• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.83-90
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• 2017

Objective: To investigate the effect of short-term vibration frequencies on muscle force generation capabilities. Method: Six healthy participants were recruited for this study and only their dominant leg was tested. The subjects were tested under five conditions of vibration frequencies with constant amplitude: 0 Hz (no vibration), 30 Hz, 60 Hz, and 90 Hz, and the vibration amplitude was 10 mm for all frequency conditions. The vibration was applied to the rectus femoris (RF). The subjects were then instructed to maintain a steady-state isometric knee joint torque (100 Nm) for the first 6 s. After the steady-state torque production, the subjects were required to produce isometric knee joint torque by leg extension as hard as possible with a start signal within the next 3 s. The vibration was applied for ~4 s starting from 1 s before initiation of the change in the steady-state knee joint torque. Results: The results showed that the maximum voluntary torque (MVT) of the knee joint increased with the vibration frequencies. On average, the MVTs were 756.47 Nm for 0 Hz (no vibration) and 809.61 Nm for 90 Hz. There was a significant positive correlation (r = 0.71) between the MVTs and integrated electromyograms (iEMGs). Further, the co-contraction indices (CCIs) were computed, which represent the ratio of the iEMGs of the antagonist muscle to the iEMGs of all involved muscles. There was a significant negative correlation (r = 0.62) between the CCIs and MVTs, which was accompanied by a significant positive correlation (r = 0.69) between the iEMGs of the vibrated muscle (RF). There was no significant correlation between the MVTs and iEMGs of the antagonist muscle. Conclusion: The results of this study suggest that the short-term vibration on the muscle increases the level of muscle activation possibly owing to the increased Ia afferent activities, which enhances the muscle force generation capability.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.4
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• pp.29-37
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• 2017

PURPOSE: This study investigated the immediate effect of inspiratory muscle training with whole-body vibration on the pulmonary function of subacute stroke patients. METHODS: All participants (n=30) were allocated to the following groups: (1) the inspiratory muscle training group with whole-body vibration (n=10), wherein the patients received inspiratory muscle training with whole-body vibration comprising 3minutes of vibration per session and respiratory training of 30 times and 2 sessions for one day. (2) the inspiratory muscle training group with visual feedback (n=10), wherein the patients received inspiratory muscle training with visual feedback. (3) the inspiratory muscle training group (n=10), wherein the patients received inspiratory muscle training. RESULTS: After the experiment, the inspiratory muscle training group with whole-body vibration exhibited significantly higher forced vital capacity, forced expiratory volume at 1 second, peak inspiratory flow rate, maximal inspiratory pressure, and chest expansion (p<.05), compared to the other groups. Inspiratory muscle training group with whole-body vibration had significantly higher peak expiratory flow rate and maximal voluntary ventilation than the other groups (p<.05). CONCLUSION: These results show that pulmonary function, maximal inspiratory pressure, and chest expansion were significantly better in the inspiratory muscle training group with whole-body vibration than in the other groups. Thus, this treatment will help recovery of pulmonary function in stroke patients.

• Journal of International Academy of Physical Therapy Research
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• v.11 no.1
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• pp.1975-1980
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• 2020

Background: It has been argued that changes in muscle activity in the upper trapezius and serratus anterior may or may not cause shoulder joint pain and dysfunction. Objective: To investigate the effects of active vibration exercise on muscle activity regarding scapular stabilization using a flexi-bar. Design: A randomized controlled trial. Methods: A total of 24 subjects were randomly assigned to a flexi-bar group with active vibration and general stick group with non-active vibration. Both groups performed the same four action programs for 6 weeks, three times a week for 30 minutes at a time. The upper trapezius muscle, middle trapezius muscle, lower trapezius muscle and serratus anterior muscle of the dominant side was measured by electromyography before and after the 6 weeks of exercise. The independent t-test and paired t-test were used to analyze data. Results: There was a significant difference between groups in upper trapezius muscle and serratus anterior muscle activity after exercise (P<.05). Also, there was a significant difference in upper trapezius muscle and serratus anterior muscle activity before and after exercise in the flexi-bar group (P<.05). Conclusion: This study demonstrates that active vibration exercise using a flexi-Bar contribute to reduce the activity of the upper trapezius muscle and promote the activity of the serratus anterior muscle.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.4
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• pp.67-74
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• 2018

PURPOSE: This study was conducted to investigate the effects of vibration frequency and amplitude on scapular winging during the knee push-up plus exercise. METHODS: A total of 26 female subjects with scapular winging were evaluated while performing the knee push-up plus exercise with no vibration, low-frequency/low-amplitude (5 Hz/3 mm) vibration, low-frequency/high-amplitude (5 Hz/9 mm) vibration, high-frequency/low-amplitude (15 Hz/3 mm) vibration, and high-frequency/high-amplitude (15 Hz/9 mm) vibration. The surface EMG of the serratus anterior (SA) muscle was compared between the vibration frequency and amplitude. The EMG amplitude was normalized using the maximal voluntary isometric contraction (MVIC). The statistical significance of the results was evaluated using one-way ANOVA. RESULTS: The SA muscle EMG values increased at low-frequency/low-amplitude vibration and at low-frequency/high-amplitude vibration compared to no vibration. Furthermore, the same values increased at high-frequency/low-amplitude vibration and high-frequency/high-amplitude vibration compared to no vibration. In general, a higher vibration frequency and amplitude was associated with higher EMG values of the SA muscle, with particularly greater increases observed during high-frequency/high-amplitude vibration. There was also a significant difference between each condition with a high-frequency/high-amplitude vibration (p<.05). CONCLUSION: This study suggests that there were remarkable clinical effect of the knee push-up plus exercise with vibration, which enhanced the SA muscle activation in persons with scapular winging. Furthermore, applying a higher vibration frequency and amplitude more effectively increased for increasing SA muscle activation.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.55-63
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• 2006

The purpose of this study was to investigate the effects of vibration exercise using surface electromyography. Seven male collegiate wrestlers were participated in this study. Each subject stood on the platform and the vibration was induced for 1min. WEMG8 EMG system was used to record muscle activity from Vastus lateralis, Biceps Femoris, Tibialis Anterior, and Gastrocnemius. The EMG data were sampled for 30 sec. during non-vibration and vibration half squat position, respectively. The raw data were band pass filtered to remove noise and full wave rectified Paired sample t-test were performed to see the differences of maximum and average EMG between non-vibration and vibration trials. The results indicated that vibration produced much more muscle contraction than that of non-vibration trial for all selected muscles even though the significant difference was found only from Biceps Femoris. This phenomenon was due to the individual differences so care must be taken to evaluate vibration intensity and position before personal training.

• Korean Journal of Applied Biomechanics
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• v.31 no.1
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• pp.59-63
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• 2021

Objective: Through comparative analysis of muscle activity for whole-body vibration, walking and running movements, it is to verify the training effect of whole-body vibration exercise in terms of amount of exercise and muscle activity characteristics. Method: Flat ground walking and slope walking (10 degrees) at a speed of 5 km/h, flat ground running and slope running (10 degrees) at a speed of 11 km/h for running were performed on treadmill, and squats were maintained at 12 Hz, 20 Hz, and 29 Hz conditions on Whole body vibration exercise equipment (Galileo). Muscle activity was analyzed through EMG analysis device for one minute for each condition. Results: The Anterior Tibialis and Erector Spinae show greater exercise effect in whole-body vibration than walking and running. The Rectus Femoris, Biceps Femoris, and Gluteus Maximus have the best effect of exercise in flat running. Whole-body vibration exercise showed greater muscle activation effect as the frequency increased, and exercise effect similar to walking during the same exercise time. Conclusion: The amount of exercise through Whole-body vibration exercise was similar to that of walking exercise, and the Anterior Tibialis and Erector Spinae shows better exercise effect than walking and running.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.2
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• pp.39-47
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• 2019

Purpose : This study was investigated effects of vibration on scapular winging of knee push-up plus exercise. Methods : Twenty-eight female subjects with scapular winging were evaluated after performing knee push-up plus exercise, with or without vibration, three times a week for four weeks. Muscle activation of the serratus anterior and upper trapezius, and the ratio of activation of the upper trapezius to serratus anterior were measured using surface EMG; and scapular winging length was measured by using the caliper. Results : The findings showed that knee push-up plus exercise -with and without- vibration induced a significant increase in muscle activation of serratus anterior (p<.05) and a significant decrease in muscle activation of the upper trapezius (p<.05), the ratio of muscle activation of the upper trapezius to the serratus anterior (p<.05) and scapular winging length (p<.05). There was also a significant difference in muscle activation of the serratus anterior (p<.05) and upper trapezius (p<.05) between control and experimental group at post-test. Conclusion : This study suggests positive clinical effects of knee push-up plus exercise with vibration which enhanced muscle activation of serratus anterior and reduced muscle activation of upper trapezius in person with scapular winging. However, vibration had no effectiveness to improve muscle imbalance between serratus anterior and upper trapezius, and reduce the scapular winging length.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.1
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• pp.31-40
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• 2011

This paper examines the dynamic characteristics of a human carpal muscle through theoretical analysis and experiment. The carpal muscle was modeled as a 1-DOF vibration system and vibration response due to a ramp function force was calculated. The electromyogram signal corresponding to the muscle excitation force was measured, and the excitation force function of an envelope curve from the electromyogram signal was extracted. The ramp input function of electrical stimulation to the carpal muscle was applied by using a device for functional electrical stimulation, and the angular displacements corresponding to steady state response were measured. Theoretical calculations of the vibration response displacements were compared with the experimental results of the angular displacements, and have shown a good agreement with the result that is linearly proportional to the excitation force magnitude. As a result, the relationship between the input current of the electrical stimulation and the excitation force magnitude was inferred. The result was shown that it can be applied to develop rehabilitation training devices.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.3
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• pp.313-320
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• 2020

Objectives: The aim of this study is to evaluate the association between vibration exposure and skeletal muscle mass index through a single university health check-up. Methods: We used data from 134,067 male subjects who received a general health check-up or vibration exposure health check-up out of the 1,515,322 people who underwent medical check-up at a local university hospital from 2002 to 2018. Pearson correlation analysis was conducted for comparing the association between skeletal muscle mass index and demographic and hematological variables in both groups. Mixed linear model analysis after controlling demographic and hematological variables was used to analyze the differences in skeletal muscle mass index between groups at every visit over 10 years. Results: In the Pearson correlation test, the variables that showed different results when comparing the two groups were C-reactive protein (p=0.001) and glycated hemoglobin (p=0.002) in the vibration exposure group and erythrocyte sedimentation rate (p<0.001) and vitamin D (p<0.001) in the general group. After the adjustment of demographic and hematologic variables, the skeletal muscle mass index at every visit was markedly decreased in the vibration exposure group (p<0.001). Conclusions: In the vibration exposure group, the skeletal muscle mass index showed a tendency to decrease markedly over time compared to the general health check-up group, which showed that C-reactive protein and glycated hemoglobin would have an influence on skeletal muscle index in male workers exposed to vibration.

• Physical Therapy Rehabilitation Science
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• v.9 no.2
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• pp.113-119
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• 2020

Objective: The vibration device is one of the most commonly used warm-up devices not only for healthy athletes but also for healthy individuals. Therefore, this study aimed to investigate the immediate effects of local vibration on ankle plantar flexor muscle activation and peak torque in healthy adults. Design: One-group pretest-posttest design. Methods: This was a single-group study comprising a total of 36 (16 males and 20 females) participants. The average age of the 36 participants was 22.3 years. All the participants' concentric and eccentric peak torques of the gastrocnemius lateralis muscle were measured using an isokinetic device. Simultaneously, the participants' muscle activity was measured by surface electromyography. After the pre-experimental data were collected, the participants comfortably sat on the prepared chair with their hips and knees flexed to 90°. While in sitting position, local vibration was applied for 10 minutes using a 1:1 ratio intermittent pulsing mode device based on a previous study. Then, the post-experimental data were collected immediately after the local vibration by performing a similar process performed during the pre-experimental data collection. Results: The results showed a significant difference in muscle activity and eccentric peak torque (p<0.05). On the contrary, concentric peak torque values showed an insignificant difference with pre- and post-value. Conclusions: The results of this study demonstrated that local vibration can be possibly considered as one of the effective ways to increase ankle plantar flexor muscle activity and muscle performance, specifically the eccentric peak torque, in healthy adults.