• Journal of Korean Physical Therapy Science
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• v.24 no.1
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• pp.69-78
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• 2017

Background: The purpose of the present study is to report the effect of muscle performance on knee flexion and extension by chin in exercise. Methods: This study was Participated in 10 healthy subjects. For conducting the chin-in exercise, subjects are lay down with supine position. Using the rounded towel, subjects was performed contraction of longus colli and longus capatis muscle by push the towel. Chin-in exercise was conducted 3 times a day, 4 times a week for 4 weeks. By using the Biodex system4, We measured absolute muscle strength, relative muscle strength, total exercise quantity and average rate of production in knee flexion and extension. The data was analyzed by the repeated-measure ANOVA for comparing before, after exercise 2 weeks, after exercise 4 weeks changes of factors. Results: After chin-in exercise, there was significant difference of before, after 2 weeks and 4weeks results in absolute muscle strength, relative muscle strength, total exercise quantity, average rate of production, agonist/antagonist ratio(p<.05). Conclusion: As a results of this study, chin-in exercise may help to improve muscle ability of knee joint activation and knee joint action performance.

• Korean Journal of Applied Biomechanics
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• v.25 no.3
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• pp.275-281
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• 2015

Objective : In order for Taekwondo athletes to perform destructive kicking performance, they are expected to have Taekwondo-specific muscle properties such as high muscle strength and power. The purpose of this study was to investigate the joint angle-dependent force-producing property of Taekwondo athletes' knee extensor muscles, which is one of the primary muscle groups involved in kicking performance. Method : Ten Taekwondo male athletes (age: $19.9{\pm}0.7yrs$, height: $180.6{\pm}6.2cm$, body mass: $75.9{\pm}8.9kg$, career: $9.2{\pm}2.9yrs$.) and 10 healthy male non-athletes (age: $26.3{\pm}2.6yrs$, height: $174.2{\pm}4.8cm$, body mass: $72.8{\pm}7.7kg$) participated in this study. Subjects performed maximum isometric knee extension at knee joint angles of $40^{\circ}$, $60^{\circ}$, $80^{\circ}$, and $100^{\circ}$ (the full knee extension was set to $0^{\circ}$) with the hip joint angles of $0^{\circ}$ and $80^{\circ}$ (the full extension was set to $0^{\circ}$). During the contractions, knee extension torque using an isokinetic dynamometer simultaneously with muscle activities of the rectus femoris (RF), and the vastus lateralis (VL) and vastus medialis (VM) using surface electromyography were recorded. Based on the torque values at systematically different knee-hip joint angles, the joint torque-angle relationships were established and then the optimal joint angle for the knee extensor was estimated. Results : The results of this study showed that the isometric knee extension torque values were greater for the Taekwondo athletes compared with the non-athlete group at all hip-knee joint angle combinations (p<.05). When the hip joint was set at $80^{\circ}$, the peak isometric torque was greater for the Taekwondo athletes compared with the non-athlete group ($313.61{\pm}36.79Nm$ and $221.43{\pm}35.92Nm$, respectively; p<.05) but the estimated optimum knee joint angles were similar ($62.33{\pm}5.71^{\circ}$ and $62.30{\pm}4.67^{\circ}$ for the Taekwondo athletes and non-athlete group, respectively). When the hip joint was set at $0^{\circ}$, the peak isometric torque was greater for the Taekwondo athletes compared with the non-athlete group ($296.29{\pm}45.13Nm$ and $199.58{\pm}25.23Nm$, respectively; p<.05) and the estimated optimum knee joint angle was larger for the Taekwondo athletes compared with the non-athlete group ($78.47{\pm}5.14^{\circ}$ and $67.54{\pm}5.77^{\circ}$, respectively; p<.05). Conclusion : The results of this study suggests that, compared with non-athletes, Taekwondo athletes have stronger knee extensor strength at all hip-knee joint angle combinations as well as longer optimum muscle length, which might be optimized for the event-specific required performance through prolonged training period.

• The Journal of Korean Physical Therapy
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• v.29 no.1
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• pp.39-43
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• 2017

Purpose: This study was to investigate the effects of unilateral muscle fatigue in knee and ankle joints on balance and gait in healthy adults. Methods: Exercise inducing muscle fatigue in the knee joint consisted of concentric and eccentric contraction of dominant knee extensors in healthy adults by using the Leg Extension Rehap exercise machine (HUR, Finland). Exercise inducing muscle fatigue in the ankle joint was composed of voluntary contractions and forced contractions of the dominant plantar flexors in healthy adults. Exercises to induce muscle fatigue in the knee and ankle joints were performed until the subject complained of fatigue or pain, the occurrence of muscle fatigue was confirmed by electromyography. We measured static and dynamic balance using the Good Balance system and gait performance by RS-scan. Results: Static and dynamic balance ability and spatial-temporal gait decreased significantly after muscle fatigue in knee and ankle joint. Conclusion: These results show that unilateral muscle fatigue of the lower extremities affected postural control and gait. Therefore, therapists and sport trainers should minimize the risks of fall and injuries related to unilateral muscle fatigue.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.24 no.2
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• pp.9-15
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• 2018

Background: The purpose of this study was to compare the effects of mulligan taping on knee joints on balance ability and strength with repeated measurements. Methods: Seventeen patients were randomly assigned to the 8 taping group and the 9 repeat measurement group. To measure the balance ability, fall risk assessment equipment was used, and the measurement of the muscle strength was performed by using the equipment of the same company. Results: Balanced abilities and muscle strength were increased in groups with taping only after Mulligan taping. Conclusions: The application of mulligan taping did not have the effect of stimulating the inherent receptive sensation. However, active grouping of the knee joint taping only, and muscle strength and muscle strength were increased. It increases the stability and activity of the muscles that operate on the balance of the active knee joint and muscle strength, thereby enhancing exercise prevention and prevention performance and exercise performance.

• Journal of Korean Physical Therapy Science
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• v.22 no.1
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• pp.43-48
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• 2015

Background : The purpose of this study was find out more effective method for improving muscle strengthening in lower extremities according squatting exercise method among knee joint angle 45, 60, 90 degree and between gym ball behind back and wall. Methods : Participants were 21 university students(males 10, females 11) who didn't have any problem with orthopedic surgery. We divided participants to two groups with gym ball group and wall group. Gym ball group were performance squatting exercise with gym ball behind back. Each group had performance squatting exercise according knee joint angle 45, 60, 90 degree. We collected data from E.M.G of Biceps femoris, Gastrocnemius, Vastus medialis and lateralis, Tibialis anterior in lower extremity according knee joint angle 45, 60, 90 degree of each groups. We analyzed data using by ANOVA and ANCOVA of SPSS PC ver. 12.0 in order to determine more effective method according various squatting exercise. Results : Each groups show significantly difference value of biceps femoris, vastus lateralis and medialis, tibialis anterior, gastrocnemius lateralis and medialis among knee joint angle 45, 60, 90 degree. But there was no significantly difference value between gym ball group and wall group according knee joint angle. Conclusions : We suggested that squatting exercise with gym ball was more effective method improving lower extremity muscle strengthening, and changing knee joint angle was more effective compared than continued knee joint angle.

• The Journal of Korean Physical Therapy
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• v.27 no.5
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• pp.351-355
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• 2015

Purpose: This study was conducted to determine how stimulation using Russian current changes isokinetic exercise performance of quadriceps muscle and its antagonist muscles. Methods: Subjects were 20 20-year-old healthy adults who were instructed in the flexion to extension of knees in angular velocity $60^{\circ}/sec$ and $180^{\circ}/sec$ using a Biodex (Biodex system 3). We measured the difference in muscle performance between the Russian current stimulated at the same time during the flexion to extension of knees and not stimulated. Results: The results showed that when Russian current stimulation was applied at the angular velocity $60^{\circ}/sec$, the flexed and extended muscles and the angular velocity $180^{\circ}/sec$ increased significantly, but the peak torque of flexing muscles at the angular velocity $180^{\circ}/sec$ did not increase. Conclusion: These findings suggest that Russian current stimulation with isokinetic exercise of the knee joint could affect the quadriceps muscle and its antagonist muscle performance of muscle strength and endurance.

• Journal of Fashion Business
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• v.27 no.5
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• pp.93-107
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• 2023

This study aimed to design a knee brace with dry electrode EMS (Electrical Muscle Stimulation) for elite badminton players suffering from knee pain and assess its effectiveness in relieving pain and improving mobility. The assessment measured knee joint range of motion (ROM), Sargent jump height, and pain perception using a visual analog scale (VAS). Four experimental groups were established: stability, pain induction after 100 squats, muscle soreness induction with a regular knee brace, and muscle soreness induction with the EMS knee brace. The most suitable knee brace was selected from four samples to design the EMS knee brace. The conductive fabric was integrated into the inner surface of the knee brace to enhance EMS conductivity for the quadriceps muscles. Tensile strength tests showed that the dry electrode did not significantly affect the physical functionality of the knee brace.Regarding knee joint ROM and Sargent jump height, the EMS knee brace outperformed muscle soreness induction with a regular knee brace and wearing a standard knee brace. VAS measurements demonstrated that the EMS braces effectively alleviated pain perception in most cases. The results indicate the potential for developing EMS braces to alleviate pain and prevent injuries for athletes across various sports.

• Journal of muscle and joint health
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• v.23 no.3
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• pp.139-151
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• 2016

Purpose: The study was conducted to examine the effects of motivational interviewing intervention on exercise performance and maintenance, exercise and pain self-efficacy, functional status, and quality of life in the patients with total knee replacement. Methods: This study used a nonequivalent control group non-synchronized design. A total of 100 patients with total knee replacement (33 patients in motivational interviewing group (MG), 33 patients in exercise group (EG), 34 patients in comparison group (CG)) were participated in this study. MG and EG had 7 scheduled sessions for 4 weeks. Data were analyzed with repeated measures ANOVAs by using IBM SPSS Statistics 20. Results: MG showed better exercise maintenance, higher exercise and pain self-efficacy, higher muscle strength, and mental component of quality of life than the other groups. MG and EG showed better knee flexion, less knee extension, longer walking distance for 6 minutes, and better functioning than CG. Conclusion: The results showed that motivational interviewing intervention is an effective intervention for elderly patients with total knee replacement. Future study examining long term effects of motivation interviewing intervention is necessary.

• Journal of Biomedical Engineering Research
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• v.40 no.6
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• pp.223-229
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• 2019

The number of knee-related disease patients and knee joint surgeries is steadily increasing every year, and for knee rehabilitation training for these knee joint patients, it is necessary to strengthen the muscle of vastus medialis and quadriceps femoris. However, because of the cost and time-consuming difficulties of receiving regular hospital treatment in the course of knee rehabilitation, we developed knee exoskeleton using rapid prototype for knee rehabilitation with feedback from the electromyogram (EMG) and inertia motion unit (IMU) sensor. The modules was built on the basis of EMG and an IMU sensor applied complementary filter, measuring muscle activity in the vastus medialis and the range of joint operation of the knee, and then performing the game based on this measurement. The IMU sensor performed up to 97.2% accuracy in experiments with ten subjects. The functional game contents consisted of an exergaming platform based on EMG and IMU for the real-time monitoring and performance assessment of personalized isometric and isotonic exercises. This study combined EMG and IMU-based functional game with knee rehabilitation training to enable voluntary rehabilitation training by providing immediate feedback to patients through biometric information, thereby enhancing muscle strength efficiency of rehabilitation.

• Physical Therapy Rehabilitation Science
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• v.13 no.2
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• pp.223-230
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• 2024

Objective: In this study, we compared the key indices of isokinetic tests for knee joint extension and flexion according to the presence or absence of pain in elite athletes with past knee and thigh injuries. Design: Crossed-sectional study Methods: This study was conducted on 33 elite athletes. The elite athletes who participated in this study were divided into a group with pain and a group without pain due to past knee and thigh injuries. The subjects in each group performed an isokinetic muscle strength test for knee joint extension and flexion. After the isokinetic muscle strength test, the main indices of the isokinetic test were compared between the pain group and the non-pain group. Results: In the comparison of the pain group and the non-pain group for 60°/s knee flexion and extension in elite athletes, there was a significant difference only in the torque max average/kg for knee extension. However, there was no statistically significant difference in all other variables. The comparison of the pain group and the non-pain group for 240°/s also showed a significant difference in the torque max average/kg for knee extension, and there was no statistically significant difference in all other variables. Conclusions: In subjects who have experienced previous knee or thigh injuries and have mild pain during strong isokinetic strength tests, torque average/kg is affected, but other strength variables are not affected. Therefore, it would be good to consider this aspect and use it as a basis for testing and training elite athletes.