• Korean Journal of Applied Biomechanics
• /
• v.16 no.1
• /
• pp.31-41
• /
• 2006

The primary purpose of a TKA is to restore normal knee function Therefore, ideally, a TKA should: (a) maintain the natural leverage of the knee joint muscles to ensure generating adequate knee muscle moments to accomplish daily tasks such as rising from climbing stairs; (b) provide adequate knee joint stability. A 16-channel MyoResearch XP EMG system was used to collect the differential input surface electromyography signals VM, VL, RF, BF, ST during climbing/descending stair tests. A Peak Motion Measurement System was used to collect the kinematic and kinetic data. AKIN-COM Ill isokinetic dynamometer was used for EMG of VM, VL, RF, BF and ST during maximal voluntary contraction. I Quadriceps EMG results for the VM of the passed 1year group limb demonstrated significant less RMS EMG than that of the passed 3year group limb $60^{\circ}-15^{\circ}$ of knee flexion(p<0.05). The VL of the passed 1year group limb also demonstrated significants less RMS EMG than that of the passed 3year group limb from $60^{\circ}-45^{\circ}$ of knee flexion(p<0.05). Similar to the VM and VL, the RF of the passed 1year group limb showed less RMS EMG than that of the passed 3year group limb from $60^{\circ}-30^{\circ}$ do knee flexion(p<0.05). Hamstring EMG results for the BF of the passed 1year group limb demonstrated less RMS EMG than that of the passed 3year group limb from $75^{\circ}-15^{\circ}$ of knee flexion(p<0.05). The passed 1year group limb tended to have less ADD displacement(p<0.071) than that of the passed 3year group limb. There was no significant difference of the ABD displacement between the passed 1year group and the passed 3year group limbs(p<0.73). The passed 3year group used compensatory adaptation movement strategies to compensate for the strength deficit of passed 3year group limbs. The passed 3year group limb also increased the quadriceps muscle activation level to produce more knee extension moment to compensate for the short quadriceps moment arm. The passe 3year group limb might have an unstable knee joint in the medio-Iateral direction during the climbing/descending by showing a tendency of more ADD displacement and greater hamming co-activation EMG than the passed 1year group limbs. The TKA design was not able to help the knee joint to produce adequate knee extension moment with less quadriceps muscle effort. I think that old man needs continuous exercise for muscle strength.

• Journal of Convergence for Information Technology
• /
• v.9 no.7
• /
• pp.153-158
• /
• 2019

The purpose of this study was to compare the isokinetic muscular strength of the knee joint between female volleyball and table tennis players. A total of 27 elite volleyball players and 27 table tennis players participated in the study. This study measured both knee extensor and flexor strengths of volleyball and table tennis players using the isokinetic dynamic test. Peak torque was measured by performing maximal voluntary flexion and extension three times at $60^{\circ}/s$. Volleyball players had higher knee extensor and flexor strengths than table tennis players. No significant difference in both knee strengths was noted in table tennis players. However, volleyball players showed significant differences in both knee strengths. Height and weight showed a positive correlation with knee strength. This study found that volleyball players had greater knee strength than that of table tennis players. We also found that volleyball players have asymmetrical knee strength. Comparison with other sport players is warranted to better understand isokinetic muscular strength of the knee joint.

• Archives of Orthopedic and Sports Physical Therapy
• /
• v.14 no.2
• /
• pp.45-53
• /
• 2018

Purpose: The purpose of this study was to investigate the effects of muscle activity and muscle strength according to verbal command volume during isokinetic and isometric quadricep exercises. Methods: To measure muscle activity and muscle strength, surface electrodes were attached to the participants, as they sat on a Biodex chair. The isometric exercise was performed three times, with maximum exercise at $30^{\circ}$ bending angle, based on a maximum extension state of the knee at $0^{\circ}$. The average holding time was unified to three seconds. In addition, the isokinetic exercise was performed three times, at $60^{\circ}/sec$. The verbal command ranged between 0∾60 dB and 0∾75 dB. Muscle activity was measured using surface electromyography (4D-MT, Relive, Gimhae, Korea). The Biodex System 4 was used to measure the isometric and isokinetic strength of the nodal line, and 4D-MT was used to measure muscle activity. Results: There were significant improvements in the maximal and relative muscle strengths, when the 0∾ 60 dB and 0∾75 dB verbal commands were applied with isokinetic extension/flexion (p<.05). The isokinetic exercise (0∾75 dB) group showed a significant difference in the vastus medialis oblique muscle activity change (p<.05), while the isometric exercise (0∾75 dB) group showed a significant difference in the rectus femoris muscle activity change (p<.05). Conclusions: Our results reveal that verbal commands effectively improve muscle activity and muscle strength during isokinetic and isometric quadricep exercises.

• Journal of Life Science
• /
• v.19 no.12
• /
• pp.1821-1828
• /
• 2009

The purpose of this research was to investigate how the plyometric training and weight training program, applied in the field for exercise performance of throwing players, influenced improvement of athletic abilities, including agility, maximum muscular power, and strength. After implementing plyometric training and weight training to 21 high school throwing players for 10 weeks, we designed the next step. The 21 subjects were divided into two groups - women's group and men's group. All subjects were tested to determine agility using sidestep, burpee test, reaction time, lower body power and strength using standing long jump, standing jump, 30 m running, squats and leg presses. Additionally, isokinetic strength was measured using Cybex isokinetic dynamometer. The results showed that both groups demonstrated improvement in the standing long jump, standing jump and 30 m running after training. Particularly, the women's group indicated better improvement. Second, women's groups showed higher improvement in the sidestep and burpee test. However, in the reaction time test, the men's group indicated better improvement. Third, both groups showed better improvement in squats and leg presses after training. Particularly, the women's group indicated better improvement. Fourth, in the left and right side extension torque and flexion torque at a velocity of $60^{\circ}$/sec, both groups showed better improvement after training. In the left side extension peak torque, the men's group showed higher improvement, but the women's group showed higher improvement in the left side flexion and extension peak torque. Fifth, both groups showed better improvement in bench pressing and back strength after training. Particularly, the women's group indicated higher improvement.

• The Korean Journal of Physiology and Pharmacology
• /
• v.18 no.5
• /
• pp.441-446
• /
• 2014

Ursolic acid (UA), a type of pentacyclic triterpenoid carboxylic acid purified from natural plants, can promote skeletal muscle development. We measured the effect of resistance training (RT) with/without UA on skeletal muscle development and related factors in men. Sixteen healthy male participants (age, $29.37{\pm}5.14$ years; body mass index=$27.13{\pm}2.16kg/m^2$) were randomly assigned to RT (n=7) or RT with UA (RT+UA, n=9) groups. Both groups completed 8 weeks of intervention consisting of 5 sets of 26 exercises, with 10~15 repetitions at 60~80% of 1 repetition maximum and a 60~90-s rest interval between sets, performed 6 times/week. UA or placebo was orally ingested as 1 capsule 3 times/day for 8 weeks. The following factors were measured pre-and post-intervention: body composition, insulin, insulin-like growth factor-1 (IGF-1), irisin, and skeletal muscle strength. Body fat percentage was significantly decreased (p<0.001) in the RT+UA group, despite body weight, body mass index, lean body mass, glucose, and insulin levels remaining unchanged. IGF-1 and irisin were significantly increased compared with baseline levels in the RT+UA group (p<0.05). Maximal right and left extension (p<0.01), right flexion (p<0.05), and left flexion (p<0.001) were significantly increased compared with baseline levels in the RT+UA group. These findings suggest that UA-induced elevation of serum irisin may be useful as an agent for the enhancement of skeletal muscle strength during RT.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.12 no.1
• /
• pp.53-62
• /
• 2018

In this study, we developed a smart 1RM system for national health management and physical fitness, which enables quantitative 1RM measurement in various types of exercise using digital pulley technology, and to test the effect on training by using it. We developed the smart 1RM system, which is composed of portable muscle strength measuring device, Bluetooth communication based mobile phone data transmission and circuit diagram, and height adjustable system body. We recruited the 30 participants with 20th aged and divided into training and non-performing groups with 15 participants randomly. The participants performed 5 sets of elbow, lumbar, knee extension / flexion 10 times using smart 1RM system and the experimental period was 3 days a week for a total of 8 weeks. The experimental results showed that the maximum strength of the elbow, lumbar, and knee joints was significantly improved before and after maximal muscle strength training in the training group. Oxygen intakes during 1RM exercise mode showed 10.91% than endurance. To verify the validity of the smart 1RM maximal strength data, the reliability was 0.895 (* p <0.00). This study can be applied to the early rehabilitation treatment of the elderly and rehabilitation patients more quantitatively using the national health care.

• Physical Therapy Korea
• /
• v.25 no.4
• /
• pp.46-52
• /
• 2018

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.

• Journal of Korean Orthopaedic Sports Medicine
• /
• v.3 no.1
• /
• pp.66-72
• /
• 2004

Purpose: To evaluate the compensatory mechanism in vivo and develop the treatment guide by performing the comprehensive functional tests of the posterior cruciate ligament (PCL) deficient subjects. Material and Methods: 10 PCL deficient subjects and 10 healthy control group were evaluated. Performed functional tests were range of motion, posterior drawer test, Telos, 30$^{\circ}$ flexion wt-bearing view, KT-1000 arthrometer, gait analysis, EMG test and isokinetic tests. Results: Physical, KT-1000, Telos posterior tests showed significant differences, but 300 full weight bearing lateral view, muscle strength test revealed no difference between two groups. Less knee flexion at initial contact and reduced maximum valgus moment were observed in PCL deficient group. In vertical drop landing, PCL group had increased plantar flexion angle at initial contact. Conclusion: Compensatory mechanisms such as reduced unstable components and absorbing the maximal load of the joint were occurred after PCL insufficiency, which result in good clinical and functional outcomes. Further investigations would be needed to understand the functional adaptations of PCL deficient subjects.

• Journal of the Korean Society of Physical Medicine
• /
• v.12 no.4
• /
• pp.83-92
• /
• 2017

PURPOSE: The purpose of this study was to investigate the effect of the elastic band and stretching exercise program on ankle joint maximal voluntary isometric contraction (MVIC) and plantar pressure in high-heel wearing women in their 20s. METHODS: Twenty women in their twenties were randomly assigned to the experimental group (n=10) and the control group (n=10). The experimental group (n=10) performed the elastic band exercise program, while the control group (n=10) performed the stretching exercise program. Both exercise programs were performed three times a week for a total of four weeks. The BTE Primus RS was used in order to measure the ankle joint MVIC during dorsiflexion, plantar flexion, inversion, and eversion. Maximum pressure ($N/cm^2$), average pressure ($N/cm^2$) were measured using the Pedoscan. SPSS v. 21.0 software was used for all statistical analyses in this study. RESULTS: The measurement of the ankle joint's MVIC revealed that in inversion, a significant change in both feet was seen in both the experimental and control groups. In eversion, there was a significant change in both feet only in the experimental group. In terms of the rest of the results, no significant changes were visible. With regard to the plantar pressure, no significant results were seen for either foot in the comparison between or within the groups. CONCLUSION: Exercise program using elastic band and exercise program using stretching were effective on MVIC of ankle joint muscles, although it had no effect on changes of plantar pressure.

• Journal of Biomedical Engineering Research
• /
• v.34 no.4
• /
• pp.163-169
• /
• 2013

The purpose of this study was to verify exercise effect of horse riding exercise according to estimate basal physical fitness and activities of daily living(ADL) function in the aged. Participants were nineteen peoples who have no impediment of activity. They performed horse riding exercise using SRider(Neipplus, Co., Korea) at sixty minutes a day. Exercise has progressed three days a week for eight weeks. We measured trunk flexion, sit up, whole body reaction, leg strength and maximal oxygen uptake as basal physical fitness. Also three meter gait, single stance with eyes opened and single stance with eyes closed as ADL function were estimated once a month. The result of legs strength and whole body reaction showed the higher significantly than before the exercise. Moreover, the result of three meter walking ability only increased significantly among the ADL function. This means that horse riding exercise might be activated continuous muscular contraction with maintained tonus of muscle. We thought that continuous movement of horse riding could be lead to isometric muscle contraction in lower limbs. Our study found that horse riding exercise could improve lower strengths and muscle reaction for exercise effect. Also we suggested that horse riding exercise could be adapted to exercise methods that could provide rehabilitation and treatment enough for the aged or disabled person.