The burden of conveyor belt work in the canteen kitchen: A question of working height?

BACKGROUND: Working in forced postures and standing continuously can be classified as straining the musculoskeletal system. OBJECTIVE: Since such postures are frequently used in hospital canteen kitchens, we used kinematic analysis to determine the working postures of canteen kitchen staff. METHODS: In this study, the daily work routine of 18 (11 w/7 m) workers of a hospital canteen kitchen (Frankfurt Main/Germany) aged 21-62 years (46±13 years) was examined by means of kinematic analysis (CULEA system; IFA; Sankt Augustin/Germany) and a detailed computerized analysis of the activities performed on-site. Angle values of the head and trunk were evaluated in accordance with ergonomic standards and presented using percentile values (P05-P95). The OWAS method was also employed to capture the proportions of standing, walking and sitting work. RESULTS: The kinematic posture analysis showed for all activities on the conveyor belt a tendency towards a dorsally inclined body position: trunk inclination (-7.5° to 0), thoracic spine inclination or a bending forward (-11.3° to 0°) and curvature of the back within the thoracic spine (-15.2° to 0°). In addition, >90% of the "activities on the belt" (46% of the daily working routine) were carried out standing. CONCLUSION: The activities on the conveyor belt were characterized by a tendency towards hyperextension of the trunk, possibly due to a too high working environment. Furthermore, an increased burden on body structures while standing can be concluded. From a primary prevention perspective, this increased standing load should be reduced by behavioral and relational prevention measures.

A kinematic posture analysis of neurological assistants in their daily working practice-a pilot study.

BACKGROUND: The aim of this pilot study was to analyze postures during the work of neurologists with respect to their occupational activities. METHODS: A total data material of 64.8 h (3885.74 min) of nine (three m/six f) neurologists (assistant physicians) was collected. Kinematic data were collected using the CUELA system (electro-goniometry). In addition, the occupational tasks performed on-site were subject to a detailed objective activity analysis. All activities were assigned to the categories "Office activities" (I), "Measures on patients" (II) and "Other activities" (III). The angle values of each body region (evaluation parameters) were evaluated according to ergonomic ISO standards. RESULTS: Only 3.4% of the working hours were spent with (II), while 50.8% of time was spent with (I) and 45.8% with (III). All tasks of category (II) revealed an increased ergonomic risk to the head, neck, trunk and back areas. During category (I) especially neck and back movements in the sagittal plane showed higher ergonomic risk levels. CONCLUSION: Despite frequently performed awkward body positions in (II), the ergonomic risk is considered as rather low, since the percentage time share totaled only 3.4%. As a result, "Office activities" have been detected as high predictor to cause stress load on the musculoskeletal system in the daily work of neurologists.

Constrained posture in dentistry - a kinematic analysis of dentists.

BACKGROUND: How a dentist works, such as the patterns of movements performed daily, is also largely affected by the workstation Dental tasks are often executed in awkward body positions, thereby causing a very high degree of strain on the corresponding muscles. The objective of this study is to detect those dental tasks, during which awkward postures occur most frequently. The isolated analysis of static postures will examine the duration for which these postures are maintained during the corresponding dental, respectively non-dental, activities. METHODS: 21 (11f/10 m) dentists (age: 40.1 ± 10.4 years) participated in this study. An average dental workday was collected for every subject. To collect kinematic data of all activities, the CUELA system was used. Parallel to the kinematic examination, a detailed computer-based task analysis was conducted. Afterwards, both data sets were synchronized based on the chronological order of the postures assumed in the trunk and the head region. All tasks performed were assigned to the categories "treatment" (I), "office" (II) and "other activities" (III). The angle values of each body region (evaluation parameter) were examined and assessed corresponding to ergonomic standards. Moreover, this study placed a particular focus on static positions, which are held statically for 4 s and longer. RESULTS: For "treatment" (I), the entire head and trunk area is anteriorly tilted while the back is twisted to the right, in (II) and (III) the back is anteriorly tilted and twisted to the right (non-neutral position). Static positions in (I) last for 4-10s, static postures (approx. 60%) can be observed while in (II) and (III) in the back area static positions for more than 30 s are most common. Moreover, in (II) the back is twisted to the right for more than 60 s in 26.8%. CONCLUSION: Awkward positions are a major part of a dentists' work. This mainly pertains to static positions of the trunk and head in contrast to "office work." These insights facilitate the quantitative description of the dentist profession with regard to the related physical load along with the health hazards to the musculoskeletal system. Moreover, the results allow for a selective extraction of the most unfavorable static body positions that dentists assume for each of the activities performed.

Restricted posture in dentistry - a kinematic analysis of orthodontists.

BACKGROUND: This study aims at identifying orthodontic activities with the highest frequency of unfavorable/awkward and static postures held over a period of more than 4 s based on kinematic analysis. Moreover, a separate analysis of static postures for orthodontic and non-orthodontic activities serves to evaluate the duration for which these particular postures are assumed. METHODS: In total, 21 (13f/8 m) orthodontists (age: 31.5 ± 3.8 years) participated in this study. CUELA, a personal measurement system, was used to collect kinematic data for all orthodontic activities in a working day. Angle values of the head and torso were evaluated in accordance with ergonomic standards. Only those postures that were held statically for 4 s and longer were selected for further analysis. Alongside the kinematic analysis, the activities performed on-site were also subject to a detailed computerized analysis. The synchronization of data collected from both measurements arranges the patterns of posture found chronologically and in conjunction with the orthodontic activities performed ((I) "treatment" (II) "office" and (III) "other activities"). RESULTS: For (I) we observed an anterior inclination of the head and torso area as well as a twist of the head and neck area to the right. We found anterior back inclination and lateral back torsion to the right for (II) and (III). If, furthermore, we differentiate the duration of static postures, there are primarily short to medium-term (4-30s) static postures identified for (I). Also, categories (II) and (III) predominantly demonstrate static back postures with a duration of up to 30 s. With regard to (II) we observed that the back is ventrally inclined for 10.1% of the total activity duration. CONCLUSIONS: During treatment static strains are observed in the entire head and torso area. On the contrary, static postures prevalent in the torso area are essential for activities of the other categories, particularly office work. These findings allow for a careful selection of unfavorable and static postures for each of the activities performed and help to develop specific preventive measures.

Kinematic analysis of work-related musculoskeletal loading of trunk among dentists in Germany.

BACKGROUND: In Germany, about 86.7 % of the dentists have stated to suffer from pain in the neck and shoulder region. These findings are predominantly based on surveys. Therefore the objective of this study is to conduct a kinematic analysis of occupational posture in dentistry. METHODS: Twenty one dentists (11 f/10 m; age: 40.1 ± 10.4 years) have participated in this examination. The CUELA-System was used to collect kinematic data of the activities on an average dental workday. A detailed, computer-based task analysis took place parallel to the kinematic examination. Through the synchronization of data collected from both measurements, patterns of posture were arranged chronologically and in conjunction with the tasks performed: (I) "treatment" (II) "office" and (III) "other activities". For the data analysis, characteristic data of joint angular distributions (percentiles P05, P25, P50, P75 and P95) of head, neck and torso at pre-defined tasks were examined and assessed corresponding to ergonomic standards. RESULTS: Forty one percent of tasks executed on an average dental workday can be categorized as the treatment of patients. These tasked are most frequently performed in "straight back" positions (78.7 %), whereas 20.1 % were carried out in a "twisted or inclined" torso posture, 1.1 % "bowed" and only 0.1 % "bowed and twisted/inclined to the side" upper body position. In particular, it can be observed that in the area of the cervical and thoracic spine the 75th and 95th percentile show worse angular values during treatment than during non-dental tasks. For the period of treatment (at a standardized dental chair construction), a seated position with a strong inclination of the thoracic spine to the right while the lumbar spine is inclined towards the left is adopted. CONCLUSION: The kinematic analysis of dentists illustrates typical patterns of postures during tasks that are essential to the dental treatment of patients. The postures in the area of the cervical and thoracic spine have higher angular values during treatment compared to other dental tasks. Consistently, appropriate ergonomic design measures to optimize the dental chair and equipment as well as integrated training in ergonomics as part of the study of dentistry to prevent musculoskeletal are recommended.

Influence of different safety shoes on gait and plantar pressure: a standardized examination of workers in the automotive industry.

OBJECTIVE: Working conditions, such as walking and standing on hard surfaces, can increase the development of musculoskeletal complaints. At the interface between flooring and musculoskeletal system, safety shoes may play an important role in the well-being of employees. The aim of this study was to evaluate the effects of different safety shoes on gait and plantar pressure distributions on industrial flooring. METHODS: Twenty automotive workers were individually fitted out with three different pairs of safety shoes ( "normal" shoes, cushioned shoes, and midfoot bearing shoes). They walked at a given speed of 1.5 m/s. The CUELA measuring system and shoe insoles were used for gait analysis and plantar pressure measurements, respectively. Statistical analysis was conducted by ANOVA analysis for repeated measures. RESULTS: Walking with cushioned safety shoes or a midfoot bearing safety shoe led to a significant decrease of the average trunk inclination (p<0.005). Furthermore, the average hip flexion angle decreased for cushioned shoes as well as midfoot bearing shoes (p<0.002). The range of motion of the knee joint increased for cushioned shoes. As expected, plantar pressure distributions varied significantly between cushioned or midfoot bearing shoes and shoes without ergonomic components. CONCLUSION: The overall function of safety shoes is the avoidance of injury in case of an industrial accident, but in addition, safety shoes could be a long-term preventive instrument for maintaining health of the employees' musculoskeletal system, as they are able to affect gait parameters. Further research needs to focus on safety shoes in working situations.

Medical work assessment in German hospitals: a study protocol of a movement sequence analysis (MAGRO-MSA).

BACKGROUND: Medical doctors are essential for the German public and occupational health system. They ensure the productivity of German society by enabling people to regain and recover their health. That is why the physicians' health and hence their productivity require special attention. Musculoskeletal disorders have a high prevalence in this work area. As a consequence, movement sequences, range of motions, and body postures of physicians in the course of the working day are in focus of this research project. METHODS: For this investigation 21 male or female junior physicians of various conservative medical disciplines will be covered. Data will be collected over one working day (approx. 9 hours). The CUELA system attached to the test person's body detects body posture and/or movements. This biomechanical measurement system ensures a locomotor and posture analysis that includes movement sequences, movement intensity, and range of motions to qualify the work tasks. For data analysis intra- and inter-professional comparisons are chosen. CONCLUSIONS: Working movement sequence analysis of physicians by means of the CUELA system is exclusive and novel in its focus. Up to now, knowledge of the working tasks of medical doctors has only been acquired by real-time observation approaches to work activity. In addition to this method of analysis, the CUELA system is able to record quantified biomechanical data about musculoskeletal loads of ordinary working tasks. Workloads and activities of physicians can be improved by ergonomic work design to reduce musculoskeletal disorders by utilizing the data collected. The healthcare system in Germany will thus be optimized by improving medical doctors' health. Consequently, MAGRO-MSA will also be used for other healthcare professions such as nurses and physicians assistants.

Optimization of inertial sensor-based motion capturing for magnetically distorted field applications.

Inertial measurement units (IMU) are gaining increasing importance for human motion tracking in a large variety of applications. IMUs consist of gyroscopes, accelerometers, and magnetometers which provide angular rate, acceleration, and magnetic field information, respectively. In scenarios with a permanently distorted magnetic field, orientation estimation algorithms revert to using only angular rate and acceleration information. The result is an increasing drift error of the heading information. This article describes a method to compensate the orientation drift of IMUs using angular rate and acceleration readings in a quaternion-based algorithm. Zero points (ZP) were introduced, which provide additional heading and gyroscope bias information and were combined with bidirectional orientation computation. The necessary frequency of ZPs to achieve an acceptable error level is derived in this article. In a laboratory environment the method and the effect of varying interval length between ZPs was evaluated. Eight subjects were equipped with seven IMUs at trunk, head and upper extremities. They performed a predefined course of box handling for 40 min at different motion speeds and ranges of motion. The orientation estimation was compared to an optical motion tracking system. The resulting mean root mean squared error (RMSE) of all measurements ranged from 1.7 deg to 7.6 deg (roll and pitch) and from 3.5 deg to 15.0 deg (heading) depending on the measured segment, at a mean interval-length of 1.1 min between two ZPs without magnetometer usage. The 95% limits of agreement (LOA) ranged in best case from -2.9 deg to 3.6 deg at the hip roll angle and in worst case from -19.3 deg to 18.9 deg at the forearm heading angle. This study demonstrates that combining ZPs and bidirectional computation can reduce orientation error of IMUs in environments with magnetic field distortion.

Frequent bending--an underestimated burden in nursing professions.

OBJECTIVES: The aim of the present study was to quantify the total duration per shift in which nurses work in a forward bending position over 20°. Furthermore, the influence of several factors on the occurrence of sagittal trunk inclinations in nurses was investigated. METHODS: Trunk postures were recorded for nine nursing home nurses from four German nursing homes and 18 hospital nurses from seven hospitals using the CUELA measurement system. A total of 79 shifts, 27 in nursing homes and 52 in hospitals, were analysed. All measurements were supported by video recordings. Specially developed software (WIDAAN 2.75) was used to synchronize the measurement data and video footage. RESULTS: The total duration of inclinations per shift was significantly affected by the working area (nursing home or hospital) with an increase of 25.3 min in nursing homes (95% confidence interval 2.4-48.2; P = 0.032). Another factor was the extent of personal basic care tasks performed by the nurses (P < 0.001). Nursing home nurses worked about twice as long per shift in a forward bending position compared with hospital nurses (112 versus 63 min; P < 0.001) and they assumed almost one-third more inclinations per shift (1541 versus 1170; P = 0.005). CONCLUSIONS: Nursing staff perform a large number of inclinations. The amount of time spent by nurses working in a forward bending position was highly dependent on the working area and the extent to which patients were in need of help. It is very likely that future preventive measures, focussing on reducing the huge amount of inclination, would reduce the physical stress in everyday nursing work substantially.

Assessing combined exposures of whole-body vibration and awkward posture--further results from application of a simultaneous field measurement methodology.

The drivers of ten vehicles (tram, helicopter, saloon car, van, forklift, two mobile excavators, wheel loader, tractor, elevating platform truck) were studied with regard to the combined exposures of whole-body vibration and awkward posture during occupational tasks. Seven degrees of freedom (DOFs), or body angles, were recorded as a function of time by means of the CUELA measuring system (Computer-assisted registration and long-term analysis of musculoskeletal workloads) for the purpose of posture assessment. The vibrational exposure is expressed as the vector sum of the frequency-weighted accelerations in the three Cartesian coordinates; these were recorded simultaneously with the posture measurement. Based upon the percentage of working time spent under different workloads, a scheme is proposed for classification of the two exposures into three categories. In addition, a risk of adverse health effects classified as low, possible or high can be assigned to the combination of the two exposures. With regard to posture, the most severe exposure was measured for the drivers of the wheel loader and for the tractor driver, whereas the lowest exposure was measured for the helicopter pilots and van drivers. With regard to the combination of whole-body and posture exposures, the tractor driver and the elevating platform truck driver exhibited the highest workloads.