• PNF and Movement
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• v.18 no.3
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• pp.375-382
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• 2020

Purpose: The purpose of this study was to investigate the muscle contraction onset time characteristics of the gluteus maximus, semitendinosus, and biceps femoris muscles at different knee flexion angles in individuals with shortened or over-lengthened hamstrings performing prone hip extension. Methods: Twenty-six participants were divided into a hamstring shortened group (n = 12) and hamstring lengthened group (n = 14). Wireless surface electromyography was used to verify the muscle onset time of the gluteus maximus, semitendinosus, and biceps femoris when performing prone hip extension at different knee flexion angles. Results: There were significant differences in the muscle onset times of the semitendinosus and biceps femoris between the hamstring shortened group and hamstring lengthened group (p < 0.05). In addition, there was a significant difference in the muscle contraction onset times among of the gluteus maximus, semitendinosus, and biceps femoris muscles when performing prone hip extension at a knee flexion of 90° in the hamstring shortened group (p < 0.05) and a knee flexion angle of 0° in the hamstring lengthened group (p < 0.05). Conclusion: In all groups, there was no effect on the onset time of the gluteus maximus muscle according based on the knee angle. In addition, the knee flexion angles affected the onset time of the muscle contraction of the gluteus maximus muscle in the hamstring shortened group and hamstring lengthened group with an abnormal length of the hamstring muscle.

• Korean Journal of Applied Biomechanics
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• v.34 no.1
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• pp.25-33
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• 2024

Objective: The purpose of this study was to compare the lower extremity muscle activity and knee joint load according to movement speed conditions during the barbell back squat. Method: Nine males with resistance training experience participated in this study. Participants performed the barbell back squat in three conditions (Standard, Fast, and Slow) differing movement speed. During the barbell back squat, muscle activity of the rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris long head (BFL), semitendinosus (ST), gluteus maximus (GM), gastrocnemius (GCN), and tibialis anterior (TA) was collected using an 8 channel wireless EMG system. The peak flexion angle of the lower extremity joints and the peak resultant joint force in each direction of the knee joint were calculated using eight motion capture cameras and ground reaction force plates. This study was to used the Friedman test and the Wilcoxon signed rank test, to compare lower extremity muscle activity and peak resultant joint force at knee joint according to movement speed conditions during the barbell back squat, and the statistical significance level was set at .01. Results: In the downward phase of the barbell back squat, the RF and TA showed the higher muscle activity in the fast condition, and in the upward phase, RF, VL, VM, BFL, ST, GM, and TA showed the higher muscle activity in the fast condition. As a results, analyzing of the load on the knee joint, in the downward phase, and in the upward phase, the higher peak compressive force of the knee joint was showed in the fast condition. Conclusion: The barbell back squat with fast movement speed was more effective due to increased muscle activity of lower extremity, but one must be careful of knee joint injuries because the load on the knee joint may increase during the barbell back squat with fast movement speed.

• The Journal of Korean Physical Therapy
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• v.16 no.4
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• pp.1-10
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• 2004

The purpose of this study was to investigate the effects of treadmill aerobic exercise training on isokinetic muscle strength in students with cerebral palsy. The subjects consisted of 9 female students with cerebral palsy between the ages of 10 to 22. The subjects performed treadmill aerobic exercise training with $0\%$ grade by free speed with three times a week for 20 minutes a session and 12 weeks. Concentric peak torque of knee flexors and knee extensors was measured before training and after training at $30^{\circ}/sec$ and $60^{\circ}/sec$ by isokinetic dynamometer. Paired t-test was used to assess changes in variables of isokinetic muscle strength. The results of analysis are as followings. 1) After training, concentric peak torque of the least affected knee flexors(p<.01) and the most affected knee flexors (p<.01) and concentric peak torque of the least affected knee extensors(p<.01) and the most affected knee extensors(p<.01) at $30^{\circ}/sec$ significantly increased. 2) After training, concentric peak torque of the least affected knee flexors(p<.05) and the most affected knee flexors(p<.01) and concentric peak torque of the least affected knee extensors(p<.05) and the most affected knee extensors(p<.01) at $60^{\circ}/sec$ significantly increased. These findings provide evidence that treadmill aerobic exercise training improves isokinetic muscle strength in students with cerebral palsy.

• Physical Therapy Korea
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• v.26 no.2
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• pp.69-75
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• 2019

Background: Knee osteoarthritis (OA) diagnosis using Kellgren-Lawrence scores is commonly used to help decision-making during assessment of the severity of OA with assessment of pain, function and muscle strength. The association between Kellgren-Lawrence scores and functional/clinical outcomes remains controversial in patients with knee OA. Objects: The purpose of this study was to examine the relationships between Kellgren-Lawrence scores and knee pain associated with OA, function during daily living and sports activities, quality of life, and knee muscle strength in patients with knee OA. Methods: We recruited 66 patients with tibiofemoral knee OA and determined knee joint Kellgren-Lawrence scores using standing anteroposterior radiographs. Self-reported knee pain, daily living function, sports/recreation function, and quality of life were measured using the knee injury and OA outcome score (KOOS). Knee extensors and flexors were assessed using a handheld dynamometer. We performed Spearman's rank correlation analyses to evaluate the relationships between Kellgren-Lawrence and KOOS scores or muscle strength. Results: Kellgren-Lawrence scores were significantly negatively correlated with KOOS scores for knee pain, daily living function, sports/recreation function, and quality of life. Statistically significant negative correlations were found between Kellgren-Lawrence scores and knee extensor strength but not flexor strength. Conclusion: Higher Kellgren-Lawrence scores were associated with more severe knee pain and lower levels of function in daily living and sports/recreation, quality of life, and knee extensor strength in patients with knee OA. Therefore, we conclude that knee OA assessment via self-reported KOOS and knee extensor strength may be a cost-effective alternative to radiological exams.

• Clinical Pain
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• v.20 no.2
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• pp.105-121
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• 2021

Objective: Physiologically, the vastus medialis muscle is the first muscle to undergo muscle atrophy, and it was thought that pain in patients with knee osteoarthritis could be reduced if this muscle could be strengthened and stabilized. The purpose of this study was to prove the effectiveness in knee osteoarthritis using polydioxanone sutures that have been tried in other musculoskeletal areas. Method: Forty knee osteoarthritis patients voluntarily participated in the study, and divided into 30 polydioxanone suture needle (MEST-B2375 produced by Ovmedi Co.) and 10 sham needle (without suture). And the needles were inserted into the vastus medialis muscle. In all patients, safety evaluation including blood tests and ultrasonography as well as efficacy evaluation including isometric maximal contractile strength of quadriceps muscle, weight bearing pain, impression of change, quadriceps angle, rescue drug intake were evaluated up to 30 weeks after the procedure. Results: Isometric maximal contractile strength showed a significant improvement at 4 weeks after the procedure in the polydioxanone suture group, and the weight-bearing pain showed a significant improvement at every visit in the polydioxanone suture group compared with baseline values. Patient global impression of change score showed significant improvement at 20 and 30 weeks, and clinical score showed improvement at every visit. Conclusion: Insertion of polydioxanone sutures showed improvement in muscle strength and knee pain by supporting and fixation of the vastus medialis muscle in patients with degenerative knee osteoarthritis. Insertion of polydioxanone sutures is considered to have a therapeutic effect in knee osteoarthritis patients.

• Journal of the Ergonomics Society of Korea
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• v.29 no.3
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• pp.357-364
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• 2010

This study proposes a lower-limb exoskeleton system that is controlled by a wearer's muscle activity. This system is designed by following procedure. First, analyze the muscle activation patterns of human leg while walking. Second, select the adequate actuator to support the human walking based on calculation of required force of knee joint for step walking. Third, unit type knee and ankle orthotics are integrated with selected actuator. Finally, using this knee-assistive system (KAS) and developed muscle stiffness sensors (MSS), the muscle activity pattern of the subject is analyzed while he is walking on the stair. This study proposes an operating algorithm of KAS based on command signal of MSS which is generated by motion intent of human. A healthy and normal subject walked while wearing the developed powered-knee exoskeleton on his/her knees, and measured effectively assisted plantar flexor strength of the subject's knees and those neighboring muscles. Finally, capabilities and feasibility of the KAS are evaluated by testing the adapted motor pattern and the EMG signal variance while walking with exoskeleton. These results shows that developed exoskeleton which controlled by muscle activity could help human's walking acceptably.

• Journal of International Academy of Physical Therapy Research
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• v.3 no.1
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• pp.406-411
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• 2012

This study aims to examine the effect of patellar taping common to patients with patellofemoral pain syndrome on the change of knee joint location. The total number of participants is 12 patients with no pain in their knee. There are three different experiments: no-taping, placebo taping, and patellar taping. After application, they squat on their hams. As a result, both the muscle activity of vastus medialis and that of vastus lateralis increased in placebo taping compared to no-taping, which wasn't statistically significant. However, the muscle activity of vastus medialis and that of vastus lateralis decreased in patellar taping compared to no-taping, which was statistically significant. This suggests that patellar taping causing the lateral attraction of knee joint is more influential to the dynamics of knee joint than skin afferent input in placebo taping. Therefore, patellar taping is effective to change the location of knee joint, affect the muscle activity of quadriceps muscle of thigh, and thus correct the misalignments of the knee joint.

• The Journal of Korean Physical Therapy
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• v.32 no.1
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• pp.58-63
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• 2020

Purpose: This study examined the effects of the right or left knee lift during push up plus in the quadruped position on the serratus anterior (SA) muscle activity. Methods: Twenty-one subjects (male 11, female 10) performed the quadruped position on push up plus. The muscle activities of the lower trapezius (LT), SA, and upper trapezius (UT) were measured by surface electromyography. Repeated measurements of one-way ANOVA were performed for statistical analysis of the data, and the criterion for statistical significance was set to p<0.05 and comparative analysis of the UT and SA ratio using a Paired t-test. Results: The right SA increased the muscle activity of the right knee lift during quadruped position push up plus (p<0.05). In particular, the right SA muscle activity was higher than the left. In addition, comparative analysis of the UT and SA ratio to the right knee lift during quadruped position push up plus was performed (p<0.05). The right was found to be a significant statistic compared to the left, but the left SA increased the muscle activity of the left knee lift during quadruped position push up plus (p<0.05). The left SA muscle activity was higher than right. In addition, comparative analysis of UT and SA ratio to the left knee lift during quadruped position push up plus was performed (p<0.05). The left was found to be a significance statistic than the right. In addition, the interaction effect between the groups showed significant differences (p<0.05). Conclusion: Knee lift during push up plus is recommended for the selective activation of a research exercise protocol of one side of the serratus anterior.

• Journal of the Korean Applied Science and Technology
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• v.37 no.1
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• pp.1-6
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• 2020

The purpose of this study was to investigate the effects of sling and vibrator application of knee push-up plus motion on trunk muscle activities. Ten healthy adult males(age, 23.00±0.45 years; height, 176.60±1.64 cm; body mass, 67.50±1.22 kg; and BMI, 21.65±0.34 kg/㎡) were participated in this study as subjects. Three types' knee push-up plus motions were performed(basic knee push-up plus motion, BKPP; knee push-up plus motion with sling, KPPS; knee push-up plus motion with vibration, KPPV). We measured the right side's trunk muscle activities of the upper trapezius(UT), pectoralis major(PM), serratus anterior(SA), rectus abdominis(RA), and external oblique(EO). The research findings were as follows. UT, PM, SA, RA, and EO muscle activities were greatest during KPPV(p<.001). These results are expected to serve as reference materials for knee push-up plus motion applications in training programs for trunk muscle strengthening.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.16 no.2
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• pp.82-87
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• 2010

Purpose : This study was investigate The correlations between the Balance and the knee muscle power and the ankle muscle power. Methods : This studied selected 9cases of the healthy persons. Each measure of muscle power used Bio-dex pro-3. Balance measure was used balance-meter the ability to measure Ant-post, lateral, overall balance. Result : 1. Knee flexor and extensor causes ankles that plantar flexion strength and high correlation r= .745, r= .825 have, Ankle dorsi flexor strength and a bit of correlation r= .249, r= .221) have. 2. Ankle plantar flexor strength and overall balance and correlation was the r= .204, Ankle dorsi flexor strength and lat. balance and correlation was the r= .314. 3. Knee extensor strength and overall balance and correlation was the r=.212.