengthening for 4 weeks, 3 times a week, once a day. Before and after the therapy, measurements were made on the visual analog scale (VAS) and of the ROM, and a lower extremity functional scale (LEFS) was conducted. Results: The results showed positive changes in VAS and range of motion and lower extremity functional scale. First VAS of knee changed from 6 to 2. Second hip joint range of motion showed that internal rotation recored from $53^{\circ}$ to $58^{\circ}$ and external rotation recorded from $32^{\circ}$ to $37^{\circ}$. Third The lower extremity functional scale showed before therapy of 44; after therapy, 63. Conclusion: The hip joint traction and hip posterolateral muscles strengthening was effective in alleviating knee pain, increasing ROM and Lower extremity functional scale of the PFPS patients.

• Korean Journal of Applied Biomechanics
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• v.28 no.1
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• pp.61-67
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• 2018

Objective: The human body is often modelled as a spring-mass system. Lower extremity stiffness has been considered to be one of key factor in the performance enhancement of running, jumping, and hopping involved sports activities. There are several different classification of lower extremity stiffness consisting of vertical stiffness, leg stiffness, joint stiffness, as well as muscle and tendon stiffness. The primary purpose of this paper was to review the literature and describe different stiffness models and discuss applications of stiffness models while engaging in sports activities. In addition, this paper provided a current update of the lower extremity literature as it investigates the relationships between lower extremity stiffness and both functional performance and injury. Summary: Because various methods for measuring lower extremity stiffness are existing, measurements should always be accompanied by a detailed description including type of stiffness, testing method and calculation method. Moreover, investigator should be cautious when comparing lower extremity stiffness from different methods. Some evidence highlights that optimal degree of lower extremity stiffness is required for successful athletic performance. However, the actual magnitude of stiffness required to optimize performance is relatively unexplored. Direct relationship between lower extremity stiffness and lower extremity injuries has not clearly been established yet. Overall, high stiffness is potentially associate risk factors of lower extremity injuries although some of the evidence is controversial. Prospective injures studies are necessary to confirm this relationship. Moreover, further biomechanical and physiological investigation is needed to identify the optimal regulation of the lower limb stiffness behavior and its impact on athletic performance and lower limb injuries.

• Korean Journal of Applied Biomechanics
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• v.27 no.1
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• pp.45-52
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• 2017

Objective: The aim of this study was to investigate the periodicity of the lower extremity joint flexion/extension angle to compare the local stability between young and elderly women during walking on a treadmill. Method: Eighteen young women (mean $age=21.2{\pm}1.6y$; mean $mass=57.1{\pm}6.1kg$; mean $height=1.61{\pm}0.04m$) and 18 elderly women (mean $age=66.4{\pm}1.2y$; mean $mass=55.4{\pm}8.3kg$; mean $height=1.56{\pm}0.04m$) participated in this study. Approximate entropy (ApEn) was used to determine the periodicity in the lower limb joint angles. Results: The ApEn values of the two groups were statistically greater in the surrogate data test than in the original time series data (p<.05). The periodicity of the hip and ankle flexion/extension angles decreased in the elderly women group compared with the young women group (p<.05). The periodicity of the lower extremity joint flexion/extension angle showed that the ankle joint increased dominatingly in both groups (p<.05); the hip joint decreased compared with the knee joint in the young women group; and the knee joint decreased compared with the hip joint in the elderly women group (p<.05). Conclusion: These results suggest that the lower extremity joint flexion/extension angles of the young and elderly women during walking contained random noises as well as biological signals. In addition, the differences in the periodicity in the lower extremity joint between the young and elderly women may provide some insight in predicting potential falls and be used as a characteristic indicator for determining local stability in elderly women during walking.

• The Journal of Korean Physical Therapy
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• v.14 no.4
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• pp.55-63
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• 2002

Human body balances right and left leg centering around pelvis and spine. Therefore, imbalance of lower extremity means disequilibrium of the body. The difference of lower extremity length can cause a number of clinic symptoms including scoliosis, low back pain, sacroiliac pain, and sports injury. In this study, we tried to analyze low back pain and joint stiffness resulting from the difference of lower extremity length. The subjects were 80 male students who are 20-25 years old. The results of this study were as following: 1. Low back pain depending on the difference of lower extremity length One group which the difference of lower extremity length is above 12mm showed average different length as 18.0mm, the other group which one is below 12mm showed as 6.3mm. A group of above 12mm had more severe low back pain than a group of below 12mm. 2. Joint stiffness depending on the difference of lower extremity length A group of above 12mm had more severe joint stiffness than a group of below 12mm.

• Korean Journal of Applied Biomechanics
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• v.34 no.1
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• pp.25-33
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• 2024

Objective: The purpose of this study was to compare the lower extremity muscle activity and knee joint load according to movement speed conditions during the barbell back squat. Method: Nine males with resistance training experience participated in this study. Participants performed the barbell back squat in three conditions (Standard, Fast, and Slow) differing movement speed. During the barbell back squat, muscle activity of the rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris long head (BFL), semitendinosus (ST), gluteus maximus (GM), gastrocnemius (GCN), and tibialis anterior (TA) was collected using an 8 channel wireless EMG system. The peak flexion angle of the lower extremity joints and the peak resultant joint force in each direction of the knee joint were calculated using eight motion capture cameras and ground reaction force plates. This study was to used the Friedman test and the Wilcoxon signed rank test, to compare lower extremity muscle activity and peak resultant joint force at knee joint according to movement speed conditions during the barbell back squat, and the statistical significance level was set at .01. Results: In the downward phase of the barbell back squat, the RF and TA showed the higher muscle activity in the fast condition, and in the upward phase, RF, VL, VM, BFL, ST, GM, and TA showed the higher muscle activity in the fast condition. As a results, analyzing of the load on the knee joint, in the downward phase, and in the upward phase, the higher peak compressive force of the knee joint was showed in the fast condition. Conclusion: The barbell back squat with fast movement speed was more effective due to increased muscle activity of lower extremity, but one must be careful of knee joint injuries because the load on the knee joint may increase during the barbell back squat with fast movement speed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.502-508
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• 2012

An analytical model for a human body is important to predict muscle and joint forces. Because it is difficult to estimate muscle or joint forces from a human body, the objective of this study is the development of a reliable analytical model for a human body to evaluate the lower extremity muscle and joint forces. The musculoskeletal system of the human lower extremity is modeled as a multibody system employing the Hill-type muscle model. Muscle forces are determined to minimize energy consumption, and we assume that motion is constrained in the sagittal plane. Muscle forces are calculated through an equilibrium analysis while rising from a seated position. The musculoskeletal model consists of four segments. Each segment is a rigid body and connected by frictionless revolute joints. Muscles of the lower extremity are simplified to seven muscles with those that are not related to the sagittal plane motion are ignored. Muscles that play a similar role are combined together. The results of the present study are compared with experimental results to validate the lower extremity model and the assumptions of the present study.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.3
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• pp.1-10
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• 2020

Purpose : The purpose of this study is to analyze the corrective effect of the general coordinative manipulation (GCM) joint intervention model on distort leg with imbalance of the lower extremity joints, pelvic and shoulder girdles, and lumbar spine. Methods : The study used a comparative analysis of the size of the distort leg and the imbalance of the lower extremity joints, pelvic and shoulder girdles, and lumbar spine before and after the application of the GCM joint intervention model. A total of 31 subjects from movement center G and the department of physical therapy at university M were selected as research subjects, and they were divided into two groups. The GCM joint intervention model was applied to 18 subjects in the bow knee group and 13 subjects in the knock knee group. The two groups received daily intervention three times a week for four weeks. The corrective effect of the GCM joint intervention model for each type of distort leg was compared and analyzed. Results : The effects of the GCM joint intervention model in correcting bow knee and knock knee with knee deformation and imbalance of the lower extremity joints, pelvic and shoulder girdles, and lumbar spine were significant in most domains (p<.05). The correlation between the bow knee and knock knee groups showed significance in most domains (p<.05). Conclusion : The GCM joint intervention model showed significant corrective effect in the bow knee and knock knee groups in terms of knee deformation, lower extremity joints, pelvic and shoulder girdles, and lumbar spine (p<.05).

• PNF and Movement
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• v.6 no.1
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• pp.53-60
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• 2008

Purpose : To describes the important aspects of knee joint movement and function used when applying PNF technique to the lower limb. Method : The knee was a very important roles in the lower limb movement and ambulation. This study summarizes the physiologic movement of knee to the PNF lower extremity patterns. Result : The tibiofemoral joint is usually described as a modified hinge joint with flexion-extension and axial rotation by two degrees of freedom movement. These arthrokinematics are a result of the geometry of the joints and the tension produced in the ligamentous structures. The patellofemoral joint is a sellar joint between the patella and the femur. Stability of the patellofemoral joint is dependent on the passive and dynamic restraints around the knee. In a normal knee the ligaments are inelastic and maintain a constant length as the knee flexes and extends, helping to control rolling, gliding and translation of the joint motions. Conclusions : It is important to remember that small alterations in joint alignment can result in significant alterations in patellofemoral joint stresses and that changes in the mechanics of the patellofemoral joint can also result in changes in the tibiofemoral compartments. Successful treatment requires the physical therapist to understand and apply these arthrokinematic concepts. When applied to PNF low extremity patterns, understanding of these mechanical concepts can maximize patient function while minimizing the risk for further symptoms or injury.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.3
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• pp.690-696
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• 2013

This study, which is conducted on two groups of skilled people and unskilled people, is purposed to analyze joint angle of lower extremity during short track speed skating in order to find out efficient body position and propose ideal training method. Short Track Speed Skating has a wide range of research areas, but their findings indicate a promising area for further research. Targeting 8 people who are skilled in short track speed skating and 8 people who are not skilled in it, this study analyzes three dimensional images using super-high speed camera to compare differences between these two groups of people. In this study, 6 sections of body positions including right foot push-off, right foot recovery, right foot basic position, left foot push-off, left foot recovery, and left foot basic position were analyzed using 8 super-high speed cameras of VICON. These body positions were analyzed in order to find out joint angles of the hip joint, the knee joint, and the ankle joint. In the section 4 of the inner and outer parts of the left hip angles showed significant difference, and most of the sections of knee joint angles also showed significant difference. In the section 1 and 2 of the plantar flexion, dorsiflexion of ankle joints showed significant difference(p<.001) It was found out that there were differences between groups of skilled people and unskilled people in terms of lower extremity's joint angles such as angles of the hip joint, the knee joint, and the ankle joint.

• Korean Journal of Applied Biomechanics
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• v.21 no.2
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• pp.215-222
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• 2011

The purpose of this study was to analyze the effects of the use of the lower extremity supporter to ground reaction force(GRF) & EMG in women. Five women participated in the experiment conducted in the study(age: $46.7{\pm}3.5$ yrs, weight: $52.3{\pm}2.2$ kg, lower extremity height: $74.1{\pm}0.9$ cm, knee height: $40.7{\pm}1.4$ cm). The Ground reaction force was measured by AMTI ORG-6 and the Muscle activity of the lower extremity was measured by an 8-channel surface EMG system(Noraxon Myoresearch, USA, 1000Hz). We statistically compared muscle activity and ground reaction force with and without the lower-extremity supporter by one-way repeated ANOVA. The results were as follows. First, the use of the lower extremity supporter affects the ground reaction force along the anterior-posterior axis(Y). Second, the vertical(Z-axis) reaction force on the upper part of the lower extremity supporter increase because of the difference between the interval of vertical movement. Third, the muscle activity of the lateral gastrocnemius and rectus femoris was higher in the upper part of the lower extremity supporter. Further research for example, on a comparative analysis of joint moments, the effects of direct stressor on joints. and the relationship between muscle activity and joint movement, is necessary for a better understanding of the effects of the lower-extremity supporter.