• The Journal of Korean Physical Therapy
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• v.33 no.5
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• pp.252-257
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• 2021

Purpose: The purpose of this study was to compare the influence of external scapular stabilization on the isometric strength of shoulder flexor muscle in subjects with and without scapular winging and conditions with and without external scapular stabilization. Methods: A total of 30 subjects with and without scapular winging were enrolled. Two groups were classified using clinical and diagnostic tests to divide the groups with and without scapular winging (15 with scapular winging 15 without scapular winging). The isometric strength of the shoulder flexor was measured using a tensiometer. The isometric strength was evaluated in the sitting position with and without an external scapular stabilization. The external scapular stabilization was provided with the examiner's hand to fix scapular winging during shoulder flexion. The changing value was calculated to determine the isometric strength difference between shoulder flexion with and without the external scapular stabilization in each group. The changing value between isometric strength of shoulder flexor with and without scapular winging was compared using the independent t-test. Statistical significance was set at 0.05. Results: In the group with scapular winging, the shoulder flexor isometric strength in the sitting position was greater with an external scapular stabilization than without an external scapular stabilization (p<0.05). There was no significant difference in the shoulder flexor isometric strength in the subjects without scapular winging between conditions with or without an external scapular stabilization (p>0.05). Conclusion: The external scapular stabilization in the individuals with scapular winging may increase shoulder flexor isometric strength in the sitting position.

• Korean Journal of Exercise Nutrition
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• v.17 no.2
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• pp.25-34
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• 2013

This study was conducted to investigate the relationship between ACE gene polymorphism and muscle damage parameters after eccentric exercise. 80 collegiate males were instructed to take an eccentric exercise with the elbow flexor muscle through the modified preacher curl machine for 2 sets of 25 cycles (total 50 cycles). The maximal isometric strength, muscle soreness, creatine kinase (CK), and myoglobin (Mb) were measured before exercise, and 0, 24, 48, 72, and 96 hrs after exercise. The result showed that after the eccentric exercise, the maximal isometric strength significantly decreased by more than 50% (p < 0.001) and the muscle soreness, CK, and Mb significantly increased compared to those before the exercise (p < 0.001). The ACE gene polymorphism of the subjects was classified using real-time polymerase chain reaction (real-time PCR). The result showed that it consisted of 38 cases of type II (46.4%), 33 cases of type ID (43.4%), and 9 cases of type DD (10.2%). The Hardy-Weinberg equilibrium for ACE gene polymorphism was shown to have p = 0.653, which showed that each allele was evenly distributed. Although significant differences in the changes in the maximal isometric strength, muscle soreness, CK, and Mb were found according to time course (p < 0.001), no significant differences in the changes in the maximal isometric strength, muscle soreness, CK, and Mb were found according to ACE gene polymorphism. Furthermore, no significant difference in the changes in the muscle damage parameters was found according to interaction between ACE gene polymorphism and time course (p > 0.05). In conclusion, the level of the muscle damage parameters changed in the injured muscle after eccentric exercise, but these changes in the muscle damage parameters were not affected by ACE gene polymorphism. The result of this study indicates that ACE gene is not a candidate gene that explains muscle damage.

• Physical Therapy Korea
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• v.27 no.4
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• pp.241-249
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• 2020

Background: Prolonged standing during work causes a lower extremity pain and disorders. Patellofemoral pain syndrome (PFPS) is one of the common diagnoses of the knee pain. Although the etiology of PFPS is not completely understood, it is considered to be multifactorial. Objects: The purpose of this study was to investigate difference in strength of knee muscles, quadriceps:hamstring muscles strength ratio (Q:H ratio), asymmetry ratio of knee muscles strength and dorsiflexion range of motion (ROM) between standing workers with and without PFPS. Methods: Twenty-eight standing workers with PFPS and 26 age-, height-, and weight-matched standing workers without PFPS participated in this study. A tension sensor measured knee muscle strength, and motion sensor measured dorsiflexion ROM. The asymmetry ratio of knee muscles was calculated by a specific formula using the knee muscles strength of the dominant side and the sound side. An independent t-test was used to identify significant differences in the strength, ROM, Q:H ratio, and asymmetry ratio between the PFPS and normal groups. Results: The standing worker with PFPS have significantly lower dorsiflexion ROM (p < 0.000) and higher asymmetry ratio of the hamstring muscles strength (p < 0.000) compare to the standing worker without PFPS. No significant differences were seen in the strength of quadriceps muscle and hamstring muscles, Q:H ratio, and asymmetry ratio of quadriceps muscle strength. Conclusion: There was a significant difference in the asymmetry ratio of the isometric hamstring muscle strength. This finding suggests that the asymmetry ratio of isometric hamstring muscle strength may be more important than measuring only the hamstring muscle strength of the PFPS side. Furthermore, the results of this study showed a significant difference in dorsiflexion ROM between the standing industrial workers with and without PFPS. Dorsiflexion ROM and isometric hamstring muscle strength should be considered when evaluating the subjects with PFPS.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.14 no.1
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• pp.31-38
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• 2008

Purpose : The purpose of this study was to compare the effectiveness of both neuromuscular electrical stimulation(NMES) and isometrical exercise(IE) to strengthen the quadriceps femoris muscle. The relationships between the strength changes and the relative force and duration of training contractions were also studied. Methods : The subjects were divided into three group. The control group(n=6) received no exercise and/or stimulation. The isometric exercise (IE) group(n=6) performed maximum isometric contractions, and the neuromuscular electrical stimulation(NMES)(n=6) engaged electrically stimulated isometric contractions, three days a week for four weeks. Results : Results showed that both IE group and NMES group were found to have an increase in strength significantly greater(p<0.05) than the control group at 4 week. But between IE group and NMES group were not found to have an difference in strength significantly. Conclusion : The relative increase in isometric strength, using IE and NMES, may be determined by the ability of the subjects to tolerate longer and more forceful contractions. Suggestions for further research and implications for the clinical of IE and NMES for strength-training are discussed.

• Physical Therapy Korea
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• v.31 no.1
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• pp.18-28
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• 2024

Background: Lateral instability of the ankle is one of the most common causes of musculoskeletal ankle injuries. The peroneus longus (PL) and peroneus brevis (PB) contribute to ankle stability. In early rehabilitation, isometric exercises have been selected for improvement of ankle stability. To effectively train the peroneal muscles during eversion, it is important to consider ankle and body posture. Objects: This study aimed to compare activation of the PL, PB, and biceps femoris (BF) muscles during eversion in different ankle postures (neutral [N], plantarflexed [PF]) and body postures (sitting and side-lying). Methods: Thirty healthy individuals with no history of lateral ankle sprains within the last 6 months were included in the study. Maximal isometric strength of eversion and muscle activation were measured simultaneously. Muscle activation at submaximal eversion was divided by the highest value obtained from maximal isometric eversion among the four postures (percent maximal voluntary isometric contraction [%MVIC]). To examine the differences in muscle activation depending on posture, a 2 × 2 repeated measures analysis of variance (ANOVA) was conducted. Results: There were significant interaction effects of ankle and body postures on PL muscle activation and evertor strength (p < 0.05). The PL muscle activation showed a significantly greater difference in the side-lying and PF conditions than in the sitting and N conditions (p < 0.05). Evertor strength was greater in the N compared to the PF condition regardless of body posture (p < 0.05). In the case of PB and BF muscle activation, only the main effects of ankle and body posture were observed (p < 0.05). Conclusion: Among the four postures, the side-lying-PF posture produced the highest muscle activation. The side-lying-PF posture may be preferred for effective peroneal muscle exercises, even when considering the BF muscle.

• Korean Journal of Applied Biomechanics
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• v.22 no.2
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• pp.201-208
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• 2012

The purpose of this study was to investigate the effect of leg extension exercises performed on outdoor resistance exercise machines on knee extension muscle strength and quadriceps muscle group cross sectional area (CSA) in elderly women. Two groups were recruited for this study, including an exercise group (EG: n=13, $71.38{\pm}2.79$ yrs) and a control group (CG: n=5, $73.4{\pm}5.94$), In all subjects, maximum isometric and isokinetic muscle strength of knee flexion and extension were measured using an isokinetic dynamometer (Cybex(R) Humac Norm Testing & Rehabilitation System, USA). Quadriceps muscle group CSA were measured using MRI (Philps, Intera 1.5 T, NE Netherlands). The results of this study showed that post-intervention isometric knee extension peak torque value were higher than pre-intervention measures in the EG. However, the EG did not show improvement in quadriceps muscle group CSA, Also, no differences in the shift of optimal knee joint angle were observed between pre and post-intervention exercise. Outdoor leg extension exercise showed small increases in muscle strength in comparison to other resistance training exercises. The results of this study suggest that because outdoor leg extension exercise machines lack a progressive loading mechanism, significant increases in muscle strength may not be obtained.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.1
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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.

• Journal of Korean Institute of Industrial Engineers
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• v.7 no.2
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• pp.3-17
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• 1981

Isometric muscle strength has become important as it is realized that a large variation in the human exists and is affected by many personal and environmental factors. Experiments have been performed for estimating the individual capabilities of the quadriceps femoris muscle in man. The surface EMG has been recorded on the belly of the rectus femoris muscle during voluntary isometric continuous exertion at 25%, 50%, 75%, and 100% MVC. As a muscle force (% MVC) increases, the rectified mean EMG amplitude increases in a non-linear form. The rectified mean EMG amplitude also increases in a non-linear with respect to fatigue progression. As the muscle force (% MVC) increases, an endurance time of isometric exertion decreases linearly. Analysis shows that rectified mean EMG amplitude is a consistent and sensitive measure of motor unit recruitments and can be useful in estimating an individual capability of a local muscle. Further, the result satisfies the sufficient condition that type S motor units are recruited first, while large motor units are recruited progressively as the fatigue develops.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.3 no.1
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• pp.1-12
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• 2005

This study aimed at examining the maximal isometric contraction caused by voluntary exercise and at comparing its aspects of decrease and restoration in their different repeated application, as to the quadriceps muscles of thigh in the subjects composed of patients with spastic hemiplegia and normal adults. Using isokinetic exercise analyser(Biodex Medical Systems Inc., Biodex System 3PRO, U.S.A.), experiment was conducted as to the normal group composed of fifteen adults and the patient group composed of fifteen patients with spastic hemiplegia. As to each group, MVIC(maximal voluntary isometric contraction) of the quadriceps muscle of thigh caused by voluntary exercise and the aspects of decrease and restoration of the isometric contraction were examined with the method to induce isometric exercise, and their SDI(strength decrement index) and SRI(strength recovery index) were also calculated. The results can be summarized as follows: 1. As for decrease of maximal isometric contraction, both groups showed slow decrease in voluntary exercise, but the normal group showed rapid decrease later phase. 2. As for SDI, no significant differences could be observed in comparison between groups. 3. As for restoration of maximal isometric contraction, both groups showed slow restoration in voluntary exercise, but the normal group showed rapid restoration early phase. 4. As for SRI, comparison between groups showed significant differences in voluntary exercise. These results lead us to the conclusions that spastic muscle is characterized by slow decrease and restoration of MVIC in comparison with normal muscle in voluntary exercise.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.1
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• pp.61-66
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• 2017

PURPOSE: The purpose of this study was to investigate the effects of isometric upper limb contraction on the trunk and lower extremity muscles during the sit-to-stand activity in elderly females. METHODS: Eighteen healthy elderly females performed three directional isometric upper extremity contractions (flexion, extension, and horizontal abduction movements) using an elastic band during sit-to-stand activity. Electromyography signals were collected from the internal oblique, erector spinae, rectus femoris, and biceps femoris muscles. RESULTS: Internal oblique activity was greater in bilateral shoulder flexion and bilateral shoulder horizontal abduction than in neutral position (p<.05). Erector spinae and rectus femoris muscle activities in bilateral shoulder flexion was greater than in neutral position and bilateral shoulder extension (p<.05). Biceps femoris activity was significantly greater in bilateral shoulder flexion than in bilateral shoulder extension and horizontal abduction, and in neutral position compared to bilateral shoulder extension (p<.05). CONCLUSION: These results suggest that incorporating isometric upper limb contraction may be beneficial for enhancing the contribution of trunk and lower extremity muscle activities to trunk stabilization during sit-to-stand activity. Therefore, isometric upper limb contraction during sit-to-stand tasks, especially in flexion, may be used to elicit contraction of the lumbopelvic region muscles within a tolerable range, for developing endurance and strength in the elderly.