• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.611-613
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• 1998

A structure of musculotendon model with a fatigue profile is investigated. The Hill-type musculotendon model can predicts the decline in muscle force for a given fatigue profile. It consists of nonlinear activation and contraction dynamics based on the physiological concepts. It is normalized for generalization to deal with the various muscles. Muscle force generated by continuous tetanic electrical monophasic pulsewidth modulation stimulation is decreased in time. A fatigue profile is expressed by a function of intramuscular acidification and applied to the relationship between muscle force and shortening velocity in contraction dynamics. The results of computer simulation are well matched with data in a literature which are isometrically performed for knee extension muscles. Also change in optimal fiber length has an effect only on muscle time, constant not on the steady-state tetanic force.

• 대한물리의학회지
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• 제15권1호
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• pp.55-63
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• 2020

PURPOSE: This study examined the effects of handgrip exercise, which was started two weeks after surgery for shoulder rotator cuff repair, on the extent of muscle activation around the shoulder and the cross-sectional area of the supraspinatus muscle. METHODS: Among patients diagnosed with rotator cuff rupture by an orthopedic surgeon and rotator cuff repair was performed using an arthroscope, 28 were selected as subjects. These subjects were allocated randomly to the experimental group and control group with 14 subjects in each group. An electromyogram was measured as a measure of the extent of muscle activation around the shoulder for a total of six times (%RVC). The cross-sectional area of the supraspinatus muscle was measured before and after the rotator cuff repair by magnetic resonance imaging. RESULTS: The extent of muscle activation in accordance with time in both the experimental group and control group displayed significant differences in various muscles including the anterior deltoid, pectoralis major, upper trapezius and infraspinatus muscle(p<.05). A significant difference in the variation of the cross-sectional area of the supraspinatus muscle was observed between the experimental group and the control group(p<.05). CONCLUSION: Handgrip exercise helps rehabilitate the shoulder joint at the acute stage after rotator cuff repair when assertive exercise therapy cannot be applied.

• PNF and Movement
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• 제16권1호
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• pp.143-150
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• 2018

Purpose: The purpose of this study was to investigate the influence of opposite lower extremity lateral muscle activation by proprioceptive neuromuscular facilitation (PNF) exercise targeting the lower extremities. Methods: Nineteen patients with chronic hemiplegia volunteered to participate in this study. PNF flexion, abduction, and internal rotation patterns; initial, end range, and extension patterns; abduction and internal rotation patterns; and initial and end range patterns were applied to the dominant lower extremity. Activation of lateral muscles (multifidus, gluteus medius, tensor fascia lata, and peroneous longus) of the paralyzed leg was then measured by electromyography (EMG). Results: There were significant differences in lateral muscle activation, depending on the PNF pattern applied, with the differences more significant in flexion, abduction, internal rotation, and end range patterns. Conclusion: PNF flexion, abduction, and internal rotation patterns can improve lateral muscle activation of one leg in the standing position in the gait cycle.

• PNF and Movement
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• 제17권1호
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• pp.111-118
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• 2019

Purpose: This study aimed to investigate the correlation between trunk stabilization muscle activation and the parameters of gait analysis in healthy individuals. Methods: Thirty healthy adults (15 male, 15 female) with no history of lower back pain (LBP) or current musculoskeletal and neurological injuries were studied. Trunk stabilization muscle activation (e.g., external oblique, internal oblique, transverse abdominis, erector spinae) were assessed using surface electromyography. To analyze gait, we measured temporal parameters (e.g., gait velocity, single support phase, double support phase, swing phase, and stance phase) and a spatial parameter (e.g., H-H base of support). Results: A statistically significant correlation was found between the internal oblique, transverse abdominis, and erector spinae muscle activity and gait velocity, single support phase, double support phase, swing phase, and stance phase. No statistically significant correlation was found between the external oblique muscle activity and the gait velocity, single support phase, double support phase, swing phase, and stance phase. No statistically significant correlation was found between the external oblique, internal oblique, transverse abdominis, and erector spinae muscle activity and the spatial parameter. Conclusion: This study demonstrated that a relationship exists between trunk stabilization muscle activation and temporal parameter (i.e., gait velocity, single support phase, double support phase, swing phase, and stance phase) during gait analysis. Therefore, the trunk's stabilizer muscles play an important role in the gait of healthy individuals.

• PNF and Movement
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• 제20권2호
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• pp.285-293
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• 2022

Purpose: The purpose of this study was to confirm that the activation of the contralateral muscles changes according to posture after applying the proprioceptive neuromuscular facilitation leg pattern. Methods: Ten healthy adults (four males and six females) with no history of current musculoskeletal/neurological injuries were recruited for this study. Abdominal muscle (transverse abdominis) and hip joint muscle (gluteus maximus and gluteus medius) activation was assessed using surface electromyography (Ultium EMG, Noraxon Inc., USA). We evaluated muscle activation during the application of the PNF leg pattern. The data were analyzed using the SPSS version 21.0 program. Results: The results were found to be statistically significantly different in the 90/90 supine posture and sitting posture for the gluteus maximus (p < 0.05). The results were found to be not statistically significantly different for the transverse abdominis according to posture (p > 0.05). The results were found to be not statistically significantly different for the gluteus medius according to posture (p > 0.05). Conclusion: Application of the PNF leg pattern resulted in a significant change in the muscle activation of the contralateral segment according to posture, and the 90/90 supine posture induced high muscle activation of the gluteus maximus. In addition, the activation of the transverse abdominis was high in all three postures.

• Physical Therapy Rehabilitation Science
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• 제13권1호
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• pp.53-70
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• 2024

Background: The conventional deadlift is a popular exercise for enhancing trunk, core, and lower extremity strength. However, its use in sports medicine is constrained by concerns of lumbar injuries, despite evidence supporting its safety and rehabilitative benefits. To optimize muscle activation using resistive bands in variable resistance therapy, we explored their feasibility in the deadlift. Design: Comparative experimental design Methods: Surface electromyography recorded muscle activity in the trunk and lower extremities during lifting, with normalization to the isometric Floor Lift using Maximal Voluntary Contraction. Kinematics were measured using inclinometer sensors to track hip and trunk sagittal plane angles. To prevent fatigue, each subject only used one of the three pairs of bands employed in the study. Results: Our study involved 45 healthy subjects (mean age: 30.4 ± 6.3 years) with similar baseline characteristics, except for years of lifting and strength-to-years-of-lifting ratio. Various resistance band groups exhibited significantly higher muscle activity than conventional deadlifts during different phases. The minimal resistance band group had notably higher muscle activity in the trunk, core, and lower extremity muscles, particularly in the end phase. The moderate resistance band group showed increased muscle activity in the mid-and end-phases. The maximum resistance band group demonstrated greater muscle activity in specific muscles during the early phase and overall higher activity in all trunk and lower extremity muscles in the mid and end phases of the deadlift (p<0.05). Conclusion: Our findings provide valuable insights into muscle activation with various resistance bands during deadlift exercise in clinical and gym settings. There appears to be a dose-response relationship between increased resistance bandwidth, external load, myoelectric activation, and range.

• 대한물리의학회지
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• 제6권2호
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• pp.215-223
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• 2011

Purpose: The purpose of this study was to determine the effect of leg muscle activation by applying proprioceptive neuromuscular facilitation (PNF) arm patterns to unilateral upper extremities under the condition of both open and closed kinetic chains in a seated position. Methods: Twenty-two healthy subjects participated in this study. Four PNF patterns were applied to each subject's unilateral upper extremity. EMG data were collected from the vastus medialis, biceps femoris, tibialis anterior and gastrocnemius. The measured EMG data were digitized and processed to root mean square (RMS) and expressed as percentage maximal voluntary isometric contraction (%MVIC). The data were analyzed using two-way analysis of variance (ANOVA) with repeated measures to determine the statistical significance. Results: The results of this study were summarized as follows: Firstly, in comparison to muscle activation of the biceps femoris, there was a significant increase in the D2 flexion pattern when it was compared with D2 extension pattern and when it was compared with D1 flexion pattern (p<.05). Secondly, there was a significant increase in the muscle activation of the vastus medialis and tibialis anterior with a closed kinetic chain rather than an open kinetic chain (p<.05). Conclusion: In conclusion, in order to increase muscle activation of the biceps femoris, the D2 flexion pattern can be applied, regardless of kinetic chain. In addition, in order to increase muscle activation of the vastus medialis and tibialis anterior, four arm patterns can be applied with a closed kinetic chain.

• 생명과학회지
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• 제32권2호
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• pp.175-188
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• 2022

혈관과 섬유증 기관들의 평활근과 세포외기질에 대한 릴랙신의 조절기능이 입증되어왔다. 본 총설에서는 저항성 소동맥과 방광을 포함한 섬유증 기관들의 세포외기질에 작용하는 릴랙신의 다양한 기전들을 고찰한다. 릴랙신은 혈관 평활근육의 수축을 억제하고, 콜라겐과 같은 세포외기질의 구성성분들을 감소키켜 혈관벽의 수동적 신전성을 증가시킴으로써, 혈관확장을 유도한다. 릴랙신이 동맥의 혈관확장을 유도하는 주된 세포기전은 RXFP1/PI3K의 활성화, Akt 인산화 및 eNOS 활성화를 통한 내피세포-의존성 산화질소의 생성에 의해 매개된다. 추가적으로, 릴랙신은 또한 다른 대체경로들을 작동하여 신장과 장간막 동맥의 혈관확장을 증가시킨다. 신장 소동맥에서, 릴랙신은 내피세포의 MMPs 및 EtB 수용체의 활성화와 VEGF 및 PlGF의 생성을 촉진하여, 평활근의 수축성과 콜라겐의 침착을 억제함으로써 혈관확장을 초래한다. 이와 달리, 장간막 소동맥에서, 릴랙신은 bradykinin (BK)-유도 이완을 시간-의존적으로 증강시킨다. BK-매개 이완의 신속 증가는 IK_Ca 이온통로와 뒤이은 EDH 유발에 의존하는 반면, BK에 의한 지속적 이완은 COX 활성과 PGI₂에 의존한다. 릴랙신의 항섬유화 효과는 염증유발 면역세포의 침투, endothelial-to-mesenchymal transition (EndMT) 및 근섬유아세포의 분화와 활성을 억제하여 매개된다. 릴랙신은 또한 근섬유아세포 내 NOS/NO/cGMP/PKG-1 경로를 활성화하여, TGF-β1-유도 ERK1/2 및 Smad2/3 신호의 활성과 ECM 콜라겐의 침착을 억제한다.

• 한국전문물리치료학회지
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• 제27권1호
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• pp.87-92
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• 2020

Background: Bridging exercises are used to enhance the functional stability of the lumbopelvic region in clinical settings. Although most of the studies on bridging exercises have compared the complete activation of the trunk muscles, some recent studies have examined the functional stability of the trunk and the lumbopelvic region and assessed the appropriate recruitment of the local and global muscles during different task levels. Objects: The purpose of this study was to investigate the changes in muscle thickness in the transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles during a common bridging exercise on an unstable surface and to determine whether these changes differ based on the surface used. Methods: Twenty-five healthy young adults (8 males, 17 females) were recruited. The subjects were randomly assigned to either the exercise progression with a sling bridge group or the ball bridging exercise progression group, each with three stages of increasing difficulty. Each position was measured three times with an ultrasonic diagnostic imaging system, and the mean values were recorded for analysis. Results: No significant differences were observed between the TrA, IO, or EO muscle thickness ratios between the sling and ball exercise groups (p > 0.05). There were also no significant differences in the EO muscle thickness ratios between the tasks irrespective of whether the sling or ball was used. However, the TrA and IO thickness ratios in both groups were significantly greater during stages 2 and 3 compared to stage 1. Conclusion: The results suggest that the use of slings and balls during bridging exercises is effective in activating the deep abdominal muscles.

• 대한물리의학회지
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• 제17권2호
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• pp.21-28
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• 2022

PURPOSE: This study examined the effect of changes in the knee angle and weight shifting of the sole on the activity of the lower extremity muscles during bridge exercise. METHODS: The subjects of this study included 20 healthy adult women (mean age 29.8 ± 4.32). The subjects performed the bridge exercise under three weight-shifting conditions general bridge (GB), hindfoot press bridge (HPB), and fore-foot bridge (FPB) and at two knee angles (90° and 60°). During the bridge exercise, the activity of the quadriceps femoris (rectus femoris, vastus medialis oblique, and vastus lateralis) and biceps femoris muscles were measured using an electromyography sensor. RESULTS: In the quadriceps femoris, the muscle activity of HPB and FPB was significantly higher than that of the GB at knee angles of 90° and 60° (p < .05). In the biceps femoris, the muscle activity increased significantly in the order of GB < HPB < FPB, and the knee angle increased significantly at 60° rather than at 90° (p < .05). There was no significant difference according to the knee angle in all muscles except for the biceps femoris. CONCLUSION: These findings suggest that the weight-shifting bridge of sole bridge exercise was more effective in increasing the activation of the lower extremity muscles than the GB.