Background: The hamstring muscles in the lower extremity are highly important for knee joint stability and can be classified into medial and lateral hamstrings according to the anatomical position, which have some different functions. To measure the strength of the individual hamstring muscles, manual muscle testing is clinically performed by dividing rotation postures into internal and external postures. However, this has no sufficient scientific background. Objects: This study aimed to test the difference that the tibial rotation would cause in the muscle activity of the medial and lateral hamstrings. Methods: The muscle activities of the biceps femoris, semitendinosus, and semimembranosus were measured in a total of three different postures (neutral position and internal and external rotations) with 3 replications. During the maximal isometric contraction, resistance was constantly provided by the string attached to the strap, not by manual resistance of the examiner. Before and after electromyography measurements, the participants underwent hamstring flexibility measurement using the active knee extension test in the supine position on the treatment table Results: The semitendinosus had a 12.56% reduction in muscle activity in external rotation as compared with that in neutral position. The biceps femoris and semimembranosus showed reduced muscle activities in both external and internal rotations as compared with those in neutral position. Only the women showed significant decreases in the comparison between pre and post-active knee extension. Conclusion: Only the semitendinosus muscle was consistent with the anatomical speculation. However, the reduction in the muscle activity of the semitendinosus as compared with that in neutral position was only 12.56%, the clinical value of which may be difficult to justify.

This study aimed to identify the effects of kinesio taping (KT) applied in a proprioceptive neuromuscular facilitation (PNF) pattern on the pain, weight-bearing distribution (WBD), and walking ability of knee osteoarthritis (KOA) patients. Thirty women with KOA were randomly allocated to a control group (n=15) with KT at the quadriceps only, and a PNF pattern group (n=15) with KT at the quadriceps and gastrocnemius muscle. Pain intensity was measured using a visual analogue scale during walking. In addition, WBD, and walking ability were measured before and 30 minutes after KT application. The VAS significantly reduced in both groups after the intervention (p<.05). WBD (p<.05, ES=.32) and walking ability (p<.05, ES=.38) showed a significant change in the PNF pattern group, and in the inter-group comparison, the PNF pattern group showed a significant difference compared to the control groups. These results demonstrate that KT application with PNF pattern effectively attenuate the pain and improves WBD and walking ability in KOA patients.

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 α 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.

The main focus of this study was to investigate effects of lumbar central posteroanterior (PA) mobilization on isometric knee extension (IKE) ability and patellar tendon reflex amplitude (PTRA) in healthy university students. University students aged 19-26 (male; 10, female; 10) without any neurological disorders participated voluntarily and excluded the subjects with abnormal reflexes. The participation had an average body mass of 64.25±13.52 kg, an average height of 1.66±0.08m, and an average Body Mass Index (BMI) of 23.07±3.21. Every student was randomly assigned to be received squatting exercise and PA mobilization sequentially with 5 days of wash out period. IKE and PTRA were not significantly different between the two groups after the intervention. All the outcome measures were arranged into two data groups; PA mobilization and squatting exercise data group. In the PA mobilization data group, IKE and PTRA significantly increased after the intervention, however, these aspects were decreased in the squatting exercise group. These findings suggest that IKE and PTRA increase immediately after PA mobilization, therefore PA mobilization could be a valuable topic for controlled clinical trials.

This study was conducted to observe the isokinetic strength (IS) of the hip, ankle, and knee joints in young age groups. Thirty eight men and thirty one women with mean age of 30.4 ± 3.5 and 32.8 ± 4.4 years, respectively, were enrolled in this study. Measurements of hip flexion, extension, abduction, and adduction at 30° / sec, Knee flexion and extension at 60° / sec, ankle inversion, eversion, plantarflexion, and dorsiflexion 30° / sec were conducted. Absolute IS (Nm), relative IS (Nm/kg), strength ratios, correlations between movements were observed. Significant differences in absolute and relative strength were observed between groups in all movement except in the relative ankle strength. Relative isokinetic strength ratios of hip flexion/extension were .45 and .55, knee flexion/extension were .84 and .89, ankle dorsi/plantarflexion were .30 and .29, and ankle eversion/inversion were .86 and .84 for men and women, respectively. In the hip extension, men had about three times the body weight ,and women had about 2.5 times the strength. The abduction muscle had about 1.5 times the body weight of both men and women. Height and body weight showed the significantly strong correlating relationship with hip (r, .76-.86) and knee (r, .67-.84) strength. However, ankle strength showed the comparatively correlating relationship, especially in women (r, .03 - .36). Similar age and physique characteristics of female and male groups could provide useful isokinetic strength reference values for developing the exercise program for healthy and rehabilitation groups.

무릎 임플란트에서 접촉압력이 마모에 큰 영향을 미친다. 본 연구에서는 본 연구기관에서 개발한 무릎 임플란트 모델을 이용하여 유한요소해석을 하였다. 연구와 산업에서 실제로 사용하는 조합을 이용하여 총 10가지의 무릎 임플란트의 재료조 합에 대한 접촉압력을 분석하였다. 무릎이 30도, 45도 60도 기울어져있을 때의 하중을 가하여 접촉압력을 구하였다. 접촉압 력을 계산한 결과 티타늄합금-UHMWPE 조합에서 가장 작은 접촉압력이 나왔다. UHMWPE의 경우 대퇴골부에 어떠한 재 료를 사용하여도 접촉압력이 크게 변하지 않았다. 접촉압력이 가장 큰 조합과 작은 조합을 비교하였을 때 0.77% 차이를 보 였다. 반면에 Carbon/PEEK 복합재료의 경우 접촉압력이 가장 큰 경우와 작은 경우를 비교하였을 때 5.3% 차이를 보였다. 이를 통해 Carbon/PEEK 복합재료를 베어링부로 사용할 경우 대퇴골부의 재료가 마모에 영향을 미침을 알 수 있다. 본 연구 는 무릎 임플란트 마모예측과 마모를 최소화 연구에 도움이 될 것이라 생각한다.

Background: The active knee extension (AKE) test commonly used to assess the flexibility of the hamstring muscles. Many researchers have tested the reliability of the AKE test; however, no published studies have examined the intrarater and interrater reliability of the AKE test using a PBU. Objects: The purpose of this study was to determine the intrarater and interrater reliability of the AKE test performed with a pressure biofeedback unit (PBU) on healthy subjects. Methods: Sixteen healthy male participants volunteered and gave informed consent to participate in this study. Two raters conducted AKE tests independently with a PBU. Each knee was measured twice, and the AKE testing was repeated one week after the first round of testing. Results: The interrater reliability’s intraclass correlation coefficients (ICC2,1) were .887∼.986 for the right knees and .915∼.988 for the left knees. In addition, the intrarater (test-retest) reliability (ICC3,1) values ranged between .820∼.915 and .820∼.884 for Raters 1 and 2, respectively. The values for the standard error of mesurement were low for all tests (.81∼2.97˚); the calculated minimum detectable change was 2.24∼8.21˚. Conclusion: These findings suggest that the AKE test performed with a PBU had excellent interrater and intrarater reliability for assessing hamstring flexibility in healthy young males.

목 적 : 후방십자인대는 무릎 관절의 안정화를 위한 중요한 인대로 인체의 균형을 유지하는데 매우 중요한 역할을 한다. 본 연구에서는 후방십자인대의 해부학적 구조에 따라 사방향 관상면 영상과 이중 사방향 시상면 영상을 획득하여 그 유용성을 평가하고자 한다. 대상 및 방법 : 2016년 12월부터 2017년 1월까지 환자 20명을 대상으로 검사하였고 SIEMENS사의 Skyra 3.0T에서 knee coil을 사용하였다. 검사 방법은 T2 COR, PD SAG을 획득하고 원위부 후방십자인대의 해부학적 구조를 고려한 PD OBL COR과 전체적인 구조를 고려한 PD Dual OBL SAG을 획득하였다. PCL의 관상면 비교를 위하여 밑단점의 길이와 폭을 측정하여 비교하였고, 시상면 평가를 위하여 기시점, 중간지점, 밑단점을 측정하여 비교하였다. 측정결과를 Mann-Whitney 방법을 사용하여 통계적 유의성을 검정하였다. 정성적 방법은 기존의 관상면, 시상면 영상과 사방향 관상면, 이중 사방향 시상면 영상에서 후방십자인대를 비교하여 미흡, 대등, 우월 세 단계로 평가하였다. 결 과 : 검사를 진행한 결과 기존 관상면 영상보다 사방향 관상면 영상에서 원위부 후방십자인대의 길이는4 7.9%, 폭 14.9% 증가하였고, 기존 시상면 영상보다 이중 사방향 시상면 영상에서 기시점 19.8%, 중간지점 18.3%, 끝단점 33%의 증가된 것 으로 측정되었다. 결 론 : 사방향 관상면 영상과 이중 사방향 시상면 영상 모두 기존 영상보다 우월한 영상 검사방법으로 평가되었다. 이에 슬 관절 후방십자인대의 해부학적 관찰에는 기존 검사 방법에 사방향 관상면 영상 검사와 이중 사방향 시상면 영상 검사를 병 행하는 것이 유용할 것으로 사료된다.

Background:Individuals with spinal cord injury (SCI) rely on their upper limbs for body-lifting activity (BLA). While studies have examined the electromyography (EMG) and kinematics of the shoulder joints during BLA, no studies have considered foot position during BLA.Objects:This study compared the effects of different foot positions during BLA on the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion in individuals with SCI.Methods:The study enrolled 13 mens with motor-complete paraplegic SCI, ASIA (American Spinal Injury Association) A or B. All subjects performed BLA with the feet positioned on the wheelchair footrest and on the floor independently. Surface EMG was used to collect data from the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii. The peak plantar pressure was measured using pedar-X and the knee flexion angle with Image J. Borg’s rating perceived exertion scale was used to measure the physical activity intensity level. The paired t-test was used to compare the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion between the two feet positions during BLA.Results:The activity of the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii and rating perceived exertion decreased significantly and the peak plantar pressure and knee flexion angle increased significantly when performing BLA with the feet positioned on the wheelchair footrest compared with on the floor (p<.05).Conclusion:These findings suggest that individuals with SCI may perform BLA with the feet positioned on the wheelchair footrest for weight-relief lifting to decrease the shoulder muscle activities and the rating perceived exertion and to increase the peak plantar pressure and the knee flexion angle.

Background: The wall squat is considered an effective exercise because it can reduce the knee load and prevent excessive lumbar movement. However, the relationship between wall squat performance and strength of knee extensors and hip extensors remained unclear. Objects: The purpose of this study was to compare the strengths of the knee extensors and hip extensors between groups with low and high wall squat performance. Method: Nineteen males (low performance group: 9 subjects, high performance group: 10 subjects) participated in this study and performed wall squats. The subjects who were performing less than 30% of the average wall squat count were classified into the low wall squat performance group (less than or equal to 4 times) and the subjects who performed more than 30% of the average wall squat count were classified into the high wall squat performance group (greater than or equal to 8 times). Knee extensor and hip extensor strength were measured with a strength measurement system. An independent t-test was used to compare the strengths of the knee extensors and hip extensors between the groups with low and high wall squat performance. Results: The ratios of knee extensor and hip extensor strength to bodyweight were greater in the high wall squat performance group than in the low wall squat performance group (knee extensors: p<.001; hip extensors: p=.03). In the high- and low-performance groups, the ratios of knee extensor strength to bodyweight were 42.74±5.72 and 30.76±8.54, respectively, and the ratios of hip extensor strength to bodyweight were 31.95±10.61 and 20.66±11.25, respectively. Conclusion: Our findings suggest that knee extensor and hip extensor strength are needed for high wall squat performance. Thus, exercise to increase the knee and hip extensors strength can be recommended to improve squat performance.

Background: Many studies have reported positive results of the various mirror training and virtual reality games in improving dynamic standing balance and posture adjustment in chronic stroke patients. However, no systematic study has been conducted to compare the effects of virtual reality games and the mirror balance training. Objects: The purpose of this study was to compare the effectiveness of Wii balance games and Mirror Self- Balancing Exercises in improving proprioception of knee joint and standing balance of people with chronic stroke. Methods: Twenty patients with chronic stroke volunteered for this study. The subjects were randomly divided into a Wii balance games group and a Mirror Self-Balancing Exercises group with 10 patients in each group. Each training was performed for 30 mins a day for 4 days. In addition to the balance training, 30 mins neuro-developmental-treatment based routine physical therapy was given to both groups. Proprioception was measured using two continuous passive motion devices, and static balance was measured using a Wii balance board. Dynamic balance assessment tools included the Berg Balance Scale, Dynamic Gait Index, and Timed Up-and-Go test. Results: All measured variables before and after the experimental results showed a significant improvement in both groups (p<.05). Only the improvement of the affected knee proprioception appeared to be significantly greater in the Wii balance game group (p<.05). However, other variables did not differ between the groups (p>.05). Conclusion: The findings suggest that both Wii balance games and Mirror Self-Balancing Exercises may be helpful for improving the proprioception of knee joint and the balance of patients with chronic stroke.

Background: Squatting is one of the best functional exercises to strengthen the quadriceps muscle in independent gait and activities of daily living. Although the use of a gym ball during squat exercise is the most common way of strengthening the vastus medialis oblique (VMO) muscle, published data on this subject are limited. Objects: The purpose of this study was to compare the sequential muscle activation of the VMO and vastus lateralis (VL) muscles during squat exercise using a gym ball at different knee flexion angles. Methods: Forty healthy adults were randomly divided into experimental (squat exercise using a gym ball) and control (squat exercise alone) groups, in which squats were performed at 45° and 90° knee flexion. Electromyographic (EMG) activity data were collected over 10 seconds under the 2 angles of knee flexion (45° and 90°). Results: There was significant group and time interaction effect for VMO and VL muscle activation at 45° knee flexion. This was similarly demonstrated at 90° knee flexion. No significant group main effect and time main effect for VMO and VL muscle activation were noted at 45° knee flexion, respectively. In contrast, there was significant group main effect and time main effect for VMO and VL muscle activation at 90° knee flexion. These significant differences were demonstrated through two-way analysis of variance over repeated measurements, suggesting that the EMG activity of the VMO muscle during squatting with a gym ball showed remarkable improvement compared to that of the VL muscle. Conclusion: This research suggests that squat exercise using a gym ball may be more beneficial in improving the activity of VMO than of the VL muscle at both 45° and 90° of knee flexion, respectively. We highly recommend squat exercises with a gym ball for selective strengthening of the VMO muscle in knee rehabilitation.

Background: Various methods are used for recovery of knee flexion range of motion (ROM) due to a tightened rectus femoris muscle (RFM) or limited inferior glide of the patella. Stretching methods are common interventions for restoring the tightened RFM length. Also patellar inferior gliding (PIG) technique can recover tightened RFM length too. However, effect of applying the PIG to passive knee flexion (PKF) has not been studied. Objects: The purpose of this study was to investigate the effect of combining PIG with RFM stretching for improving knee flexion ROM in subjects with RFM tightness. Methods: Twenty-six subjects with RFM tightness were recruited. Two different methods of knee stretching were tested: 1) PKF during modified Thomas test (MTT) and 2) PKF with PIG during MTT. The passive stretching forces was controlled by hand-held dynamometer. The knee flexion ROM angle was measured by a MTT with ImageJ software. Differences between the conditions with and without PIG were identified with a paired t-test. Results: The knee flexion ROM was significantly greater for PKF with PIG (114.44±9.33) than for PKF alone (108.97±9.42) (p<.001). Conclusion: A combination of passive knee flexion exercise and PIG can be more effective than PKF in increasing knee flexion ROM in individuals with RFM tightness.

The purpose of this study was to investigate the effects of combined wedge on the range of motion in ankle and knee joint, ankle eversion moment and knee adduction moment, and center of pressure excursion of foot for genu varus among adult men during gait. This study was carried out with 10 adult men for genu varus in a motion analysis laboratory in J university. The subjects of the experiment were measured above 5cm width between the knees on contact of both medial malleolus of ankle while standing. The width of their knees in neutral position was measured without the inversion or eversion of the subtalar joint by the investigator. The subjects of the experiment were ten who were conducted randomly for standard insole, insole with 10° lateral on rear foot wedge, insole at 10°lateral on rear foot and 5° medial on fore foot wedge. Before and after intervention, changes on the range of motion in ankle and knee joint, ankle eversion moment and knee adduction moment, and center of pressure excursion were measured. In order to compare analyses among groups; repeated one-way ANOVA and Scheffé post hoc test were used. As a result, combined wedge group was significantly decreased compared to control wedge group in terms of knee varus angle in mid-stance(p<.05). Combined wedge group was significantly decreased compared to lateral wedge group in terms of ankle eversion moment in whole stance(p<.05). Combined wedge group was significantly decreased compared to lateral wedge group in terms of knee adduction moment in whole stance(p<.05). Combined wedge group was significantly decreased compared to lateral wedge in terms of center of pressure excursion in whole stance(p<.05). The results of this study suggest that combined wedge for genu varus decreased ankle eversion moment and knee adduction moment upon center of pressure excursion. We hypothesize that combined wedge may also be effective in the protection excessive ankle pronation.

Background: Total knee arthroplasty (TKA) recovers the alignment of the knee joint, but fails to automatically restore the alignment and function of the hip and ankle joints. It may affect the alignment and stability of the knee joint, therefore therapeutic intervention in hip and ankle joint is necessary for the rehabilitation process after TKA. Objects: The aim of this study was to comparison of the effects of the two exercise methods on the coronal plane alignment after TKA. This study conducted an experiment by dividing subjects into a lower extremity isometric co-contraction group (LEIC) and a quadriceps isolated isometric contraction (QIIC) group. Methods: A total of 37 subjects were randomly assigned to the LEIC (n1=19) or the QIIC (n2=18). Exercise was applied to five times per week for three weeks, starting on the eighth day after surgery. Range of motion exercises were performed as a common intervention and then each group performed quadriceps isometric contraction exercises with 10 sets of 5 repetitions. Radiological imaging was performed prior to surgery, one month and six months after surgery. In addition, the hip-knee-ankle angle (HKA) and tibiotalar angle (TTA) were measured. Results: The HKA was close to neutral in the LEIC rather than the QIIC (p<.05). The LEIC showed varus and the QIIC exhibited valgus TTA (p<.05). In a comparison of HKA and TTA over time, there was no significant change in either group (p>.05). According to the comparison of the TTA before surgery, the LEIC showed significant changes in the varus direction (p<.05), while there was no significant change in the QIIC (p>.05). Conclusion: The LEIC method triggered changes in the TTA and brought the HKA close to the neutral. Thus, LEIC is more effective than QIIC in creating stability in the coronal plane alignment of the knee and ankle joints after TKA.

The purpose of this study was to identify the effects of mechanical traction applied to the knee joint on pain, knee range of motion (ROM), timed up and go (TUG) and Western Ontario and MacMaster Universities Osteoarthritis (WOMAC) in patients with knee osteoarthritis (KOA) of Kellgren-Lawrence radiological rating scale Ⅱ or Ⅲ. Twenty three patients participated in the experiment for a period of four weeks. After baseline assessment, the patients with KOA were randomized into two groups: the traction group (n1=12), which received traction with general physical therapy; and the control group (n2=11), which received general physical therapy only on unilateral knee joints. Patients received interventions once a day, three times a week, for four weeks. Wilcoxon signed-rank test was used to analyze the change of dependent variances within the group during pre and post intervention. Mann-Whitney U test was used to analyze the change of dependent variances as TUG and passive ROM between the two groups. Analysis of covariance was used to analyze the change of dependent variances as numeric pain rating scale (NPRS) and WOMAC score between the two groups. In Wilcoxon signed-rank test, the traction group improved significantly with regard to NPRS (p<.01), passive knee flexion ROM (p<.01), passive knee extension (p<.05), TUG (p<.01) and WOMAC scores (p<.01) after intervention for four weeks, but not for the control group. In the Mann-Whitney U test and analysis of covariance, no significant difference was seen among all the dependent variances after intervention for four weeks between the two groups. These outcomes suggest that further studies should be carried out to determine the effects of mechanical traction prior to using it for the treatment of patients with knee osteoarthritis.

The purpose of this study was to investigate the effect of taping on knee joint for patellofemoral compressive force (PCF) during stair descent for elderly women. Ten healthy elderly women voluntarily participated in this study. A three-dimensional motion analysis system and force plates were used to analyze the movements of the joints for the lower extremities. The results were as follows: There were no significant differences for the maximum PCF, maximum quadriceps contraction force and maximum knee extension moment (p>.05) but, there was a pattern decreasing all values with the taping during stair descent. There were significant differences for the knee and ankle angle on the event of maximum PCF (p<.05) and there was a pattern decreasing all values with the taping during stair descent. Therefore, taping on the knee would be effective to relieve the pain like patellofemoral pain syndrome in the knee joint.

The common features of walking in patients with stroke include decreased gait velocity and increased asymmetrical gait pattern. The purpose of this study was to identify important factors related to impairments in gait velocity and asymmetry in chronic stroke patients. The subjects were 30 independently ambulating subjects with chronic stroke. The subjects’ impairments were examined, including the isokinetic peak torque of knee extensors, knee flexors, ankle plantarflexors, and ankle dorsiflexors. Passive and active ranges of motion (ROM) of the ankle joint, ankle plantarflexor spasticity, joint position senses of the knee and ankle joint, and balance were examined together. In addition, gait velocity and temporal and spatial asymmetry were evaluated with subjects walking at their comfortable speed. Pearson correlations and multiple regressions were used to measure the relationships between impairments and gait speed and impairments and asymmetry. Regression analyses revealed that ankle passive ROM and peak torque of knee flexors were important factors for gait velocity (R2=.41), while ankle passive ROM was the most important determinant for temporal asymmetry (R2=.35). In addition, knee extensor peak torque was the most significant factor for gait spatial asymmetry (R2=.17). Limitation in ankle passive ROM and weakness of the knee flexor were major contributors to slow gait velocity. Moreover, limited passive ROM in the ankle influenced the level of temporal gait asymmetry in chronic stroke patients. Our findings suggest that stroke rehabilitation programs aiming to improve gait velocity and temporal asymmetry should include stretching exercise for the ankle joint.

This study investigates the wear degree of the shock absorber at the artificial knee joint due to bending degree of knee. As the stress distribution due to this angle is understood when the knee is bent, it can be shown how much and which configuration the wear of the shock absorber progresses in. On the basis of the analysis result, the stress applied at the shock absorber becomes higher and the equivalent stress becomes higher as the bending angle of knee is increased. The walking habit as the right attitude can be examined by applying the general joint as well as the artificial knee joint by using this study result

The purpose of this study was to determine the muscle activities of the erector spinae (ES), gluteus maximus (Gmax), gluteus medius (Gmed), and the hamstring (HAM) and the ratios of Gmax/ES, Gmax/HAM, and Gmed/HAM during the prone heel squeeze (PHS) with different knee flexion angles (45˚, 90˚, and 135˚). Fifteen young and healthy subjects (8 men, 7 women) were recruited for the study. Surface electromyography signals were collected on ES, Gmax, Gmed, and HAM during PHS. A separate one-way analysis of variance with repeated measures was used to determine the significance of the muscle activities of ES, Gmax, Gmed, and HAM and the ratios of Gmax/ES, Gmax/HAM, and Gmed/HAM with different knee flexion angles during PHS. There was a significant increase in the Gmax activity at the knee flexion of 90˚ in comparison with that of the 45˚ (p=.016). There were significant increases in the Gmed activity at the knee flexion of 90˚ (p=.008) and 135˚ (p=.006) in comparison with that of the 45˚. There were significant decreases in the HAM activity at the knee flexion of 90˚ (p=.009) and 135˚ (p=.004) in comparison with that of the 45˚. There were significant increases in the Gmax/HAM muscle activity ratio at the knee flexion of 90˚ (p=.007) and 135˚ (p=.012) in comparison with that of the 45˚. There were significant increase in the Gmed/HAM muscle activity ratio at the knee flexion of 135˚ in comparison with that of the 45˚ (p=.008). The knee flexion of 90˚ during PHS can induce decreasing activity of HAM and increasing activity of Gmax, and the knee flexion of 135˚ during PHS can induce decreasing activity of HAM and increasing activity of Gmed. Hence, PHS with different knee flexion positions could be considered for the different target muscle.