• Title/Summary/Keyword: Ergonomic Intervention

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The Influences of Pulsed Electromagnetic Field Treatment Following Experimentally Induced Delayed-Onset Muscle Soreness in Biceps Brachii (펄스자기장이 위팔 두갈래근의 지연성 근육통에 미치는 영향)

  • Kang, Sun-Young;Park, Joo-Hee;Jeon, Hye-Seon;Lee, Hyun-Sook
    • Physical Therapy Korea
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    • v.20 no.2
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    • pp.11-19
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    • 2013
  • Delayed onset muscle soreness (DOMS) is a painful condition that arises from exercise-induced muscle damage after unaccustomed physical activities. Various therapeutic interventions have been applied to reduce the intensity and duration of DOMS-related symptoms. Recently, pulsed electromagnetic field (PEMF) intervention has been introduced as an alternative noninvasive treatment for DOMS. This randomized, double-blind, placebo-controlled experiment was conducted to examine the effects of PEMF therapy on DOMS in elbow flexors at 24, 48, and 72 hours after the experimental DOMS induction. Thirty healthy volunteers ($23{\pm}2.4$ yrs, $175{\pm}5.7$ cm, and $74{\pm}7.8$ kg) participated in this study. Each was randomly assigned to a PEMF or placebo group. On the first day, DOMS was induced in the elbow flexors by repeated isokinetic motions at low ($60^{\circ}/s$) and fast ($120^{\circ}/s$) speeds in all subjects. Thereafter, the PEMF group received 15-min daily treatment with a PEMF device. The placebo group received sham treatment of the same duration. Overall, PEMF application was more effective than the sham treatment in reducing the physiological symptoms associated with the DOMS including perceived soreness, median frequency, and electromechanical delay of the surface electromyography. In addition, median frequency and isokinetic peak torque of the PEMF group recovered to the pre-DOMS induction level earlier than the placebo group. In conclusion, this study suggests that PEMF can be applied as a new recovery strategy in reducing DOMS symptoms. Further experiments are required to examine the effect of the PEMF treatment on different types of exercise conditions and to determine the optimal treatment dosage and duration in a real clinical setting.

Occupational Diseases Among Office Workers and Prevention Strategies

  • Lee, Jongin;Koo, Jung-Wan
    • Journal of the Ergonomics Society of Korea
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    • v.34 no.2
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    • pp.125-134
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    • 2015
  • Objective: In this review we discuss the health effects among office workers. Background: Even if office workers are not exposed hazardous or harmful environment frequently, some problems could be happened to the office workers. Although serious occupational diseases rarely occur to the office workers, it is important to consider occupational risk factors for the office worker because the portion of the office workers is relatively high in all industries. Method: We divided possible health effects for the office workers into three categories; musculoskeletal disorders, indoor environment, and cerebro-cardiovascular diseases. We reviewed related articles, textbooks, and statistical materials non-systematically and described risk factors, related illnesses, and prevention strategies on each category. Results: Office workers have various musculoskeletal disorders to be intervened. By medical treatment, improving working environment, and ergonomic intervention, office workers can be prevented from musculoskeletal injuries. Poor indoor environment can cause many building-related illnesses or sick building syndrome. Although the etiology of some problems by poor indoor environment is not clear, it helps to maintain adequate humidity, temperature, and clarity of indoor air. Cerebro-cardiovascular diseases are a rising issue because office workers in Korea tend to work for a lot of time. To prevent the diseases, it is needed to work for adequate time, lengthen activity level, and manage other medical risk factors for the diseases. Conclusion: There is no distinct occupational disease for office workers. However, there are some aspects to consider the health effects of office workers and it is important to prevent the possible health problems. Application: A strategy against occupational diseases among office workers can be established by reviewing this article.

Bio-mechanical Evaluation of Squatting Posture with Asymmetric Trunk Motion (몸통 비틀림 운동을 고려한 쪼그려 앉은 작업자의 요추부 작업부담 평가)

  • Lim, Dae-Seob;Kim, Young-Jin;Lee, Kyoung-Suk;Mun, Joung-Hwan
    • Journal of Biosystems Engineering
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    • v.36 no.1
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    • pp.58-67
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    • 2011
  • A high prevalence of protected horiculture farmer's work-related musculo-skeletal disorders (MSDs) have been reported in precedent studies. One of the tasks required ergonomic intervention to reduce the musculo-skeletal risks is the task of harvesting. The purpose of this study is to evaluate quantitatively the spinal load of worker harvesting with squatting posture to predict and prevent musculo-skeletal risks. Spinal load in Squatting posture with asymmetric trunk motion were analyzed. Before evaluating spinal load on harvesting worker by bio-mechanical approach, it is needed to validate human model. In this study, ADAMS LifeMOD human model shows satisfactory results, comparing with already validated model's results or measured results. While worker reached arms (20%, 40%, 70% arm reach) with various asymmetric trunk motion (0, 45, 90 degree), their spinal loads (extension, twisting and lateral bending moment) were evaluated. In case of extensor moment at lumbo-sacral joint, the more the arm reach got increased, the moment increased. however, in case of twisting moment and lateral bending moment, the more both arm reach and asymmetric trunk motion got increased, the moment increased significantly. The findings of this study suggest that it need to be determine the spinal load, especially twisting, lateral bending moment in evaluating musculo-skeletal workload in squatting posture.

Bio-mechanical Analysis on the Lower Back using Human Model during Pushing the Manual Vehicles (인체모델을 이용한 농작업자의 밀기 작업시 요추부 생체 역학적 평가)

  • Lim, Dae-Seob;Lee, Kyoung-Suk;Choi, Ahn-Ryul;Kim, Young-Jin;Mun, Joung-Hwan
    • Journal of Biosystems Engineering
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    • v.34 no.4
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    • pp.286-294
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    • 2009
  • A high prevalence of protected horticulture farmer's work-related musculo-skeletal disorders (MSDs) have been reported in precedent studies. One of the tasks required ergonomic intervention to reduce the musculo-skeletal risks is the task of product transporting. The purpose of this study is to evaluate quantitatively the spinal load of operator using manual vehicles to predict and prevent musculo-skeletal risks. Spinal load in operators using 4 kinds of manual vehicle were analyzed. Before evaluating spinal load on operator using the manual vehicles by bio-mechanical approach, it is needed to validate human model. In this study, ADAMS LifeMOD human model shows satisfactory results, comparing with already validated model's results or measured results. While Operators pushed the manual vehicles(wheelbarrow, Trolley, 2 wheel cart, and 4 wheel cart) contained loads that were 0 N and 800 N, their spinal loads(compression force, shear force) were evaluated. The compression force demonstrated under the NIOSH action limits - 3410N - for all 4 manual vehicle's operators(McGill 1997; Marras 2000). However, the lateral shear force demonstrated over the University of Waterloo - 500N - for all 3 manual vehicle's operators except 4Wheel cart (Yingline and McGill, 1999). Therefore, operators have risks in prevalence of the musculo-skeletal disorders due to shear force. The findings of this study suggest that it need to be determine the spinal load, especially lateral shear force in designing the manual vehicles in the future.

The Effects of Seat Surface Inclination on Forward Reaching in Children with Spastic Cerebral Palsy

  • Jeong, Jeong Yun;Lee, Ho-Cheol;Shin, Hwa-Kyung
    • The Journal of Korean Physical Therapy
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    • v.27 no.2
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    • pp.106-111
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    • 2015
  • Purpose: Impaired reaching movement is commonly observed in children with cerebral palsy. The purpose of this study was to determine whether the inclination of seat surface can influence the reaching movement in children with spastic diplegic cerebral palsy (CP). Methods: The subjects were 31 children, 16 children with spastic bilateral CP and 15 typically developing (TD) children. The children performed static sitting and forward reaching under three conditions: a horizontal seat surface (Horizontal $0^{\circ}$), a seat surface inclined anterior 15 degrees (Ant $15^{\circ}$), and a seat surface inclined posterior 15 degrees (Post $15^{\circ}$). A 3-axis accelerometer ('ZSTAR3') was used for analysis of the reaching movement. A 3-axis accelerometer was attached on the manubrium of the sternum, lateral epicondyle of the humerus, and styloid process of the ulna. We measured the reaction time, movement time, and data amount during reaching the 8 cm target with an index finger on the three inclined seat surfaces. Results: Reaction time and movement time for CPs showed significant delay; comparing the TD's and CP's amount was significantly greater than the TD's during reaching task (p<0.05). In particular, CP's reaction time and movement time on a seat surface inclined Ant $15^{\circ}$ was significantly more delayed compared with the other seat surfaces (p<0.05). Conclusion: Our results suggest that seat-inclination intervention may provide an ergonomic approach for children with spastic cerebral palsy.

Bio-mechanical Analysis of the Grapevine Cluster Thinning Task using Working Chair

  • Lee, Kyung-Suk;Kim, Hyo-Cher;Chae, Hye-Seon;Kim, Kyung-Ran;Lim, Dae-Seop
    • 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.

Effect of Back Strap Length Differences on Upper Extremity Muscle Activity, Center of Pressure, and Weight Distribution (가방 끈 길이 차이가 상지 근활성도, 압력중심 및 체중분포에 미치는 영향)

  • Lee, Hyun Ju;Kim, Min Su;Kim, Ah Yeon;kang, Hyun Gu;Tae, Ki Sik
    • Journal of Biomedical Engineering Research
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    • v.42 no.5
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    • pp.225-231
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    • 2021
  • The purpose of this study was to investigate the effect on the activity of the upper trapezius and erector spinae according to the length difference of the backpack using electromyogram (EMG). We also conducted a study comparing the center of pressure (COP) and weight distribution before and after using Wii® balance board. Thirty individuals were randomly assigned to the experimental group (n=14) wearing a backpack with a short right strap length and a control group (n=16) wearing a backpack with the same strap length. Data were collected by dividing into groups, carring a 15% weight backpack and walking for 20 minutes on a treadmill. As a result of analyzing the EMG data, there was no significant change in the upper extremity muscle activity of the control group, but it was significantly decreased in the right upper trapezius activity of the experimental group (p<0.05). In addition, there was a significant change of COP in the experimental group (p<0.05), but there was no significant difference of the weight distribution in both groups. Recognizing mechanical changes in the body that may occur due to the asymmetry of the strap length is thought to be helpful for systematic ergonomic intervention according to changes in the external environment in the future.

Comparative Effects of Novel Modified Sleeper and Cross-body Stretching on Scapular Anterior Tilting and Shoulder Internal Rotation in Subjects With Anterior Tilted Scapular and Shoulder Internal Rotation Deficits

  • Yeonghun Han;Chung-hwi Yi;Woochol Joseph Choi;Oh-yun Kwon
    • Physical Therapy Korea
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    • v.30 no.1
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    • pp.59-67
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    • 2023
  • Background: Posterior capsule tightness (PCT), commonly seen in overhead athletes, is a soft tissue adaptation that is also noted in non-throwers. PCT is associated with scapular and humeral kinematic alterations, significant restriction of shoulder internal rotation (IR) range of motion (ROM), and significant scapular anterior tilting. Sleeper and cross-body stretches (CBS) are suggested for PCT and IR deficits, and have been modified since introduction. A novel modified sleeper stretch (NMSS) was designed in this study to prevent the risk of anterior translation of the humeral head. Though the effects of posterior shoulder stretching exercise have been widely studies, to the best of our knowledge, no previous studies have investigated the effectiveness of posterior shoulder exercises in decreasing scapular anterior tilting. Objects: To compare the immediate effects of two posterior shoulder stretching exercises (NMSS and CBS) on scapular anterior tilting and shoulder IR ROM. Methods: Thirty-two subjects with anteriorly tilted scapula and IR deficits [mean age: 24.3 ± 2.5 years; 15 males and 17 females] participated in this study. Subjects were randomly assigned to either the NMSS or CBS groups. Scapular anterior tilting (at rest and at shoulder 60° active IR) and shoulder IR ROM were measured before and immediately after intervention. Results: Scapular anterior tilting significantly decreased, while the shoulder IR ROM significantly increased in both groups. However, there was no significant group-by-time interaction effect or significant difference between the groups. Conclusion: Both stretching exercises were effective in restoring shoulder IR ROM and decreasing scapular anterior tilting.

The Adoption of Risk Assessment Methodology in Exposure Assessment (근로자 노출평가제도 내 위험성평가 방법론의 적용)

  • Kim, Seung Won;Choi, Sangjun;Phee, Young Gyu;Kim, Kab Bae
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.25 no.4
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    • pp.482-492
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    • 2015
  • Objectives: Exposure Assessment for workplace hazards where the exposure level is below occupational exposure limits(OELs) has been performed without considering either the degrees of risk or exposure levels and has failed to lead to intervention in many cases. The objective of this study was to suggest and test an application framework for risk assessment methodology under the current exposure assessment system in Korea. Materials: First, we investigated the exposure assessment systems in Korea and other countries. To adopt some risk assessment techniques, we also analyzed risk assessment systems and compared them to exposure assessment systems. A few suggestions were made. We held a public hearing during an industrial hygiene conference and took surveys using a questionnaire. Results: The first suggestion was to implement the risk assessment and exposure assessment through a "one-stop" system. In that case, one expected question would be who has been doing the jobs so far. In most cases, industrial hygiene consulting services or laboratories have been performing exposure assessment for business owners. Business owners are required to perform risk assessment. As two different groups of people will be required to implement two things in a one-stop system, they need to share information. As an information vehicle to share information, commonly filed survey checklists were suggested. The second suggestion was to categorize exposure level into four groups instead of the current binary divisions based on OELs. In the risk assessment system, exposure level is divided into four groups utilizing the cut-points of 10%, 50%, and 100% of OELs. The same schema can be adopted in the exposure assessment system and different levels of requirements can be assigned for each group. The third suggestion was regarding the regulation system. To provide the suggestions some thrust toward being implemented in the field, changes should be made in the legal system. Two different types of new exposure assessment result reporting forms were suggested. Some investigations such as an ergonomic survey are officially accepted as risk assessment under the current legal system. A few items were suggested to be included in the exposure assessment result reporting to be accepted as risk assessment. A pilot study in two small factories was performed and pointed out the strengths and weakness of our suggestions. Conclusions: Discussions and studies on the improvement of the exposure assessment system have been held for decades and no tangible changes have yet been made. We hope this result can help realize healthy lives for workers in Korea.

Risk Assessment and Intervention of Ergonomic Risk Factor in Beekeeping (치과위생사의 직무스트레스 그리고 작업자세와 상지의 증상여부 및 기능과의 관련성)

  • Kwon, Yu-jin;Kang, Yong Ju;Seo, Sung-Hyo;Kim, Bokyoung;Park, Ki-Soo
    • Journal of agricultural medicine and community health
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    • v.44 no.4
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    • pp.209-219
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    • 2019
  • Objectives: This study investigated musculoskeletal symptoms in upper limbs according to the working environment (job stress) of dental hygienists and examine their relationship with upper limb functions. Methods: The subjects include 198 dental hygienists in dental hospitals and dental clinics in Pusan and Gyeongnam. The questionnaire was consisted of general characteristics of the subjects, job stress, musculoskeletal symptoms in upper limbs and function (Disability Measurement Tool for Upper Extremity Disorders-11, DASH-11). Results: The study was analyzed their musculoskeletal symptoms in upper limbs according to their general characteristics and found that the symptoms occurred in the neck (39.4%), the shoulders (54.6%), elbows (14.7%), and the hands (50.0%). Job stress was associated with upper limb functions (DASH-11) (model 3, B=5.210, p=0.012) and repeated elbow bending and spreading posture was associated with DASH-11 (model 3, B=6.561, p=0.029). Elbow symptoms were associated with DASH-11 in the upper limbs (B=10.679, p=0.003). Conclusion: Dental hygienists are experiencing limitations of upper limb function due to job stress. In particular, even if the correction of their uncomfortable posture is significantly related to the job stress and upper limb function, in order to improve the upper limb function of the dental hygienist, efforts to reduce the job stress as well as the uncomfortable posture are necessary.