• Journal of the Korean Society of Physical Medicine
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• v.14 no.3
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• pp.81-89
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• 2019

PURPOSE: To solve the problems of chronic obstructive pulmonary disease (COPD) patients complaining of muscle fatigue and having limited motor abilities, this study provided the clinical basic data for pulmonary rehabilitation by examining the effects of High Low-Frequency Neuromuscular Electrical Stimulation (NMES) on the respiratory muscle strength, quadriceps muscle activity, and life quality. METHODS: Samples were collected from 20 COPD patients and placed randomly in a low-frequency group (n=10) and high-frequency group (n=10). For a pretest, the respiratory muscle strength (MIP, MEP), quadriceps muscle activity (LF, VM, VL), and life quality (SGRQ) were measured. After applying NMES to each group for 30 minutes at a time, five times a week, for four weeks, a posttest was conducted in the same way as the pretest. RESULTS: Both groups showed significant differences in the respiratory muscle strength, quadriceps muscle activity, and quality of life within the groups and there were significant differences in the quadriceps muscle activity between the groups. CONCLUSION: The four-weeks NMES positively influenced the respiratory muscle strength and life quality by enhancing the function of the quadriceps and exercise tolerance. In particular, high-frequency(75 Hz) NMES was more effective than low-frequency (15 Hz) NMES. This result can be an alternative means to improve the physical functions of COPD patients clinically in the future.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.28 no.1
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• pp.29-38
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• 2022

Background: Task-oriented training on an unstable support surface is an effective intervention for improving the ankle joint stability and muscle strength in patients with ankle instability. This study examined the effects of balance training on an unstable support surface in patients with ankle sprains with ankle instability. Methods: Forty-four patients with ankle sprains participated in this study. Screening tests were performed and assigned to an experimental group, who performed task-oriented training on an unstable support surface (n=22), and a control group, who performed task-oriented training on a support surface (n=22) using a randomization program. All interventions were applied 3 times per week for 4 weeks. The numeric rating scale (NRS), cumberland ankle instability tool (CAIT), balance ability, muscle activity, and muscle thickness were compared to evaluate the effects of the intervention. Results: Both groups showed significant differences in the NRS, CAIT, balance ability, and muscle activity between before and after the intervention (p<.05). In addition, there were significant differences in balance ability, muscle activity, and muscle thickness between the experimental and control groups (p<.05). Conclusion: Task-oriented training on an unstable support surface is an effective intervention for improving the balance ability, muscle activity, and muscle thickness during contraction.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.77-84
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• 2015

Objective : The purpose of this study was to analyze the effects of lower limb muscle activity on postural stability and ground type in elderly women subjects. Method : Forty two subjects participated in the experiment (high group - age: $74.29{\pm}4.13yr$, height: $152.44{\pm}5.54cm$, weight: $57.43{\pm}6.16kg$, BMI: $24.77{\pm}2.99$, low group - age: $77.67{\pm}5.16yr$, height: $151.40{\pm}3.93cm$, weight: $60.92{\pm}6.40kg$, BMI: $26.59{\pm}2.57$). Wireless EMG with eight channels was used. Ground types were classified as flat and cushion. Results : In the double-support phase, left and right rectus femoris, left biceps femoris, left and right tibialis anterior, and left gastrocnemius did not show a significant difference in postural stability according to ground type. However right biceps femoris and gastrocnemius showed higher muscle activity in the elderly women group with lower postural stability. In the single-support phase, left and right rectus femoris, right biceps femoris, and left and right tibialis anterior did not show a significant difference in postural stability according to ground type. In addition, left biceps femoris had higher muscle activity in the elderly women group with lower postural stability. Left gastrocnemius had higher muscle activity in the elderly women group with higher postural stability and right gastrocnemius had higher muscle activity in the elderly women group on cushion ground. Conclusion : In a dynamic postural stability and cushion ground, biceps femoris and gastrocnemius muscle activity were high. As a result, biceps femoris and gastrocnemius muscle strengthening exercise on cushion ground could be beneficial in the prevention of falling.

• Physical Therapy Korea
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• v.17 no.1
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• pp.1-8
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• 2010

The purpose of this study was to compare EMG activity for pectoralis major muscle during shoulder movement with various abduction angle and rotation position in supine position. Fifteen healthy subjects were recruited for this study. All subjects performed shoulder horizontal adduction holding a 2 kg dumbbell in shoulder abduction $40^{\circ}C$, $70^{\circ}C$, $90^{\circ}C$, $130^{\circ}C$, $160^{\circ}C$ with shoulder neutral, internal rotation (IR), and external rotation (ER). Surface EMG activity was recorded from pectoralis major clavicle part and pectoralis major sternum part for 5 seconds and EMG activity was normalized to the value of maximal voluntary isometric contraction (%MVIC). Dependent variables were examined with 3 (Neutral, IR, ER) ${\times}$ 5 ($40^{\circ}C$, $70^{\circ}C$, $90^{\circ}C$, $130^{\circ}C$, $160^{\circ}C$) analysis of variance with repeated measures. The EMG activity of pectoralis major muscle was significantly different between shoulder abduction angles and between shoulder rotation positions (p<.05). The highest value of EMG activity of pectoralis major clavicle part among shoulder abduction angles was in $70^{\circ}C$ and, $90^{\circ}C$ in that order. The highest value of EMG activity of pectoralis major sternum part among shoulder abduction angles was in $130^{\circ}C$ and, $90^{\circ}C$ in that order. According to the rotation degree, shoulder ER showed the highest value and IR showed the lowest value in both muscle parts. These results suggest that shoulder abduction $70^{\circ}C$, $90^{\circ}C$, $130^{\circ}C$ will be effective during manual muscle testing (MMT) and strengthening exercise for pectoralis major muscle. It is also supposed that shoulder ER is the efficient posture for strengthening of pectoralis major muscle.

• Physical Therapy Korea
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• v.27 no.4
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• pp.264-271
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• 2020

Background: Because a forward-leaning posture can cause increased back muscle activity and pain. Therefore, an innovative method to reduce back muscle activity and pain is required. Objects: This study aimed to investigate the effects of a head support on muscle activity and pain in a forward-leaning posture. Methods: A total of 14 male and 16 female students (average age, 21.65 ± 2.37 years; height, 166.15 ± 7.90 cm; and weight, 60.65 ± 9.00 kg) were recruited for the experiment. Two of them were excluded due to musculoskeletal disorders. The muscle activity and pain in the forward-leaning posture were assessed while participants washed dishes for 7 minutes with and without a head support. The condition of using a head support was randomly performed with a 5-minutes break. To confirm a lumbar flexion angle of 30° during the experiment, myoVIDEO was used, and surface electromyography was used to measure muscle activity. Pain was assessed using a 10-point visual analog scale (VAS). The Wilcoxon signed-rank test was used to analyze the data, with p < 0.05 indicating statistical significance. Results: The cervical, thoracic, and lumbar erector spinae muscle activities significantly decreased with the use of the head support, but there was no significant change in the gluteus maximus. There was a significant decrease in the VAS score for the lumbar erector spinae (p < 0.05), but there was no significant change in the VAS score for the cervical region. Conclusion: The use of a head support in a forward-leaning posture reduced cervical, thoracic, and lumbar erector muscle activity and pain. Therefore, it could be recommended during working in a forward-leaning posture, such as during dishwashing, cooking, and working as a factory employee.

• Physical Therapy Rehabilitation Science
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• v.5 no.1
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• pp.15-21
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• 2016

Objective: The purpose of this study was to see the changes in muscle activity of the upper limb in persons using a smartphone. Design: Cross-sectional study. Methods: An experiment was conducted to target 15 right-handed university students. Experiments were carried out for students using cell phones for more than a year. In this study, experiments were carried out with one-handed and both handed operation of smartphone use in a sitting position, the same parameters with smartphone use in a standing position. The experiments were carried out by having the subjects write a text message in Korean on the smartphone for 3 minutes repeated 3 times with a rest period of 10 seconds given between each 3 minute period. Electromyography (EMG) was used to record the muscle activity of the upper trapezius (UT), extensor carpi radialis (ECR), and abductor pollicis (AP) during phone operation. Results: The muscle activity of the AP and ECR were significantly higher during single handed compared to double handed in both sitting and standing position (p<0.05). The muscle activity of the ECR was significantly higher in standing position compared to sitting position with double handed use of the smartphone (p<0.05). UT muscle activity of the right has been activated more than twice compared to the left UT in a sitting position (p<0.05). And UT muscle activity on the right has been activated more than five times compared to the left in a standing position (p<0.05). Conclusions: Using smartphone with double hand is useful for the prevention of musculoskeletal disorders.

• PNF and Movement
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• v.15 no.2
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• pp.167-176
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• 2017

Purpose: This study investigated the effect of core and abdominal muscle-strengthening exercises on muscle activity in the lower extremity on unexpected perturbation. Methods: Twenty subjects were randomly divided into the core exercise group (n=10) or the abdominal muscles strengthening group (n=10). The two groups performed their exercises during three sessions a week for a total of four weeks. The muscle activity in the lower muscles (rectus femoris, biceps femoris, tibialis anterior, gastrocnemius) was assessed using surface electromyography (EMG) and normalized maximal voluntary isometric contraction (MVIC) before and after the exercises. Results: An increase in the tibialis anterior activity after the core and abdominal muscles strengthening exercises was found after four weeks. A significant difference in the pre- and post-exercise was found. The gastrocnemius muscle activity increased in the core exercise group more than the abdominal muscles strengthening group. However, the difference was not significant. Conclusion: The results of this study suggest that the core and abdominal muscles strengthening exercises increased the tibialis anterior muscle activity. It is expected to help make more balance ability that affect who has abdominal muscles weakness.

• Physical Therapy Korea
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• v.18 no.1
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• pp.1-8
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• 2011

Push-up plus has been advocated for increasing the activity of the serratus anterior muscle, the most critical scapular stabilizer. However, no previous study has reported the possibility of compensatory motion on the part of the pectoralis major, which could substitute for the action of the serratus anterior during push-up plus. The aim of the current study was to investigate the immediate effect of electromyography (EMG) biofeedback of the pectoralis major muscle on the pectoralis major, upper trapezius, and serratus anterior muscles during push-up plus. Fourteen healthy young subjects voluntarily participated in this study; each subject performed push-up plus from the quadruped position, in two conditions (i.e., with or without visual and auditory biofeedback). Surface EMG was used to measure pectoralis major, serratus anterior, and upper trapezius activity. A paired t-test was used to determine any statistically significant difference between the two conditions. Additionally, effect size was calculated to quantify the magnitude of EMG biofeedback in each muscle. Visual and auditory feedback reduced pectoralis major muscle activity significantly (p=.000) and increased the serratus anterior muscle activity significantly (p=.002), but did not induce a significant difference in upper trapezius muscle activity (p=.881). Thus, it is concluded that the visual and auditory feedback of pectoralis major muscle activity can be used to facilitate serratus anterior muscle activity during push-up plus.

• PNF and Movement
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• v.18 no.3
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• pp.403-414
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• 2020

Purpose: This study examined how performing chin tuck exercises in supine, sitting, and standing positions affects changes in the muscle activity of the neck and shoulder. Methods: Seventeen men and three women with forward head posture participated in the study. The subjects performed the chin tuck exercise using a pressure biofeedback unit. After determining the ideal order for performing the chin tuck exercise in supine, sitting, and standing positions through randomized controlled trials, muscle activity was measured in the dominant-side sternocleidomastoid, scalenus anterior, upper trapezius, and levator scapulae. Muscle activity was measured three times in each muscle for each position, and the average of the three measurements was used for analysis. Results: In this study, the chin tuck exercise performed in a supine position reduced muscle activity of the sternocleidomastoid, scalenus anterior, upper trapezius, and levator scapulae significantly more than performing the exercise in either sitting or standing positions (p < 0.05). No significant difference in muscle activity was observed when the exercise was performed in a sitting position versus a standing position (p < 0.05). Conclusion: Performing a chin tuck exercise in a supine position is more effective for stabilizing the neck and shoulder than performing it in a sitting or standing position, as it reduces excessive tension and fatigue in the neck and shoulder.

• Physical Therapy Rehabilitation Science
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• v.6 no.1
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• pp.33-38
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• 2017

Objective: This study tried to examine the muscle activity of the neck and trunk according to head posture changes during use of laptops. Design: Cross-sectional study. Methods: This study included nineteen young men and women. All subjects maintained each posture while practice typing on laptops for ten minutes with a 5-minute break between each posture. For the neutral head posture, the subjects practiced typing while pulling their chins down towards the Adam's apple and were able to look at their knees while having their external auditory meatus, acromion, and greater trochanter vertical to the ground. For the natural head posture, they practiced typing while balancing their posture between extension and flexion of the cervical vertebrae by themselves without any guidelines. While a forward head posture was created by having their heads face the front horizontal to the rope hanging from the ceiling, they practiced typing with their external auditory meatus located in the place which was 5 cm in front of the vertical plane. The subjects used general word process but practiced typing with accuracy and high speed. Muscle activities were randomly measured using surface electromyography according to each postures. Results: The research result had found that muscle activity with the natural head posture was more significantly reduced than that of the forward head posture in the sternocleidomastoid muscle, upper trapezius, cervical vertebral spinae, and thoracic vertebrae spinae muscles (p<0.05) and that the neutral head posture was more significantly reduced than that of forward head posture in the upper trapezius, cervical vertebral spinae, and thoracic vertebrae spinae muscle activity (p<0.05) with significant increases in lumbar spinae muscle activity (p<0.05). Also, muscle activity with the neutral head posture significantly increased more in the sternocleidomastoid muscle and lumbar spinae than that of the natural posture (p<0.05). Conclusions: Our study results suggest that in order to prevent musculoskeletal pain, the neutral head posture with use of laptops is effective in reducing load to the shoulders and vitalizing the postural muscles.