• Journal of The Korean Society of Integrative Medicine
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• v.11 no.1
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• pp.21-29
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• 2023

Purpose : Using a smartphone while walking districts attention and increases the risk of losing balance or falling. Ankle instability is caused by decreased muscle strength and decreased neuromuscular ability leading to postural control problems. Dual tasks increases the risk of falls by reducing postural control in adults with ankle instability. This study aimed to investigate the effect of performing a dual task on balance and muscle activity in adults with ankle instability using a smartphone. Methods : Forty-nine individuals with ankle instability participated in this study. A game of finding the wrong picture was performed using a smartphone in the dual task, and only looking at the blank screen of a smartphone was evaluated in the single task. The participants randomly performed single and dual task to evalutate balance and muscle atcitivy. Balance was evaluated using the Biodex balance system (BBS), and muscle activity was evaluated using surface EMG. Muscle activity of the gastrocnemius and tibialis anterior was measured at the same time as balance. Results : The results of this study showed that overall, anteior/posterior, and medial/lateral balance indices all showed significant differences when performing the dual task compared with those during the single task (p<.05). The muscle activity results showed a significant difference compared with that of the gastronemius muscle on the nondominant side during the dual task (p>.05). Conclusion : The results of this study showed that maintaining balance is more difficult when performing the dual task than during the single task, and only the muscle activity of the nondominant gastrocnemius muscle decreased. The dual task causes a decrease in concentration for postural control, which negatively affects postural stability. Individuals with ankle ankle instability should refrain from performing dual tasks, such as using smartphones, to prevent ankle damage.

• Journal of Oral Medicine and Pain
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• v.15 no.1
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• pp.27-35
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• 1991

In order to evaluate muscular activity patterns of masticatory muscles and asymmetry patterns of muscular activity according to the levels of occlusal force, twenty-one individuals of age ranged from 23 to 27 years were examined. They were selected according to the following criteria : 1) no symptoms of temporomandibular disorder, 2) complete dentition except third molars, 3) normal or Angle's class I molar relationship and 4) no experience of dental treatment. The electromyographic amplitudes was measured for evaluation of muscular activity and asymmetric patterns of masseter and anterior temporal muscle during unilateral clenching at the levels of 10%, 20%, 40% and 50% of the maximum occlusal force by use of electromyogram and bite force meter. The obtained results were as follows : 1. The muscle activity indices of masticatory muscles of clenching side at the clenching levels of 10%, 20% and 30% of the maximum occlusal force were -19.12, -9.87, -0.49%, so that activity of anterior temporal muscle was dominant than that of masseter muscle. At the levels of 40%, 50% of the maximum occlusal force, muscle activity indices were 4.68%, 6.70%, so that activity of masseter was dominant at all level and as the levels of occlusal force was increased, muscular activity index was tend to decrease. 2. In masseter, asymmetry indices of muscular activity at the levels of 10%, 20% of maximum occlusal force were -10.34 and -1.24%, so that muscular activity of non-clenching side were dominant and at the levels of 30%, 40% and 50% each of maximum occlusal force, muscular activity was dominant on clenching side as 4.68, 7.18 and 10.9%. In anterior temporal muscle, asymmetry indices were 33.38%, 25.46, 2095, 10.23 and 15.45% at the levels of 10%, 20%, 30%, 40% and 50% each of maximum occlusal force, so that activity of clenching 15.45% at the levels of 10%, 20%, 30%, 40% and 50% each of maximum occlusal force, so that activity of clenching side was dominant than that of non-clenching side at all levels, but as the levels of occlusal force was increased, asymmetry indices of muscular activity was tend to decrease. 3. Between both sides, average electromyographic amplitudes of masseter and anterior temporal muscle were correlated, so that as the levels of occlusal force was increased, average electromyographic amplitudes of both side in same muscle were increased proportionally. But asymmetry indices between muscular activities of masseter and anterior temporal muscle were not correlated.

• PNF and Movement
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• v.17 no.1
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• pp.111-118
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• 2019

Purpose: This study aimed to investigate the correlation between trunk stabilization muscle activation and the parameters of gait analysis in healthy individuals. Methods: Thirty healthy adults (15 male, 15 female) with no history of lower back pain (LBP) or current musculoskeletal and neurological injuries were studied. Trunk stabilization muscle activation (e.g., external oblique, internal oblique, transverse abdominis, erector spinae) were assessed using surface electromyography. To analyze gait, we measured temporal parameters (e.g., gait velocity, single support phase, double support phase, swing phase, and stance phase) and a spatial parameter (e.g., H-H base of support). Results: A statistically significant correlation was found between the internal oblique, transverse abdominis, and erector spinae muscle activity and gait velocity, single support phase, double support phase, swing phase, and stance phase. No statistically significant correlation was found between the external oblique muscle activity and the gait velocity, single support phase, double support phase, swing phase, and stance phase. No statistically significant correlation was found between the external oblique, internal oblique, transverse abdominis, and erector spinae muscle activity and the spatial parameter. Conclusion: This study demonstrated that a relationship exists between trunk stabilization muscle activation and temporal parameter (i.e., gait velocity, single support phase, double support phase, swing phase, and stance phase) during gait analysis. Therefore, the trunk's stabilizer muscles play an important role in the gait of healthy individuals.

• The Journal of Korean Physical Therapy
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• v.35 no.3
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• pp.83-88
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• 2023

Purpose: This study was to investigate the effect of forward head posture (FHP) and round shoulder posture (RSP) on changes in muscle activities according to shoulder flexion and abduction tasks. Methods: Twenty-two male subjects with no history of neurological, musculoskeletal surgery or injuries, or pain in the spine region within the previous 3-month periods were recruited for this study. Craniovertebral angle (CVA) and Scapula Index were measured before performing 90° abduction and flexion tasks holding a 3kg dumbbell. Muscle activities were measured during the tasks. All measurements except height of the acromion were carried out in a sitting position at the height of the subject's knee angle of 90 degrees, and two tasks were randomly performed with the arm that the subject mainly use to throw the ball. The abduction and flexion angles were checked by the examiner using a goniometer beside the subject. Results: Correlation coefficient analysis between Scapular Index and upper trapezius muscle activity during shoulder abduction task showed significant positive correlation. No significant correlation was observed between CVA, Scapular Index, and other muscle activities. Conclusion: FHP showed increased muscle activation, making it difficult to change muscle activity under lower loads, and RSP was correlated with UT activation in shoulder abduction. Therefore, in the RSP, the loaded shoulder abduction is considered a potential risk factor for increasing shoulder muscle tension. This paper proposes an approach to treating RSP before FHP.

• Physical Therapy Korea
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• v.23 no.2
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• pp.67-74
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• 2016

Background: Lumbar stabilization (LS) improve the thickness of the quadratus lumborum (QL) muscle and muscle activity of the gluteus medius (GM) muscle during hip abduction in a side-lying position in patients with low back pain (LBP). Objects: The purpose of this study was to assess the effects of LS on muscle thickness of QL and muscle activity of GM during hip abduction in side-lying in patients with LBP. Methods: The study included 32 patients with LBP, who were randomly divided into the control group and experimental group, each with 16 patients. All subjects performed $35^{\circ}$ preferred hip abduction (control group) and $35^{\circ}$ hip abduction with LS (experimental group) during side-lying. An ultrasonography and a surface electromyography were used to measure the thickness of the QL muscle, and the muscle activities of the GM muscle respectively. Independent t-test was used to compare the muscle thickness of the QL and the muscle activity of the GM muscle, respectively. Results: Anterio-posterior diameter in the muscle thickness of QL muscle was decreased significantly in hip abduction with LS more than in preferred hip abduction (p<.001), but medio-lateral diameter in the muscle thickness of QL muscle was not significantly different between in preferred hip abduction and in hip abduction with LS (p=.06). The muscle activity of GM was increased significantly in hip abduction with LS more than in preferred hip abduction (p<.001). Conclusion: These findings suggest that hip abduction with LS could be recommended as a hip abduction for LS and a prevention unwanted compensatory pelvic lateral tilting movement.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.4
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• pp.533-538
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• 2013

PURPOSE: This study was performed to investigate the effect of Low-dye Taping on muscle activity during single-leg standing in subjects with flexible flatfoot. METHODS: Thirteen able-body volunteers who had flexible flatfoot were recruited for this study. Subjects were measured navicular drop test to evaluate pronation of foot and muscle activity during single-leg standing before and after taping. The muscle activity was recorded using surface EMG from the tibialis anterior and the peroneus longus during single-leg standing on stable and unstable surface. RESULTS: The results show that the navicular drop height and the tibialis anterior muscle activity were significantly decreased after Low-dye taping. CONCLUSION: The results suggest that Low-dye taping could be useful in managing overuse of the tibialis anterior by reducing their level of activation during single-leg standing.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.426-433
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• 2023

The purpose of this study was to investigate the muscle activity of the lower extremity during driver swing in three-foot positions (Feet Open Stance, Feet Straight Stance, Lead Foot Open Stance). The electromyograms of gastrocnemius, tibialis anterior, and vastus lateralis during swing were measured and analyzed in three sections (take away - back swing, back swing - down swing, and down swing - follow swing). There was no significant difference in muscle activity according to foot position. Muscle activity according to phase was significantly higher in right gastrocnemius and tibialis anterior, and the left and right vastus lateralis in down swing - follow swing. In conclusion, the difference in muscle activity according to foot position is insignificant, and it is considered that the muscle activity to maintain the balance of the body increases toward the end of swing.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.2
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• pp.165-171
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• 2012

Purpose : The purpose of this study was to investigate the change of abdominal muscle activation during unilateral leg raising in supine position among three hip abduction angles($0^{\circ}$, $15^{\circ}$, $30^{\circ}$). Methods : Twenty eight able-body volunteers who had no medical history of low back and hip joint were recruited for this study. Abdominal muscle activity was recorded using surface EMG from both sides of the rectus abdominis, internal/external oblique muscle during leg raising in each position. Results : The muscle activations induced under the three different positions were compared and results showed that there was significant difference only in the right external oblique muscle activation. Conclusion : This study suggest that leg raising of different hip abduction angles without trunk control has little influence on abdominal muscle co-activation.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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• pp.581-588
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• 2011

Objective: The objective of this study is to compare muscle activity levels of the lumbar and rectus femoris muscle when entering and exiting RV and passenger vehicles. Background: Three varieties of RVs and two varieties of passenger vehicles were selected for this study. Method: Twenty individual(10 male and 10 female) in their twenties and thirties with no chronic back pain or any other illness participated in this study. Participants performed entering and exiting the three models of RVs and two models of passenger cars. Appropriate rest time was given to participants between entering and exiting each vehicle in order to recover from muscle fatigue while performing their tasks. Results: Results from this study show that muscle activity levels were highest for entering RVs and exiting passenger vehicles. There were no significant differences in muscle activity levels for left and right side muscles in regards to entering and exiting vehicles. Application: These results can be used to provide baseline information for reduce muscle fatigue when getting in and out of vehicles.

• Journal of the Ergonomics Society of Korea
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• v.24 no.4
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• pp.55-62
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• 2005

This study examined the effect of ergonomic heel rest that was designed for drivers who have physical handicap in the low leg muscles or have to drive prolonged hours with frequent foot pedaling. An experiment was designed to test the ergonomic heel rest with traditional foot pedal. Forty subjects participated in the experiment. Electromyography(EMG) was used to monitor the muscle activity and fatigue of right leg, and Electro-goniometer was used to measure the ranges of motions of the knee and ankle. A simulator of driver's seat was built for the experiment and the heel rest was installed on it. In order to examine the low muscle activity and range of motion, subjects used the foot pedal for 15 minutes repetitively for each experimental condition. Another 15 minutes test without the heel rest was also performed for comparison. The Root Mean Square(RMS) and Mean Power Frequency(MPF) Shift were used to quantify the level of muscle activity and local muscle fatigue. In results, statistically significant decreases of muscle activity and fatigue were found in all the low leg muscles. The range of motion of the knee and ankle joint also decreased when the heel rest was used. The mechanism of the heel rest effect was discussed in this study. This type of heel rest can be applied to real driving situation after ensuring the safety, or overcoming the psychological discomfort possibly due to unfamiliarity.