• Journal of the Korean Society of School Health
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• v.12 no.2
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• pp.321-337
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• 1999

The purpose of this study was to obtain basic data for the prevention and control of adolescent back pain through analyzing connections between study environments and physical posture. The subjects were 960 male general high school students in the Chonju area and the data were collected by a self-reported questionnaire from Mar. 17 to Mar. 22, 1999. The collected data were analyzed by a frequency, chi-square and t-test using an SPSS program. The results are as follows; 1) The experience rate of back pain perceived by subjects was 67.5% and by each grade: 1st-27.5%, 2nd-35.4%, 3rd-37.1%. The relationship between grades and the experience of back pain didn't show any significant difference. 2) The causes of back pain perceived by subjects such as 'postures are not good' was 56.7%, 'sitting too much time in a chair' was 39.1%, and 'too severe exercise' was 32.4%. 27.8% had back pain first during the 3rd grade of middle school, and 23.9% had it first during the 1st grade of high school. 3) Intensity of subjects' back pain spread from 'moderate' at 49.6%, to 'severe' at 16.4%. Concerning the frequency of back pain, 58.6% said it was 'irregalar'. 4) Among interventions to deal with back pain: 'move by exercising my back or ask friends to beat my back' was 41.0%, 'just bear it' was 23.1%, and at home 'don't have 'any treatment' was ranked first, at 54.9%. 5) The relationship between subjects' general characteristics and back pain experiences: height (t=-1.99, P=.046), sitting/height (t=-2.61, P=.009), self-perceived condition of health (${\chi}^2=23.530$, P=.000), family history (${\chi}^2=43.903$, P=.000) showed significant difference, but the kinds of transportation, sleeping postures, sleeping method and smoking didn't show significant differences. 6) The relationship between subjects' learning environment and back pain experiences, the height of students' desk and chair showed significant difference (${\chi}^2=23.054$, P=.000), but the sitting time didn't show significant difference. 7) The relationship between the characteristics of subjects' physical postures and back pain experiences: standing postures (${\chi}^2=15.105$, P=.001), and sitting postures (${\chi}^2=20.264$X2, P=.001) showed significant difference, but lifting postures didn't show significant difference.

• Journal of the Korean Society of Safety
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• v.14 no.3
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• pp.174-180
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• 1999

The objective of this study was to investigate the effects of carrying postures and weight of load carried one time on a worker when carrying heavy loads. Six male students participated in this study to perform a manual materials carrying task as subjects. To make comparison of work loads with physical work capacity, maximal oxygen uptake measurement tests were performed with submaximal test. The average oxygen consumption for the tasks of this study was 27.59~31.93% $VO_2$max. The results showed that the weight of load carried one time affects on working heart rate and oxygen consumption($VO_2$). It was found that the workload was significantly lower when handling a 20kg load at a frequency rate of 3times/min than when handling a 40kg load at a frequency rate of 1.5 times/min. There was no difference between carrying postures. It is concluded from the results of this study that the workload can be reduced by controlling conditions of a manual materials handling task.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.4
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• pp.413-423
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• 2001

Low back disorders (LBDs) are one of the most common and costly work-related musculoskeletal disorders. One of the major possible risk factors of LBDs is to work with static and awkward trunk postures, especially in a complex trunk posture involving flexion, twisting and lateral bending simultaneously. This study is to examine the effect of complex trunk postures on the postural stresses using a psychophysical method. Twelve healthy male students participated in an experiment, in which 29 different trunk postures were evaluated using the magnitude estimation method. The results showed that subjective discomfort significantly increased as the levels of trunk flexion, lateral bending and rotation increased. Significant interaction effects were found between rotation and lateral bending or flexion when the severe lateral bending or rotation were assumed, indicating that simultaneous occurrence of trunk flexion, lateral bending and rotation increases discomfort ratings synergistically. A postural workload evaluation scheme of trunk postures was proposed based on the angular deviation levels from the neutral position. Each trunk posture was assigned numerical stress index depending upon its discomfort rating, which was defined as the ratio of discomfort of a posture to that of its neutral posture. Four qualitative action categories for the stress index were also provided in order to enable practitioners to apply corrective actions appropriately. The proposed scheme is expected to be applied to several field areas for evaluating trunk postural stresses.

• Korean Journal of Applied Biomechanics
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• v.27 no.4
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• pp.279-285
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• 2017

Objective: The purpose of this study was to perform a muscle function path analysis of muscle function on myofascial meridians. Method: Seven male students (mean age: $22{\pm}3.46years$; mean mass: $72.71{\pm}8.19kg$; mean height: $174{\pm}4.39cm$) without a history of musculoskeletal system symptoms or injuries were recruited for this study. The measurement muscle of the myofascial line was selected along with the muscle presented in "anatomy trains (Thomas W. Myers. 2014)", and the attachment of the surface EMG (Telemyo 2400T G2, USA) pad was determined according to "EMG analysis (Kim Tae Wan et al., 2013)". The subjects underwent maximum volumetric contraction of their fascia line end muscles three times in lying and standing postures and were subjected to the maximum number of contractions of the myofascial line muscle three times in the lying and standing postures. The sampling rate of the EMG signal was set to 1,000 Hz, and the bandwidth was 20 to 350 Hz. The activity of each muscle was quantitated using the Pearson correlation coefficient, and SPSS 22.0 was used for data analysis. Results: In myofascial meridians, a positive correlation in the myofascial connection and a negative correlation in the mechanical connection were observed. Conclusion: Muscles that show significant contract correlations with one another may be expected to be used as an effective clinical marker in muscle strengthening or relaxation therapy, and rehabilitative training. In this study, the correlation of total myofascial meridians may differ without consideration of functional posture. Future studies need to consider these points.

• Journal of Korean Dental Hygiene Science
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• v.1 no.2
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• pp.41-52
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• 2018

The purpose of this study was to examine the state of oral prophylaxis practice among dental hygiene students and their awareness of musculoskeletal diseases in an effort to provide some information on how to strengthen education on treatment posture to manage musculoskeletal diseases and how to raise awareness of musculoskeletal diseases. From November 2 to 13, 2016, a self-administered survey was conducted on 653 sophomores, juniors and seniors with an experience of oral prophylaxis practice. SPSS version 20.0 for Windows was employed to analyze the collected data. The findings of the study were as follows: 1. The largest group that accounted for 37.4% responded that the total number of students undergoing oral prophylaxis practice during a semester was four to six. The biggest group that represented 65.4% answered that the required practice time per student was one to fewer than three hours. 76.0% continued to be in the repeated same posture. 2. As for the posture of patients, supine position was most common for the maxillary sinus, which accounted for 82.2%. And semi-upright position was most common for the mandibular sinus, which represented 49.6%. 3. In regard to the burden of oral prophylaxis practice, 33.9% considered the required for the practice appropriate. 42.3% took the repeated long-lasting posture, and 53.5% were under physical pressure. 55.4% suffered from mental pressure and stress. 4. The most dominant musculoskeletal area that they experienced pain after oral prophylaxis practice was neck with 52.5%; waist with 48.2, shoulders/wrists/hands with 45.5, back with 10.3, buttocks with 4.1, elbows with 2.3, legs with 2.1, ankles/feet with 0.8 and knees with 0.6%. 5. Concerning the maintenance of repeated treatment postures and pain experience, the students who continued to be in the repeated same position underwent more pain than the others who didn't on the shoulders(2.92±1.05), in the waist(3.02±1.01), buttocks(1.75±0.92), elbows(1.55±0.79) and ankles/foot(2.52±1.25). The differences were statistically significant(p<.05, p<.01). 6. As to educational experience on treatment posture and musculoskeletal diseases, 88.8% received education on treatment posture; 87.9%, on what position should be taken in times of cooperation; 46.9%, on musculoskeletal diseases; 51.9%, on carpal tunnel syndrome; 42.3%, on varicose vein. The students who replied education on occupational diseases was necessary accounted for 89.6%. 7. The students who experienced treatment posture education were better aware of the causes of musculoskeletal diseases(3.23±3.00), ways for preventing the diseases(3.33±.834) and how to stretch the body(3.63±.858). The differences were statistically significant(p<.05, p<.001). 8. The students who experienced education on occupational diseases heard more about musculoskeletal diseases(3.27±.965), were better cognizant of the causes of the diseases(3.45±.847), were better aware of how to prevent them(3.55±.805) and found themselves to know how to stretch to prevent the diseases (3.73±.826). The differences were statistically significant(p<.001).

• The Journal of Korean Physical Therapy
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• v.27 no.3
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• pp.154-158
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• 2015

Purpose: The purpose of this study was to propose a new reference point for measurement of the infrasternal angle and to investigate the intra- and inter-rater reliabilities of infrasternal angle measurement using photographs. Methods: Twenty-four healthy male college students participated as subjects in this study. Photographs were taken of subjects in two postures, one standing with the shoulders relaxed and one standing with the shoulders at $150^{\circ}$ abduction. All photographs were analyzed using Image J software. Raters used the photographs to measure the infrasternal angle between the xiphoid process, the medial margin of rib and navel on the right and left sides. The reliability of the infrasternal angle measurement was assessed by means of intraclass correlation coefficients [ICC (3,1)]. The level of statistical significance was set at p<0.05. Results: The intra- and inter-rater reliabilities of the infrasternal angle measurement for the right side at rest were excellent (ICC=0.866 and 0.813, respectively), as were those for the left side at rest (ICC=0.919 and 0.846, respectively). At $150^{\circ}$ shoulder abduction, the intra- and inter-rater reliabilities for measurement of the infrasternal angle on the right side were excellent (ICC=0.972 and 0.778, respectively), as were those for the left side (ICC=0.914 and 0.826, respectively). Conclusion: These findings suggest that this technique can be successfully used to measure the infrasternal angle, thus suggesting a new reference point for determining the length of the internal oblique and external oblique muscles in clinical situations.