• 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.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.1
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• pp.21-30
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• 2021

Background: This study aimed to investigate the effects of muscle energy technique (MET) and instrument assisted soft tissue mobilization (IASTM) on knee extension ROM, knee extensor/flexor strength and muscle thickness immediately and after 24 hours. Methods: A total of 30 subjects participated in this study. The participants were assigned to either MET (n=15) or IASTM (n=15). 90-90 straight leg raise, knee extensor/flexor muscle strength, muscle thickness test were measured before, immediately after and 24 hours after the intervention. Results: Both groups significantly improved knee extension ROM on immediate (MET 10.7°, IASTM 10.21° increased) and after 24 hours assessment (MET 5.61°, IASTM 5.47° increased)(p<.05). In the MET group, knee extension and flexion muscle strength increased immediately after intervention (p<.05). In the IASTM group, knee extension muscle strength increased and knee flexor muscle strength decreased immediately after intervention (p<.05). Furthermore, both groups showed a pattern of returning to the initial strength after 24 hours. In both groups, no significant difference in muscle thickness immediately and after 24 hours was observed (p>.05). Conclusion: According to the results of the present study, MET and IASTM technique showed lasting effectiveness in flexibility of shortened hamstring immediately after and in 24 hours after the intervention. In both groups, MET increased muscle strength and increased ROM, while IASTM decreased muscle strength and increased ROM, with no change in muscle thickness.

• 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.

• Journal of Korean Physical Therapy Science
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• v.9 no.3
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• pp.67-75
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• 2002

The purpose of this study was to evaluate the effects of quadriceps femoris flexibility exercise which would improve the degree of knee flexion range of motion, extension torque, and the activities of daily living (ADL) in elderly subjects with degenerative knee arthritis. Fourteen elderly patients (two men and twelve women) with degenerative knee arthritis participated and had a quadriceps femoris flexibility exercise intervention program in this study. The mean age of the patients was 70.00 years for men and 71.16 years for women. This study carried out the experimental study of one group pretest-posttest design, which evaluated the degree of knee flexion range of motion, extension torque, the ADL ability of the patients before and after applying the exercise intervention for five weeks. The results of this study are as follow: 1. The knee flexion ranges of motion of the patients were measured before and after the intervention and the ranges increased significantly both in the left and right knee flexion range of motion (p < 0.05). 2. The peak torque of the knee muscle, the peak torque/body weight, and average power of the patients showed significant increases in both in the left and right knee after applying the intervention (p < 0.05). 3. The intervention produced a significant reduction in pain of the patients (p < 0.05). Their functional activities of ADL improved significantly compared with before the intervention (p < 0.05). It has been shown that the quadriceps femoris flexibility exercise intervention program increased significantly the knee flexion range of motion, and extension torque, as well as an increase in performance of functional activities of ADL of the patients. Thus, the quadriceps femoris flexibility exercise should be considered as one of the therapeutic exercises for the elderly patients with degenerative knee arthritis applied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.435-441
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• 2006

The anterior cruciate ligament(ACL) is an important stabilizer of knee joint. The ACL injury of knee is common and a serious ACL injury leads to ligament reconstruction surgery. Gait analysis is essential to identify knee condition of patients who display abnormal gait. The purpose of this study is to evaluate and classify knee condition of ACL deficient patients using a nonlinear dynamic method. The nonlinear method focuses on understanding how variations in the gait pattern change over time. The experiments were carried out for 17 subjects(l2 healthy subjects and five subjects with unilateral deficiency) walking on a motorized treadmill for 100 seconds. Three dimensional kinematics of the lower extremity were collected by using four cameras and KWON 3D motion analysis system. The largest Lyapunov exponent calculated from knee joint flexion-extension time series was used to quantify knee stability. The results revealed the difference between healthy subjects and patients. The deficient knee was significantly unstable compared with the contralateral knee. This study suggests an evaluation scheme of the severity of injury and the level of recovery. The proposed Lyapunov exponent can be used in rehabilitation and diagnosis of recoverable patients.

• Korean Journal of Applied Biomechanics
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• v.21 no.2
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• pp.197-205
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• 2011

Various jumping and landing motions are shown during sports event. But most previous studies have not considered landing height and distance simultaneously. The purpose of this study was to identify the effects of landing height and distance on knee injury mechanism. Fourteen male(age: $28.86{\pm}1.99$ yrs, height: $177.00{\pm}4.69$ cm, weight: $76.50{\pm}6.41$ kg) participated in this study. The subjects attempted drop landing task onto the ground from 30 cm to 45 cm heights and to 20 cm to 40 cm distances. The results were as follows. First, higher drop landing height and longer distance showed greater degree of maximal knee flexion and valgus. Second, higher drop landing height and longer distance showed greater maximal knee extension moment and varus moment. Third, higher drop landing height and longer distance showed larger maximal knee absorption power. Lastly, higher drop landing height showed increased Peak GRF. Landing height was more related to the cause of injury, which was indicated by increased maximal knee extension moment, peak GRF and maximal knee absorption power. Landing distance was also associated with increased knee valgus moment and absorption power during landing. These results suggest that landing height and distance may be the cause of injury.

• Journal of Korean Physical Therapy Science
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• v.6 no.4
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• pp.229-240
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• 1999

I examined the isokinetic knee extension mean torque in 30 patients with hemiplegia and 30 healthy subjects matched by age, sex, height, and weight at knee extension velocities of $30^{\circ},\;60^{\circ},\;90^{\circ}$, and $120^{\circ}$/sec. The purpose of this study is as follows: first, to compare isokinetic data between the involved and uninvolved side of patients and healthy subjects. secondly, to determine whether the relative decreases in knee extension mean torque at velocities greater than $30^{\circ}$/sec were different on the two sides. Mean torque of quadriceps on both sides of patients with hemiplegia was significantly less than the mean torque of muscle of healthy subjects at various speeds. Relative decreases in knee extension mean torque differed between speeds, but not between sides. Torque at speed greater than $30^{\circ}$/sec were correlated significantly with the torque at $30^{\circ}$0/sec. These finding indicated that isokinetic testing can provide objective information about quadriceps muscle performance in hemiplegia, and suggested that hemiplegia may have difficulty in moving forcefully at higher speeds than $30^{\circ}$/sec because they are weak. Therapeutic intervention, therefore, might be most beneficial when they are directed toward helping patients with hemiplegia activate their muscle weakness.

• Physical Therapy Korea
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• v.2 no.1
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• pp.36-43
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• 1995

The purpose of this study was to determine whether the vastus medialis oblique muscle(VMO) had greater electrical activity than the vastus lateralis muscle(VL) when hip adduction and knee extension exercise were performed. Electrical activity of the VMO and VL was measured on 42 healthy subjects (28 men, 14 women) during maximal voluntary isometric contractions of hip adduction and knee extension by an EMG-BIOFEEDBACK. The results showed that the electromyographic activity of the VMO was significantly greater than that of the VL during the hip adduction exercise. Differences noted with knee extension by performing hip adduction exercises. Isometric hip adduction exercises, therefore, may be advisable in the treatment of patients with patellofemoral pain.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.4
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• pp.1602-1607
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• 2018

This study examined the correlation between power error (PE) and velocity error (VE) according to the condition and frequency of self-controlled feedback (SCF) during knee extension. One hundred participants were randomly assigned to 30% SCF, 70% SCF, 30% yoked feedback (YF), 70% YF and control group, respectively. The SCF group was provided with feedback when they requested it, whereas the YF group did not influence the feedback schedule. Participants in the control group were not given any visual feedback during the experiment. The isotonic, isometric, and isokinetic dynamometer (PRIMUS RS, BTE, USA) was used to measure the power and velocity error during knee extension. The collected data was analyzed using a Pearson test and SPSS 21.0. The correlation between PE and VE according to the condition and frequency of feedback on each phase during knee extension was significant. Both PE and VE were significantly higher when the feedback was provided with high frequency, passive, and no feedback. Our study suggests that application of SCF can help to improve the proprioception of the healthy person while reducing errors through low frequency and active feedback.

• The Journal of Korean Physical Therapy
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• v.3 no.1
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• pp.97-108
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• 1991

The purpose of this article is to know the standard figures of joint range of motion, in conjuction with age and sen, for normal adults. The results of assessment and analysis io shoulder and hip joint range of motion are as follows : 1) The average shoulder joint range of motion in normal adults are $160.5^{\circ}$ in flexion, $53.5^{\circ}$ in extension, $159.3^{\circ}$ in adduction, $62.3^{\circ}$ in internal rotation, $83.9^{\circ}$ in external rotation, The average hip joint range of motions are $116.8^{\circ}$ in flexion, $16.1^{\circ}$ in extension, $41.1^{\circ}$ in abduction, $33.8^{\circ}$ in abduction, $40.0^{\circ}$ in interne rotation, $41.2^{\circ}$ in external rotation. 2) There is no significant difference in shoulder and hip joint range of motion between male and female (p>0.05). 3) As to the inter-relation in age and range of motion, the left flexion and extension, internal rotation and right extension in shoulder joint is decreased gradually with increasing age, and left flexion (knee flexion, knee extension) and right flexion (knee extension) in hip joint is decreased with increasing age (p<0.01). 4) Relating to age and sex, the twenties male shows highest range of motion in shoulder and hip joint, with .the fifties female shows, lowest range of motion.