• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.8 no.2
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• pp.31-43
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• 2002

The subjects of this study were 15 woman soccer players and 15 untrained woman students at H-Cheju University. Each subject was measured on the muscle strength and peak torque of knee extensors and knee flexors with isokinetic load ($60^{\circ}$/sec, $180^{\circ}$/sec). The results were as follows: 1. There was no significant difference between right and left leg strength measured isokinetically in each group. 2. The peak torque of knee extensors and flexors was significantly higher in scoccer players than untrainded students (p<0.001). 3. For the angle of knee joint showing the highest peak torque, there was significant difference between soccer players and untrained students in knee extensors(p<0.05) and right flexors (p<0.01). 4. For knee H/Q ratio, there was significant difference between two groups(p<0.05). 5. For the total work and average power at $180^{\circ}$/sec, there was significant difference between two groups in knee extensors(p<0.001) and flexors(p<0.01). 6. In soccer players at $60^{\circ}$/sec, there were significant correlations between peak torque and height and between peak torque and weight.(p<0.001). 7. For the muscular contraction velocity at $60^{\circ}$/sec, there was significant difference between two groups in flexors (p<0.01). 8. For the muscular indurance at $180^{\circ}$/sec in extensors and flexors, there was no significant difference between two groups(p<0.05). In conclusion, there were significantly higher in peak torque, contraction velocity, knee joint's angle with the highest peak torque, H/Q ratio, total work and average power in woman scoccer player than general students. But there was no significant difference in muscular endurance. Soccer performance is based on the various components including muscular endurance that is one of the most important components. So it is necessary that the training method to improve the various components (especially including muscular endurance) should be done.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.37-44
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• 2016

The aim of the present study was to compare the strength, balance, and flexibility across two age groups (older adults vs. young adults). The isokinetic muscle function, ankle ROM, trunk forward flexibility, stability, and antropometric data for the elderly and 46 university students were collected. The results indicated that male older adults possessed relatively low flexibility (2.97cm) among the groups and showed better stability in the right foot than in the left foot and $35^{\circ}$ of plantar flexion ROM, which was not in the normal range. Their peak strength at the knee joint was below 50% of their counterpart. They revealed a hamstring deficit of 18.55%, ankle eversion deficit of 23.08%, and ankle inversion deficit of 19.19%. The results indicated that female older adults possessed comparable flexibility compared to female young adults. The reciprocal muscle strength ratio of both knees was under 50%, and the deficit was 14.32% (extension) and 19.73% (flexion). The ankle plantar flexion peak torque was approximately 62% (left) and 73% (right) of WS's. The ankle dorsi flexion deficit was 25.05% and the plantar flexion was 26.86%. The eversion deficit was 19.97% and the inversion was 21.09%. These results will be significant in establishing an elderly fitness enhancement program and policy.

• Journal of the Korean Chemical Society
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• v.25 no.2
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• pp.110-118
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• 1981

Kinetics and mechanism for the reaction of substituted phenacyl bromides with substituted pyridines have been determined at 25, 35 and $45^{\circ}C$ in methanol and dimethylformamide by the conductivity method. The rate constants for the reaction of various pyridines with phenacyl bromide shown that electron-donating substituents in the pyridine increase the rate, while electron-attracting one decrease in both solvents. The effect of substituents in substrate, the rate being increased by electron-attracting substituents. This is as expected for nucleophilic attack of amines on the carbon atom. Isokinetic and $Br{\psi}nsted$ linear relationship were shown in the reaction of phenacyl bromide with pyridines in both solvent in which isokinetic temperature were obtained 614, $202^{\circ}K$ and ${\beta}$ values were 0.29, 0.36 in methanol and dimethylformamide respectively. In the case of the reaction of substituted phenacyl bromide with pyridines, isokinetic temperature decreases with increasing electron-attracting ability of the substituents in the phenacyl bromide, while the ${\beta}$ values were reverse. From the above results, it can be inferred that N…C bond formation decreases progressively from p-chloro- to p-methoxyphenacyl bromide and the bond formation predominates in DMF than methanol. The ${\rho}$ values of Hammett equation of the reaction of phenacyl bromide with substituted pyridines are negative in both solvent, but its value was larger negative in DMF than methanol and the ${\rho}$ value of that of substitutted substrates with pyridine was 0.3, the low value is ascribed to direct $S_N2$ attack of the nitrogen atom in pyridine ring at the methylene carbon.

• Journal of Korean Academy of Nursing
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• v.26 no.3
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• pp.556-575
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• 1996

In an attempt to investigate the effect of a muscle strengthening exercise program on muscle strength, pain, depression, self-efficacy and quality of life of patients with knee osteoarthritis, a pre-experiment, one group pre-test & post-test design, was planned. Muscle strengthening exercise was carried out from May 22 through August 14, 1995 at isokinetic exercise room in rehabilitation department of University Hospital in Taejon. The subjects were seven female clients conveniently sampled from University Hospital located in Taejon, between 39 and 61 years of age, who had a osteoarthritis in knee. Muscle strengthening exercise program was composed of three sessions per week, one isokinetic exercise at angular velocity of 60° and 180° with Cybex isokinetic dynamometer and two resistance home exercise sessions with elastic band. Data were analyzed with frequency, percentage of change, Friedman test, Duncan test using SAS program. Results were obtained as follows : 1) Flexion and extension muscle strength at angular velocity of 60° and 180° were increased after 12weeks' exercise than those of before experiment. But exept flexion muscle strength at angular velocity of 180°(F=3.34, P=0.0261), there was no statistically significant difference among muscle strengths, which is measured every 3 weeks. 2) Pain was decreased after 6weeks' exercise than that of before experiment, and after 12weeks' exercise than that of 6weeks' exercise. There was statistically significant difference (F=4.28, P=0.0396). 3) Depression was increased after 6weeks' exercise than that of before experiment, and after 12weeks' execise than that of 6weeks' exercise. There was no statistically significant difference between before experiment and after 6weeks' exercise. But, there was statistically significant difference between after 6weeks' exercise and 12weeks' exercise(F=9.38, P=0.0035). 4) Self-efficacy was decreased after 6weeks' exercise than that of before exercise. But, it was increased after 12weeks' exercise than that of be-fore exercise and after 6weeks' exercise. But there was no statistically significant difference (F=1.46, P=0.2706). 5) Quality of life was increased after 6weeks' exercise than that of before exercise, and after 6weeks' exercise than that of 12weeks' exercise. But there was no statistically significant differ once (F=1.06, P=0.3816). Thus, the significant of muscle strengthening exercise for the improvement of muscle strength, pain, depression, is verified. But, this study was a pre-experiment with small size subjects. So, con-trolled experimental study is necessary to determine the effect of this muscle strengthening exercise program on muscle strength, pain, depression, self-efficacy, and quality of life of patients with knee osteoarthritis.

• Journal of the Korea Convergence Society
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• v.12 no.10
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• pp.277-286
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• 2021

This study investigated the effect of a 12-week rehabilitation program on the range of motion (ROM) and muscle strength of high school baseball players with shoulder instability. We allocated 12 players with shoulder instability to the rehabilitation group and 13 players without shoulder instability to the normal exercise group. Covariate analysis (ANCOVA) was performed to assess the ROM of the internal (IR) and external (ER) rotational joints before and after participating in the 12 weeks of rehabilitation, and two-way ANOVA was performed to assess isokinetic muscle strength. The statistical significance level was set at p<.05. The IR ROM of the dominant (D) shoulder with instability and non-dominant (ND) shoulder was significantly increased before and after the rehabilitation program. The total ROM of the D shoulder with instability significantly increased after rehabilitation. IR isokinetic strength significantly improved at an angular velocity of 180°/s after rehabilitation. These results indicate that the rehabilitation program used in this study could be effective in improving ROM and muscle strength in patients with shoulder instability. However, due to the limited results, additional research on the premise of extending the rehabilitation period is necessary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.162-169
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• 2020

This study was conducted from November 25 to December 4, 2019, to unmask differences in physical fitness based on the weight class of high school Ssirum elite-players. A total of 28 high school Ssirum elite-players were compared and analyzed by measuring physical factors (muscle strength/power, agility, anaerobic power, aerobic ability, flexibility, and isokinetic muscle function) by weight class. Data were analyzed using SPSS ver. 23.0. One-way ANOVA was used for comparison between groups. There was no difference by weight class in terms of grip strength, sit-ups, sergeant jump, long jump, flexibility, side step, and reaction time. Evaluation of back muscle strength revealed that the group with more than 100 kg had greater strength than lower weight categories, whereas it was lower in the sit-ups, 20 m shuttle run and the relative values anaerobic power. Considering isokinetic muscle function, no difference was observed between the groups of back muscle strength and knee joint. The results of this study indicate that amongst the high school Ssirum elite-players, there is no difference in muscle power, flexibility, agility, and anaerobic average power per body weight, isokinetic trunk strength, and knee flexion strength, when evaluated according to weight class.

• Korean Journal of Applied Biomechanics
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• v.32 no.3
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• pp.94-102
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• 2022

Objective: The purpose of this study was to investigate the effect of acute transcranial direct current stimulation (tDCS) on the isokinetic muscular endurance of the lower extremity for young adults. Method: Thirteen young adults performed isokinetic fatigue tasks for two experimental conditions including real tDCS and sham stimulation protocols. Before and after the task, the tensiomyography was used for evaluating muscle contraction characteristics of vastus medialis and semitendinosus. Paired t-test was performed to compare the fatigue index, changes in maximum radial displacement (∆Dm), delay time (∆Tc), and velocity of contraction (∆Vc) between tDCS conditions. Results: We found no significant differences in the fatigue index between real and sham conditions. In addition, the analyses identified no significant different values of ∆Dm, ∆Tc, and ∆Vc in the vastus medialis and semitendinosus between real and sham conditions. Conclusion: These findings suggest that the tDCS protocols may have no acute effect on lower limb muscle endurance for young adults. Future studies should consider the long-term effects of repetitive tDCS sessions, various stimulation positions, exercise tasks, and participant characteristics to more clearly understand the effect of tDCS on muscle endurance of lower extremities.

• Journal of Advanced Technology Convergence
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• v.1 no.1
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• pp.33-42
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• 2022

The flexors and extensors of the knee joint are essential for maintaining body stability. The purpose of this study was to investigate the correlation between the isokinetic parameters of the knee flexor and extensor muscles and the function of the lower extremity muscles. Twenty-two healthy adults participated in this study. The time to peak torque (TTP), acceleration time (AT), and peak torque (PT) of the knee flexor and extensor muscles were measured. A 20m sprint, Sargent jump, one leg hop test, and side shuffle were measured to evaluate lower extremity function. The correlation between each variable was analyzed using Pearson correlation coefficient. PT of the knee flexor showed a significant correlation with single leg hops and 6M hops in a single leg. PT of knee extensors was found to be significantly correlated with Sargent jumps and triple hops. Based on the results of this study, we suggest that the strength of the knee flexor and extensor muscles has the potential to be used to predict lower extremity function.

• Journal of The Korean Society of Integrative Medicine
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• v.12 no.2
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• pp.47-53
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• 2024

Purpose : This study investigated the effects of concentric and eccentric contractions on muscle strength using an isokinetic dynamometer (ID) in college students in their 20s. It aimed to understand the impact of differences between the dominant and non-dominant sides on strength asymmetry and to elucidate the clinical implications of these differences to establish an appropriate posture and environment for patients. Methods : The experiment was conducted with 30 healthy adult participants. Prior to the experiment, participants underwent a warm-up targeting the shoulders, and efforts were made to eliminate factors that could potentially influence the measurement results. Subsequently, the maximum safe range of motion of shoulder joint abduction, extension, and flexion was measured using an isokinetic muscle function testing device. Muscle strength was assessed using concentric and eccentric contractions alternating between the dominant and non-dominant sides, and paired sample t-tests were used for the analysis. Results : There was no significant difference between bilateral peak torques for eccentric contraction in shoulder joint abduction, extension, and flexion (p>0.05). There was also no significant difference between bilateral peak torques for concentric contraction in shoulder joint abduction, extension and flexion (p>0.05). Conclusion : This study found no statistically significant difference in muscle strength between the dominant and non-dominant sides during concentric and eccentric contractions. However, previous studies have shown significant differences between the dominant and non-dominant sides during eccentric and concentric contractions during internal shoulder rotation in the general population, as well as significant differences in the upper trapezius muscle. Therefore, further research is needed to support the application of different intensities for bilateral muscle strengthening exercises in clinical practice.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2008.03a
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• pp.135-135
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• 2008