• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.172-173
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• 2013

• Physical Therapy Rehabilitation Science
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• v.9 no.3
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• pp.197-200
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• 2020

Objective: The purpose of this study was to develop and investigate the feasibility of a sit-to-stand assistive chair using a pneumatic cylinder. Design: Cross-sectional study. Methods: The sit-to-stand assistive chair was developed to assist the sit-to-stand movement by rising up of the chair by a pneumatic cylinder. After the user is seated on the chair, if the pneumatic cylinder pulls the seat plate when standing up, the spring of the pneumatic cylinder, which has been stretched, assists in rising the rear end of the seat plate so that the user can stand conveniently and comfortably. A feasibility test was performed in 10 heathy adults. The electromyographic muscle activation of the trunk and lower extremity muscles was analyzed, which included the erector spinae, rectus abdominis, quadriceps, tibialis anterior, gastrocnemius when standing up from sitting using the developed chair and standing up without using the developed chair. Results: As a result, the sit-to-stand assistive chair using a pneumatic cylinder was developed. In the feasibility test, the use of the developed chair had a decrease in rectus abdominis, quadriceps, tibialis anterior activation compared to those who did not use the device in the healthy adults. Conclusions: The sit-to-stand assistive chair using a pneumatic cylinder may be helpful to reduce the activation of the rectus abdominis, quadriceps, tibialis anterior muscles when performing a sit-to-stand movement. Through the results, the efficacy of the sit-to-stand assistive chair can be confirmed. In the future, further studies are warranted to investigate for the safety and efficacy of its use in the elderly population or those who are disabled.

• Physical Therapy Korea
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• v.8 no.2
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• pp.1-16
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• 2001

This study was designed to identify the effects of foot position on electromyographic (EMG) activity of the quadriceps femoris during maximum voluntary contraction (MVC) in standing. Twenty young adults who had not experienced any knee injuries were recruited. Their Q-angles were within a normal range. They were asked to stand in five different foot positions ($40^{\circ}$ externally rotated, $30^{\circ}$ internally rotated, neutral, $20^{\circ}$ plantarflexed, and $10^{\circ}$ dorsiflexed foot position). The EMG activities of the vastus lateralis (VL), rectus femoris (RF), and vastus medialis oblique (VMO) were recorded in standing by surface electrodes and normalized by MVC EMG values derived from manual muscle test. The normalized EMG activity levels (%MVC EMG) of muscles in the five foot positions were compared using repeated measures ANOVA. The EMG activity levels of the VL, RF, and VMO were the highest when foot was externally rotated. The EMG activity levels of the VL and RF were significantly different among the foot positions (p<.05). However, EMG activity levels of the VL, RF, VMO, and VMO/VL ratio did not show significant differences in each foot position (p> .05). The results suggest that the quadriceps femoris may be effectively activated by performing MVC at an externally rotated foot position. Therefore, the externally rotated foot position can be considered as an effective foot position for quadriceps femoris strengthening exercise. Further studies are needed to identify whether there are differences in the effects of foot position on muscle strength after MVC exercise of quadriceps femoris in standing.

• PNF and Movement
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• v.17 no.2
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• pp.311-319
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• 2019

Purpose: This study was conducted to determine the structural change in knees caused by quadriceps angle and the muscle activity in lower limbs. Indirect intervention was provided by using taping for stability in the ankle joints, which affected patellofemoral pain. Methods: The subjects in this study were 20 patients with patellofemoral pain who visited ${\bigcirc}{\bigcirc}{\bigcirc} $ Hospital in Busan. The visual analogue scale measured the dynamic quadriceps angle and the degree of pain felt by the patients while walking down stairs, which was a known factor of patellofemoral pain. In addition, muscle activities in the rectus femoris, vastus lateralis, vastus medialis, tibialis anterior, peroneus longus, and biceps femoris, which affect the knees and ankles, were measured using surface electromyography. The muscle activities were converted into %RVC for this study. The data obtained in this study were analyzed with the Wilcoxon signed-rank test using the SPSS Ver. 25.0 statistical program. The significance level ${\alpha}$ was 0.05. Results: The study results showed that the pain and dynamic quadriceps angle were significantly reduced statistically when applying the calcaneus fixation taping (p<0.05). Muscle activity in the lower limbs was significantly decreased in the vastus medialis, vastus lateralis, and tibialis anterior (p<0.05). Conclusion: The summary of the study results verified that the calcaneus fixation taping reduced the pain and dynamic quadriceps angle by providing stability in the ankle joints. It also produced efficient movement due to the difference in lower-limb muscle activity.

• Journal of Korean Physical Therapy Science
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• v.29 no.3
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• pp.21-28
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• 2022

Background: Hamstring shortness results in the inappropriate activation of the quadriceps femoris because of the loss of the reciprocal inhibition mechanism. The purpose of this study was to investigate the effects of that activation during lunge exercises on the vastus medialis, vastus lateralis, medial, and lateral hamstrings in participants with hamstring shortness and normal length. Design: Quasi-experimental design Methods: Participants were divided into a hamstring shortness group(n=20) and a hamstring normal length group(n=23), based on a hamstring length test. During lunge exercises, muscle activation of the vastus lateralis, vastus medialis, medial, and lateral hamstrings were measured by electromyography. Results: Each muscle tested was less activated in the hamstring shortness group than in the hamstring normal length group. However, there was no statistically significant difference between the groups (p>.05). Conclusion: Although there was no significant difference between the shortness and normal hamstring groups during short lunge exercise time, longer exercising periods will result in the inappropriate activation of the quadriceps femoris. During lunge exercise, hamstring shortness causes an imbalance activation of quadriceps femoris and hamstring, and continuous hamstring shortness can cause damage on joints of lower limb.

• Physical Therapy Rehabilitation Science
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• v.12 no.1
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• pp.33-42
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• 2023

Objective: This study aims to analyze the effect of regular exercise through the combined walking-oriented aerobic and resistance exercises using EX1 in young adults. Design: Experimental one group pre and post test Methods: Participants comprised17 healthy young adults. All subjects performed a combined exercise program for 10 times using EX1. We measured quadriceps muscle thickness using ultrasound. Additionally, the hand grip strength test, and sit and reach test were performed before and after the exercise. Through paired t-test, we investigated whether there was a statistically significant difference in the measurement results after exercise program. Results: The rectus femoris muscle contraction ratio showed significant difference after exercise(P< 0.01). In the sit and reach test, flexibility showed significant difference after exercise(P < 0.01). The hand grip strength test also showed significant difference after exercise(P < 0.05). Conclusions: Healthy young adults can effectively perform various exercises commonly performed in daily life using EX1.

• Korean Journal of Applied Biomechanics
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• v.33 no.2
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• pp.45-51
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• 2023

Objective: The aim of this study was to examine the effect of strength training targeting medial quadriceps/hamstrings and non-targeting strength training on dynamic balance. Method: A total of 51 healthy subjects were randomly assigned to control, targeting strength training, or non-targeting training groups. To measure the dynamic balance, the star excursion balance test (SEBT) was performed before and after training. The SEBT parameters were compared using repeated measures ANOVA, and post-hoc paired t test at a significance level of 0.05. Results: Greater anterior (p= .011), anteromedial (p= .001), medial (p< .001), lateral (p< .001), and anterolateral (p= .001) reach distances were found between pre- and post-training in the strength training targeting medial thigh muscles group. Only greater lateral reach distance was found after non-targeting strength training (p= .029). In addition, no differences were found for any SEBT scores in the control group. Conclusion: Strength training targeting medial quadriceps and hamstrings can improve the dynamic balance, thereby it positively affected in lower extremity injury risk, whereas non-targeting strength training rarely changes the dynamic balance.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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• pp.581-588
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• 2011

Objective: The objective of this study is to compare muscle activity levels of the lumbar and rectus femoris muscle when entering and exiting RV and passenger vehicles. Background: Three varieties of RVs and two varieties of passenger vehicles were selected for this study. Method: Twenty individual(10 male and 10 female) in their twenties and thirties with no chronic back pain or any other illness participated in this study. Participants performed entering and exiting the three models of RVs and two models of passenger cars. Appropriate rest time was given to participants between entering and exiting each vehicle in order to recover from muscle fatigue while performing their tasks. Results: Results from this study show that muscle activity levels were highest for entering RVs and exiting passenger vehicles. There were no significant differences in muscle activity levels for left and right side muscles in regards to entering and exiting vehicles. Application: These results can be used to provide baseline information for reduce muscle fatigue when getting in and out of vehicles.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.20 no.1
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• pp.35-38
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• 2014

Background: The case study examined the effect of a hip joint traction and hip posterolateral muscles strengthening on knee pain, range of motion, and lower extremity function scale of patients with patellofemoral pain syndrome (PFPS). Although PFPS has previously been attributed to quadriceps dysfunction, more recent research has linked this condition to impairment of the hip musculature and kinematic. Methods: Subject is a 27-years-old female with PFPS. Performed hip joint traction with belt and posterolateral muscles(hip abductors, external rotators) strengthening for 4 weeks, 3 times a week, once a day. Before and after the therapy, measurements were made on the visual analog scale (VAS) and of the ROM, and a lower extremity functional scale (LEFS) was conducted. Results: The results showed positive changes in VAS and range of motion and lower extremity functional scale. First VAS of knee changed from 6 to 2. Second hip joint range of motion showed that internal rotation recored from $53^{\circ}$ to $58^{\circ}$ and external rotation recorded from $32^{\circ}$ to $37^{\circ}$. Third The lower extremity functional scale showed before therapy of 44; after therapy, 63. Conclusion: The hip joint traction and hip posterolateral muscles strengthening was effective in alleviating knee pain, increasing ROM and Lower extremity functional scale of the PFPS patients.

• International Journal of Contents
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• v.6 no.1
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• pp.1-5
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• 2010

Kinesio Taping (KT) is widely used by physical therapists to treat a variety of neuromusculoskeletal disorders. In this study it was examined whether or not KT has an effect on the peak torque and muscle activity of the quadriceps muscles in healthy subjects. KT was applied to the anterior thigh and tibia of fifteen healthy males (mean age, 25.42${\pm}$1.38 years, mean body height 178.58${\pm}$3.03 cm, mean body weight 71.58${\pm}$6.42 kg) who have no problem within past 2 months. The quadriceps peak torque was assessed using an isokinetic dynamometer while the mean data of muscle activity was measured by surface electromyography (EMG). The maximal voluntary isometric contraction was carried out on all subjects at $0^{\circ}$, $30^{\circ}$ and $60^{\circ}$ before, during, and after KT. There were no significant differences in the peak torque and mean data of quadriceps muscle(vastus lateralis, rectus femoris, and vastus medialis oblique) activity at $0^{\circ}$, $30^{\circ}$ and $60^{\circ}$ before, during and after application of KT (p>.05). From this study it could be concluded that the application of KT to the anterior thigh and tibia doesn't affect the peak torque and the muscle activity.