• 한국체육학회지인문사회과학편
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• 제54권1호
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• pp.505-514
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• 2015

이 연구는 다양한 불안정면에서의 스쿼트 운동이 체간과 하지근육의 활성도에 미치는 영향을 비교하는데 목적이 있다. 10명의 피험자가 안정면, 불안정면인 스타빌리티 블루와 블랙, 보수에서 75% 1RM의 강도에서 스쿼트 동작을 실시하였다. 체간근육으로는 복직근, 외복사근, 내복사근 및 다열근에 근전도를 부착하였고, 하지근육으로는 대둔근, 중둔근, 대퇴이두근, 대퇴직 근, 외측광근, 내측광근, 내측비복근, 외측비복근, 가지미근, 전경근에 근전도를 부착하여 스쿼트 동작의 상승과 하간구상의 근활성도를 측정하였다. 안정면과 불안정면에서의 근활성도를 비교하기 위하여 일원변량분석을 실시하였으며, 사후검증으로 sheffe를 이용하였다. 하강구간에서 근활성도는 보수에서의 스쿼트 동작 시 내측광근, 다열근, 대둔근과 중둔근의 활성도가 안정면과 다른 불안정면에서의 스쿼트 동작 시보다 높게 나타났다. 상승구간에서 근활성도는 보수에서의 스쿼트 동작 시 대둔근의 활성도가 안정면과 다른 불안정면에서의 스쿼트 동작 시보다 높게 나타났다. 이러한 결과는 보수에서의 스쿼트 동작이 체간근육과 둔근의 활성도를 증가시키는데 효과적이라고 제시할 수 있다. 그러나 하지근육의 활성도는 불안정성에 따른 차이가 없는 것으로 사료된다.

• 한국운동역학회지
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• 제27권3호
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• pp.197-203
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• 2017

Objective: The purpose of this study was to determine how exercise intensity affects muscle activity and kinematic variables during squat. Method: Fifteen trainers with >5 years of experience were recruited. For the electromyography (EMG) measurements, four surface electrodes were attached to both sides of the lower extremity to monitor the rectus femoris (RF) and biceps femoris. Three digital camcorders were used to obtain three-dimensional kinematics of the body. Each subject performed a squat in different conditions (40% one-repetition maximum [40%1RM], 60%1RM, and 80%1RM). For each trial being analyzed, three critical instants and two phases were identified from the video recording. For each dependent variable, one-way analysis of variance with repeated measures was used to determine whether there were significant differences among the three different conditions (p<.05). When a significant difference was found, post hoc analyses were performed using the contrast procedure. Results: The results showed that the average integrated EMG values of the RF were significantly greater in 80%1RM than in 40%1RM during the extension phase. The temporal parameter was significantly longer in 80%1RM than in 40%1RM and 60%1RM during the extension phase. The joint angle of the knee was significantly greater in 80%1RM than in 40%1RM at flexion. The range of motion of the knee was significantly less in 80%1RM than in 40%1RM and 60%1RM during the flexion phase and the extension phase. The angular velocity was significantly less in 80%1RM than in 40%1RM and 60%1RM during the extension phase. Conclusion: Generally, the increase of muscle strength decreases the pace of motion based on the relation between the strength and speed of muscle. In this study, we also found that the increase of exercise intensity may contribute to the increase of the muscle activity of the RF and the running time in the extension phase during squat motion. We observed that increased exercise intensity may hinder the regulation of the range of motion and joint angle. It is suitable to perform consistent movements while controlling the proper range of motion to maximize the benefit of resistance training.

• 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.

• 디지털융복합연구
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• 제17권3호
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• pp.463-471
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• 2019

본 연구는 무릎 근력의 불균형이 백 스쿼트 시 인체 움직임의 제한 요인으로 작용하는지를 확인하는 것에 목적이 있다. 백 스쿼트 유경험자로 최근 2년간 부상이 없는 서울시 소재 S대학교 학생 8명을 연구 대상자로 선정하였다. Cybex 770으로 무릎관절의 등속성 근력을 측정한 후, 동측 주작용근과 대항근의 근력 불균형 정도와 좌 우 같은 근 군의 결손율에 따라 그룹을 나눈 후, 개인별 몸무게의 25%, 50%, 100%, 125%의 중량과 같은 바벨을 백 스쿼트로 들게 하였다. 무릎 굽힘 각도, 신체중심의 수직 변위, V-COP의 측정 구간 내 평균 위치로부터 매 순간 V-COP 까지의 거리 합 변인들에 대한 집단별 차이를 검증하기 위해 독립표본 T 검정을 실시하였다. 125%BW 조건에서 무릎관절 근력의 동측 불균형은 쭈그려 앉는 자세의 제한 요인으로, 좌 우측 폄 근력의 불균형은 평형성 유지의 제한 요인으로 작용하였다. 근력의 불균형이 인체 움직임의 제한 요인으로 작용할 수 있음을 확인하였으므로, 차후 임상에서는 근력 불균형에 대한 검사법과 함께 교정 및 재활 운동 방법 또한 발전시켜 나갈 필요가 있다.

• 대한조선학회논문집
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• 제51권6호
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• pp.539-547
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• 2014

Ship squat is a well known phenomenon, which means an additional sinkage and a change of trim when a ship sails in shallow water. As a series of ship squat study, a HPMM(Horizontal Planar Motion Mechanism) test of KVLCC2 model ship to measure a sinkage and a trim in shallow water was conducted. Additionally a CFD(Computational Fluid Dynamics) analysis was carried out to simulate fluid flows around the ship surface. A change in ship speed, drift angle at three depth conditions(H/T = 1.2, 1.5 & 2.0) is considered for comparing these results. As a result, an increase of the ship speed and the drift angle caused an increase in ship squat in EFD(Experimental Fluid Dynamics), and created a lower pressure on the ship bottom area in CFD. Lastly the sinkage results of KVLCC2 by EFD and CFD are compared to results by three empirical formulas. The tendency of sinkage by EFD and CFD is similar to the results of empirical formulas.

• 한국운동역학회지
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• 제34권1호
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• pp.9-17
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• 2024

Objective: The purpose of this study is to apply 8-week velocity-based training to domestic professional athletes and the kinematic and kinetic analysis of the 1-RM improvement of back squat and power clean, which can represent strength-power ability, to verify the effectiveness of velocity-based training in Korea and to establish a basic basis. Method: The subjects who participated in this study were 10 professional athletes from K University (age: 21.40 ± 0.97 yrs., height: 179.90 ± 3.54 cm., body mass: 71.298 ± 2.98 kg). All subjects performed back squat and power clean 1-RM before and after 8-weeks of velocity-based training. A 3-dimensional motion analysis with 8 infrared cameras and 4 channels of EMG was performed in this study. A paired t-test was used for statistical verification. The significant level was set at α=.05. Results: Both Back squat and Power Clean 1-RM showed statistically significant increases (p<.05). In the case of back squat, there was no statistically significant difference in both kinematic and kinetic variables (p>.05). In the case of Power Clean, only the quadriceps of Phase 1 showed a statistically significant decrease (p<.05). Conclusion: Domestic professional athletes can improve their strength-power ability through velocity-based training, and such training for at least 8-weeks is considered a way to improve their performance.

• The Journal of Korean Physical Therapy
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• 제31권4호
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• pp.216-221
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• 2019

Purpose: This study examined the effect of visual feedback squat on the core muscle thickness of young adults experiencing back pain. Methods: Thirty adult men and women who experienced back pain were assigned randomly to 15 members of the visual feedback squat group (VSG) and 15 of the normal squat group (NSG) to train three times a week for a total of eight weeks. The core muscle thickness was compared prior to the test for four weeks and eight weeks after the test by dividing it into warm-up exercise, main exercise, and 10 minutes finishing exercise. Before, and four weeks and eight weeks later, the thickness of the core muscle was compared using an ultrasonic imaging system. Repeated measured ANOVA was performed to compare the groups, and a Bonferroni test was performed as a post-hoc test to assess the significance of the timing of the measurements in each group according to the periods. An independent t-test was conducted to test the significance between the groups according to the measurement points. Results: A significant change in the main effects of time and interactions of the time difference in muscle thickness of transvers abdominis were observed between the visual feedback squat and control groups according to the measurement point (p<0.05). No significant difference in the muscle thickness of both muscles was observed between the groups with the exception of the right abdominis (p>0.05). Conclusion: These findings suggest that visual feedback squat exercise is expected to have positive effects on the development of transverse abdominis in core muscles.

• 한국운동역학회지
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• 제33권4호
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• pp.128-136
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• 2023

Objective: The aim of this study was to investigate the effect of an 8-week closed kinetic chain typed Reformer and Chair Pilates exercise on static and dynamic lower limb alignment for healthy female adults. Method: Ten healthy young female adults without musculoskeletal injury history in last 6 months (Age: 29.3 ± 3.5 yrs., Height: 165 ± 3.4 cm, Body mass: 58.2 ± 5.4 kg) participated in this study. All participants asked to join the 8-week closed kinetic chain typed Reformer and Chair Pilates exercise, and the program was conducted for 60 minutes twice a week. Participants were asked to be measure a static Q-angle and performed free squat one week before and after the program. A 3-D motion analysis with 8 infrared cameras and 5 channels of EMG was executed in this study. The effectiveness of the training was evaluated by paired t-test, and the significance level was set at .05. Results: A significantly decreased in internal rotation angles was found at hip joint during free squat after the training. Also, significantly decreased in lateral rotation angles were found at knee and ankle joint during free squat after training. Finally, significantly decreased in muscle activations were found at adductor longus and peroneus longus during free squat after training. Conclusion: From results of our study, it is concluded that an 8-week closed kinetic chain typed Pilates exercise positively effect on lower limb alignment during dynamic movement.

• 한국전문물리치료학회지
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• 제25권3호
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• pp.19-26
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• 2018

Background: Genu varum is also known as bow leg. It is a deformity wherein there is lateral bowing of the legs at the knee. it does give rise to pain, and persistent bowing can often give rise to discomfort in knees, hips and ankles. Objects: This study investigated the effect of narrow squats on the knee joint during a gait and distance between the knees of person with genu varum. Methods: This study analyzed 23 patient with genu varum that grade III, 12 narrow squat group and 11 genenal squat group in motion analysis laboratory. The subjects of experiment took gait before and after intervention, the range of joint motion, moment of knee joint adduction, power, distance of the knees were measured. And in order to make an analysis between groups, an paiered t-test and independent t-test was carried out. For statistical significance testing, it was decided that significance level ${\alpha}$ be .05. Results: It was shown that the group of narrow squat exercise significantly decreased in distance of knees (p<.05),In moment of adduction of knee joint, it was shown to significantly decrease in two groups (p<.05), was significantly decreased in adduction, abduction, and rotation (p<.05). In relation of peak-knee adduction moment and valgus angle, there was significant decrease in narrow squat group (p<.05). Conclusion: When the above result of study were examined, a narrow squat exercise given to the genu varum patients significantly decreased the distance between the knees, range of knee adduction and abduction, knee adduction moment, knee power. And stability gains through the decrease of excursion of knee medial part be effective for the correction of genu varum deformation.

• 대한의용생체공학회:의공학회지
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• 제31권3호
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• pp.217-226
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• 2010

The lower limb orthosis with a pneumatic rubber actuator, which is intended for the assistance and the enhancement of muscular activities of lower limbs was developed in this study. Compared to other knee extension assistive devices being developed by other researchers, our device is designed especially for the elderly people and intended only for slight assistance so that the subjects can keep their muscular strength. For the effectiveness of system, muscular activities of major muscles in lower limbs during sit-to-stand (STS) and squat motion were measured and analyzed. Subjects were performed the STS and squat motion with and without lower limb orthosis. We made comparison muscular activities between with and without lower limb orthosis. Lower limb orthosis was controlled using muscular stiffness force feedback that is controlled by muscular activities of the measured muscle from force sensor. For analysis of muscular activities, electromyography of the subjects was measured during STS and squat motion, and these were measured using MP 150(BIOPAC Systems, Inc.). Muscles of interest were rectus femoris(RF), vastus lateralis(VL), vastus medialis(VM) and vastus intermedius(VI) muscles in lower limbs of the right side. A biodex dynamometer was used to measure the maximal concentric isokinetic strength of the knee extensors of wearing and not wearing orthosis on right side. The test were performed using the concentric isokinetic mode of test with the velocity set at 60°/s for muscles around the knee joints. The experimental result showed that muscular activities in lower limbs wearing orthosis using muscular stiffness force of a vastus medialis muscle was reduced and knee extension torque of an knee joint wearing lower limb orthosis was increased. With this, we confirmed the effectiveness of the developed lower limb orthosis.