Epidemiological and biomechanical evaluation of airline baggage handling

Objectives. Musculoskeletal disorders (MSDs) are prevalent among airline baggage handlers due to manual materials handling. In this study, the Nordic musculoskeletal questionnaire (NMQ), the revised National Institute for Occupational Safety and Health (NIOSH) lifting equation, and the University of Michigan 3D Static Strength Prediction Program? (3DSSPP) were used to analyze MSDs among baggage handlers. Methods. The NMQ was filled out by 209 baggage handlers and 46 arbitrarily selected baggage handlers were evaluated using the NIOSH method and 3DSSPP. Results. The obtained results showed that the most common MSDs occurred in the lower back region. The next risky regions included knees, neck, and upper back, respectively. The NIOSH results confirmed that the subjects lifted loads heavier than the permitted limit and their lifting postures were inappropriate. The results of the 3DSSPP also indicated that compression forces exceeded the NIOSH limit in these awkward postures. Conclusions. Relying on this study, holding compulsory ergonomic lifting training courses could be proposed for workers and regulations adjusting an upper limit for maximum baggage weight must be also enacted in order to improve occupational health and prevent the prevalence of increasing MSDs.     

Load Acceleration and Footstep Strategies in Asymmetrical Lifting and Lowering

Accelerated execution effects for lifting and lowering a 12-kg box using two footstep strategies associated with experienced workers were studied. Eight healthy male participants performed a normal and an accelerated execution of a lifting task and a lowering task, using a minimal feet displacement strategy (oblique-step) and a strategy with a step (crossed-step). It was hypothesized that the accelerated executions, as compared to the normal executions, would have a different effect on L5/S1 resultant moment, body posture, and other kinematic variables. A tridimensional dynamic rigid body model was used to compute L5/S1 resultant moments. Results showed that the accelerated condition did not reduce body asymmetry of posture, but it reduced the length of the path of the global center of gravity and the duration of the supporting phase of the box, and it did not significantly affect L5/S1 maximal resultant moments for lifting but increased them for lowering. These results indicate that the net work production for accelerated strategies might be smaller, which may represent an economy of energy. Furthermore, the results showed that the use of an accelerated strategy for lowering should be avoided.     

Three-Dimensional Lifting Model For Non-Homogeneous Loads

A 3-dimensional model and analysis methodology is suggested for treating lifting tasks when unbalanced loads are involved. The paper describes the biomechanical equations that are coupled with the worker’s posture geometry, to address a practical problem of non-symmetric lifting. The analysis has a dominant biomechanical modeling scope, as it contains a breakdown of the internal lifting forces resulting from posture and external loads acting on the body. The load model represents the acting forces due to unbalanced lifting, which is commonly found in industrial situations. The suggested model allows the user to simulate the influence of the practical load distribution, aiding safe design of a lifting job.     

Manual Material Handling Assessment Among Workers of Iranian Casting Workshops

Manual material handling (MMH) tasks can be found in most workplaces and they may constitute a risk factor for work-related musculoskeletal disorders (WMSDs). This study was conducted to determine the prevalence of WMSDs and to compare MMH loads with the acceptable weight and force limits among Iranian casting workers. Data were collected from 50 workers of casting workshops who performed MMH tasks. The Nordic musculoskeletal disorders questionnaire and the Snook tables were used as tools for data collection. Hand/ wrist symptoms were the most prevalent problems among the workers (84%). The results of the Snook tables showed that the loads in lifting (84%), lowering (86%), carrying (66%), pushing with initial (43%) and sustained force (59%), and pulling tasks with initial (48%) and sustained force (93%) exceeded recommended limits. WMSDs occurred in high rates among the workers and, thus, ergonomics interventions should focus on decreasing WMSDs and redesigning MMH tasks.     

Development of statistical models for predicting muscle and mental activities during repetitive precision tasks

This study was conducted to develop muscle and mental activities on repetitive precision tasks. A laboratory experiment was used to address the objectives. Surface electromyography was used to measure muscle activities from eight upper limb muscles, while electroencephalography recorded mental activities from six channels. Fourteen university students participated in the study. The results show that muscle and mental activities increase for all tasks, indicating the occurrence of muscle and mental fatigue. A linear relationship between muscle activity, mental activity and time was found while subjects were performing the task. Thus, models were developed using those variables. The models were found valid after validation using other students’ and workers’ data. Findings from this study can contribute as a reference for future studies investigating muscle and mental activity and can be applied in industry as guidelines to manage muscle and mental fatigue, especially to manage job schedules and rotation.     

Ergonomic assessment of airport shuttle driver tasks using an ergonomic analysis toolset

This study aimed to (a) evaluate strength requirements and lower back stresses during lifting and baggage handling tasks with the 3D Static Strength Prediction Program (3DSSPP) and (b) provide additional analyses using rapid entire body assessment (REBA) and the NASA task load index (TLX) to assess the risks associated with the tasks. Four healthy female shuttle drivers of good health aged between 55 and 60 years were observed and interviewed in an effort to determine the tasks required of their occupations. The results indicated that lifting bags and placing them in a shuttle were high risk for injury and possible changes should be further investigated. The study concluded there was a potential for injury associated with baggage storing and retrieval tasks of a shuttle driver.     

Lifter,a Computerized Lifting Analysis Technique

A computer driven technique to analyze lifting forces, in non-homogeneous load situations, is described and tested. Analysis is based on a dynamic algorithm aimed to evaluate unconstrained lifting posture and non-homogeneous content of loads. For inputs we use actual geometrical body postures in the form of 3-dimensional co-ordinates obtained from pictures taken at a work site. The outputs show a good match between the findings and pre-study assumptions for balanced and non-balanced load lifting practice. The results of the experiments show a good degree of correlation with results reported by researchers for symmetrical lifting tasks and with National Institute for Occupational Health (NIOSH) lifting guidelines. It is believed that the technique can serve as the proper choice for industrial and safety analysts of lifting activities.     

Lifting Belts: A Review

This article reviews and evaluates the literature related to the effectiveness of protective restraints on abdominal strength, lower back injuries, and workers’ discomfort. The studies indicate that back belts have potential disadvantages as well as advantages. Belts seem to reduce lifting stress. They may, however, lead to a false sense of security while being worn and may also weaken the body, so injury occurs when they are not being worn. There also seems to be comfort problems with some belts. More scientific research is needed before any conclusions can be drawn about positive, negative, or long-term effects of lifting belts.     

园林工人割灌作业职业性肌肉骨骼疾患的工效学研究

职业性肌肉骨骼疾患是园林工人的常见职业病,严重影响园林工人的工作效率和身体健康。对18名从事园林割灌作业的工人通过NMQ北欧肌肉骨骼系统问卷调查表进行调查,统计得出园林割灌作业的下背痛患病率约在60%左右,从事割灌整枝作业工人下背痛患病率为25%,从事割草作业下背痛患病率达444%,割草作业的下背痛患病率明显高于割灌整枝操作者。应用SPSS190软件进行下背痛的危害因子分析,得出下背痛的发生主要与重复动作、工龄、日提举负荷等有关。     

Prediction models for psychophysical lifting capabilities and the resulting physiological responses for work shifts of varied durations

This paper presents models for predicting estimates of maximum weights of lift acceptable to industrial workers for 8-hour work shifts. Prediction models are also presented for heart rate and oxygen uptake at the maximum acceptable weight of lift. Experimental data collected on 37 males and 37 females were used in developing and verifying these models. Each subject performed nine variations of a lifting task involving three heights, four frequencies, and three box sizes to determine estimates of acceptable lifts for 8-hour shifts. The final lifting capability prediction models explained 76 to 82% variance in the experimental data. A procedure is also described to determine, from these models, acceptable lifts for work periods of variable lengths. The physiological-response-prediction models, which provide estimates of heart rate and oxygen uptake at the maximum acceptable weight of lift, were, however, relatively inferior to other similar response models available in the literature. This is thought to be due to the differences between the psychophysical and physiological methodologies.     

Handling Techniques: The Influence of Weight and Height for Experts and Novices

The purpose of this study was to evaluate the influence of the weight of the load (12 kg, 22 kg) and of the height of the grasp (high: 126 cm; middle: 64 cm and 95 cm; low: 33 cm) on the handling techniques adopted by six experienced handlers and six novices having only limited handling experience during a free box-handling task. Each subject had to transfer two sets of 16 boxes from a platform to a four-wheel cart. The observations dealt with the position of the subject at the beginning of transfer and at deposit (position of the back, knees and feet, pelvic orientation, position of the hands), his way of moving during the transfer (position of the feet), and his way of positioning and moving the box during handling (tilt of the box, impulse given to the box, grip change). The results show that the weight and the height of grasp/deposit had an influence on the techniques adopted by expert handlers and novices. Some of these variations are common to both groups but many of them are not, such as the position of the knees, the grips and the position of the box. This study suggests that there is not one method that is suitable for all situations, and that expert handlers may have learned how to adjust their methods to the working environment. A better understanding of the experts’ techniques could help in redesigning efficient training programs.     

机械加工工人慢性肌肉骨骼损伤的调查研究

机械加工作业十分普遍，通过对１４０名机加工工人的调查，发现手、腕、臂、肩、颈和上背的疼痛及腕、上臂和上背的压痛与对照人群比，Ｐ＜ ０．０５差异明显，下背酸痛虽较对照人群高，但无统计学意义。这可能与机械加工时需取低头、颈前弯、上背前倾体位及勿需常弯腰等因素有关     

The use of assistance while lifting

Using assistance during lifting is a desirable behavior. Assistance can eliminate or reduce the amount of biomechanical stress associated with a lift, significantly reducing the risk of low back injury. This paper describes lifting activities engaged in by nursing care workers. Only 15% of all lifts performed by the hospital nursing personnel in this study were assisted lifts. The analysis suggests that the use of assistance can be associated with specific factors such as type of object lifted, work stress associated with the lift, number of preparations that must be made before the lift can be attempted, years of experience of the lifter, and the idiosyncratic behavior patterns of lifters with respect to using assistance. It is recommended that attention be given to psychological and social, as well as biomechanical, factors in the control of low back injury.     

缓闭止回阀防护水锤的研究

笔者就水泵扬水的压力输水系统中设置气压式调压室和缓闭止回阀的问题 ,建立了实验模型和相应的数学模型 ,并进行了理论分析研究、数值模拟和实验研究 ;通过实验 ,验证了数值模拟的数学模型和计算程序 ,并且指出了缓闭止回阀使用的范围 ,纠正了使用缓闭止回阀的误区 ,对提高压力水系统安全性及降低工程成本具有现实意义。     

A comparative assessment of the impact of different occupations on workers' static musculoskeletal fitness.

An ergonomic assessment of the involvement of static muscular forces like back strength, grip strength and pinch strength in different occupations was made. A study was conducted on 45 normal adult males (15 subjects per group) which included video display terminal (VDT) operators, industrial workers and safety inspectors. Their maximum back strength, handgrip strength and pinch strength were measured with dynamometers. The observed values of back strength were significantly lower in VDT operators while significantly higher in safety inspectors and moderate in industrial workers. The values of grip strength and pinch strength of all sample groups were more or less similar. The findings clearly indicate that static muscular strength varies significantly in different occupations. Heavy static muscular load might lead to an accumulation of metabolic waste and toxins on the back resulting in lower back strength in VDT operators and industrial workers.     

Back injury research: Have we overlooked something?

Most back injury research and the safety programs based on its findings have assumed disc and vertebral failure to be the result of compression and/or shear forces. This paper draws on selected references along with a knowledge of how materials fail under simple and combined stresses to postulate alternative failure mechanisms which, if proven, could lead to improvements in back injury prevention programs.     

Predictive models of safety belt use: a regression analysis of MVOSS data

A substantial portion of the U.S. population fails to regularly use their safety belts. The explanations for the differential belt use have addressed, for example, socioeconomics, state law, attitudes, and perceived likelihood of being ticketed. The current analyses create predictive models of safety belt use. Using NHTSA's Motor Vehicle Occupant Safety Surveys (Years 1998 and 2000; N = 9577), variables related to belt use were entered into backward stepwise logistic regressions to produce two predictive models (Demographic and Attitudinal) of safety belt use (Always versus Not always). The results indicated that belt use is a complicated issue as there were several interactions between variables. The Demographic predictive model contained main effects for, law types, socioeconomics, population density, a gender-law type interaction, and a three-way interaction between age, marital status, and vehicle type. The Attitudinal model included perceived effectiveness of the belt, fatalistic attitudes, and an interaction between perceived effectiveness of the belt and perceived risk of being ticketed. These models survived a multinomial logistic regression when belt use was parsed into three categories (Always, Part-time, and Infrequent). In addition to variables that affect belt use, the results suggested that the structure of "belt use" as a psychological/behavioral construct is more complicated than once thought. Specifically, a dichotomous breakdown of belt use (Always and Not always) oversimplifies the construct because the predictor factors sometimes affect "part-time" belt users differently than "infrequent" belt users (compared to "full-time" users). Many of the factors included in the models have been previously shown to impact belt use, but the interaction effects--indicating a more complicated relationship between these variables than previously suggested--may contribute to a better understanding of safety belt use.     

Psychosocial and Individual Characteristics and Musculoskeletal Complaints Among Clinical Laboratory Workers

Musculoskeletal disorders (MSDs) are an important health problem among healthcare workers, including clinical laboratory ones. The aim of the present study was to investigate the prevalence of MSDs and individual and psychosocial risk factors among clinical laboratory workers. A cross-sectional study was carried out among 156 workers of 30 clinical laboratories in 3 towns of Iran. The Nordic questionnaire with individual and psychosocial risk factors was used to collect data. Multiple logistic regression analysis was performed. The prevalence of reported MSDs among the study population was 72.4% in the past 12 months. The most prevalent MSDs were pain in the lower back and neck; 42.7% and 33.3%, respectively. Significant relations were found between MSDs and age, gender, heavy work at home and job control (p < .05). MSDs among laboratory workers were high and associated with age, gender, heavy work at home and job control. More research into measuring these factors and workplace physical demands is suggested.