• Physical Therapy Korea
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• v.15 no.2
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• pp.30-37
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• 2008

Anticipatory postural adjustments are pre-planned by the central nervous system (CNS) before the activation of agonist muscles in the limbs, and minimize postural sway. Most previous studies on this topic have focused on upper-limb movement, and little research has been conducted on lower-limb movement. The purpose of this study was to investigate the recruitment order of left and right trunk muscles during limb movement. Fifteen healthy subjects (10 male, 5 female) were enrolled. Electro-myographic signals were recorded on the muscles of: (1) deltoid, lumbar erector spinae, latissimus dorsi and internal oblique during shoulder flexion, (2) rectus femoris, rectus abdominis, external oblique and internal oblique during hip flexion. During right upper limb flexion, the onset of left erector spinae muscle and left internal oblique muscle activity preceded the onset of right deltoid by 8.09 ms and 19.83 ms, respectively. But these differences were not significant (p>.05). A similar sequence of activation occurred with lower limb flexion. The onset of left internal oblique muscle activity preceded the onset of right rectus femoris muscle by 28.29 ms (p<.05). The onset of right internal oblique muscle activity preceded the onset of left rectus femoris muscles by 23.24 ms (p<.05). The internal oblique muscle was the first activated during limb movement. Our study established the recruitment order of trunk muscles during limb movement, and explained the postural control strategy of the trunk muscles in healthy people. We expect that this study will be used to evaluate patients with an asymmetric recruitment order of muscle activation due to impaired CNS.

• Physical Therapy Rehabilitation Science
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• v.5 no.1
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• pp.29-33
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• 2016

Objective: This study compared the muscle activities of the erector spinae (ES), the external oblique (EO), and the rectus abdominis (RA) on three different surfaces. The purpose of this study was to determine which surface induces the highest muscle activity during the plank exercises. The information from this study can be used to recommend plank exercises to athletes and patients with weak core muscles. Design: Cross-sectional study. Methods: The subjects include 20 adult males attending S University in Seoul. Participants completed each plank exercise on three different surfaces. To measure muscle activities, researchers used the values from electromyography. The measurement excluded the initial two and final two seconds and collected information on the RA, EO, and ES in each posture of each subject. Results: The left external oblique showed significant differences between the plank position on stable ground (ST) and the plank position using a suspension device (SL) (p<0.05) and between the plank position on the unstable ground (US) and SL (p<0.05). The right rectus abdominis and left rectus abdominis displayed statistically significant differences between the ST and the US (p<0.05) and between the ST and the SL (p<0.05). The right erector spinae had a statistically significant difference between ST and US (p<0.05). Conclusions: The plank exercise strengthens the core muscles effectively, and muscle activity is related to the posture of the exercise and the location of the muscle. These results suggest that plank exercises improve muscle activities. Additionally, plank exercises can be applied to general medical care.

• Journal of Convergence for Information Technology
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• v.7 no.4
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• pp.97-103
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• 2017

The purpose of this study was to investigate muscle activity of cervical erector spinae & upper trapezius while using a smartphone according to anterior pelvic tilt & posterior pelvic tilt in sitting position. & we also want to obtain basic data necessary for development of IoT devices. Fifteen healthy men & women aged 20-30 were enolled, After anterior pelvic tilt & posterior pelvic tilt in sitting position were adjusted, they used a smartphone for 5 minutes & EMG signal was measured simultaneously. We used median 3 minutes of measured EMG signal. The results of this study were as follows: In the sitting position, the use of smartphone in anterior pelvic tilt had significantly lower %RVC values in both cervical erector spinae (p <.001), left upper trapezius (p <.001) & right upper trapezius (p <.002) in comparison with posterior pelvic tilt. This means that anterior pelvic tilt make vertebrae maintain normal curvature & prevent forward head posture occurred while using a smartphone. It reduces loads around neck & shoulders, so that %RVC value is significantly lowered. In the future, new posture corrected IoT devices with an aspect of pelvic tilt should be developed.

• Physical Therapy Korea
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• v.11 no.3
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• pp.51-58
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• 2004

The purpose of this study was to compare the postural muscle activity during wearing a lead apron with and without applying waist belt at working posture. Ten healthy male subjects were recruited for this study. Electromyography using a surface EMG recorded the activity of the splenius capitis, trapezius, and erector spinae. EMG activity was recorded at quiet standing, 45 degrees of neck flexion, 45 degrees of neck flexion with 15 degrees of trunk flexion. The testing order was selected randomly. The subjects were asked to maintain the each posture for 3 minutes. The mean root mean square (RMS) of EMG activity was calculated. EMG activity was normalized using the maximum voluntary isometric contraction (MVIC) elicited using a manual muscle testing technique. Two-factor repeated measures analysis of variance (ANOVA) was used to compare the average RMS value of EMG activity for each condition. The EMG activity of trapezius muscle was significantly decreased with applying waist belt (p<.05). The muscle activity of splenius capitis and erector spinae showed significant difference according to postures (p<.05). These results suggest that applying waist belt during wearing a lead apron will be useful to prevent shoulder pain.

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.265-276
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• 2003

The objective of this research is to provide basic data for improving athletic performances, suggesting methods that can be utilized at games and coaching movements in the snatch, by analyzing the level of contribution of muscles to the movements of the snatch lift through three-dimensional imaging and EMG analysis between skilled and unskilled lifters. To this end, three high school students (the skilled group), three middle school student (the unskilled group) were selected; two digital video cameras and electromyography were used. The muscles measured by an EMG include gastrocnemius muscle, biceps femoris muscle, erector spinae, latissimus dorsi muscle, trapezius muscle, and brachioradialis. Based on the Ariel Performance Analysis System (APAS) program, the results of the analysis are summarized as follows. 1. In performing snatch pulls, the skilled lifters were found to simultaneously move the weight centers of the body and the barbell close to vertical, close to the shoulders in the pulling portion; in snatching and grabbing the barbell from a sited position, it was observed that the shorter the time for adjusting to change in the height of the barbell by using rotational inertia, the better it is to perform the movements. 2. The skilled lifters were observed to perform stable and efficient movements in grabbing the bar in a sited position, by moving the barbell and weight center of the body close to vertical and moving the shoulder joint under the bar fast. 3. The results of the EMG analysis of the entire movements from the snatching portion to the portion of grabbing the bar in a sited position show that when the skilled lifters lifted the barbell vertically during the pulling portion, their shoulder joints were extended to put more weight on biceps femoris muscle and brachioradialis; and in snatching and grabbing the bar from a sited position, it was found desirable to increase the myoelectrical activity of erector spinae in order to achieve a balance in the movements of the hip joint between font and rear, as the weight centers of the body and the barbell move higher. On the other hand, the unskilled lifters were found that in response to change in posture, they increase their muscular strength inefficiently in performing the movements throughout the entire lifting process.

• Physical Therapy Korea
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• v.16 no.1
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• pp.1-9
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• 2009

An abdominal drawing-in maneuver (ADIM) with a pressure biofeedback unit can be used to prevent excessive lumbar lordosis during bridging exercise. Therefore, in this research, the effects of an ADIM on lumbar lordosis and lower extremity muscle activity during bridging exercise were investigated in thirty healthy adults. Surface electromyography (EMG) and VICON system were used to collect kinematic data and muscle activity, respectively. A paired t-test was used to determine a statistical significance. The results showed as follows: (1) When performing bridging exercise with an ADIM, the height of the anterior superior iliac spine and greater trochanter decreased significantly (p<.05). (2) When performing bridging exercise with an ADIM, the trunk extension angle and pelvic angle increased significantly (p<.05). (3) When performing bridging exercise with an ADIM, the EMG signal amplitude increased significantly in the rectus abdominis, internal oblique abdominis, external oblique abdominis, medial hamstring, and lateral hamstring (p<.05). (4) When performing bridging exercise with an ADIM, the EMG signal amplitude decreased significantly in the erector spinae (p<.05). From the result of this research, an ADIM trained with pressure biofeedback unit during bridging exercise is effective to prevent excessive contraction of erector spinae, to limit excessive motion of pelvis from sagittal plane and to increase muscle activity of abdominal muscles and hamstring muscle.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.4
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• pp.221-229
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• 2009

Purpose : The purpose of this study was to assess the effect of bridging stabilization exercises of trunk muscles activity on a Swiss ball according to change of position. Methods：30 healthy university students volunteered to participate in this study. Subjects were required to complete following three exercise positions. Exercise position 1; Supine bridge with Swiss ball, Exercise position 2; Side bridge with Swiss ball, Exercise position 3; Prone bridge with Swiss ball. Surface electromyography from selected trunk muscles was normalized to maximum voluntary isometric contraction. Results : A repeated measures of ANOVA with Duncan's correction was used to determine the influence of exercise type on muscle activity for rectus abdominis, external oblique, erector spinae. The erector spinae of exercise position 1 showed significantly higher muscle activity than exercise position 2, 3(p<.05). The external oblique of exercise position 2, 3 showed significantly higher muscle activity than exercise position 1(p<.05). The rectus abdominis of exercise position 3 showed significantly higher muscle activity than exercise position 1, 2(p<.05) Conclusion： These results indicate that muscle activity can be influenced by addition of a Swiss ball in bridging exercises. It is recommend to use a Swiss ball for trunk stabilization exercise.

• Korean Journal of Applied Biomechanics
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• v.32 no.1
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• pp.31-36
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• 2022

Objective: The purpose of this study was to investigate muscle activation according to the four strap lengths in the TRX plank exercise to provide scientific and accurate data on effective training methods. Method: Twenty healthy men who had at least 6 months of weight training experience and could fully adjusted plank exercise, were participate in this study (age: 25.2 ± 3.7 yrs., height: 174.2 ± 3.9 cm., weight: 71.2 ± 9 kg). To pursue the study purpose, surface electrodes were attached to trunk muscles (pectoralis major, rectus abdominis, external oblique, internal oblique, erector spinae, latissimus dorsi) and lower extramity muscles (gluteus maximus, rectus femoris, gastrocnemius), and the muscle activity was measured using 11-channel electromyography equipment. In order to verify the muscle activation according to the four strap lengths during TRX plank exercise, an one-way ANOVA with repeated measure was used with statistical significance level set at as α=.05. Results: First, there were statistically significant differences in pectoralis major, rectus abdominis, external oblique, internal oblique, and erector spinae among TRX strap lengths. Second, there were statistically significant differences in gluteus maximus, rectus femoris, and gastrocnemius among TRX strap lengths. Third, even though no statistically significant difference found in latissimus dorsi, but increased muscle activation tendency was showed as the length of the strap increased. Conclusion: From the results of this study, it may be possible that TRX exercise prevent injuries and improve lower extremity muscle as well as trunk muscles by setting appropriate length of strap.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.21-28
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• 2015

Objectives : The purpose of this study was to compare differences in muscle activities according to distance changes, and success or failure in relation to approaches during a round of golf in order to obtain basic data on golf swings. Methods : To achieve our research goal, we asked eight professional golfers playing for the Korea Professional Golfers' Association (height: $1.76{\pm}0.05m$, weight: $73.87{\pm}9.21kg$, career duration: $12.87{\pm}4.48yr$) to perform approach swings at distances of 30, 50, and 70 m. Results : No differences were observed in the muscle activity of the extensor carpi radialis that were caused by the distance changes. In addition, we found that the wrist extensors seemed unaffected by the increase in approach distance. Also, we found that the powers of the approach shots were driven by efficient movements rather than by the strength of the arms. We confirmed that when the distance of the approach increased, the golfers should perform their back-swing tops and follow-through right from the right to the left pelvic limb. To achieve successful approach swings despite distance changes, golfers should first work on the activity of the erector spinae to prepare for rotatory power in the P1 section. Moreover, golfers should increase the activity of the erector spinae on the left when they need to deal with the distance improvements in the P2 and P3 sections. Conclusion : In the light of the discussion above, we may infer that despite approach distance changes during a round of golf, ideal swings can be realized by consistent activities of the wrist extensor muscles and improved performances of the pelvic limb muscles. Furthermore, this study suggests that golfers should improve the consistency of muscle activities in all the other body parts to achieve the ideal swing.

• Physical Therapy Korea
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• v.18 no.3
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• pp.1-7
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• 2011

The effects of an abdominal drawing-in maneuver (ADIM) using a pressure bio-feedback unit (PBFU) were compared to the effects of a pelvic belt (PB) on the muscle activities of the hip and back extensor muscles during hip extension in the prone position. Fifteen healthy male participants all performed prone hip extensions under three conditions: 1) preferred hip extension (PHE), 2) performing an ADIM, and 3) using a PB. The muscle activities of the erector spinae, the gluteus maximus, and the medial hamstring on the right side were recorded by surface electromyography. The muscle activity of the erector spinae was significantly lower while performing an ADIM during prone hip extension than during PHE or with a PB (p<.05). Gluteus maximus muscle activity was significantly higher while performing an ADIM (p<.05). No significant difference was found for the medial hamstring muscle among the three conditions (p>.05). We concluded that the internal stabilization of the pelvis and lumbar spine afforded by the ADIM using a PBFU could be more effective than the external stabilization provided by a PB in terms of increasing selectively gluteus maximus activation during prone hip extension.