• Physical Therapy Rehabilitation Science
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• 제8권2호
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• pp.61-66
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• 2019

Objective: The purpose of this study was to investigate the effects of resistance applied in various directions on lower extremity muscle activity and balance during squat exercise performance. Design: Cross-sectional study. Methods: Forty-one adults (19 males and 22 females) agreed to the study purpose and procedures. All subjects randomly performed squat exercises with an intensity of overcoming 10% of body weight resistance pulled forward, backward and general squats with $60^{\circ}$ of knee joint flexion. Electromyography was used to measure muscle activity of the vastus medialis oblique (VMO), rectus femoris (RF), vastus lateralis oblique (VLO), biceps femoris (BF), and semitendinosus (ST) muscles. The Wii Balance Board was used to assess balance during the three-method squat operation. Each operation was measured three times for 10 seconds. Results: There were significant differences in muscle activities of the VMO, RF, VLO, ST and balance ability with the application of three directions of resistance (p<0.05). Post hoc comparisons revealed that squats performed with resistance pulled in the backward direction resulted in higher VMO, RF and VLO activity than with the resistance placed in a pulled forward direction (p<0.05). In the ST, resistance applied in the pulled forward direction showed greater muscle activity compared to the pulled backward direction (p<0.05). With balance, squats performed with resistance pulled in the forward direction showed greater muscle activity than with resistance applied in the pulled backward direction and during general squat performance (p<0.05). Conclusions: In this study, squat exercises performed with resistance applied in the direction of pulling backwards was found to be the most effective in improving quadriceps muscle strength and balance. It is effective to provide resistance that is placed in the forward when it is difficult to perform a general squat due to weakness of the quadriceps.

• Physical Therapy Rehabilitation Science
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• 제12권1호
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• pp.33-42
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• 2023

Objective: This study aims to analyze the effect of regular exercise through the combined walking-oriented aerobic and resistance exercises using EX1 in young adults. Design: Experimental one group pre and post test Methods: Participants comprised17 healthy young adults. All subjects performed a combined exercise program for 10 times using EX1. We measured quadriceps muscle thickness using ultrasound. Additionally, the hand grip strength test, and sit and reach test were performed before and after the exercise. Through paired t-test, we investigated whether there was a statistically significant difference in the measurement results after exercise program. Results: The rectus femoris muscle contraction ratio showed significant difference after exercise(P< 0.01). In the sit and reach test, flexibility showed significant difference after exercise(P < 0.01). The hand grip strength test also showed significant difference after exercise(P < 0.05). Conclusions: Healthy young adults can effectively perform various exercises commonly performed in daily life using EX1.

• 한국전문물리치료학회지
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• 제11권3호
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• pp.85-90
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• 2004

The purpose of this study was to find the difference in muscle firing rate between each muscle according to the knee angle with the quadriceps femoris which is a representative action muscle of the lower extremity. Seven normal healthy subjects were recruited. The median frequency (MDF) of muscle contraction was recorded from vastus lateralis, vastus medialis, and rectus femoris muscles using the surface EMG, in 5 seconds, during maximal isometric knee extension. The data were analyzed by the two-way repeated ANOVA. The results of the study were as follows: 1) median frequency of muscle contraction was significantly higher at the vastus lateralis, vastus medialis, and rectus femoris in descending order. 2) median frequency of muscle contraction was significantly higher at the $30^{\circ}$, $60^{\circ}$, and $90^{\circ}$ in descending order. Consequently, muscle recruitment at the knee decreases the EMG activity of the lengthened muscle. This study suggests that the change in EMG activity at different muscle lengths resulted in affecting the muscle firing rate during the knee extension.

• 대한물리치료과학회지
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• 제28권2호
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• pp.57-64
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• 2021

Background: During squat exercises, Ankle joint stability during squat movement transfers forces produced by unstable supports or various loads to the leg joints and trunk, reducing the risk of injury; therefore, a reference is needed for correct ankle joint posture during squat exercises. The purpose of this study was to examine the effect of ankle joint stability on quadriceps femoris and hamstring activation during squat exercises. Design: Quasi-experiment one group pretest-posttest design. Methods: The participants in this study were 20 volunteers who performed squat exercises with and without kinesiology tape. We measured quadriceps femoris and hamstring activation using surface electromyography. The ankle joint was stabilized with kinesiology tape using the ankle balance taping (ABT) method. A paired t-test was performed to compare differences between taping conditions. Results: Vastus medialis and vastus lateralis activation were greater following squat exercises with kinesiology tape than without; however, the difference was not significant. Medial and lateral hamstring activation was not significantly different between taping conditions. Conclusion: Although it is difficult to maintain stability using kinesiology tape alone, ankle joint stability is believed to affect quadriceps femoris muscle activity, which increases the effectiveness of the squat exercise.

• 대한물리치료과학회지
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• 제19권1호
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• pp.55-62
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• 2012

Objectives : The purpose of this study was to determine the effects of high heeled shoes on the static & dynamic balance performance and electromyography(EMG) of back and lower extremity muscles. Materials & Methods : Sixteen women participated in this study. Subjects were composed two groups with LL shoes group and higher heel shoes group. We carried out Romberg's test and muscle activity of left and right Paraspinalis, Quadriceps femoris, Tibialis anterior, Gastrocnemius muscles by EMG in order to determine static balance performance according heel height. Using by Biorescue(Incenierie company), we trained subject to transfer of COG each direction(Anterior, posterior, Right, Left), we carried out this test for distance, surface, distance/surface in order to determine dynamic balance performance according heel height. The data were analyzed by independent t-test between lower and high heel height using SPSS(ver. 17.0)/PC program. Results : There was significant difference of distance(p<.05) of weight perturbation between lower and high group in dynamic balance performance and EMG value of left Gastrocnemius(p<.05), both Tibialis anterior(p<.05) muscle in static balance performance. Conclusions : Height of heel has effect on dynamic balance performance in distance of the Anterior, posterior direction. EMG of Gastrocnemius and Tibialis anterior muscles were affected by Romberg's test.

• International Journal of Contents
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• 제6권1호
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• pp.1-5
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• 2010

Kinesio Taping (KT) is widely used by physical therapists to treat a variety of neuromusculoskeletal disorders. In this study it was examined whether or not KT has an effect on the peak torque and muscle activity of the quadriceps muscles in healthy subjects. KT was applied to the anterior thigh and tibia of fifteen healthy males (mean age, 25.42${\pm}$1.38 years, mean body height 178.58${\pm}$3.03 cm, mean body weight 71.58${\pm}$6.42 kg) who have no problem within past 2 months. The quadriceps peak torque was assessed using an isokinetic dynamometer while the mean data of muscle activity was measured by surface electromyography (EMG). The maximal voluntary isometric contraction was carried out on all subjects at $0^{\circ}$, $30^{\circ}$ and $60^{\circ}$ before, during, and after KT. There were no significant differences in the peak torque and mean data of quadriceps muscle(vastus lateralis, rectus femoris, and vastus medialis oblique) activity at $0^{\circ}$, $30^{\circ}$ and $60^{\circ}$ before, during and after application of KT (p>.05). From this study it could be concluded that the application of KT to the anterior thigh and tibia doesn't affect the peak torque and the muscle activity.

• 근관절건강학회지
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• 제17권2호
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• pp.142-150
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• 2010

Purpose: The purpose of this study was to examine EMG activities and VMO/VL ratio of the vastus medialis oblique, vastus lateralis, and rectus femoris during squat exercise (knee angle: 15, 45, and 60 degrees; tibial rotation: internal rotation, neutral, and external rotation). Methods: Twelve subjects performed squat exercise at each knee angle and tibial rotation while electromyographic (EMG) activity was collected. Statistical analysis consisted of two-way repeated measures analysis of variance with post hoc analysis. Results: There were significant main effects of knee angles and foot positions and interaction effect on EMG activities of vastus medialis oblique and vastus lateralis. VMO/VL ratios were significantly different by tibial rotations and there was an interaction effect. A neutral position produced significantly more VMO/VL activity ratio than that from internally rotated position and externally rotated position at 60 degrees. Conclusion: Considering the interaction effects for EMG activity across quadriceps muscles tested, the 60 degrees knee angle with a neutral foot position may provide the most effective condition for patients with acute patellofemoral syndrome.

• 한국운동역학회지
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• 제28권1호
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• pp.37-43
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• 2018

Objective: The aim of this study was to analyze muscle activation of the lower extremities as a function of changes of the center of pressure (CoP) of the foot during squats in order to provide quantitative information to trainers who would like to teach correct movements for developing muscles. Method: Ten men with over three years of weight training experience participated in this study (age: $26.1{\pm}0.8yrs$, height: $171.2{\pm}3.9cm$, body mass: $71.1{\pm}5.7kg$, 60%RM: $84{\pm}9kg$, career: $4.0{\pm}0.7yrs$). The participants were instructed to perform a squat in each of 3 conditions, with different CoP's (the front, middle, and rear of the foot). Results: The position of the CoP showed significant differences according to instructions in both the eccentric and concentric contraction phases (p < .05). The range of movement of the hip and ankle joints showed significant differences corresponding to changes of the CoP position (p < .05). The rectus femoris and gluteus maximus muscle showed significant differences for different CoP positions only in the concentric contraction phase, while the gastrocnemius and anterior tibialis were significantly different in both the concentric and eccentric contraction phase (p < .05). Conclusion: When the target muscle of squat training is the gastrocnemius, the CoP should be located in the front of the foot for effective muscle training. When the target muscles of squat training are the gluteus maximus and quadriceps femoris, the CoP should be located on the rear of the foot.

• 한국정보전자통신기술학회논문지
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• 제8권1호
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• pp.65-69
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• 2015

작업치료에서 관절의 가동성은 치료 절차와 기간에 영향을 미치는 중요한 요소이다. 수동적 스트레칭과 능동적 스트레칭을 병행하는 고유수용성 신경근 촉진법이 고관절의 가동성에 미치는 영향과 주요 굽힘/폄근의 근전도 활성정도 바탕으로 고유수용성 신경근 촉진 스트레칭의 생체역학적 특징을 고찰하였다. 10명의 20대 학생을 대상으로 고유수용성 신경근 촉진 스트레칭을 실시한 결과 고관절의 가동성이 전담 보조자의 도움을 받았을 때, 평균 $18.9^{\circ}$ 증가하였고 넙다리네갈래근과 뒤넙다리근의 근전도의 활성 또한 고유수용기의 생체역학적 특징을 나타내었다.

• 대한정형도수물리치료학회지
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• 제27권2호
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• pp.37-43
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• 2021

Background: The purpose of this study is to compare and analysis the changes in strength and endurance of the knee extensor muscles after Anterior cruciate ligament reconstruction. Methods: Twelve male subjects with ligament injury were seated on Biodex and the hip joint was flexed at 110°, and torso, lower extremities, and legs were fixed using Velcro. The resistance device was placed at a point 3cm above the ankle, and measurements were taken before and a surgery at 60°/sec and 180°/sec when the knee was maximally extended. The postures ingeniously combine forward-bending poses countered with backward-bending ones. Results: There was no significant difference in the comparison of muscle strength of 60°/sec and 180°/sec before surgery. But there was a significant difference after surgery. There was significant difference in muscle endurance both before and after surgery. There was a significant difference in the pre- and post- operative comparison values of muscle strength and endurance in isokinetic movements at 60°/sec and 180°/sec during knee extension on the injured side. Conclusion: For cruciate ligament tears, Orthopedic reconstruction is recommended. Correct alignment of the knee ligament after surgery can enhance the strength and endurance of the quadriceps femoris during knee extension rejuvenated.