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36 ReferencesEvaluation of the ability of power to predict low frequency lifting capacity
Abstract
An experiment was conducted to examine the role that maximal lifting power has in predicting maximum acceptable weight of lift (MAWL) for a frequency of one lift per 8 h. The secondary aim of the study was to compare the ability of power to predict MAWL to previously used measures of capacity including two measures of isometric strength, five measures of isokinetic strength, and isoinertial capacity on an incremental lifting test. Twenty-five male subjects volunteered to participate in the experiment. The isometric tests involved maximum voluntary contractions for composite lifting strength at vertical heights of 15 and 75 cm. Peak isokinetic strength was measured at velocities of 0.1, 0.2, 0.4, 0.6 and 0.8 m s-1 using a modified CYBEX II isokinetic dynamometer. Isoinertial lifting capacity was measured on the X-factor incremental lifting machine and peak power was measured on the incremental lifting machine by having subjects lift a 25 kg load as quickly as possible. The results indicate that peak isoinertial power is significantly correlated with MAWL, and this correlation was higher than any of the correlations between the other predictor variables and MAWL. The relationships between the isokinetic strength measures and MAWL were stronger than the relationships between the isometric measures and MAWL. Overall, the results suggest that tests used to predict MAWL should be dynamic rather than static.
- CitationsCitations15
- ReferencesReferences36
- EMG techniques were combined with biomechanical methods, stature measurements, and psychophysical methodology, and applied by Leskinen et al. [25] to study continuous lifting work. Also, a prediction of lifting capacity was conducted [15] to examine the role that maximal lifting power has in predicting maximum acceptable weight of lift (MAWL). Compared were two measures of isometric strength, five measures of isokinetic strength, and isoinertial capacity on an incremental lifting test.
[Show abstract] [Hide abstract] ABSTRACT: The objective of this study was to analyze human perception of load heaviness in manual material handling tasks under varying task parameters taking into consideration participants' physical ability and willingness to lift loads. These conditions were: 1) box color, 2) instruction set, and 3) space confinement. The effect of each parameter on the maximum acceptable weight that people are willing to lift was investigated. This study showed that the box color significantly affects a participant's perception of weight. The average maximum acceptable weight participants were willing to lift was higher for the black boxes than for the white boxes in both open and constrained spaces. When using the white boxes, the maximum acceptable weight participants were willing to lift was smaller in the confined space than in the open space. This study introduces an ecological approach to manual handling tasks and proposes the paradigm of maximum acceptable weight of load (MAWL) to the maximum loads that people perceive they are able and willing to lift (MLWL).- [Show abstract] [Hide abstract] ABSTRACT: Objective. To review the literature that evaluates the influence of trunk motion on trunk strength and structural loading. Background. In recent years, trunk dynamics have been identified as potential risk factors for developing low-back disorders. Consequently, a better understanding of the underlying mechanisms involved in trunk motion is needed. Methods. This review summarizes the results of 53 studies that have evaluated trunk motion and its impact on several biomechanical outcome measures. The biomechanical measures consisted of trunk strength, intra-abdominal pressure, muscle activity, imposed trunk moments, and spinal loads. Each of these biomechanical measures was discussed in relation to the existing knowledge within each plane of motion (extension, flexion. lateral flexion, twisting, and asymmetric extension). Results. Trunk strength was drastically reduced as dynamic motion increased, and males were impacted more than females. Intra-abdominal pressure seemed to only be affected by trunk dynamics at high levels of force. Trunk moments were found to increase monotonically with increased trunk motion. Both agonistic and antagonistic muscle activities were greater as dynamic characteristics increased. As a result, the three-dimensional spinal loads increase significantly for dynamic exertions as compared to isometric conditions. Conclusions. Trunk motion has a dramatic affect on the muscle coactivity, which seems to be the underlying source for the decrease strength capability as well as the increased muscle force, IAP, and spinal loads. This review suggests that the ability of the individual to perform a task 'safely" might be significantly compromised by the muscle coactivity that accompanies dynamic exertions. It is also important to consider various workplace and individual factors when attempting to reduce the impact of trunk motions during dynamic exertions.
- [Show abstract] [Hide abstract] ABSTRACT: The aim of the study was to present a method enabling a reduction of the number of measurements when quantifying isokinetic muscle strength (IMS), and to describe an expression for IMS which is independent of measuring conditions. IMS is a measure of muscle strength used to categorise patients and to assess changes over time. IMS measurements involve one or several measures of peak torque at different chosen angular velocities. Comparisons between studies are difficult and an expression of IMS independent of measuring conditions is needed. Thirty-six women with rheumatoid arthritis were followed for 1 year. IMS was measured on five occasions on both knees at seven angular velocities, giving 10 sets of peak-torque data for each patient. The log[peak-torque]-angular-velocity diagram showed a linear relationship. From this, the peak-torque value at the chosen angular velocity of 30 degrees/s (IMS30) was estimated for each test and the uncertainties involved were quantified. IMS30 is a reliable parameter when comparing effort between knees, visits and patients, and may be based on three sets of data only. IMS may be expressed by a single value, IMS30, representing the fitted line in a log[peak-torque]-angular-velocity diagram. The regression line may be fitted by three or more angular velocities. In principle, IMS30 is independent of the chosen angular velocity, which makes it possible to use an estimated value as IMS30 to compare results, studies and centres in between.
- [Show abstract] [Hide abstract] ABSTRACT: The safety and productivity of workers engaged in materials handling has been a topic of interest to industrial engineers and ergonomists for some time. One of the fundamental questions that has generated considerable research is that of how to define and measure material handling capacity. The potential role of human muscle power and the resultant capacity to exert power on an external load as a measure of materials handling capacity is explored. Aside from applied literature in the exercise and sports science disciplines supporting this notion, a more theoretical basis is provided by the muscle physiology and morphology literature. The further empirical investigation of power as a means of defining materials handling capacity is supported.
- [Show abstract] [Hide abstract] ABSTRACT: (1) To find a universal strategy for the identification of specific demands of a job or task, focusing on occupations in which there may be an increased risk for health complaints owing to these specific demands. (2) To select reliable and valid tests concerning lifting, pushing, and pulling, which consider the relation between occupational work demands and the assessment of the maximally acceptable load on an individual level. Literature search was performed using Medline (1988 to May 2001), Embase (1966 to May 2001), and NIOSHTIC (1971-98). No universal strategy was found for the definition of specific occupational demands. Therefore a "three step strategy" was formulated for defining specific occupational demands in a job or a task in order to prevent health complaints on an individual level. Many tests were found in the literature concerning lifting, but only a few concerning pushing and pulling. None of the tests concerning pushing, pulling, or lifting considered the relation between work demands and the assessment of the maximally acceptable load on an individual level. Furthermore, none of the tests met the criteria of reliability and prognostic value for musculoskeletal complaints completely. Only for the prognostic value of relative strength capacity tests concerning pushing pulling and lifting, did there appear to be limited proof for the development of musculoskeletal complaints. In general, for the prevention of work related health complaints, it can be suggested that more attention should be paid to: (1) the definition of specific occupational demands; (2) the assessment of specific occupational demands; and (3) the quality of tests for specific occupational demands.
- [Show abstract] [Hide abstract] ABSTRACT: Functional capacity evaluation (FCE) is commonly used in work rehabilitation to assess the capacity of the injured worker for return to work. Occupational therapists are major providers of FCE, especially in Australia. Despite a history of involvement in the functional assessment of clients for work, occupational therapy has few theoretical models for work assessment in general, and for FCE in particular. This may account for some of the confusion that exists about the conceptual basis of FCE in occupational therapy practice. This paper presents a framework for FCE that parallels occupational therapy's occupational performance model and the World Health Organisation's International Classification of Functioning, Disability and Health. The framework is used to clarify some of the confusions that exist in FCE research and practice, particularly the issue of measuring a client's function versus impairment. A redefinition of FCE for occupational therapy practice in the work assessment continuum is presented that supports occupational therapy practice and research in the area.
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