• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.139-148
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• 2009

D. W. HAN. Y. R. AHN., N. J. LEE and E. J. LEE. Effects of Combined Restistance Training Program of Concentric and Eccentric Contraction Using Theraband on Shoulder Rotation Torque Max and Peak Power. Korean Joumal of Sport Biomechanics, Vol. 19, No. 1, pp. 139-148, 2009. The purpose of this study was to find out that combined concentric with eccentric resistance training program using Thera-Band was more effective than only concentric resistance training program on shoulder rotation torque max and peak power. 30 female students were randomly assigned to 3 equal group; concentric and eccentric, concentric, non training group. Subjects were tested in concentric and eccentric torque max and peak power of internal and external rotation using a CON-TERX isokinetic dynamometer. Subjects in training group participated in their regular five times a week for 4 weeks. After exercise, in concentric and eccentric training group, concentric and eccentric torque max, and peak power of internal rotator at 60 deg/sec were increased significantly. concentric peak power at 120 deg/sec were increased significantly. In concentric training group, only concentric peak power of internal rotator at 60 and 120 deg/sec was increased. In conclusion, we found out that combined concentric with eccentric resistance training program using Thera-Band was more effective than only concentric resistance training program on shoulder rotation torque max and peak power.

• PNF and Movement
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• v.2 no.1
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• pp.25-33
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• 2004

Purpose : The purpose of this article is to summarize the characteristics of isotonic combination. Method : Some studies of the motor unit activation patterns during isometric, concentric, and eccentric actions, neural strategies in the control of muscle force, and concentric versus combined concentric-eccentric training were reviewed. Results & Conclusions : Eccentric torque may be relatively higher than concentric torque for two potential reasons: 1) stretch responses in the antagonist are not elicited to restrain the motion as can occur concentrically and 2) stretch responses in the agonist may augment eccentric torque production. Concentric-eccentric training has a greater influence on functional capacity than that of concentric training. Both maximal force and average force throughout the motion were significantly higher when the dynamic action was started with preactivation as compared to the mode without preactivation. The peak torques observed during the concentric phase of the eccentric-concentric muscle actions were higher than those noted in the pure concentric contraction.

• The Journal of Korean Physical Therapy
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• v.16 no.4
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• pp.1-10
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• 2004

The purpose of this study was to investigate the effects of treadmill aerobic exercise training on isokinetic muscle strength in students with cerebral palsy. The subjects consisted of 9 female students with cerebral palsy between the ages of 10 to 22. The subjects performed treadmill aerobic exercise training with $0\%$ grade by free speed with three times a week for 20 minutes a session and 12 weeks. Concentric peak torque of knee flexors and knee extensors was measured before training and after training at $30^{\circ}/sec$ and $60^{\circ}/sec$ by isokinetic dynamometer. Paired t-test was used to assess changes in variables of isokinetic muscle strength. The results of analysis are as followings. 1) After training, concentric peak torque of the least affected knee flexors(p<.01) and the most affected knee flexors (p<.01) and concentric peak torque of the least affected knee extensors(p<.01) and the most affected knee extensors(p<.01) at $30^{\circ}/sec$ significantly increased. 2) After training, concentric peak torque of the least affected knee flexors(p<.05) and the most affected knee flexors(p<.01) and concentric peak torque of the least affected knee extensors(p<.05) and the most affected knee extensors(p<.01) at $60^{\circ}/sec$ significantly increased. These findings provide evidence that treadmill aerobic exercise training improves isokinetic muscle strength in students with cerebral palsy.

• The Journal of Korean Physical Therapy
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• v.15 no.2
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• pp.168-181
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• 2003

The purpose of this study was to investigate the effects of circuit weight training(CWT) on isokinetic muscle strength and body composition in elderly. The subjects who engaged in this experiment exercised at 40$\%$ of 1-RM, 12 repetitions, followed by 15 sec as the subject moved to the each break training program which was consist of the circuit of 10 stations performed on 3 set a day, circuits 3 days a week during 10 weeks. The assessment of isokinetic factor was in concentric flexors and extensors of right and left knee joint. Tests were performed on the Cybex 770 Isokinetic Dynamometer and body composition were estimated the three parts of chest, abdomen and anterior thigh by using skinfold caliper, calculated the average and followed by Seri and Brozek way. Statistical analysis were performed using analysis of variance paired t-test, accepting level for all significant was above $\alpha$=.05 and $\alpha$=.01. Following is as a result of 10 weeks circuit weight training. 1. At the $60_{\circ}$ /sec, the right and left knee isokinetic concentric flexors and extensors peak torque increased significantly (p < .01). 2. At the $180_{\circ}$ /sec, the right and left knee isokinetic concentric flexors and extensors peak torque increased significantly (p < .01). 3. At the $60_{\circ}$ /sec, the right and left knee isokenetic concentric flexors and extensors average power increased significantly(p < 0.5, p < .01) and at the $180_{\circ}$ /sec, the right extensors didn't show any statistical significant. 4. At the $60_{\circ}$ /sec, the right and left knee Isokinetic concentric flexors and extensors total work increased significantly(p < .05, p < .01) but at the $180_{\circ}$ /su right concentric flexors didn't show any statistical significant. 5. The body composition changed significantly(p < .01). These results suggest that 10 weeks circuit weight training increases the peak torque, average power, total work significantly and decreases the $\%$body fat significantly.

• The Journal of Korean Physical Therapy
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• v.15 no.4
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• pp.398-411
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• 2003

The purpose of this study was to investigate the effects of circuit weight training(CWT) on isokinetic muscle strength and body composition in elderly. The subjects who engaged in this experiment exercised at $40\%$ of 1-RM, 12 repetitions, followed by 15 sec as the subject moved to the each break training program which was consist of the circuit of 10 stations performed on 3 set a day, circuits 3 days a week during 10 weeks. The assessment of isokinetic factor was in concentric flexors and extensors of right and left knee joint. Tests were performed on the Cybex 770 Isokinetic Dynamometer and body composition were estimated the three parts of chest, abdomen and anterior thigh by using skinfold caliper, calculated the average and followed by Seri and Brozek way. Statistical analysis were performed using analysis of variance paired t-test, accepting level for all significant was above ${\alpha}=.05$ and ${\alpha}=.01$. Following is as a result of 10 weeks circuit weight training. 1. At the $60_{\circ}$ /sec, the right and left knee isokinetic concentric flexors and extensors peak torque increased significantly(p<.01). 2. At the $180_{\circ}$ /sec, the right and left knee isokinetic concentric flexors and extensors peak torque increased significantly(p<.01). 3. At the $60_{\circ}$ /sec, the right and left knee isokenetic concentric flexors and extensors average power increased significantly(p<.05, p<.01) and at the $180_{\circ}$ /sec, the right extensors didn't show any statistical significant. 4. At the $60_{\circ}$ /sec, the right and left knee Isokinetic concentric flexors and extensors total work increased significantly(p<.05, p<.01) but at the $180_{\circ}$ /sec right concentric flexors didn't show any statistical significant. 5. The body composition changed significantly(p<.01). These results suggest that 10 weeks circuit weight training increases the peak torque, average power, total work significantly and decreases the $\%$body fat significantly.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.1
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• pp.87-98
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• 2023

Purpose : This study was to verify the effectiveness of eccentric training and to make clinical recommendations on detailed application methods by comparing the effects of changes in acromiohumeral distance (AHD), pain intensity, muscle strength, and functional performance after applying a 12-week eccentric training program (ET group) or concentric training program (CT group) for patients with partial rotator cuff (supraspinatus) tears with moderate to severe shoulder pain. Methods : A total of 29 subjects were assigned to either the "ET group (n=15)" or the "CT group (n=14)" through simple randomization and were measured in the same way at baseline before intervention, 4 weeks and 12 weeks after intervention. All subjects received a physical therapy program 12 sessions 3 times a week for the first 4 weeks, and physical therapy program, 12 sessions a week, from 4 weeks to 12 weeks, for a total 20 sessions. Ultrasound machine was used for AHD, visual analog scale (VAS) was used for pain intensity, electronic hand held dynamometer was used for muscle strength, Korean Constant shoulder score (K-CSS) used for functional performance. Results : AHD, pain intensity, and muscle strength did not show significant differences at 4 weeks, but improved numerically, and showed significant differences at 12 weeks (p<.05), showing superior results in the eccentric training group compared to the concentric training group. Functional performance showed significant changes at both 4 and 12 weeks (p<.05), and excellent results were also found in the eccentric training group. Conclusion : In patients with partial rotator cuff tears with moderate to severe shoulder pain, an eccentric training program increased acromiohumeral distance (AHD), reduced pain, and increased muscle strength. Therefore, it can be clinically presented as an intervention method that can quickly and effectively improve functional performance, which is the ultimate goal of physical therapy.

• Physical Therapy Korea
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• v.12 no.3
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• pp.94-100
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• 2005

Eccentric muscle contraction is more effective than concentric and iosmetric muscle contraction in increasing muscle strength. Also, eccentric or concentric-eccentric training has greater effective in neural activation and muscle hypertrophy than concentric training. In some study, eccentric exercises have been shown to reduce pain and improve function on Achilles tendinopathy. The purpose of this study was to evaluate the effect of eccentric isokinetic exercise in a patient with dislocation of the tarsometatarsal joint by traffic accident. After eccentric isokinetic training, peak torque, average work, and average power were increased. Also, the patient was fully weightbearing with a pain free normal gait thus making good recovery.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.219-228
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• 2022

Purpose : The purpose of this study was to suggest a more effective method by comparing the effects of changes in pain intensity, muscle strength, and athletic performance after applying a 6-week eccentric training program (ET-MWM) or concentric training program (CT-MWM) with MWM for high school baseball players with shoulder internal impingement (SII). Methods : A total of 75 participants were randomly assigned to each group and divided into two groups, "ET-MWM group (n=35)" and "CT-MWM group (n=32)" according to the intervention method. Pain intensity, muscle strength (external rotation, internal rotation), and athletic performance were first measured before the intervention, and after the intervention 3 times a week for a total of 6 weeks, both groups were re-measured in the same way. Visual analog scale (VAS) was used for pain intensity, biodex dynamometer for muscle strength (60 °/sec.), and Kerlan-Jobe orthopedic clinic shoulder & elbow score (K-KJOC) for athletic performance. Results : As a result of analyzing the homogeneity of the pre-intervention characteristics and initial measurement variables of the study subjects, there was no significant difference between the two groups in all variable values. Pain intensity (VAS) was significantly reduced in the ET-MWM group than in the CT-MWM group (p<.05). In addition, the maximum muscle strength of external rotation & internal rotation of the shoulder (60 °/sec.) and athletic performance (K-KJOC) were significantly increased in the ET-MWM group than in the CT-MWM group (p<.05). Conclusion : Compared with the CT-MWM training program, the ET-MWM training program reduced shoulder joint pain and further increased the muscle strength required for throwing motion in high school baseball players. As the result showed better athletic performance improvement, the ET-MWM training program can be clinically recommended as a more effective intervention.

• The Journal of Korean Physical Therapy
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• v.14 no.4
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• pp.260-265
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• 2002

There are many methods for muscle strengthening. Muscle strengthening with eccentric contraction work is the best way by researcher's report. Also, eccentric contraction need proper resistance for muscle strengthening. Combination of isotonic in PNF is a muscle strengthening method with manual resistance. It makes concentric contraction $\rightarrow$ eccentric contraction $\rightarrow$ concentric contraction with continually and without muscle relaxation. Combination isotonic technique use with PNF pattern. Therefore, it will make development and increasing of active control motion, coordination, actual range of motion, strengthen and functional training in eccentric control of movement. Concentric contraction have the 3rd lever system and eccentric contraction have the 2nd lever system with combination of isotonic. Serial concentric contraction $\rightarrow$ eccentric contraction $\rightarrow$ concentric contraction make strong SEC and PEC. It will be increase elasticity of SEC, PEC and contractile components either.

• Korean Journal of Applied Biomechanics
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• v.28 no.1
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• pp.37-43
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• 2018

Objective: The aim of this study was to analyze muscle activation of the lower extremities as a function of changes of the center of pressure (CoP) of the foot during squats in order to provide quantitative information to trainers who would like to teach correct movements for developing muscles. Method: Ten men with over three years of weight training experience participated in this study (age: $26.1{\pm}0.8yrs$, height: $171.2{\pm}3.9cm$, body mass: $71.1{\pm}5.7kg$, 60%RM: $84{\pm}9kg$, career: $4.0{\pm}0.7yrs$). The participants were instructed to perform a squat in each of 3 conditions, with different CoP's (the front, middle, and rear of the foot). Results: The position of the CoP showed significant differences according to instructions in both the eccentric and concentric contraction phases (p < .05). The range of movement of the hip and ankle joints showed significant differences corresponding to changes of the CoP position (p < .05). The rectus femoris and gluteus maximus muscle showed significant differences for different CoP positions only in the concentric contraction phase, while the gastrocnemius and anterior tibialis were significantly different in both the concentric and eccentric contraction phase (p < .05). Conclusion: When the target muscle of squat training is the gastrocnemius, the CoP should be located in the front of the foot for effective muscle training. When the target muscles of squat training are the gluteus maximus and quadriceps femoris, the CoP should be located on the rear of the foot.