• Physical Therapy Korea
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• v.30 no.2
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• pp.152-159
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• 2023

Background: The gluteus medius (Gmed) plays a critical role in maintaining frontal plane stability of the pelvis during functional activities, such as one-leg lifting. Side-lying hip abduction (SHA) has been used as a dynamic test to evaluate Gmed function. However, the abduction force of the lower leg against the floor is not controlled during SHA. Therefore, hip abduction performance with contralateral adduction in the side-lying position (HAPCA) can be proposed as an alternative method to assess performance of hip abduction. If the number of HAPCA is related to the lateral pelvic shift distance, a new quantitative measurement for hip abductor function may be presented. Objects: This study aimed to investigate the relationship between the number of successful HAPCA and the lateral pelvic shift distance during one-leg lifting. Methods: Thirty healthy participants were recruited, and lateral pelvic shift distance was measured during one-leg lifting test using two-dimensional analysis. The number of successful HAPCA was counted when participants touched both target bars at the beat of a metronome. Results: There was a negative correlation between the number of HAPCA and lateral pelvic shift distance during one-leg lifting (r = -0.630, p < 0.05). The number of HAPCA accounted for 39.7% of the variance in the lateral pelvic shift distance during one-leg lifting (F = 18.454, p < 0.001). Conclusion: The number of successful HAPCA is significantly correlated with lateral pelvic shift distance during one-leg lifting. This finding suggests that HAPCA can be proposed as a new measurement for hip abductor performance and more research is needed on its relationship with hip abductor strength.

• Journal of the Korea Convergence Society
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• v.7 no.5
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• pp.51-57
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• 2016

The purpose of this study was to determine the effectiveness of the pelvic compression belt on the thickness of the erector spinae and multifidus during hip extension on quadruped position. Thirty male university students volunteered to participate in this study. The pelvic compression belt was positioned below the anterior superior iliac spines with the stabilizing pressure using elastic compression bands. Subjects were instructed to perform hip extension in quadruped position with and without applying the pelvic compression belt. The thickness of the erector spinae and multifidus was measured ultrasound during prone position, quadruped position without applying pelvic compression belt and quadruped position applying pelvic compression belt. Data were analyzed using repeated ANOVA. Muscle thickness of multifidus was significantly higher applying the pelvic compression belt than without applying the pelvic compression belt (p<.05). Muscle thickness of elector spinae was significantly higher applying the pelvic compression belt than without applying the pelvic compression belt (p<.05). Therefore, the research can contribute to the prescription and application of quadruped position exercises in clinical practices.

• Physical Therapy Rehabilitation Science
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• v.3 no.2
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• pp.101-106
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• 2014

Objective: To investigate the appropriate position for abdominal drawing-in maneuver (ADIM) exercise by rehabilitative ultrasound image. Design: Cross-sectional study. Methods: Twenty-eight young adults with no history of low back pain participated in the study. Three positions compared were crook lying position with hip $60^{\circ}$ flexion, standing position with the feet hip width apart and knees straight, and saddle standing positionunsupported with the knees $20^{\circ}$ flexed. Once in the appropriate position, the subjects were verbally cued to draw in their abdominal wall, with the intention of pulling their navel inward toward their lower back. The thickness of each transversus abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles were measured via ultrasound and recorded at the end of inspiration. Results: When compared to the TrA thickness of rest, the TrA thickness was significantly increased in all three positions (crook lying, standing, and saddle standing) during the ADIM (p<0.05). IO thickness was significantly greater in standing and saddle standing than in crook lying (p<0.05). EO thickness was constant in all the three positions. Conclusions: The present study suggests that standing and saddle standing positions could be recommended for the ADIM to maximize recruitment of the TrA and IO activation. Specifically, the saddle standing position with knees flexed to $20^{\circ}$ was observed to increase the TrA activation more than the standing position. These findings should be considered when core stability exercises such as the ADIM are conducted.

• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.445-453
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• 2014

The purpose of this study was to analyze the gait characteristics and interaction between lower extremity joints according to shoe's heel heights in young women. Participants were selected as subject consisted of young and healthy women (age: $23.71{\pm}1.49yrs$, height: $165.92{\pm}2.00cm$, body weight: $54.37{\pm}3.46kg$) and walked with 3 types of shoe's high-heel (0, 5, 9 cm). The variables analyzed consisted of the displacement of Y axis in center of mass ([COM]; (position, velocity), front rear(FR) and left right(LR) angle of trunk, lower extremity joint angle (hip, knee, ankle) and asymmetric index (AI%). The displacement of Y axis in COM position showed the greater movement according to increase of shoe's heel heights, but velocity of COM showed the decrease according to increase of shoe's heel heights during gait. The hip and knee angle didn't show significant difference statistically according to increase of shoe's heel height, but left hip and knee showed more extended posture than those of right hip and knee angle. Also ankle angle didn't show significant difference statistically, but 9 cm heel showed more plantarflexion than those of 5 cm and 0 cm. The asymmetric index (AI%) showed more asymmetric 9 cm heel than those of 0 cm and 5 cm. The FR and LR angle in trunk tilting didn't show significant difference statistically according to the increase of shoe's heel height during gait in young women.

• Physical Therapy Rehabilitation Science
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• v.12 no.1
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• pp.1-11
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• 2023

Objective: This study aimed to investigate the effects of squat posture, band position, and contraction type on the muscle activity of the hip abductors during resisted lateral band walking. Design: A cross-sectional survey study Methods: 24 healthy male subjects were recruited, and surface electromyography was used to measure the muscle activity of the gluteus maximus, gluteus medius, and tensor fascia lata of the dominant leg during lateral walking exercises. Resistance bands were applied to the knees, ankles, and feet in semi-squat and squat postures, and exercises were randomly performed under six different conditions. Results: The results showed significant differences in muscle activity in the gluteus maximus, gluteus medius, and tensor fascia lata according to posture, band position, and contraction type (p<0.05). The muscle activity of the hip abductors increased in the squat posture and with the band placed on the distal joint compared to the proximal joint (p<0.05). Additionally, muscle activity was higher in the eccentric contraction phase than in the concentric contraction phase (p<0.05). Contrary to previous studies, moving the resistance band from the ankle to the foot increased the muscle activity of the tensor fascia lata while the activity of the gluteus maximus and gluteus medius also increased. Conclusions: According to the results, squat posture with a resistance band placed on the feet and using an eccentric contraction phase were found to be the most effective methods for strengthening the hip abductors.

• Physical Therapy Rehabilitation Science
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• v.8 no.3
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• pp.146-151
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• 2019

Objective: The purpose of this study was to investigate the test-retest reliability and concurrent validity of the joint angle of the lower extremities during sit-to-stand movements with wearable sensors based on a portable gait analysis system (PGAS), and the results were compared with a analysis system (MAS) to predict the clinical potential of it. Design: Cross-sectional study. Methods: Sixteen persons with stroke (9 males, 7 females) participated in this study. All subjects had the MAS and designed PGS applied simultaneously and eight sensor units of designed PGAS were placed in a position to avoid overlap with the reflexive markers from MAS. The initial position of the subjects was 90º of hip, knee, and ankle joint flexion while sitting on a chair that was armless and backless. The height of the chair was adjusted to each individual. After each trial, the test administrator checked the quality of data from both systems that measured sit-to-stand for test-retest reliability and concurrent validity. Results: As a result, wearable sensor based designed PGAS and MAS demonstrated reasonable test-retest reliability for the assessment of joint angle in the lower extremities during sit-to-stand performance. The intra-class correlation coefficients (ICCs) for wearable sensor based designed PGAS showed an acceptable test-retest reliability, with ICCs ranging from 0.759 to 0.959. In contrast, the MAS showed good to excellent test-retest reliability, with ICCS ranging from 0.811 to 0.950. In concurrent validity, a significant positive relationship was observed between PGAS and MAS for variation of joint angle during sit-to-stand movements (p<0.01). A moderate to high relationship was found in the affected hip (r=0.665), unaffected hip (r=0.767), affected knee (r=0.876), unaffected knee (r=0.886), affected ankle (r=0.943) and unaffected ankle (r=0.823) respectively. Conclusions: The results of this study indicated that wearable sensor based designed PGAS showed acceptable test-retest reliability and concurrent validity in persons with stroke for sit-to-stand movements and wearable sensors based on developed PGAS may be a useful tool for clinical assessment of functional movement.

• Advances in Computational Design
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• v.4 no.3
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• pp.295-305
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• 2019

The sealing cement of total hip arthroplasty is the most widely used binder in orthopedic surgery for anchoring implants to their recipient bones. Nevertheless, this latter remains a fragile material with weak mechanical properties. Inside this material cracks initiate from cavities. These cracks propagate under the effect of fatigue and lead to the failure of this binder and consequently the loosening of the prosthesis. In this context, this work consists to predict the position of cracks initiation and their propagations path using the Extended Finite Element Method (XFEM). The results show that cracks can only be initiated from a sharp edges of an ellipsoidal cavity which the ratio of the minor axis over the major axis is equal to 0.1. A maximum crack length of 19 ?m found for a cavity situated in the proximal zone position under a static loading. All cracks propagate in same(almost) way regardless of the cavity(site of initiation) position and its inclination in the proximal zone.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.167-174
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• 2010

In this study, the optimal position for the backrest pivot of an office chair was investigated by evaluating its performance in terms of the lumbar support and sliding distance of the back from the backrest during tilting motions. The simulation was performed using a mathematical model, which included a human body and a chair. Forty-two backrest pivot points were selected on the sagittal plane around the hip joint of a sitting model. A motion analysis study was also performed using a prototype of an office chair (A-type) with a backrest pivot located on the hip joint of a normal Korean model and a typical office chair (B-type) with its pivot located under the seat. The simulation results showed that both the lordosis angle and the slide distance of the back were minimized when the backrest pivot was positioned close to the hip joint. The experimental results showed that the slide distance and gap between the sitter's lumbar and the backrest was smaller with the A-type than the B-type. Based on the simulation and experimental results, it can be concluded that the backrest can support the sitter's lumbar area more effectively as the pivot position for reclining approaches closer to the hip joint. In this position, the sitter can maintain a comfortable and healthy sitting posture. This paper presents the methods and guidelines for designing an office chair with ergonomic considerations.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.18 no.2
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• pp.41-47
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• 2012

Background: This study was designed to investigate the correlation between electromyography (EMG) activities in the vastus medialis oblique (VMO) vs vastus lateralis (VL) activity ratio and the valgus collapse knee position while stepping down. Methods: Twenty healthy women volunteered to participate in this study. We measured the frontal-plane projections of the knee valgus angle, knee valgus distance, and hip adduction angle by using a digital camcorder. After 3 repetitions of the step down (dominant side) exercise, the findings of the static and dynamic phases were analyzed. EMG activities data of the VMO:VL activity ratio were recorded during the step down exercise and were normalized to the maximal voluntary isometric contraction (MVIC) of the quadriceps. A paired t-test was used to compare the findings of the static and dynamic phases. We analyzed the Spearman's rank order correlation coefficient between the and VMO:VL ratio. Results: Hip adduction angle, knee valgus angle, VMO activity, VL activity, VMO:VL activity ratio were statistically higher in the dynamic phase than in the static phase (p<.05). Frontal-plane projections of knee valgus angle were significantly correlated with hip adduction angle (r=.459, p<.05) and knee valgus distance (r=.505, p<.05). However, the EMG activity ratio of the VMO and the VL did not show a significant change during step down exercise with respect to hip adduction angle (p=.875), knee valgus angle (p=.618), and knee valgus distance (p=.701). Conclusion: The results from this study indicate that frontal-plane projections of knee valgus angle were associated with hip adduction angle and knee valgus distance. On the basis of these results, the knee valgus distance may be used to determine the valgus collapse knee position while stepping down.

• Proceedings of the Korea Contents Association Conference
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• 2010.05a
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• pp.161-163
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• 2010

본 연구의 목적은 등속성 운동수행 및 측정시 hip joint angle에 따라 대퇴근육의 concentric 과 eccentric 근력차이를 분석하기 위하여 등속성 기기 의자 등받이 경사각도를 $100^{\circ}$, $120^{\circ}$, $140^{\circ}$에서 peak torque를 검사하였다. 대상자는 20대 초반의 건강한 남자 대학생 12명을 대상으로, 등속성 기기(Isomed 2000, Germany)를 이용하여 seated position에서 $60^{\circ}/s$ 의 각속도를 사용하여 검사를 수행하였다. 측정순서는 등속성기기 의자 등받이 경사각도 $100^{\circ}$, $120^{\circ}$, $140^{\circ}$ 순으로 2-3일 간격으로 진행하였다. 통계처리 방법은 SPSS 12.0 프로그램을 이용하여 평균과 표준편차를 산출하였으며, 각각의 hip angle에 따른 단축성과 신장성 peak torque 값의 차이는 one-way ANOVA(3RM)을 이용하여 처리하였고, 사후검증은 Tukey를 사용하였으며, 유의수준은 p<.05로 하였다. 연구결과 대퇴사두근의 단축성 근력은 등속성 기기 의자 등받이 경사각 $100^{\circ}$, $120^{\circ}$, $140^{\circ}$사이에 유의한 차이(p=.000)가 나타나 사후 분석결과 $100^{\circ}$와 $120^{\circ}$ 사이(p<.01) 그리고 $100^{\circ}$와 $140^{\circ}$ 사이(p<.001)에 유의한 차이를 나타내었으며, 신장성 근력에서는 유의한 차이가 나타나지 않았다. 햄스트링의 단축성 근력은 3종류의 hip angle사이에 유의한 차이(p=.001)가 나타나 사후분석결과 $100^{\circ}$와 $140^{\circ}$사이(p<.05) 그리고 $120^{\circ}$와 $140^{\circ}$ 사이(p<.01)에 유의한 차이를 나타내었으며, 그러나 신장성 근력에서는 유의한 차이가 나타지 않았다. 이러한 결과로 미루어 볼 때 등속성 운동수행 및 근력측정 시 hip joint angle 에 따라 대퇴사두근과 햄스트링의 단축성 근력에서 유의한 차이가 나타나 hip joint angle을 고려하여 대퇴근육의 운동및 측정이 이루어져야 할 것으로 사료된다.