• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.159-166
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• 2006

The purpose of this study were analysed fatigue character of lumbar extension Muscle during repeated trunk flexion-extension motion we used EMG multi-telemeter (WEB 5000, Nihon Koden, Japan), Medex lumbar extension machine(Ocala, USA). We evaluated 20 persons on chronic low back pain group and 20 persons on control group. We analysed the quantitative variables IMF, MF, decreased ratios of MF to investigate fatigue. As a result, the following conclusion was drawn : 1. Each lumbar IMF of CLBP was L5> L3> L1 in the order of their size. CON group was similar quantitative and same order. But the relationship of two groups were not significantly. 2 The IMF within lumbar position(L1-L3, L1-L5, L3-L5) of two groups was significantly all positions(p<.05). 3. The MF shifting at lumbar position of two groups during repeated trunk flexion-extension motion was decrease shifting pattern with increase repeating motion, especially CLBP group was suddenly dropping than CON at all lumbar positions(L1, L3, L5) on early stage motion(34 set). 4. The lumbar fatigue of CLBP was higher than CON during repeated trunk flexion-extention motion, so CLBP supposed more tired than CON. And it was significantly within two groups at lumbar positions(L1, L3 : p<.05, L5 : P<.01).

• Journal of the Ergonomics Society of Korea
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• v.20 no.2
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• pp.71-82
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• 2001

Twisting posture in lifting tasks has been identified as a risk factor of low back pain. However, it has been usually estimated in terms of compressive stress or muscular activity. Thus, this study was conducted to predict the influence on muscular fatigue during lifting simulation. Fifteen young and healthy subjects were recruited and performed isometric trunk exertions during upright standing, two-level flexions and five-level asymmetric twisting conditions. EMG signals from five primary trunk muscles in right part of body were collected during 20sec for 45 different lifting conditions. RMS(root mean square) and MPF(mean power frequency) parameters were used to analyze the EMG signals. Twisting postures were significant in right erector spinae(ERSR), right latissimus dorsi(LATR), right internal oblique(INOR) for muscular activities. Especially, when trunk was $30^{\circ}$ CCW twisting posture. ERSR and INOR activities increased respectively by 11% and 3%. Regarding the trunk muscle fatigue, we found that MPF shifts in twisting posture increased 2.3 and 2.6 times for ERSR and INOR muscles respectively. Therefore, It is probable for workers to suffer from low back disorders when they were exposed to a extreme twisting posture during prolonged lifting. This study suggests NIOSH(National Institute for Occupational Safety and Health) lifting equation needs the time-duration multiplier in addition to asymmetric multiplier.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.29 no.1
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• pp.1-9
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• 2023

BACKGROUND: The purpose of this study was to find out which exercise is more effective for the activation of the trunk, when the suspension plank and modified bridge exercise are performed. Weakening of the trunk muscles can lead to secondary injuries such as back injuries. In order to prevent injury, trunk muscles must be strengthened, and representative trunk strengthening exercises include planks and bridges. Each has been developed with a modified method, but since there is no paper comparing which exercise is more effective for trunk muscle strength, it was written to compare the two exercises. METHODS: The subjects were a random sample of 30 healthy men who agreed to participate in the study. The subjects were divided into two groups of 15 people each, and the suspension plank and the modified bridge exercise were performed for six weeks. The thickness of the transverse abdominis (TrA), internal abdominal oblique (IO), external abdominal oblique (EO), rectus abdominis (RA), multifidus (MF) was measured before and after the exercise. The two groups were analyzed using an independent t-test and paired t-test to compare the muscle thickness and the difference before and after exercise. RESULTS: The trunk muscle thickness was increased in both groups with suspension plank and modified bridge exercise, and there was a statistically significant difference. When comparing the two groups, the suspension plank group also showed a significant difference in RA (p<.05). CONCLUSION: As a result of this study, suspension plank exercise can have a positive effect on activating the trunk muscles and strengthening the strength of RA. Therefore, it is considered that suspension plank exercise is a more effective intervention to strengthen trunk muscle than modified bridge exercise.

• Journal of Acupuncture Research
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• v.27 no.3
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• pp.93-104
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• 2010

Objectives : The purpose of this study is to observe the effects of work environment and low back pain on the structural and muscle strength changes in lumbar spine to helpful for preventation and cure of low back pain. Methods : Through measuring of lumbosacral angle, lumbar lordotic angle, lumbar gravity line ratio analyzed structure of lumbar spine and using Trunk Extension Flexion Program of CYBEX NORM System(cybex770+TMC, USA) analyzed Flex. PT, Ext. PT, E/F ratio of lumbar spine of company employees given a medical examination. Results : According to work environment, lumbar gravity line ratio is higher in white collar group than in blue collar group, Ext. PT is significantly lower in white collar group than in blue collar group. According to low back pain or not, lumbar gravity line ratio, Ext. PT is lower in low back pain group than in non-low back pain group. Conclusions : Work environment and low back pain effects on the structural and muscle strength changes in lumbar spine.

• 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.

• Journal of the Ergonomics Society of Korea
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• v.30 no.3
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• pp.395-401
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• 2011

Objective: This study examined the effects of working chair that was developed for farmers who work in grapevine's cluster thinning. Background: Agricultural work involves some of the nation's highest occupational risk exposures. Fruit cultivation has been recognized as one of the most hazardous crops in which to work. Grapevine cluster thinning task involve activities related to the main risk factors associated with upper limb work-related musculoskeletal disorders. Method: An experiment was designed to test the working chair. Six healthy male($25.8{\pm}4.9years$) were selected as the subjects for this study. Electromyography(EMG) was used to monitor the muscles activity, and Electro-goniometer was used to measure the ranges of motions of the elbow, trunk and knee. Subjective test was also carried out to examine discomfort body parts and their pain intensity. A grapevine's working space was built for the experiment and working chair was installed on it. In order to examine the muscle activity and range of motion, subjects used to the working chair for 30 minutes for each experimental condition. Another test without working chair was also performed for comparison. %MVC was used to quantify the level of muscle activity. Results: Decreases of muscle activity was found in all leg muscles and significant decrease of muscle activity was found in left Gastrocnemius. The range of motion of the trunk and knee also decreased when working chair used. Discomfort in lower back, thigh and shank region were reduced significantly. However, in upper limbs muscle activity tended to increase in working chair compared with conventional task. Conclusion: Improvement for cushion in seat back and pan required to reduce discomfort in buttocks. Application: Overall findings verified that the working chair might help to prevent upper limb and lower back MSDs based on the current study. These results can be practically used for work improvement for the grapevine growers to prevent MSDs.

• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.67-74
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• 2005

The purpose of this study is to compare and analyze the muscle activations between the professional golfers without low back pain symptom and the professional golfers with low back pain symptom, and so identify the stress related to golf swings, and provide the basic data to minimize the low back pain and the injury risk. Using surface electrode electromyography, we evaluated muscle activity in 6 male professional golfers during the golf drive swing. Surface electrodes were used to record the level of muscle activity in the Abdominal Oblique, Elector Spinae, Rectus Abdominis, Gluteus Maximus muscles during the golfer's swing. These signals were compared with %RVC(Reference voluntary contraction) which was normalized by IEMG(Integrated EMG). The golf swing was divided into five phases: take away, forward swing, acceleration, early follow through, late follow through. we observed patterns of trunk muscle activity throughout five phases of the golf swing. The results can be summarized as follows: RES(Right Elector Spinae) had statistically significant difference in take away phase, LGM(Left Gluteus Maximus), LRA(Left Rectus Abdominis), LOA(Left Oblique Abdominal) had statistically significant difference in forward swing phase, RES(Right Elector Spinae), RGM(Right Gluteus Maximus), ROA(Right Oblique Abdominal) had statistically significant difference in acceleration phase, RES(Right Elector Spinae), RGM(Right Gluteus Maximus) had statistically significant difference in early follow-through phase, LES(Left Elector Spinae), RGM(Right Gluteus Maximus) had statistically significant difference in late follow through phase.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.91-99
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• 2019

PURPOSE: This study was conducted to evaluate the activity of trunk muscles according to width of the foot and posture of the arm during sit to stand (STS). METHODS: Thirty subjects were recruited and examined for variation in muscle activity of the erector spine, gluteus maximus, gluteus medius and external oblique during different STS conditions; namely, the cross arm basic sit to stand (CBSTS), overhead basic sit to stand (OBSTS), cross arm wide sit to stand (CWSTS), and overhead wide sit to stand (OWSTS). Repeated measures ANOVA (Analysis of Variance) was used for analysis. RESULTS: Erector spinae muscle activity showed a significant increase in the OBSTS condition (p<.05) and external oblique muscle activity showed a significant increase in the OWSTS condition ((p<.05). There was no significant difference in the activity of the gluteus maximus and gluteus medius under any conditions (p>.05). CONCLUSION: During evaluation of the performance of the STS, the CWSTS condition will be useful to decrease the muscle activity of the erector spinae and the OWSTS condition will be useful to increase the muscle activity of the external oblique. The results of this study can be used as an index to find a suitable exercise method for subjects who have back pain or to strengthen the abdomen.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.10 no.3
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• pp.399-407
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• 2003

Purpose: This study was done to identify levels of physical fitness in student nurses and to ascertain the relationship among the different aspects of physical fitness of strength, power, muscle endurance, agility, balance and flexibility. Method: The participants were 266 students selected from one college of nursing. From May 1 to July 31 in 2003, physical constitution, muscle strength (grip strength, back strength), power (standing long jump), muscle endurance (sit-ups), agility (whole body reaction time-light, sound), balance (close-eyes foot-balance), and flexibility (sitting trunk flexion) were measured. Result: The mean(standard deviation) for grip strength was 22.59(3.93) kg., for back strength, 48.52(12.85) kg., for standing long jump, 135.29(20.54) m., for sit-up's, 23.66(9.35) per minute, whole body reaction time (light), 0.43(0.11) sec, whole body reaction time (sound), 0.50(0.16) sec, close-eyes foot-balance, 33.35(38.67) sec, and sitting trunk flexion 34.72(9.37) cm. Conclusion: This study showed that the physical fitness of student nurses is very low compared to the results in a report from the Korea Sports Science Institute. It is necessary to include exercise programs for student nurses in order to improve their physical fitness.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.9 no.1
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• pp.9-14
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• 2011

Purpose : The purpose of this study is to examine the influence of a core stability exercise program using Swiss Ball on muscle activity, muscle thickness, maximum muscular strength, and pain in the trunk region during a 6-weeks program involving participants who have lower back pain. Methods : A total of 21 males between the ages of 20 and 33 years old were divided into 3 Swiss Ball exercise groups. Group 1 performed isometric exercises, group 2 performed isotonic exercises, and group 3 performed mixed exercises. Measurements were taken prior to starting the exercise program and after completing the program at the 6-week period using ME6000 to measure muscle activity and VAS to measure pain reduction. Comparisons were made using a paired t-test and ANOVA on SPSS 10.0. Results : There was a statistically significant effect in muscle activity for group 1 and group 3. Secondly, there was a statistically significant effect in pain reduction for group 1, group 2, and group 3. Conclusion : We found that isometric exercises performed by group 1 were effective in improving muscle activity and pain reduction.