• International Journal of Contents
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• 제5권4호
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• pp.35-39
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• 2009

The purpose of this study was to evaluate the changes in skeletal muscle architecture and qualitative properties by muscle contraction force when neuromuscular electrical stimulation (NMES) of 50% MVIC was applied. Sixteen subjects (8 male, 8 female) without neuromuscular disease volunteered to participate in the study. All subjects were divided into two subgroups: control (no electrical stimulation) group and 50% maximal voluntary isometric contraction (MVIC) group. NMES training program was performed in the calf muscle three times a week for 10 weeks. Before and after the experiments, the MVIC of ankle plantar flexor was measured by the use of dynamometer, and the ultrasonography in the gastrocnemius medialis muscle was measured. The following results were obtained; MVIC was significantly increased in the electrical stimulation groups. Pennation angle, muscle density, and white area index also considerably changed in the electrical stimulation groups. In conclusion, the NMES training of 50% MVIC, comparative low level, improved the skeletal muscle architecture and the qualitative properties as well as the muscle contraction force.

• 한국전문물리치료학회지
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• 제12권2호
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• pp.11-19
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• 2005

Patellofemoral pain syndrome (PFPS) is often attributed to malalignment and maltracking of patella within the patellofemoral joint. Most exercise for PFPS has focused on selectively strengthening the vastus medialis oblique muscle (VMO). This study was designed to identify the effect of medial, lateral wedge and difference of Quadriceps angle (Q-angle) on vastus medialis oblique/vastus lateralis muscle (VL) activity ratios. The subjects were twenty young adult males who had not experienced any knee injury. They were asked to perform isometric contraction exercises in three postures using medial and lateral wedge. The EMG activity of the VL and VMO were recorded in three postures by surface electrodes and normalized by %MVC values derived from seated, isometric knee extensions. The normalized EMG activity levels (%MVC) of the VL and VMO for the three postures of the lower extremities were compared using 2-way repeated measures ANOVA with 1 between-subject factor (group), and 1 within-subject factor (wedge). Results of repeated measures of ANOVA's revealed that the medial wedge isometric contraction exercise produced significantly greater EMG activity of VMO/VL ratios in Group I (Q-angle $18^{\circ}$ or less) (p<.05). But, the medial wedge isometric contraction exercise was no significant difference of VMO/VL ratios in Group II (Q-angle $19^{\circ}$ or more) (p>.05). These results have important implications for selective VMO muscle strengthening exercises in PFPS patients.

• 대한의용생체공학회:의공학회지
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• 제18권4호
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• pp.413-420
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• 1997

In this paper, we analyzed the contraction patterns of active elbow muscles during isometric, concentric and eccentric contraction. The analysis parameters consist of frequency domain parameters (mean frequency, median frequency, peak frequency, peak power, skewness, kurtosis) and time domain paraseters (zero crossing, positive maxima, integrated EMG). The results of this study were as follows; The BR/BB of isometric contraction appeared to be Venter as the elbow joint was more extended. The BR /BB during concentric and eccentric contraction tended to increase with more extension of the elbow joint angle, but there was no significant difference between concentric and eccentric contraction. Further, the EMG power spectrum due to the type of contraction were different betwen eccentric and concentric contraction. According to the results, it was found that the activation pattern in elbow flexor muscles was different during three different muscle contraction pattern. Therefore, elbow flexor muscles should not be considered a single functioning unit. Especially, at the time domain analysis, IEMG is a dominant parameter for analysis of activation patterns, and the skewness kurtosis can be useful parameters in functional recognition for prosthesis control purpose.

• 한국정밀공학회지
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• 제29권7호
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• pp.805-810
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• 2012

Determining of the exercise intensity is very important in terms of induction of low fatigue during exercise. Little information is available on the contraction level of the trunk muscles during whole body tilts with and without axial rotation. This study was to investigate the difference muscle activation level according to axial rotation. Twenty subjects were participated. The muscle activities of the five trunk muscles were bilaterally measured at eight axial rotation angles with 12 tilt angles along $15^{\circ}$ intervals. The results showed that tilt with $45^{\circ}$ axial rotation was more balanced in the same tilt angle and was maintained approximately level of 40% MVC at over $60^{\circ}$ tilt angle with respect to co-contraction of abdominal and back muscle. Lumbar stabilization exercise using whole body tilts would be more effective with axial rotation than without axial rotation in terms of muscle co-contraction.

• 대한물리의학회지
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• 제14권2호
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• pp.21-28
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• 2019

PURPOSE: This study was conducted to compare different standing postures with the use of standing aids for lumbar spine posture and muscle activity, and to identify the most desirable standing posture. METHODS: The lumbopelvic angle was assessed based on static radiographic measurement on the sagittal plane. Lumbar lordosis, lumbosacral lordosis, and the intervertebral joint angle at L1/L5 and L5/S1 were measured using radiography in three standing postures (standing on level ground, standing with one foot on a platform, and standing on a sloped surface). In addition, muscle activity was measured using surface electromyography to examine the co-contraction of the lumbar and hip muscles. RESULTS: Lumbar lordosis, lumbosacral lordosis, and L5/S1 intervertebral joint flexion occurred with one foot on the platform. No significant differences were found between standing on a sloped surface and standing on level ground. However, muscle co-contraction was reduced with the use of standing aids. CONCLUSION: This study demonstrated that standing with a foot on a platform induced lumbar lordosis, but that there was no significant difference between standing on a sloped surface and standing on level ground. However, muscle co-contraction was reduced with the use of standing aids. Based on the motor control pattern as a predictor of LBP, the use of standing aids would help workers during prolonged standing.

• 한국의류학회지
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• 제20권5호
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• pp.852-859
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• 1996

The factors and mechanism of arm surface changes were analyzed by regression analysis for the relationship between changes in arm joint angle and arm surface changes, according to the direction of upper extremity motion. Body surface change patterns among subjects were tested also. Experiments were carried out on 3 female subjects of different body types to examine 26 motions in 4 directions for 4 upper extremity parts. The major conclusions of the study are as follows: 1. The expansion or contraction of arm surface length depends on the direction of upper extremity motion. 2. Arm surface length changes by linear expansion or contraction according to the joint angle of the direction of motion. The mechanism of arm surface changes is represented by a linear relation between arm surface changes and the (actors of the direction of upper extremity motion and arm joint angle. 3. Arm surface length shows the same pattern of body surface changes regardless of body type. A quantitative model of body surface changes at upper extremity should be developed for functional sleeve design.

• The Journal of Korean Physical Therapy
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• 제35권2호
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• pp.53-57
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• 2023

Purpose: The purpose of this study was to compare the changes in the muscle activation of the quadriceps muscle (rectus femoris, vastus lateralis, vastus medialis) during the stand-to-sit (StandTS) movement according to the plantar flexion angle of the ankle joint. Methods: A total of 22 healthy young females participated in this study. During the StandTS under the three conditions (plantarflexion angle 0°, 20°, and 45° of the ankle), electromyography (EMG) data (% maximum voluntary iso¬metric contraction) of the rectus femoris, vastus lateralis, and vastus medialis were recorded using a wireless surface EMG system. Results: There was a significant difference in the muscle activation of rectus femoris, vastus lateralis, and vastus medialis according to the plantar flexion angle (0°, 20°, and 45°) of the ankle. The muscle activation of the quadriceps was the highest at a 45° angle of plantarflexion and the lowest at 0°. One-way repeated ANOVA was used to analyze the muscle activation data of the lower extremity muscles according to the angle of the ankle joint. Conclusion: Based on the results of our study, it was confirmed that the muscle activity of the quadriceps can be increased even in the StandTS movement, which involves the eccentric contraction of the quadriceps muscle. This suggests that maintaining a plantar flexion posture for a long time, say by wearing high-heeled shoes, can quickly cause muscle fatigue in the lower-limb muscles, which can cause a decrease in balance ability leading to falls.

• 한국전문물리치료학회지
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• 제23권1호
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• pp.20-30
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• 2016

Background: Total knee arthroplasty (TKA) recovers the alignment of the knee joint, but fails to automatically restore the alignment and function of the hip and ankle joints. It may affect the alignment and stability of the knee joint, therefore therapeutic intervention in hip and ankle joint is necessary for the rehabilitation process after TKA. Objects: The aim of this study was to comparison of the effects of the two exercise methods on the coronal plane alignment after TKA. This study conducted an experiment by dividing subjects into a lower extremity isometric co-contraction group (LEIC) and a quadriceps isolated isometric contraction (QIIC) group. Methods: A total of 37 subjects were randomly assigned to the LEIC ($n_1$=19) or the QIIC ($n_2$=18). Exercise was applied to five times per week for three weeks, starting on the eighth day after surgery. Range of motion exercises were performed as a common intervention and then each group performed quadriceps isometric contraction exercises with 10 sets of 5 repetitions. Radiological imaging was performed prior to surgery, one month and six months after surgery. In addition, the hip-knee-ankle angle (HKA) and tibiotalar angle (TTA) were measured. Results: The HKA was close to neutral in the LEIC rather than the QIIC (p<.05). The LEIC showed varus and the QIIC exhibited valgus TTA (p<.05). In a comparison of HKA and TTA over time, there was no significant change in either group (p>.05). According to the comparison of the TTA before surgery, the LEIC showed significant changes in the varus direction (p<.05), while there was no significant change in the QIIC (p>.05). Conclusion: The LEIC method triggered changes in the TTA and brought the HKA close to the neutral. Thus, LEIC is more effective than QIIC in creating stability in the coronal plane alignment of the knee and ankle joints after TKA.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권2호
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• pp.212-224
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• 2018

The characteristics of the relationship between the evolution of propeller trailing vortex wake and skew angle are numerically examined based on four different five-blade David Taylor Model Basin (DTMB) model propellers with different skew angles. Numerical simulations are based on Reynolds-averaged Naviere-Stokes (RANS) equations combined with SST $k-{\omega}$ turbulence model. Results show that the contraction of propeller trailing vortex wake can be restrained by increasing skew angle and loading conditions, and root vortices fade away when the propeller skew angle increases. With the increase of the propeller's skew angle, the deformation of the hub vortex and destabilization of the tip vortices are weakening gradually because the blade-to-blade interaction becomes weaker. The transition trailing vortex wake from stability to instability is restrained when the skew increases. Furthermore, analyses of tip vortice trajectories show that the increasing skew can reduce the difference in trailing vortex wake contraction under different loading conditions.

• 한국전문물리치료학회지
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• 제17권2호
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• pp.1-9
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• 2010

To develop effective training methods for strengthening a weakened quadriceps femoris muscle in hemiplegic patients, we examined the effects of maximal isometric contraction of the nonparalyzed knee joint on the electromyographic activities of the paralytic muscle. An electromyogram (EMG) was used to record the electromyographic activities of the paralytic quadriceps femoris muscle in 27 hemiplegic patients. The maximal isometric contraction was measured for each subject to normalize the electromyographic activities. The maximal isometric extension and flexion exercises were randomly conducted when the knee joint angles of the nonparalyzed knees were $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$. The patients were encouraged to maintain maximal isometric contractions in both knee joints during each measurement, and three measurements were taken. A one-minute rest interval was given between each measurement to minimize the effects of muscle fatigue. An average from the three values was taken as being the root mean square of the EMG and was recorded as being the maximal isometric contraction. The electromyographic activity obtained for each measurement was expressed as a percentage of the reference voluntary contraction, which was determined using the values obtained during the maximal isometric contraction. The results of this study are summarized as follows: First, when the knee joint angle of the nonparalyzed knee was $0^{\circ}$, the electromyographic activities of the paralytic medial aspect of rectus femoris were related to measurement by a maximal isometric flexion exercise than by an extension exercise (p<.05). Second, when the knee joint angle of the nonparalyzed knee was $90^{\circ}$, the electromyographic activities of the paralytic lateral aspect of rectus femoris were related to measurement by a maximal isometric flexion exercise than by an extension exercise (p<.05). The results show that myoelectrical activities of paralytic quardriceps were not related to measurement angles and exercise directions of the nonparalized knee joint. Studies on various indirect intervention to improve muscular strength of patients with nervous system disorders of the weakened muscle should be constantly conducted.