• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.1-12
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• 2003

This study was performed to provide normative isokinetic strength of knee muscles of middle school non-athletic and athletic populations for rehabilitation and pre-season screening for injury prevention. Seven non-athletic subjects and 8 hockey players participated in this investigation. Each subject was tested at speeds of $60^{\circ}/sec$, $180^{\circ}/sec$, and $300^{\circ}/sec$. The free weight of lower leg was measured at speed of $60^{\circ}/sec$ to take gravity effect Into consideration when peak torque of knee muscles occurred. The results showed that the relative peak torque production of knee flexors did not change but the relative peak torque of knee extensors decreased significantly. Mamstring/quadriceps ratios increased mainly due to significant decreases in knee extensors torque production. No significant differences were found between groups. The hamstring/quadriceps ratios for both groups were significantly lower when the gravity effect was not eliminated.

• Journal of Life Science
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• v.12 no.6
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• pp.780-785
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• 2002

The purpose of this study is to investigate isokinetic strength changes of knee joint in accordance with short-term weight loss of wrestlers. For this purpose, 14 male wrestlers of a K technical high school in B city participated in our research. The wrestlers were divided into two groups; one group of the wrestlers didn't lose any weight, and the other lost over 5% of their weights. The isokinetic strength was also observed before and after weight loss. The isokinetic strenght test were processed at test speed of the$60^{\circ}C$/sec, $90^{\circ}C$/sec, and $250^{\circ}C$/sec with the CYBEX NORM system(Cybex 770＋TMS, USA). Peak torque, peak torque %BW, total work, total work %BW, and endurance ratio were measured. Results showed that the isokinetic strength after the short-term weight loss of wrestlers decreased meaningfully Although endurance ratio didn't show any meaningful difference in our research, but more accurate research may find out the relationship between short-term weight loss and the endurance ratio of isokinetic strength.

• Journal of Life Science
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• v.24 no.10
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• pp.1125-1131
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• 2014

The purpose of this study was to investigate the relationship between quadriceps composition and its functional contractility in obese and nonobese elderly individuals. Thirty-four ($70{\pm}2yr$) individuals (obese, n=21; nonobese, n=13) participated in the study. The thigh composition was assessed with a CT scan, and its functional contractility was measured with an isotonic dynamometer. Variables were analyzed with a $2{\times}2$ two-way ANOVA and a contrast test (p<0.05). There were no between-group differences in the subjects' ages and heights, but individuals in the obese group were approximately 23% heavier and had 18% more fat than those in the nonobese group, regardless of gender. The total thigh volume of the obese elderly was greater (~29%) than that of the nonobese elderly, regardless of gender, and the fat volume (~39%) of the obese elderly was greater than that of the nonobese elderly, regardless of gender (p<0.05). Interestingly, the obese elderly tended to have a greater thigh muscle volume (~17% for males [p<0.05] and ~10% for females) than the nonobese. Despite the greater muscle volume, the peak knee extensor torque of the two groups was comparable or slightly greater in the obese individuals. However, when this was normalized by the total thigh volume, the nonobese males showed significantly greater peak torque (~26% for right and ~20% for left; p<0.05) compared to the obese males. The nonobese females also showed greater peak torque (~8% for both legs) than the obese females after normalization, but the result was not statistically significant. In conclusion, although the obese elderly individuals had greater quadriceps muscle mass than the nonobese, the normalized peak torque of the obese was significantly lower than that of the nonobese, implying a lower degree of muscle contractility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.538-546
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• 2017

The purpose of this study was to investigate the effect of neuromuscular electrical stimulation (NMES) and transcutaneous electrical nerve stimulation (TENS) on muscular strength, pain, range of motion and fear-avoidance in anterior cruciate ligament reconstruction (ACLR) patients. The subjects of this study who received ACLR after arthroscopic injury were divided into two groups: NMES (n=14) and TENS (n=14). Each group received intervention after routine physical therapy. Each electrotherapy intervention was applied regularly for a total of 12 times, 3 times a day (30 minutes) for 4 weeks. The evaluation by intervention method included isokinetic muscle strength in flexion and extension of the knee joint, pain, range of motion of the knee joint, and fear-avoidance beliefs. The results showed significant improvement in pain, range of motion, and fear-avoidance beliefs in both groups (p<0.05). However, there was a significant improvement in isokinetic knee flexion and extension strength only in the NMES group (p<0.05). There was no significant difference between the two electrotherapy methods in muscle strength, pain, range of motion, and fear-avoidance beliefs. These study results suggest that NMES and TENS can be effective intervention methods for pain, range of motion, and fear-avoidance response in patients with ACLR, but to improve muscle strength NMES may be more effective.

• Korean Journal of Applied Biomechanics
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• v.18 no.3
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• pp.83-92
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• 2008

Y. W. KIM, Y. J. KIM, Mechanical Properties of Unilateral & Bilateral Movements in Isokinetic Knee Extension and Flexion. Korean Journal of Sport Biomechanics, Vol. 18, No. 3, pp. 83-92, 2008. The purpose of this study was to examine the mechanical properties and patterns of bilateral and unilateral movement under varying velocities and movement patterns. The unilateral and bilateral isokinetic knee extension and flexion were taken for three speeds of 13 healthy male subjects. Although there was bilateral facilitation at the speed of $450^{\circ}$/s for the bilateral movement of knee extension, as a whole there was less resultant torque and power of bilateral movement than summed unilateral under knee flexion and extension of 3 velocity condition. There was significant correlations between bilateral deficits within individuals observed for an the same movement($120^{\circ}-240^{\circ}$ flexion, $120-240^{\circ}$ extension, $240^{\circ}-450^{\circ}$ extension), which means that same agonist was recruited. On the contrary, although there was a tendency of a similar pattern of the individuals bilateral deficit according to the varying velocities, there was not a significant correlations between bilateral deficits of flexion and extension within individual, which means that different agonist was recruited. With the analyses of this results the individuals neuromuscular characteristics and the effecting factors for bilateral movement can be speculated upon.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.69-79
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• 1996

Dynamic stress intensity factors are derives when the crack is propagating with constant velocity under longitudinal shear stress in orthotropic disk plate. General stress fields of crack tip propagating with constant velocity and least square method are used to obtain the dynamic stress intensity factor. The dynamic stress intensity factors of GLV/GTV=1(=isotropic material or transversely isotropic material) which is obtained in out study nearly coincides with Chiang's results when mode Ⅲ stress is applied to boundary of isotropic disk. The D.S.I.F. of mode Ⅲ stress is greater when α(=angle of crack propagation direction with fiber direction) is 90° than that when α is 0°. In case of a/D(a:crack length, D:disk diameter)<0. 58, the faster crack propagation velocity, the less D.S.I.F. but when crack propagation velocity arrive on ghear stress wave velocity, the D.S.I.F. but when crack propagation velocity arrive on shear stress wave velocity, the D.S.I.F. unexpectedly increases and decreases to zero.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.723-728
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• 2003

The physical restoration technology for lower limb amputees is being advanced as the biomechatronics is being applied to the area of rehabilitation. As the advanced prosthetics for lower limb amputees are introduced, a suitable prescription of biomechanical rehabilitation training becomes important to utilize the advanced full features of the devices. Since lower limb amputation significantly affects biomechanical balance of mosculoskeletal system for gait, an appropriate and optimal biomechanical training and exercise should be provided to rebalance the system before wearing the prostheses. Particularly, biomechanical muscular training for hip movements in the both affected and sound lower limbs is important to achieve a normal-like ambulation. However, there is no study to understand the effect of hip muscle strength on the gait performance of lower limb amputees. To understand the hip muscle strength characteristics for normal and amputated subjects, the isokinetic exercises for various ratios of concentric contraction to eccentric contraction were performed for hip flexion-extension and adduction-abduction. As a results. biomechanical isokinetic training protocols and performance measurement methodologies for lower limb amputees were developed in this study. Using the protocols and measurement methods, it has been understood that the appropriate and optimal biomechanical prescription for the rehabilitation process for lower limb amputees is important for restoring their gait ability

• Journal of Korean Physical Therapy Science
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• v.1 no.1
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• pp.165-173
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• 1994

The purpose of this study was to find out the effect of muscular strength of quadriceps, hamstring of knee joint to isokintic, isotonic exercise treatment in stroke. Data was collected from 80 stroke from January 10. 1994 to april 10, 1994 in a Chungnam university hospital. The results were as follows; 1. Peak torque was higher isokinetic than isotonic excercise group both in quadriceps and hamstring of knee joint, 6 weeks, 8 weeks 10 weeks showed statistically significant in isokinetic exercise training group. 2. Total work was high isokinetic than isotonic exercise group both in quadricaps and hamstring of knee joint, 10 weeks 12 weeks showed statistically significant in isokinetic exercise training group. 3. Average peak torque and total work was higher isokinetic than isotonic excercise group both in quadriceps and hamstring of knee joint, showed statistically significant in isokinetic exercise training group (p<0.05).(p<0.01). Isokinetic and isotonic exercise treatment were needed for sutable walk training in stroke. But I think that better method was isokinetic exercise treatment in muscular strength and endurance.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.10
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• pp.116-121
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• 2009

It is important to consider lumbar lordotic angle for setup of training program in field of sports and rehabilitaton to prevent unexpected posture deviation and back pain. The purpose of this study was to analyze the biomechanical impact of the level of lumbar lordosis angle during isokinetic exercise through dynamic analysis using a 3-dimensional musculoskeletal model. We made each models for normal lordosis, excessive lordosis, lumbar kyphosis, and hypo-lordosis according to lordotic angle and inputted experimental data as initial values to perform inverse dynamic analysis. Comparing the joint torques, the largest torque of excessive lordosis was 16.6% larger and lumbar kyphosis was 11.7% less than normal lordosis. There existed no significant difference in the compressive intervertebral forces of each lumbar joint (p>0.05), but statistically significant difference in the anterioposterior shear force (p<0.05). For system energy lumbar kyphosis required the least and most energy during flexion and extension respectively. Therefore during the rehabilitation process, more efficient training will be possible by taking into consideration not simply weight and height but biomechanical effects on the skeletal muscle system according to lumbar lordosis angles.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.2
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• pp.229-238
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• 2012

This study is to compare muscle strength between isotonic exercise and isotonic & isokinetic exercise. Participants are 12-man and 10-woman whom they are healthy without medical history in shoulder, elbow and lumbar joint. We performed experiment total 4-weeks that exercise 3-days a week each exercise pattern. We measured shoulder, elbow and lumbar joint torque with BIODEX and circumference of muscle in upper arms once a week. The result showed that isotonic & isokinetic exercise pattern significantly more improved joint torque in shoulder, elbow, lumbar than isotonic exercise pattern. Because that isotonic & isokinetic exercise pattern supplied muscle strengthen and caused muscle contraction. This exercise pattern can be used new exercise training method for major athlete and normal people. Also this pattern can be used rehabilitation treatment.