• The Journal of Korean Physical Therapy
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• 제18권3호
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• pp.37-45
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• 2006

Purpose: This study analyzed changes in spinal neuron and action potential of motor unit depending on voluntary contraction on spinal neuron adaptation. Methods: It selected 80 university students in their twenties and divided into experimental groups of 25% MVIC (I), 50% MVIC (II), 75% MVIC (III) and 100% MVIC (IV) depending on maximum voluntary isometric contraction (MVIC) and performed isometric exercise of plantar flexor muscle to each experimental group with given contraction for 20 times. It measured Mmax, H/Mmax, Hmax latency, V/Mmax, V wave latency before and after exercise, compared method and volume of contraction. Results: H/Mmax ratio showed significant difference in comparison among groups (p<0.01) and there was difference in I and IV groups. V/Mmax ratio showed significant difference in comparison among experimental groups (p<0.05) and there was difference in I and IV groups. When voluntary contraction level was maximum, changes were greatest. However, no significantly difference was to Mmax, H latency and V wave latency. Conclusion: These results suggest that amplitude changes of voluntary contraction level, spinal neuron and supra-spinal neuron had a dose connection that the more contraction level, the better central activation seem to decrease highly for a short time.

• The Journal of Korean Physical Therapy
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• 제18권1호
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• pp.53-64
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• 2006

Purpose: The present study purposed to examine the effects of massage and stretching on the recovery of muscle contraction force for muscle fatigue caused by sustained isometric contraction. Methods: The subjects of this study Were 64 healthy men and women (women: 30, men: 34). They Were divided into massage group (23), stretching group (21) and rest group (20), and using Biodex System we observed the pattern of changes in maximal voluntary contraction force (MVC) after causing muscle fatigue in quadriceps femoris muscle through sustained isometric contraction. Results: We measured the point of fatigue occurrence by sustained isometric contraction with 50% MVC and changes in isometric contraction force at 0, 10, 20 and 30 minutes after fatigue and compared them according to gender and treatment group. Conclusion: 1. According to the result of measuring the point of time when fatigue occurred, a difference was observed in time to task failure between men and women. It was significantly longer in women. 2. By gender, MVC changed significantly in all time frames in women, but it showed significant increases only at 10 minutes after fatigue in men. 3. In the comparison of MVC among the treatment groups, it showed significant differences among the groups at 10 minutes after fatigue. 4. In the comparison of changes in MVC among the time frames for each group, the rest group showed significant differences in MVC between 0 and 10 minutes after fatigue and between 20 and 30 minutes after fatigue. The massage group showed significant differences in MVC between 0 and 10 minutes after fatigue and between 10 and 20 minutes after fatigue. The stretching group showed a significant difference in MVC between 10 and 20 minutes after fatigue and between 20 and 30 minutes after fatigue.

• 대한물리치료과학회지
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• 제28권2호
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• pp.19-29
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• 2021

Background: The purpose of this study was to investigate the effects of pulsed-ultrasound intervention and continued-ultrasound on the MVIC (maximal voluntary isometric contraction) and active ROM (range of motion) recovery of before EIMD (exercise-induced muscle damage). Design: Randomized controlled trial. Methods: Thirty subjects who are student in their 20s at a university participated in this study, these subjects were assigned into three groups, a control group (n=10), experiment group I (n=10) and experiment group II (n=10). The subjects in experimental group were intervened by pulsed-ultrasound and continued-ultrasound, while ones on control group weren't by any intervention after induced EIMD. Results: First, In comparison of the MVIC, in the among group comparison, the MVIC of continued-ultrasound group was significantly larger than those of other groups (p<.005). Second, In the among group comparison, the active extension angle of continued-ultrasound group was significantly smaller than those of other groups (p<.005). Third, In the among group comparison, the active flexion angle of continued-ultrasound group was significantly lager than those of other groups (p<.05). Conclusion: The above results revealed that the continued-ultrasound intervention before an exercise had a significantly improve of muscle function after EIMD. Therefore we can consider the continued ultrasound as a considerable intervention method to prevent or reduce an exercise injury.

• 운동영양학회지
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• 제16권1호
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• pp.43-50
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• 2012

This study was designed to investigate the effect of vibratory stimulation on recovery of muscle function from delayed onset muscle soreness (DOMS). Volunteers performed 3 set of 70 % maximal voluntary eccentric muscle contraction and induced DOMS. volunteers were allocated to one of three treatment group after DOMS : group I (control), group II (ultrasound), group III (vibration). Maximal Voluntary Isometric Contraction (MVIC), Visual Analog Scale (VAS), Range Of Motion (ROM), Root Mean Square (RMS), Median frequency (MDF), Blood Serum Creatine Kinase (CK), Lactic dehydrogenase (LDH) were recorded at baseline, and 24, 48, 72 hours post-exercise. In MVIC measurement, there was a statistically significant difference in group III compared to group I (p < .05). In VAS measurements, there were a statistically significant difference in group II and III compared to group I (p < .05). In ROM measurement, there was a statistically difference in group II and III compared to group I (p < .05). In Muscle Volume with Ultrasonography measurement, there was no statistically significant difference in any groups (p > .05). In RMS and MDF measurement, there were a statistically significant difference in group II and III compared to group I (p < .05). In Blood samples of CK and LDH measurements, There were no statistically significant difference in any groups (p > .05). From the above result, Vibratory stimulation had a positive effect on recovery of muscle function from delayed onset muscle soreness. Further studies should be undertaken to ascertain the more effectiveness of vibratory stimulation and may be a promising treatment modality.

• 한국운동역학회지
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• 제31권2호
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• pp.140-147
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• 2021

Objective: The purpose of this study is to identify the mechanism of changes in maximum voluntary torque with the magnitude and duration of pre-activation torque during voluntary isometric knee extension. Method: 11 male subjects (age: 25.91±2.43 yrs., height: 173.12±3.51 cm, weight: 76.45±7.74 kg) participated in this study. The subjects were required to produce maximal voluntary isometric torque with a particular pre-activation torque condition. The properties of pre-activation torque consisted of the combinations of 1) three levels of magnitude, e.g., 32 Nm, 64 Nm, 96 Nm, and 2) two levels of duration, e.g., 1 sec, and 3 sec; thus, a total of six conditions were given to the subjects. The force and EMG data were measured using the force transducers and wireless EMG sensor, respectively. Results: The results showed that the maximum voluntary torque increased the most with relatively large and fast (96 Nm, 1 sec) pre-activation condition. Similarly, with relatively large and fast (96 Nm, 1 sec) preactivation, it was found that the integrated EMG (iEMG) of the agonist muscles increased, while no significant changes in the co-contraction of the antagonist muscles for the knee extension. Also, the effect of pre-activation conditions on the rate of torque development was not statistically significant. Conclusion: The current findings suggest that relatively larger in magnitude and shorter in duration as the properties of pre-activation lead to a larger magnitude of maximal voluntary torque, possibly due to the increased activity of the agonist muscles during knee extension.

• 한국전문물리치료학회지
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• 제9권3호
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• pp.101-111
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• 2002

The purpose of this study was to determine EMG biofeedback training effect on the muscle activities in 3 unilateral facial palsy patients along with multiple baseline design across subjects. The auditory feedback about facial muscles (orbicularis oris, orbicularis oculi, frontalis) was provided with each patient during facial exercise training. Electromyographic (EMG) activity during maximal voluntary contraction and maximal compound muscle action potential (CMAP) amplitude elected by supramaximal electrical stimulation on facial nerve of facial muscles were measured pre- and post- EMG biofeedback training to evaluate motor learning. EMG activity during maximal voluntary contraction was increased after EMG biofeedback training and CMAP amplitude elected by supramaximal electrical stimulation was not changed in all subjects. The results indicate that EMG biofeedback training is useful method to improve motor learning of facial excercise training in unilateral facial palsy patients.

• Physical Therapy Rehabilitation Science
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• 제10권1호
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• pp.82-89
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• 2021

Purpose: This study is to investigate the muscle activity based on real-time visual feedback training methods by rehabilitative ultrasound image in elderly and correlation between Heckmatt scale grade, muscle tone and thickness. Design: Cross-sectional study: Pilot study Methods: 6 elderly participated in the study with 2 conditions. Under the condition of rehabilitation ultrasound imaging equipment, all subjects performed voluntary maximal muscle contraction of the quadriceps 3 times using visual feedback based on Rehabilitative Ultrasound Imaging 1.0 (RUSI 1.0). Under the condition of only ultrasound images, all subjects performed voluntary maximal muscle contraction of the quadriceps 3 times using ultrasound image-based visual feedback. The muscle thickness and tone of the quadriceps were measured and the grades were classified by Heckmatt scale and all variables were comparative analyzed. Results: Heckmatt scale grade showed a negative correlation with muscle thickness at relaxation (p<0.05), and a negative correlation with the difference value obtained by subtracting muscle thickness at relaxation from muscle thickness at contraction in ultrasound image condition (p<0.05). The muscle tone during relaxation showed a negative correlation with the muscle thickness during relaxation (p<0.05). Conclusion: In the case of voluntary maximum muscle contraction of the quadriceps muscle in the elderly, it can be seen that the muscle thickness is getting larger when the RUSI 1.0-based visual feedback is provided than with only ultrasound image provided. And the lower Heckmatt scale grade is, the thicker the muscle is, and the lower the muscle tone is.

• 한국운동역학회지
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• 제15권3호
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• pp.51-59
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• 2005

To examine the influence of aging on the mechanism of muscle fatigue, we compared the magnitude of central and peripheral fatigue in young and old women before, during and after a sustained submaximaI isometric contraction of elbow flexor muscles. Twelve women (6 young. $20.7{\pm}1.2$ years and 6 old, $68.8{\pm}29$ years) performed a contraction at 20% of maximal voluntary contraction (MVC) torque with their non-dominant arm. The old women were weaker than the young women, however their endurance time for the 20% contraction was longer compared with the young women ($1822{\pm}444$ vs. $1061{\pm}678$ sec, P <. 05). Both groups had a similar reduction in voluntary activation ratio (VA) during and after the fatiguing contraction. However, the old women showed much greater variability in VA before and after the contraction ($91.61{\pm}4.54%$ and $76.70{\pm}19.55\;%$ range of $79{\sim}99$ to $87{\sim}99%$ respectively) compared with the young women ($95.71{\pm}1.86\;%$ and $83.46{\pm}7.57\;%$ range of $39{\sim}75$ to $69{\sim}90%$, respectively). Furthermore, the EMG activity of the elbow flexor muscles and triceps brachii was greater for the old women compared with the young women throughout the fatiguing contraction, indicating different activation strategies with age. Indices of peripheral fatigue including twitch properties, showed that fatigue within the muscle was more rapid for the young women compared with the old women. These results suggest that although old women are weaker than young women, they have greater endurance due to mechanisms within muscle. Furthermore, old women showed great variability in their ability to optimally activate all muscle fiber compared with young women for an isometric contraction.

• 대한임상전기생리학회지
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• 제7권1호
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• pp.43-48
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• 2009

Purpose : The purpose of this study was to study the effect of rectus abdominal muscle contraction by proprioceptive neuromuscular facilitation trunk stabilization training using extremity simultaneous pattern (PNF trunk stabilization training) and traditional trunk stabilization training methods. Methods : A group of 24 adults male and female, healthy, with no previous medical history nor disability in neuromuscular system and musculoskeletal system was chosen as subjects, and was divided into a control group, a PNF trunk stabilization training group and a traditional trunk stabilization training group. Experiments were performed on the last two groups, 3 times a week for 6 weeks, totaling 18 times. Using a dynamometer, muscle strength and endurance time on trunk flexion were measured before and after each experiment, and surface electromyography in left and right rectus abdominis were measured. Results : following results were obtained; 1. As for the change in the maximal voluntary isometric contraction (MVIC), all subjects in the trunk stabilization training group showed significant difference from those in the control group. 2. As for surface electromyography measurement and the changes in root mean square at the time of trunk flexion, in the left rectus abdominis, PNF trunk stabilization training group showed significant difference from the control group, while in the right rectus abdominis, traditional trunk stabilization training group showed significant difference. Conclusion : To sum up the results, both trunk stabilization training groups showed improvement in the MVIC of abdominal muscle, motor unit action potential activity, but the difference between two trunk stabilization training groups was not significant. Therefore, while trunk stabilization training significantly improved abdominal muscle contraction, but the difference attributable to training methods was found to be insignificant.

• 대한임상전기생리학회지
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• 제10권1호
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• pp.39-44
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• 2012

Purpose : This study purposed to analyze how dynamic stabilization exercise on an unstable surface, and static stabilization exercise on muscle strength and endurance. Methods : For this study we sampled 9 people for the unstable surface dynamic stabilization exercise group, 9 for the stable surface static stabilization exercise group, and 9 for the control group. In order to examine muscle strength and endurance, we measured changes in the maximal voluntary isometric contraction (MVIC) using a dynamometer before, 3 weeks after, and 6 weeks after the experiment. Results : First, with regard to change in muscle strength, flexion strength showed a significant change in interaction by time (p<0.05). Extension strength showed a significant change in interaction by time (p<0.05). Second, with regard to change in endurance, flexion endurance showed a significant change in interaction by time (p<0.05). Extension endurance showed a significant change in interaction by time (p<0.05). Conclusion : In conclusion, this study confirmed significant changes in interaction between the groups and by time with regard to changes in muscle strength and endurance. These results suggest the potential of surface dynamic stabilization exercise as a clinical intervention.