Michiel P. de Looze

Vrije Universiteit Amsterdam | VU · Faculty of Human Movement Sciences

Mechanical loading of the spine is a known risk factor for the development of low-back pain. The objective of this study was to assess the effect of an inclination-controlled exoskeleton on spinal compression forces during lifting with various techniques. Peak compression decreased on average by around 20%, and this was largely independent of lifti...

In this cross-sectional study associations were examined between eight shift schedule characteristics with shift-specific sleep complaints and need for recovery and generic health and performance measures. It was hypothesized that shift schedule characteristics meeting ergonomic recommendations are associated with better sleep, need for recovery, h...

Exoskeletons may form a new strategy to reduce the risk of developing low back pain in stressful jobs. In the present study we examined the potential of a so-called passive exoskeleton on muscle activity, discomfort and endurance time in prolonged forward-bended working postures. Eighteen subjects performed two tasks: a simulated assembly task with...

We examined the effects of age on automatic and voluntary motor adjustments in pointing tasks. To this end, young (20-25 years) and middle-aged adults (48-62 years) were instructed to point at a target that could unexpectedly change its location (to the left or right) or its color (to green or red) during the movement. In the location change condit...

The aim of this review was to provide an overview of assistive exoskeletons that have specifically been developed for industrial purposes and to assess the potential effect of these exoskeletons on reduction of physical loading on the body. The search resulted in 40 papers describing 26 different industrial exoskeletons, of which 19 were active (ac...

Unlabelled: This study examined associations of chronotype and age with shift-specific assessments of main sleep duration, sleep quality and need for recovery in a cross-sectional study among N = 261 industrial shift workers (96.6% male). Logistic regression analyses were used, adjusted for gender, lifestyle, health, nap behaviour, season of asses...

Unlabelled: Work-related musculoskeletal disorders are increasing due to industrialisation of work processes. Task variation has been suggested as potential intervention. The objectives of this study were to investigate, first, the influence of task variation on electromyographic (EMG) manifestations of shoulder muscle fatigue and discomfort; seco...

The objectives of this study were to (1) examine whether need for recovery differs between workers (i) not on-call, (ii) on-call but not called and (iii) on-call and called, and (2) investigate the associations between age, health, work and social characteristics with need for recovery for the three scenarios (i-iii). Cross-sectional data of N = 16...

We assessed the effects of aging in the transfer of motor learning in a sequential manual assembly task that is representative for real working conditions. On two different days, young (18-30years) and middle-aged adults (50-65years) practiced to build two products that consisted of the same six components but which had to be assembled in a partly...

In this study the effects of horizontal bin locations in an order picking workstation on upper arm elevation, trunk inclination and hand use were investigated. Eight subjects moved (self-paced) light or heavy products (0.2 and 3.0 kg) from a central product bin to an inner or outer order bin (at 60 or 150 cm) on the left or right side of the workst...

Unlabelled: BACKGROUND/STUDY CONTEXT: It has been proposed that effects of aging are more pronounced for explicit than for implicit motor learning. The authors evaluated this claim by comparing the efficacy of explicit and implicit learning of a movement sequence in young and older adults, and by testing the resilience against fatigue and secondar...

Unlabelled: The present investigation assessed the putative benefits of reducing instructions for older adults' learning of an assembly task. Young and older adults had to build a product by assembling six components. Two groups practiced following instruction methods that differed in the degree of explicit information they conveyed about the corr...

Task variation has been proposed to reduce shoulder fatigue resulting from repetitive hand-arm tasks. This review analyses the effect of task variation, both 'temporal (i.e. change of work-rest ratio)' and 'activity (i.e. job rotation)' variation, on physiological responses, endurance time (ET) and subjective feelings. Pubmed was searched and compl...

The aim of this study was to examine which individual and work-related characteristics predict work outcomes related to sustainable employment among male shift and day workers. Between 1 September 2005 and 31 December 2009, data on individual and work-related characteristics of N=5640 employees of Tata Steel in the Netherlands were retrieved from t...

The article presents an approach to developing cost-effective interventions for workplace innovations for entrepreneurs who seek to enhance the productivity of an organization. The business case method is used to extend the Q4-model of productivity, which supports developing a productivity strategy in order to choose a cost-effective intervention....

Special Issue Editors: Vincent Charles, Rolf Fare and Joe Zhu Foreword: Business Performance Management is a term that became widely used in the 1970s. The term represents a set of activities that assist the management of any organization to manage its resources and achieve its goals in an effective and efficient manner. Basically, it is a popular...

ABSTRACT The authors investigated how tracking performance, submovement organization, pen pressure and muscle activity in forearm and shoulder muscles were affected by target size in a 2D tracking task performed with a pen on a digitizer tablet. Twenty-six subjects took part in an experiment, in which either a small dot or a large dot was tracked,...

Unlabelled: This study investigated temporal changes in movement strategy and performance during fatiguing short-cycle work. Eighteen participants performed six 7-min work blocks with repetitive reaching movements at 0.5 Hz, each followed by a 5.5-min rest break for a total duration of 1 h. Electromyography (EMG) was collected continuously from th...

The design of a work station generally prescribes a global movement pattern of the operator, but also leaving some degrees of freedom regarding movement strategy. For a specific order picking work station, we studied the movement strategies, the underlying factors and its impact on performance. Eight subjects performed a task comprising, the pickin...

Purpose – The paper aims to present an approach to improve the organisation's productivity which is applicable in every industrial sector. The nucleus of the approach is to develop an optimal productivity strategy in an organization by the application of a uniform static model of productivity (Q4-model), covering quantity and quality aspects and ap...

In the present study, we investigated the effect of office tasks on posture and movements in field settings, and the comfort rating for chair characteristics and correlation with type of task. The tasks studied were: computer work, telephoning, desk work and conversation. Postures, movements, chair part inclinations and comfort rating data were col...

This paper explores the suggestion that older people would be less tolerant to shift work. Field studies on age-shift work interaction effects on sleep, fatigue, performance, accidents and health were reviewed. Studies on age-shift (morning, afternoon, night) and age-shift system (roster) interactions were also reviewed. In nine studies, shift and...

This study investigated the effect of work pace on workload, motor variability and fatigue during light assembly work. Upper extremity kinematics and electromyography (EMG) were obtained on a cycle-to-cycle basis for eight participants during two conditions, corresponding to "normal" and "high" work pace according to a predetermined time system for...

Due to shorter productlife cycles in manufacturing industry there is a lot of pressure on the process of designing new work systems. Early attention for human factors would lower the costs compared to changes at a later stage. Low cost tools for workstations design could help especially small to medium sized assembly enterprises. However, these too...

We aimed to investigate whether position sense acuity of the upper extremity and tracking performance, pen pressure and muscle activity in a tracking task are affected in subjects with neck and upper extremity pain. Twenty-three subjects with neck and upper extremity pain and 26 healthy controls participated in the study. Position sense acuity of t...

Maximization of flexibility is one of the major challenges in assembly line design. This article addresses the question of how to temporarily (in times of peak demand) increase the output of a line, which is already optimized to attain the “normal” output rate. Instead of a costly reconfiguration of the line creating extra workstations for more ope...

Early cost–benefit analysis of ergonomic interventions in manufacturing is in the interest of the production management and the ergonomics specialist. Because of the variety of factors and the complexity to quantify these factors, this task is not an easy one. In this article we present a case study that illustrates that the economic benefits of er...

Five case studies on production line design were described to study the effect of an early design support tool. Based on these case studies, the simple, interactive, real-time, medium-fidelity, mixed-reality methodology was not only found to be a good early design stage evaluative tool for ergonomics and workflow, but a teaching tool as well. Despi...

The prevention of work-related musculoskeletal disorders is one of the main goals in ergonomics. Among others, surface electromyography (sEMG) is an important tool for the evaluation of risks related to work activity. Three main issues have been approached ...

Shoulder fatigue has been suggested to be a useful risk indicator for shoulder disorders in repetitive, low-force work tasks. In contrast to high-force or purely isometric tasks, it is unclear whether measurable fatigue develops in realistic low-force work. The question addressed in this review was: 'Is there evidence of objective signs of fatigue...

In this study the influence of chair characteristics on comfort, discomfort, adjustment time and seat interface pressure is investigated during VDU and non-VDU tasks: The two investigated office chairs, both designed according to European and Dutch standards are different regarding: 1) seat cushioning and shape, 2) backrest angle and 3) controls. T...

Comfort is increasingly important in sales of cars, hand tools, seats, earth-moving machines, and airplane tickets. Discomfort is a predictor of musculoskeletal injuries and should be reduced in situations that consume a significant part of our time. Therefore, manufacturers of products such as seats, cars, beds, hand tools, and production lines ne...

The purpose of this study was to determine whether objective electromyographical manifestations of muscle fatigue develop in the upper trapezius muscle in two assembly tasks involving contractions of different low-intensity levels (8% and 12% MVC) and whether these indications of fatigue are homogeneously distributed across different muscle parts....

It has been suggested that fatigue affects proprioception and consequently movement accuracy, the effects of which may be counteracted by increased muscle activity. To determine the effects of fatigue on tracking performance and muscle activity in the M. extensor carpi radialis (ECR), 11 female participants performed a 2-min tracking task with a co...

This study was designed to determine whether trunk extensor fatigue occurs during low-level activity and whether this is associated with a drop in muscle tissue oxygenation. Electromyography (EMG) feedback was used to impose constant activity in a part of the trunk extensor muscles. We hypothesized that electromyographic manifestations of fatigue a...

In the current study, the relationship between objective measurements and subjective experienced comfort and discomfort in using handsaws was examined. Twelve carpenters evaluated five different handsaws. Objective measures of contact pressure (average pressure, pressure area and pressure-time (P-t) integral) in static and dynamic conditions, muscl...

Optimization of the temporal aspects of task design requires a better understanding of the development of muscle fatigue in the neck and shoulder region over time. The objective of the study was to investigate this in two production companies and to determine the relationship between objective and subjective estimates of fatigue. Indicators of fati...

This study investigates whether the same factors underlie comfort in using different kinds of hand tools (screwdrivers, paintbrushes and handsaws). The underlying factors of the hand tools are identified using principal components analysis. The relationships between comfort descriptors (i.e. statements in end-users’ own words that are related to co...

The study was designed to determine the effect of joystick handle size and (display-control) gain at two levels of required task precision on performance and physical load on crane operators. Eight experienced crane operators performed a simulated crane operation task on a computer by use of a joystick with either a short or a large handle. The tas...

The plenary lectures from the 16th World Congress on Ergonomics, Maastricht, July 10-14, 2006, have been documented in this special issue. Its theme was ‘Meeting Diversity'. The contributions, ranging from scientific papers to technical notes or short statements, cover different aspects of the central subject: ergonomic diversity in people, work, p...

Current assembly enterprises are under a lot of pressure, as they are faced with increasing volume demands and product variations, needs for shorter delivery times and cost reduction. This pressure is likely to increase the pressure on individual workers. In many small to medium-sized enterprises (SMEs), we observe that traditional assembly concept...

The aim of the study was to identify predictors of comfort and discomfort in using hand tools. For this purpose, the comfort questionnaire for hand tools (CQH) was developed based on the results of a previous study. In the current study, four screwdrivers were evaluated on comfort (expected comfort at first sight and comfort after short time use) u...

The objective of the present study was to compare energetic workload, perceived exertion, perceived discomfort, safety, and mechanical load at lower limb joints among window cleaners during usage of extension ladders with 30 and 35 cm rung separation. Eleven healthy male professional window cleaners of short and tall stature participated in this st...

Currently, the majority of the work force in the Netherlands is working in offices, as the service industry has grown and much work has been automated (Smulders et al. 2002). This means that many people spend much of their lifetime sitting on office chairs. Consequently, the market for office chairs is large; there are many chair manufacturers and...

International Journal of Production Research. Two major issues play a role in manual assembly operations: increasing productivity and increasing health. For a company, it is essential to have efficient operations (Yamada 2002). Handling operations such as searching and walking add only a limited value to the product and should be avoided, and the h...

To design comfortable hand tools, knowledge about comfort/discomfort in using hand tools is required. We investigated which factors determine comfort/discomfort in using hand tools according to users. Therefore, descriptors of comfort/discomfort in using hand tools were collected from literature and interviews. After that, the relatedness of a sele...

The objective of the present study was to gain insight into the effects of precision demands and mental pressure on the load of the upper extremity. Two computer mouse tasks were used: an aiming and a tracking task. Upper extremity loading was operationalized as the myo-electric activity of the wrist flexor and extensor and of the trapezius descend...

When two office chairs basically have the same functionality, we prefer the one that gives us a pleasant, desirable, or inspired feeling. The challenge is to design the appearance that evokes the emotions that are wanted by the chair’s users. These emotions are important because they primarily and strongly influence the decision to purchase the cha...

As mentioned in Chapter 9, two major issues play a role in manual assembly operations: reducing discomfort as a precursor to health problems and increasing productivity. In this project the engineering department and the workforce adapted the production lines several times. Several tools such as simulation software were used, and at first sight the...

In Chapter 1 it was shown why knowledge of comfort is important. This knowledge could support the design of products such as seats, vehicles, and hand tools and increase sales, but it could also help prevent injuries of the back, shoulders, and arms. In this chapter the knowledge available in the literature on comfort related to seat, hand tool and...

The concepts of comfort and discomfort in sitting are under debate. There is no widely accepted definition, although it is beyond dispute that comfort and discomfort are feelings or emotions that are subjective in nature. Yet, beside several subjective methodologies, several objective methods (e.g. posture analysis, pressure measurements, electromy...

Rhythm, defined as the repetitive pattern of actions in time of an individual worker, is increasingly recognized as a crucial factor in short cycle time assembly. Rhythm includes aspects like cycle time, action variation, work content and work rest schemes, and it affects productivity, quality, worker's motivation and worker's health. By the organi...

This study evaluated the effects on work-related neck and upper-limb disorders among computer workers stimulated (by a software program) to take regular breaks and perform physical exercises. Possible effects on sick leave and productivity were studied as well. A randomized controlled design was used with cluster randomization. Altogether 268 compu...

High precision demands in manual tasks can be expected to cause more selective use of a part of the muscular synergy involved. To test this expectation, load sharing of the index finger and middle finger was investigated during a pinching task. Myoelectric activation of lower arm and neck-shoulder muscles was measured to see if overall level of eff...

A participatory and integrative approach was applied to improve the productivity and ergonomics of the assembly lines in two factories, producing magnetic stop valves and office furniture, respectively. Main elements of the approach are the active participation of the company and the integration of two disciplines: assembly engineering and ergonomi...

Office chair designers have traditionally focused their design efforts on optimizing the so-called 'ergonomic fit.' Although the effort to design chairs that support physical comfort is commendable, the focus on ergonomics neglects the possible impact of emotional responses on the general experience of comfort. The general experience of comfort exp...

Manufacturers of manually assembled products are increasingly being forced to improve the flow of assembly orders, together with having more efficient employment, in order to meet increasing demands on short delivery times, high product variety, good quality and low manufacturing costs. At the same time, the human factor is increasingly important--...

Software programs cueing computer workers to apply regular breaks and physical exercises may help in reducing work-related upper limb disorders. The effects of such a program was investigated among 268 computer workers with upper limb disorders, who were randomised into a control group, a group cued to take extra breaks and a group cued to perform...

Low back loading during occupational lifting is thought to be an important causative factor in the development of low back pain. In order to regulate spinal loading in the workplace, it is necessary to measure it accurately. Various methods have been developed to do this, but each has its own limitations, and none can be considered a "gold standard...

Lifting, carrying, pushing and pulling at work are assumed to be related to increased risks of musculoskeletal injury, mainly in the low back and shoulder region. The implementation of products to reduce the physical load in heavy work is a well-known strategy to attack this problem. The success of these products depends not only on the product its...

Manufacturers are forced to improve the flow of assembly orders in order to meet demands on short delivery times. At the same time, the human factor is increasingly important. To improve assembly processes and workstation design, a participatory approach was developed by TNO and applied in companies. Goals of this approach are lead time reduction a...

Seated work has been shown to constitute a risk factor for low-back pain. This is attributed to the prolonged and monotonous low-level mechanical load imposed by a seated posture. To evaluate the potential health effects with respect to the low back of office chairs with a movable seat and back rest, trunk kinematics, erector spinae EMG, spinal shr...

To compare two methods of calibrating the erector spinae electromyographic signal against moment generation in order to predict extensor moments during asymmetric lifting tasks, and to compare the predicted moments with those obtained using a linked-segment model. Eight men lifted loads of 6.7 and 15.7 kg at two speeds, in varying amounts of trunk...

City officials from Haarlem, a Dutch city in which one of the first scientific studies on the workload of refuse collectors was performed, wanted to compare the work situation and physical workload in 1997 with the results of a study performed in Haarlem in 1985 and with the results of a national study conducted in 1993. Depending on the results, t...

A systematic review and meta-analysis of studies on the putative mechanisms of action of lumbar supports in lifting activities. To summarize the evidence bearing on the putative mechanisms of action of lumbar supports. A restriction of trunk motion and a reduction in required back muscle forces in lifting are two proposed mechanisms of action of lu...

Study Design. A systematic review and meta-analysis of studies on the putative mechanisms of action of lumbar supports in lifting activities. Objective. To summarize the evidence bearing on the putative mechanisms of action of lumber supports. Summary of Background Data. A restriction of trunk motion and a reduction in required back muscle forces i...

Force and frequency in manual handling tasks are known risk factors for work related upper arm disorders. Three force levels and three frequencies are used to define the external load in a pinching task. The effects of these external loads on subjective and objective responses are studied. Subjective ratings poorly reflect the levels of external lo...

Manufacturers of manually assembled products are more and more forced to improve the flow of assembly orders together with a more efficient employment, in order to meet increasing demands on short delivery times, high product variety, good quality and low manufacturing costs. At the same time, the human factor is increasingly important, for a well-...

The comfort of the operators in the cabins of vehicles is getting an increasingly important issue. At first glance, the cabins of professional machines (earth-moving equipment, busses, harvesting equipment) might look modern and highly comfortable. However, this does not imply that the cabins actually are comfortable, especially in the long term. H...

Occupational manual material handling (MMH) is generally not limited to the sagittal plane. Yet, for practical reasons, biomechanical modeling of low back loading during occupational MMH is mostly restricted to 2D. In this study, the limitations to such an approach are analyzed through quantification of the errors made during 2D analysis of 3D lift...

People who know the actual mass of an object to be lifted normally prepare themselves before attempting a lift to control the movement and to minimize low back loading. In this study, the trunk muscular reactions and low back torque were investigated in the situation in which the individual did not know the actual mass but only had some idea of the...

In pushing and pulling wheeled carts, the direction of force exertion may, beside the force magnitude, considerably affect musculoskeletal loading. This paper describes how force direction changes as handle height and force level change, and the effects this has on the loads on the shoulder and low back. Eight subjects pushed against or pulled on a...

We investigated to what extent subjects base anticipatory activity patterns of trunk muscles before lifting a load on knowledge of the inertial properties of the load. Eight healthy male subjects performed rapid arm lifts of a load with a varying center of mass position in the frontal plane. In one set of trials subjects were familiar with the cent...

In lifting, the abdominal muscles are thought to be activated to stabilize the spine. As a detrimental effect, they contribute to spinal compression. The existing literature is not conclusive about the biological relevance of this effect. From biological, mechanical and anatomical considerations it was hypothesised that the relative abdominal contr...

In pushing and pulling wheeled objects, the effect of the exerted force on local musculo-skeletal loads depends on