• PNF and Movement
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• v.20 no.1
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• pp.115-123
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• 2022

Purpose: The aim of this study was to investigate the effects of sit-to-stand training with various foot positions combined with visual feedback on muscle onset time and balance in stroke patients. Methods: Thirty stroke patients were randomly assigned into three standing groups: one with a symmetrical foot position (SSF; n = 10), one with an asymmetrical foot position with the affected foot at the rear (SAF; n = 10), and one with visual feedback and an asymmetrical foot position (SVAF; n = 10). Sit-to-stand training with different foot positions was performed for 30 minutes a day, 5 times a week, for a total of 4 weeks. The effects on muscle onset time and balance were assessed. Results: In a comparison of the onset time of muscle contraction, the onset time of the affected side tibialis anterior and less-affected side gastrocnemius muscle and tibialis anterior was significantly shortened in the SAVF group. And onset time of the less-affected side tibialis anterior was shortened in the SAF group. There was a significant difference in the result of functional reach testing in the SVAF group. Conclusion: VRG was effective in improving muscle activity and balance in elderly women aged 65 and older. In this study, sit-to-stand training with visual feedback and asymmetrical foot position showed significant functional improvement.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.2
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• pp.55-61
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• 2015

PURPOSE: The purpose of this study was to investigate recruiting order and onset time around shoulder muscle during the push-up according to the body tilting angle. METHODS: Twenty healthy young adult subjects were recruited for this study. They had no neurological and musculoskeletal disease. We used the sEMG for recording onset time of shoulder muscles. Shoulder Muscles were anterior deltoid(AD), posterior deltoid(PD), pectoralis major(PM), upper trapezius(UT). Body tilting angle were measured at 0 degree, 30 degree and 60 degree by using tilting table. Muscles contraction onset time were set by the push-up performed 3 times respectively. Mean of 3 measurements were used. And initiate onset time was decided by the Mean ${\pm}2$ SD in the threshold, more than 25ms. RESULTS: There were significant difference at 0 degree, 30 degree and 60 degree(p<.05). Muscles onset time were same order at 0 degree, 30 degree. UT occurred first of all contraction at 0 degree and 30 degree. And then contracted AD, PD, PM. But, at 60 degree, AD was the first contraction, and PM, UT, PD. CONCLUSION: Muscle recruitment order and onset time according to the body tilting was shown the difference when you do push-up. Therefore, this result, shoulder muscle recruitment pattern of according to the body tilting is different and it has to make effective shoulder exercise program.

• Physical Therapy Korea
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• v.28 no.1
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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.

• Journal of Biomedical Engineering Research
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• v.27 no.3
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• pp.131-141
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• 2006

A visual decision by clinical experts like physical therapists is a best way to detect onset and offset time of muscle activation. The current computer-based algorithms are being researched toward similar results of clinical experts. The new algorithm in this paper has an ability to extract a trend from noisy input data. Kalman smoother is used to recognize the trend to be revealed from disorderly signals. Histogram of smoothed signals by Kalman smoother has a clear boundary to separate muscle contractions from relaxations. To verify that the Kalman smoother algorithm is reliable way to detect onset and offset time of muscle contractions, the algorithm of Robert P. Di Fabio (published in 1987) is compared with Kalman smoother. For 31 templates of subjects, an average and a standard deviation are compared. The average of errors between Di Fabio's algorithm and experts is 109 milliseconds in onset detection and 142 milliseconds in offset detection. But the average between Kalman smoother and experts is 90 and 137 milliseconds in each case. Moreover, the standard deviations of errors are 133 (onset) and 210 (offset) milliseconds in Di Fabio's one, but 48 (onset) and 55 (offset) milliseconds in Kalman smoother. As a result, the Kalman smoother is much closer to determinations of clinical experts and more reliable than Di Fabio's one.

• Physical Therapy Korea
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• v.13 no.3
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• pp.1-9
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• 2006

The purpose of this study was to assess the influence of spine orthosis and sit-to-stand motor strategies on ground reaction force (GRF) and lower extremity muscle activity. Twenty healthy adult men participated, and subjects randomly performed sit-to-stand motions in three different conditions: Momentum-transfer strategy (MTS); MTS with spine orthosis; and zero-momentum strategy (ZMS) with spine orthosis. GRF data, onset time, and muscle activity were determined and compared using force plate and electromyography. Data were statistically analyzed by the SPSS version 13.0. One-way repeated analysis of variance (ANOVA) was used to determine the statistical significance, and least significant difference was used as a post hoc test. The level of significance was .05. The results of this study were as follows: 1. Peak GRF and relative time to peak GRF were not significantly different in the three different conditions (p>.05). 2. Onset time of four muscles, tibialis anterior, gastrocnemius, biceps femoris and rectus femoris, in the three different conditions were significantly different (p<.05). 3. The tibialis anterior and rectus femoris muscle activity before hip-off and tibialis anterior, gastrocnemius, and rectus fermoris muscle activity after hip-off were significantly different in the three different conditions (p<.05).

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.201-208
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• 1995

The information obtained from the analysis of respiratory muscle elecromyographic (EMG) activities provides a mean for studying muscular activity in relation to the ventilatory process. Thus, in order to comprehend the airflow pattern and its brain control, signal processing is required to characterize respiratory muscle activity. This paper presents a computerized method for the analysis of the electrical activity of the respiratory muscles of premature lambs, and focuses upon the automatic determination of respiratory timing points such as onset and cessation points of the burst activity. Based on experimental results, reliable timing points can be obtained using the proposed methodology.

• Journal of Digital Convergence
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• v.15 no.2
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• pp.411-419
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• 2017

This study was to investigate whether a trunk correction taping plus scapular setting exercises has an effect on trunk muscle activation and trunk balance and upper extremity function in patients with stroke. Twenty stroke patients were randomly divided into a trunk correction taping with scapular setting exercise group (n=10) and a scapular setting exercise group (n=10), and each group performed given interventions for 30 minutes for 4 weeks. In the experimental group, there were significant increases in muscle activation, K-TIS, and MFT (p<.05), and a significant improvement was detected in K-TIS and MFT compared to the control group (p<.05). This study suggests that a trunk correction taping with scapular setting exercises was more effective on trunk muscle activation, trunk balance, and upper extremity function in stroke patients compared to a scapular setting exercise. It could be clinically more significant if the change in the onset time of muscle activity is confirmed in the further researches.

• Physical Therapy Korea
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• v.10 no.2
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• pp.99-110
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• 2003

The purpose of this study was to analyze the effects of three different pelvic tilts on sit-to-stand ativities and to suggest a new therapeutic approach for movement reeducation in patients who have difficulty with sit-to-stand activities. The three different pelvic tilts were: (1) comfortable pelvic tilt sit-to-stand (CPT STS), (2) posterior pelvic tilt sit-to-stand (PPT STS) and (3) anterior pelvic tilt sit-to-stand (APT STS). To analyze the kinematic component of STS, a motion analysis system (Zebris) was applied to the ankle, knee, hip joint, and thigh-off area. Also, to determine the onset time of muscle contraction, surface electrodes were placed to the rectus femoris muscle (RF), the vastus lateralis muscle (VL), the biceps femoris muscle (BF), the tibialis anterior muscle (TA), the gastrocnemius muscle (GCM), and the soleus muscle (SOL). One-way repeated ANOVA was used for the statistical analysis. First, significant differences were found in kinematic variables for the hip, knee, ankle joint, and thigh-off among the three activities. Second, there was significant difference in muscle activation pattern in TA. VL. and BF among three activities. In conclusion, the findings of this study suggest the following evaluative and therapeutic approach for STS activity: (1) Changes in knee and ankle joints should be prioritized and recruitment order differences in VL and RF can be generated to accomplish abnormal STS activity. (2) APT STS can be introduced for movement efficiency and functional advantage when abnormal STS is treated.

• The Journal of Korean Physical Therapy
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• v.33 no.1
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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.

• Physical Therapy Korea
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• v.14 no.2
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• pp.21-28
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• 2007

The purpose of this study was to compare the onset times of muscle activities and the order of muscle firing in erector spinae, multifidus, rectus abdominis and biceps brachii during perturbation between subjects with and without work-related chronic low back pain (LBP). Twenty-nine subjects, 14 with and 15 without LBP, participated in this study. The muscle responses were measured by surface EMG (electromyography) during perturbation in eye opened and eye closed conditions. The EMG onset times of the erector spinae, multifidus, rectus abdominis and biceps brachii were similar between groups in eye closed condition. But the onset times of the erector spinae, multifidus, rectus abdominis were significantly delayed in subjects with LBP in eye opened condition. The results provide an evidence for impaired feed-forward control of the trunk muscles in subjects with LBP. Further studies are needed to identify whether the impaired feed-forward control of the trunk muscles is the contributing factor to LBP.