• 정형스포츠물리치료학회지
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• 제14권2호
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• pp.55-64
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• 2018

Purpose : The purpose of this study was to investigate the effect of the sprinter and skater combined patterns on muscle contraction onset time and muscle activation of body stabilizing muscles. Method : Our study included young and healthy men in their 20s. The participants used the sprinter and skater combined patterns of the proprioceptive neuromuscular facilitation (PNF) methods to measure muscle activation and muscle contraction onset time of the trunk muscles. To measure muscle contraction onset time and muscle activation, electrodes were attached to the rectus abdominis (RA), external oblique (EO), internal oblique (IO), and erector spinalis (ES) regions. Significant differences were identified using a paired t-test and a one-way analysis of variance (ANOVA) analysis. Result : In the sprinter combined pattern, the muscle with the fastest onset time of contraction was the RES, and that with the slowest was the RRA (p<.001). In the skater combined pattern, the muscle with the fastest onset time of contraction was the LES, and that with the slowest was the LRA (p<.001). In the sprinter combined pattern, the REO and LIO presented medium muscle contraction onset times (p<.001). In the skater combined pattern, the LEO and RIO presented medium muscle contraction onset times (p<.001). Conclusions: Based on these results, these patterns could be used as exercise methods for the elderly with delayed proactive response speeds of the body stabilization methods due to imbalances in body stabilizing muscles or limbs movement.

• PNF and Movement
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• 제21권1호
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• pp.107-117
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• 2023

Purpose: The aim of this study is to compare the immediate effects of weight-assisting methods on vastus medialis oblique (VMO) and vastus lateralis (VL) muscle activation, on the VMO/VL muscle activation ratio, and on muscle onset time in healthy subjects when ascending stairs. Methods: Healthy participants were randomly assigned to the belt group (n = 11), hand group (n = 11), and control group (n = 11). In the belt group, a belt was wrapped around the sacrum and pulled forward with both hands, moving the center of weight forward, while ascending stairs. The hand group grasped the hips with both hands and climbed stairs, assisting their weight from the rear and moving the center of weight backward, and the control group climbed the stairs without any intervention. Results: Muscle activation of the VMO decreased significantly after the intervention in the belt and hand groups, and activation of the VL muscle in both groups showed a greater decrease than that of the VMO muscle. Further, the VMO/VL muscle activation ratio increased significantly, with an improvement shown in the order of the belt group, hand group, and control group, while muscle onset time also improved in the order of the belt group, hand group, and control group. Conclusion: The belt group demonstrated the greatest effect across all dependent variables, confirming that in clinical practice, these two weight-assisting methods are more effective interventions during stair ascent for patients with knee joint instability, pain, and imbalance than no assistance.

• The Journal of Korean Physical Therapy
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• 제32권5호
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• pp.295-301
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• 2020

Purpose: The purpose of this study was to compare the electromyographic activity and onset time of the gluteus maximus (GM) and hamstring (HAM), lumbopelvic kinematics during three different prone table hip extension exercises in healthy individuals. Methods: Twenty subjects were participated. Electromyography device was used to measure the muscle activities and onset time of the GM and HAM muscles. An electromagnetic tracking motion device was used to measure lumbopelvic compensations. The subjects were asked to perform three different prone table hip extension [Prone table hip extension with the abdominal drawing-in maneuver on a chair (PTHEA), PTHEA with the ipsilateral knee flexion (PTHEAF), PTHEAF with hip 30 abduction (PTHEAFA)]. One-way repeated measures analysis of the variance and a Bonferroni post hoc test were used. Results: The electromyographic activity and onset time were significantly different among three conditions (PTHEA vs. PTHEAF vs. PTHEAFA)(p<0.01). The GM muscle activity and onset time were significantly greater and reduced during the PTHEAFA compared to PTHEA and PTHEAF (p<0.01). However, The HAM muscle activity and onset time were significantly smaller and delayed during the PTHEAFA compared to PTHEA and PTHEAF (p<0.01). Conclusions: PTHEAFA exercise can be recommended to facilitate the muscle activity and efficient muscle firing time of GM without HAM dominance.

• 대한물리치료과학회지
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• 제31권2호
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• pp.30-40
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• 2024

Background: The purpose of this study is to identify the difference in muscle activity and muscle contraction onset time according to a LLD and object weight When subjects performed a lifting task. Design: Repeated measure design Methods: 15 male adults participated in this study. When subjects performed a lifting task, we measured a difference of muscle activity and muscle contraction onset time in the rectus abdominis(RA), the erector spinae(ES), and the rectus femoris(RF) between both legs using the surface electromyogram (Telemyo DTS, Noraxon Inc., USA). When subjects performed a lifting task, the weight of the object was set to 0% kg, 10% kg, and 20% kg of the subject's body weight, excluding the weight of the box. Results: The difference in muscle activity in the RA, the ES, and the RF between both legs when lifting an object was larger in LLD condition than in non-LLD condition(p<0.05). In all of muscles, the difference of contraction onset time was generally increased as the object's weight increased. Specially, the difference in muscle contraction onset time in the RA, the ES between both legs was larger in the LLD condition than in the non-LLD condition(p<0.05). Conclusion: This study suggests that LLD affects the muscle activity and muscle contraction onset time during lifting objects. It can be used as data to prevent joint damage and muscle due to the LLD during work and movements of daily living.

• The Journal of Korean Physical Therapy
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• 제33권1호
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• pp.1-6
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• 2021

Purpose: This study examined the effects of heel insoles on the static balance and leg muscle activity and posture control strategy during external perturbation. Methods: Thirty healthy young men participated in the study. The subjects underwent two experimental conditions: 1) no heel insole condition (0cm) and 2) wearing heel insole condition (5cm). The static balance was measured using an I-Balance device, which measured the change in the center of gravity (COG). The onset time of muscle activation and muscle activation of the erector spinae (ES), hamstring (HAM), gastrocnemius (GCM) were measured using surface EMG electrodes to determine the change in posture control strategy during external perturbation. Results: The speed and distance of COG were significantly higher in the wearing heel insoles condition than the no heel insole condition (p<0.05). In addition, significant differences in the onset time of the GCM, HAM, and ES muscle activation were observed when there was no heel insole condition during external perturbation (p<0.017). On the other hand, no significant differences in the onset time of muscle activation were observed between GCM and HAM when wearing the heel insole condition during external perturbation (p<0.017). Moreover, muscle activation of the GCM was significantly higher in the wearing heel insoles condition than the no heel insole condition during external perturbation (p<0.05). Conclusion: These findings suggest that heel insoles may have disadvantages, and increased efforts are needed to maintain balance and change the posture control strategy during external perturbation.

• 한국전문물리치료학회지
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• 제8권2호
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• pp.65-72
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• 2001

The purpose of this study was to investigate the effect of knee exercises on the onset times of vastus medialis oblique muscle (VMO) and vastus lateralis muscle (VL) and in healthy subjects. Fifteen subjects (7 men, 8 women) in a mean age of 26.4 years participated in the study. Electromyographic (EMG) signals were recorded from the VMO and VL under four exercises. Knee exercises consisted of open kinematic terminal knee extension, straight leg raising, isometric hip adduction exercise, and closed kinematic terminal knee extension. No significant differences were found in the onset times of EMG activities of VMO and VL in the four exercises. There were also no significant differences among the exercises. These results coincided with previous studies that found no difference between onset of VMO and VL. However, it is difficult to say that there is no difference between onset of VMO and VL in healthy subjects. To confirm this results, further researches that follow same on set determination metod and exercises are needed. Not only is the study of onset time of muscle needed, but also the studies of the amount of activation and the rate of increase of muscle activation are needed.

• The Journal of Korean Physical Therapy
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• 제15권4호
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• pp.488-497
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• 2003

The purpose of this study was to compare the muscle onset time of sternocleidomastoid (SCM) and rectus abdominalis (RA) muscle activity during head lift in supine position between cerebral palsy and healthy children. Ten cerebral palsy children and 10 age, sex-matched healthy children were recruited for this study. Muscle activity of the SCM and RA were collected by surface electromyography (MP100SWS). Results demonstrated that the muscle onset time order was not significantly different between cerebral palsy children and healthy children. However, the DMHT and ST between SCM and RA during head lift in supine position were significantly shorter in healthy children than in cerebral palsy children. Further studies are needed to clarify the mechanism of differences in muscle activation patterns during head lift in supine position in cerebral palsy children compared with healthy children.

• 재활복지공학회논문지
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• 제7권1호
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• pp.13-19
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• 2013

본 연구는 휠체어 사이클 경사로 주행 시 척수 손상으로 인한 하지마비 장애인의 상체의 근전도 특성을 평가하고자 하였다. 이를 위하여 척수손상 장애인 3명을 대상으로 $0^{\circ}$, $3^{\circ}$, $6^{\circ}$의 경사로에서 휠체어 사이클 주행을 하도록 하였으며, 이때 이두근, 삼두근, 전 삼각근, 상승모근, 광배근, 복직근의 근 활성 최대값과 수축 시간, 수축 개시 종료 시기를 측정 및 분석하였다. 본 연구 결과 휠체어 사이클의 경사로 주행 시 수축 시간과 근 수축 종료시간이 경사도가 증가함에 따라 유의하게 길어지고 지연됐으며, 광배근의 최대 근 활성도는 평지 주행보다 유의하게 증가하였다 (p<0.05). 이와 같은 결과는 휠체어 사이클의 경사로 주행 시 광배근의 과도한 사용을 의미한다.

• 한국전문물리치료학회지
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• 제19권2호
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• pp.29-38
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• 2012

This study aimed to identify the asymmetry observed in the electromyography (EMG) activity patterns of selected trunk and thigh muscles between the affected and unaffected sides during the sit-to-stand movement in ambulatory patients with post-stroke hemiparesis. This study included 20 patients with post-stroke hemiparesis. The differences between stroke fast walkers (${\geq}8m/s$, 11 subjects) and stroke slow walkers (<8 m/s, 9 subjects) were compared. The activation magnitude and onset time of the multifidus, lumbar erector spinae, hamstrings, and quadriceps during the sit-to-stand movement were recorded through surface EMG. Moreover, the EMG activation magnitude and onset time ratios of each bilateral corresponding muscle from the trunk and leg were measured by dividing the relevant values of the unaffected side by those of the affected side. In all the subjects, the activation magnitudes of the multifidus, hamstring, and quadriceps on the affected side significantly decreased compared to those on the unaffected side (p<.05). The onset time of muscle activity in the affected side was markedly delayed for the multifidus and quadriceps during the task (p<.05). The activation magnitude ratios of the quadriceps were markedly decreased in the stroke slow walkers as compared to those in the stroke fast walkers. These findings indicate that the asymmetry in the multifidus, hamstring, and quadriceps muscle activation patterns in patients with post-stroke hemiparesis may be due to the excessive muscle activation in the unaffected side to compensate for the weakened muscle activity in the affected side. Our findings may provide researchers and clinicians with information that can be useful in rehabilitation therapy.

• 한국전문물리치료학회지
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• 제28권1호
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• pp.84-91
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• 2021

Background: A hip fracture may occur spontaneously prior to the hip impact, due to the muscle pulling force exceeding the strength of the femur. Objects: We conducted falling experiments with humans to measure the activity of the hip muscles, and to examine how this was affected by the fall type. Methods: Eighteen individuals fell and landed sideways on a mat, by mimicking video-captured real-life older adults' falls. Falling trials were acquired with three fall directions: forward, backward, or sideways, and with three knee positions at the time of hip impact, where the landing side knee was free of constraint, or contacted the mat or the contralateral knee. During falls, the activities of the iliopsoas (Ilio), gluteus medius (Gmed), gluteus maximus (Gmax) and adductor longus (ADDL) muscles were recorded. Outcome variables included the time to onset, activity at the time of hip impact, and timing of the peak activity with respect to the time of hip impact. Results: For Ilio, Gmed, Gmax, and ADDL, respectively, EMG onset averaged 292, 304, 350, and 248 ms after fall initiation. Timing of the peak activity averaged 106, 96, 84, and 180 ms prior to the hip impact, and activity at the time of hip impact averaged 72.3, 45.2, 64.3, and 63.4% of the peak activity. Furthermore, the outcome variables were associated with fall direction and/or knee position in all but the iliopsoas muscle. Conclusion: Our results provide insights on the hip muscle activation during a fall, which may help to understand the potential injury mechanism of the spontaneous hip fracture.