• 한국운동역학회지
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• 제14권1호
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• pp.133-144
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• 2004

The purpose of this study was to analyze the joint moment on lower extremity during a developpe devant. Data were collected by Kwon3D, KwonGRF program. Two professional modem female dancers were participated in this experiment. Subjects performed a developpe devant in meddle heights. On the axes of X, Y, Z, it was shown that the maximum joint moment was occurred in hip joint. The moments are plotted during developpe devant. The ankle muscles generate a plantar flexion moment and the knee muscles generate a flexion moment and The hip muscles generate a extension moment. So these muscles of joint muscles were known to play a key role in keeping the body balance while doing developpe devant. In addition adduction moment occurred at hip, knee, an ankle in the order of amount, we could assume from this data that him out motion started from the hip joint. There was small active turn out possible below the hip joint. A small amount of extra turn out could be obtained when standing because of flexion between the foot and floor, which could be used to give a passive external rotation force to the whole leg and this could produce a rotation between the knee and foot. This passive external rotation could produce very damaging results. Therefore, lower extremity joint muscles such as hip, knee, and ankle muscle should be trained to keep the body balance and prevent injury during developpe devant performance. And for the safe and perfect turn ort performance, hip joint abduction, the most important external rotating muscle for him out is needed to train and full stretching should be done in advance.

• 한국운동역학회지
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• 제29권4호
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• pp.227-235
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• 2019

Objective: The purpose of this study was to evaluate the effect of passive-acute temperature therapy of the femoral muscle and dynamic warm-up on the countermovement jump performance. Method: Twenty male track and field athletes from national team underwent three treatments applied on the femoral muscles; cold temperature treatment, thermal treatment and dynamic warm-up. The variables extracted at 2 time points (pre-measurement and post measurement) were the temperature of the left and right femoral muscle, displacement & velocity of centre of mass, peak power out, range of motion and moment & power of the knee joint. Results: There was a statistically significant difference in the temperature of the femoral muscle according to measurement time which was high in the order of thermal treatment, dynamic treatment and cold treatment. The jump height was the highest in the dynamic warm-up with no statistically significant difference for the range of motion of the knee joint. The peak power out at dynamic warm-up and the power of the knee joint were statistically significant according to the treatment and measurement time. Conclusion: Local cold and thermal treatment of femoral muscles at ambient temperature did not improve jump performance, while dynamic warm-up was considered to be effective for maintaining the performance of the activities that require strong muscular power.

• The Journal of Korean Physical Therapy
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• 제16권3호
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• pp.192-204
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• 2004

The surface electromyographic(sEMG) analyses were knee joint angle during open kinetic chain exercise (OKC) and close kinetic chain exercise (CKC) in vastus medialis (VM), vastus lateralis (VL), and rectus femoralis (RF). Ten subjects with normal , aged 20 to 30(X=27.4, SD=3.23), were randomized Statistical techniques for data analysis were applied paired t-test. The 0.05 level of significane was used as the critical level for rejection of the null hypotheses for the study. And the results were: 1) Both OKC and CKC improved the strength of quadriceps muscle as the knee joint flexion was increased. 2) In OKC, the strength of VM was improved the most at the 30 degree angle. 3) In CKC, the strength of VM was improved the most at the 30 degree angle. 4) The VM/VL ratio was the largest at the 10 and 20 degree angles in OKC and CKC. 5) The VM/VL ratio at 10, 20, and 30 degree angles was significantly different between OKC and CKC (P < 0.05). Base on the results, the OKCE is recommended for the knee joint patients, especially for the patellofemoral pain syndrome patients, during the early phase of rehabilitation. In order to improve strength of the quadriceps, muscle strength training at 30 degree angle is recommended. In order to improve VM/VL ratio, 10 and 20 degree angles are recommended during OKCE and CKCE, respectively. Future researches are warranted comparing electromyographic analysis between OKCE and CKCE in the quadriceps at a certain work lead, and muscle strength performance in the quadriceps at different positions of foot.

• 한국운동역학회지
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• 제20권1호
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• pp.13-23
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• 2010

The purposes of this study was to investigate the biomechanical influence of the walking shoe with a plate spring in the heel and interchangeable heel cushioning elements. Eighteen subjects walked in three conditions: 1) the walking shoes Type A-1 with a soft heel insert, 2) the Type A-2 shoe with a stiff heel insert, 3) a general walking shoe(Type B). Ground reaction forces, leg movements, leg muscle activity and ankle, knee and hip joint loading were measured and calculated during overground walking. During walking, the ankle is a few degrees more dorsiflexed during landing and the knee is slightly more flexed during takeoff with the Type A shoes. As a result of the changes in the walking movement, the ground reaction forces are applied more quickly and the peak magnitudes are higher. Muscle activity of the quadricep, hamstring and calf muscles decrease during the first 25% of the stance phase when walking in the Type A shoes. The resultant joint moments at the ankle, knee and hip joints decrease from 30-40% with the largest reductions occurring during landing.

• Physical Therapy Rehabilitation Science
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• 제12권2호
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• pp.201-205
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• 2023

Objective: Resistance exercise is a necessary element to improve quality of life, and measurement and evaluation of muscle strength provide important information for prescription and management of rehabilitation and exercise programs. This study analyzed the correlation between direct and indirect 1RM for isokinetic maximum torque of the knee joint in order to provide useful information in the field of exercise programs. In addition, the flexion-extension ratio and the difference in left-right deviation were verified. Design: A cross-sectional study Methods: The subjects of this study were 33 healthy adult men and women without medical problems who participated in the health exercise class program at S University in Seoul. The correlation between isokinetic maximum torque and direct and indirect 1RM was analyzed, and a dependent t-test was performed to analyze the flexion-extension ratio and left-right deviation. Results: There was a high correlation between the isokinetic maximum torque and direct and indirect 1RM, and no statistically significant difference was shown between the test methods in the analysis of the flexion-extension ratio and left-right deviation. Conclusions: Isokinetic muscle function measuring equipment is expensive, so it is difficult to use it in local exercise rehabilitation and training sites. Through this study, it was found that direct and indirect 1RM isokinetic maximum torque showed a high correlation, and there was no difference in evaluating muscle function such as flexion-extension ratio and left-right deviation. Therefore, it is considered that the muscle function evaluation using 1RM in general field can be usefully utilized.

• 대한정형도수물리치료학회지
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• 제30권2호
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• pp.13-26
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• 2024

Background: The most common form of injury in soccer is a hamstring strain. Eccentric bias exercises are crucial for reducing injury risk and improving sprinting performance. The purpose of this study was to compare a 4-week hip-dominant hamstring strengthening exercise program (HDE) with a knee-dominant hamstring strengthening exercise program (KDE) in youth soccer players. Method: The sample (n=31) was randomly divided into two groups: HDE (n=17) and KDE (n=14), with soccer players in HDE performing hip joint-dominant hamstring strengthening exercises and those in KDE performing knee joint-dominant hamstring strengthening exercises. Each intervention was conducted three times per week for four weeks. The outcome measures included the hamstring strength test (isometric strength test, eccentric strength test), knee joint range of motion (90/90 active knee extension; AKE) test, lower limb function test Y-balance test and Agility T-test. Results: Following the intervention, both groups showed significant improvement in isometric and eccentric hamstring strength on both dominant and non-dominant sides (p<.05). The AKE test showed significant improvement in the dominant leg (p<.05) and non-dominant leg only in KDE. The agility test significantly improved in HDE (p<.05). There was a slight improvement in the Y-balance test score; however, the difference was not statistically significant. There were no differences between the two groups in the values before, and after the intervention for all items. Conclusion: The hip-dominant and knee-dominant hamstring strengthening exercise should be coordinated and used based on the environment during hamstring injury prevention training.

• 한국운동역학회지
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• 제26권2호
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• pp.237-242
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• 2016

Objective: The purpose of this study was to compare the joint movements and muscle activities of novices according to pedal type (flat, clip, and cleat pedal). Method: Nine novice male subjects (age: $24.4{\pm}1.9years$, height: $1.77{\pm}0.05m$, weight: $72.4{\pm}7.6kg$, shoe size: $267.20{\pm}7.50mm$) participated in 3-minute, 60-rpm cycle pedaling tests with the same load and cadence. Each of the subject's saddle height was determined by the $155^{\circ}$ knee flexion angle when the pedal crank was at the 6 o'clock position ($25^{\circ}$ knee angle method). The muscle activities of the vastus lateralis, tibialis anterior, biceps femoris, and gastrocnemius medialis were compared by using electromyography during 4 pedaling phases (phase 1: $330{\sim}30^{\circ}$, phase 2: $30{\sim}150^{\circ}$, phase 3: $150{\sim}210^{\circ}$, and phase 4: $210{\sim}330^{\circ}$). Results: The knee joint movement (range of motion) and maximum dorsiflexion angle of the ankle joint with the flat pedal were larger than those of the clip and cleat pedals. The maximum plantarflexion timing with the flat and clip pedals was faster than that of the flat pedal. Electromyography revealed that the vastus lateralis muscle activity with the flat pedal was greater than that with the clip and cleat pedals. Conclusion: With the clip and cleat pedals, the joint movements were limited but the muscle activities were more effective than that with the flat pedal. The novice cannot benefit from the clip and cleat pedals regardless of their pull-up pedaling advantage. Therefore, the novice should perform the skilled pulling-up pedaling exercise in order to benefit from the clip and cleat pedals in terms of pedaling performance.

• 한국운동역학회지
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• 제18권4호
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• pp.41-47
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• 2008

본 연구는 정상 성인들을 대상으로 등속성 기구를 이용하여 무릎관절 신근 정적 스트레칭 빈도에 따른 등속성 변인들을 비교 분석함으로써 적절한 스트레칭에 대한 기초 자료를 제공하는데 목적이 있다. 45명의 대상자를 무작위 추출하여 3 Group 으로 각각 15명씩 나뉘었고, 우세측 다리의 무릎관절 신근 스트레칭으로 이루어진 4가지 정적 스트레칭 운동을 순서대로 각각 2회, 4회, 6회 실시하였다. 스트레칭이 끝나면 등속성 근력 검사를 실시하였다. 통계학적 처리는 paired t-test, 일원변량분석(one-way ANOVA)과 사후검정(Duncan)을 실시하였다. 결과는 스트레칭이 급성 등속성 근력의 저하를 가져오는 것을 알 수 있다. 또한 스트레칭 빈도에 따른 근력 변화에 있어선 4회 스트레칭 집단에서 보다 효과적인 근력의 감소를 나타내었다. 따라서 강한 근력을 필요로 하는 경기에 있어서 근육의 능력을 상실하지 않는 적절한 스트레칭 방법에 대한 고려가 필요할 것으로 생각된다.

• 대한정형도수물리치료학회지
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• 제8권2호
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• pp.31-43
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• 2002

The subjects of this study were 15 woman soccer players and 15 untrained woman students at H-Cheju University. Each subject was measured on the muscle strength and peak torque of knee extensors and knee flexors with isokinetic load ($60^{\circ}$/sec, $180^{\circ}$/sec). The results were as follows: 1. There was no significant difference between right and left leg strength measured isokinetically in each group. 2. The peak torque of knee extensors and flexors was significantly higher in scoccer players than untrainded students (p<0.001). 3. For the angle of knee joint showing the highest peak torque, there was significant difference between soccer players and untrained students in knee extensors(p<0.05) and right flexors (p<0.01). 4. For knee H/Q ratio, there was significant difference between two groups(p<0.05). 5. For the total work and average power at $180^{\circ}$/sec, there was significant difference between two groups in knee extensors(p<0.001) and flexors(p<0.01). 6. In soccer players at $60^{\circ}$/sec, there were significant correlations between peak torque and height and between peak torque and weight.(p<0.001). 7. For the muscular contraction velocity at $60^{\circ}$/sec, there was significant difference between two groups in flexors (p<0.01). 8. For the muscular indurance at $180^{\circ}$/sec in extensors and flexors, there was no significant difference between two groups(p<0.05). In conclusion, there were significantly higher in peak torque, contraction velocity, knee joint's angle with the highest peak torque, H/Q ratio, total work and average power in woman scoccer player than general students. But there was no significant difference in muscular endurance. Soccer performance is based on the various components including muscular endurance that is one of the most important components. So it is necessary that the training method to improve the various components (especially including muscular endurance) should be done.

• 대한의용생체공학회:의공학회지
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• 제36권5호
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• pp.235-239
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• 2015

The purpose of this study was to investigate the unstable plate system for the advanced balance ability. 7 male volunteers (age $33.7{\pm}1.2$ years, height $174.7{\pm}3.8cm$, weight $86.0{\pm}3.6kg$, BMI $28.2{\pm}2.0kg/m^2$) performed the partial squat motion on the shape of CAP type(${\cap}$) and BOWL type(${\cup}$) plate system. The range of motion (ROM) and muscle activation were acquired by the motion analysis system and the EMG system. Results of ROMs of the CAP type plate system were shown the widely range of the deviation in the ankle joint on the sagittal plane (sagittal plane - hip joint $10.7^{\circ}$ > $5.4^{\circ}$, knee joint $16.3^{\circ}$ > $6.4^{\circ}$, ankle joint $18.8^{\circ}$ > $6.3^{\circ}$ ; transverse plane - hip joint $3.5^{\circ}$ > $1.8^{\circ}$, knee joint $5.3^{\circ}$ > $3.4^{\circ}$, ankle joint $11.3^{\circ}$ > $5.3^{\circ}$ ; frontal plane - hip joint $0.9^{\circ}$ > $0.5^{\circ}$, knee joint $0.8^{\circ}$ > $0.6^{\circ}$, ankle joint $4.8^{\circ}$ > $3.7^{\circ}$). Muscle activation results of the CAP type plate system were indicated higher in major muscles for balance performance than the BOWL type plate system (vastus lateralis 0.90 > 0.62, peroneus longus 0.49 > 0.21, biceps femoris 0.38 > 0.14, gastrocnemius 0.11 > 0.05). These findings may indicate that the CAP type plate system would expect better effectiveness in perform the balance training. This paper is primary study for developing balance skills enhancement training device.