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At least 325 records · Page 18Linked to original sources
PubMed1991

The lifting team. A design method to reduce lost time back injury in nursing.

Lifting is an art, not a random task. If risk is concentrated where it can be controlled, incident rates can be reduced dramatically. It is much easier to control the variables that lead to injury in a team of two lifting members than in a population of nurses. The lifting team study shows that a 95% reduction in lost time injuries can be obtained if a professional lifting team, rather than nurses, lift clients. Secondary benefits to the lifting team approach are: greater nursing morale, recruiting tasks become easier if nurses do not have to lift, and additional time for bedside nursing care.

Accidents, Occupational↗
PubMed1988

The effect of voluntary diaphragmatic activation on back lifting.

The effect of increased intraabdominal pressure upon the activation of the erector spinae muscles during back lifting was studied in 10 healthy volunteers. The intraabdominal pressure was increased by voluntary prelifting coactivation of the diaphragm and the abdominal muscles. EMG was recorded with surface electrodes over the diaphragm and the erector spinae, abdominal and intercostal muscles. The EMG signals were rectified and averaged from 20 lifts of 10 kg with and without pressurization to give mean level of activity during 2 s before lifting and during successive angular positions of the trunk during lifting. In 7 of the 10 subjects the pre-lifting coactivation of diaphragm and abdominal muscles reduced erector spinae activity at lift-off and/or during the trunc erecting movement. An increased intraabdominal pressure thus often has an unloading effect on the erector spinae muscle during back lifting.

Abdomen↗
PubMed1984

Load on knee joint structures and muscular activity during lifting.

The load on the knee joints during lifting has been less studied than low back load. Healthy subjects lifted a 12.8-kg box from floor to table-level in three different ways; 1) with straight knees, 2) with bent knees and the box in front of the knees, and 3) with bent knees and the box between the knees. The loading moment of force about the bilateral knee axis was calculated by means of a computerized static sagittal plane model. Electromyography was recorded from quadriceps and ischiocrural muscles. The beginning of the flexed-knee lifts caused a flexing loading knee moment of about 50 Nm and a knee angle of 90 degrees. Straight-knee lifts gave all through the lift an extending loading moment. During the final phase of all lifts there was an extending loading knee moment of about 55 Nm and a knee angle of 0 degrees. The three lifts were compared and discussed from a biomechanical and ergonomical point of view.

Adult↗
PubMed2005

Stress fracture of the distal tibia and fibula through heavy lifting.

BACKGROUND: Occupational stress fractures are reported among athletes, soldiers, ballet dancers, and in connection with shoveling. METHODS: A literature search on occupational stress fractures was performed. The biomechanical stress in association with special lifting tasks was estimated. RESULTS: A 59-year-old male welder presented with a stress fracture of the left distal tibia and fibula in connection with heavy lifting. The object was in front and lifted while he partly stood on one leg, which was rotated during the lifting. There was no considerable previous exposure to heavy lifting. CONCLUSION: It is likely, that this stress fracture was the result of strain on tibia and fibula through this composite lifting operation.

Fibula↗
PubMed1999

Directionality of anticipatory activation of trunk muscles in a lifting task depends on load knowledge.

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 center of mass position, in another set of trials they were not. In both cases trunk extensor muscles were active before the onset of lift force applied to the load. In the trials with load knowledge this anticipatory activity was specific with respect to center of mass position. In the absence of load knowledge left and right extensor muscles were equally active before the lift and the rate of lifting was reduced. Thus anticipatory control of trunk muscles appears specifically tuned to counteract the expected perturbation. In the absence of load knowledge trunk stiffness is increased by bilateral activity and the perturbation is attenuated since the rate of lifting is reduced.

Abdominal Muscles↗
PubMed2005

Factors underlying the perturbation resistance of the trunk in the first part of a lifting movement.

In the first part of lifting movements, the trunk movement is surprisingly resistant to perturbations. This study examined which factors contribute to this perturbation resistance of the trunk during lifting. Three possible mechanisms were studied: force-length-velocity characteristics of muscles, the momentum of the trunk as well as the effect of passive extending of the elbows. A forward dynamics modelling and simulation approach was adopted with two different input signals: (1) stimulation of Hill-type muscles versus (2) net joint moments. Experimental data collected during an unperturbed lifting movement were used as a reference, which a simulated lifting movement had to resemble. Subsequently, the simulated lifting movement was perturbed by applying 10 kg extra mass at the wrist (both before and after lift-off and with/without a fixed elbow), without modifying the input signals. The momentum of the trunk appeared to be insufficient to explain the perturbation resistance of trunk movements as found experimentally. In addition to the momentum of the trunk, the force-length-velocity characteristics of the muscles are necessary to account for the observed perturbation resistance. Initial extension of the elbow due to the mass perturbation delayed the propagation of the load to the shoulder. However, this delay is reduced due to the impedance at the elbow provided by the characteristics of muscles spanning the elbow. So, the force-length-velocity characteristics of the muscles spanning the elbow joint increase the perturbation at the trunk.

Biomechanical Phenomena↗
PubMed2006

Comparing the results of five lifting analysis tools.

The objective of this study was to compare the results of the NIOSH, ACGIH TLV, Snook, 3DSSPP and WA L&I lifting assessment instruments when applied to a uniform task (lifting and lowering milk cases with capacities of 15 and 23l). To enable comparisons between the various lifting assessment instruments, the outputs of each method were converted to an exposure index similar to the NIOSH Lifting Index. All instruments showed higher exposures associated with lifting the 23l cases versus the 15l cases. The NIOSH, ACGIH TLV and Snook methods were similar in their results with respect to the pattern of exposure over various height levels and the differences in exposures associated with lifting 15 and 23l cases. However, the WA L&I and 3DSSPP predicted substantially lower exposures. The reasons for instrument differences are presented so that practitioners can better select the methods they need and interpret the results appropriately.

Back Injuries↗
PubMedDate not supplied

Changes in spine loading patterns throughout the workday as a function of experience, lift frequency, and personality.

BACKGROUND CONTEXT: Psychosocial stressors have been associated with low back pain reporting. However, response to psychosocial risk factors may be dependent on the individual's personality type that, in turn, can affect muscle recruitment and spine loading. This study explores how personality might be associated with spine loading during repetitive lifting performed throughout an entire work shift. PURPOSE: Assess spine loading as a function of an individual's personality type during repetitive, long-term exposure to a materials handling tasks. STUDY DESIGN: Laboratory experiment where experienced and inexperienced participants performed repetitive, asymmetric lifts at various load and lift frequency levels throughout a series of 8-hour exposure periods. Spine loads were monitored throughout the work period. PATIENT SAMPLE: Twelve novice and 12 experienced materials handlers who were asymptomatic for back pain. OUTCOME MEASURES: Spine compression, anterior-posterior (A/P) shear, and lateral shear at the L5-S1 level. METHODS: Participants were categorized into personality types based upon the Myers-Briggs personality type indicator. An electromyography-assisted biomechanical model was used to assess spine compression, A/P shear, and lateral shear throughout the exposure period. RESULTS: The results indicate that intuitors had higher shear spinal loading regardless of moment exposure, lift frequency, and time through the work period, compared with the sensor personality type. In addition, higher spine compressive and shear forces occurred in the perceiver personality compared with the judgers' personality trait, regardless of moment and, often, lift frequency. Novice lifters typically experienced greater spine loading. CONCLUSIONS: The results suggest that when there exists a personality-job environment mismatch, spinal loading increases via an increase in antagonistic co-contraction. The trends suggest that inherent personality characteristics may play a role in one's motor control strategies when performing a repetitive lifting task.

Adult↗
PubMed1998

Training for lifting; an unresolved ergonomic issue?

The paper describes a nine year project on lifting training which included nine trans-Australia consensus conferences attended by more than 900 health professionals. Major outcomes were: (1) The essence of lifting work is the need for the performer to cope with variability in task, environment, and self, and the essence of lifting skill is therefore adaptability; (2) the semi-squat approach provides the safest and most effective basis for lifting training; (3) for lifting training to be effective, the basic principles of skill learning must be systematically applied, with adaptability as a specific goal; (4) physical work capacity (aerobic power, strength, endurance, joint mobility) is a decisive ingredient of safe and effective lifting and, in addition to skill learning, should be incorporated in the training of people engaging regularly in heavy manual work; (5) if effective compliance with recommended skilled behaviour is to be achieved, then training must apply the principles and methods appropriate to adult learning and behaviour modification.

Adult↗
PubMed2001

Biomechanical simulation of manual lifting using spacetime optimization.

Previous optimization techniques for the prediction of lifting motion patterns often require a change in either the number of variables or the order of the mathematical functions used to express the angular displacement of selected joints in response to change in variant conditions. The resolution of predicted results can also be seriously constrained by the number of variables used. These restrictions may often limit the applicability of these methodologies. In this paper, we proposed a new methodology for generating the optimum motion patterns for para-sagittal lifting tasks. A detailed description of this methodology is introduced. An example of an analysis using this methodology is presented. The computer program generated lifting motion patterns with a reduction of the overall objective function values. The actual versus predicted lifting motion patterns are compared. Using this method, constraints can be added anywhere within the lifting cycle without the need of rewriting the whole program. These features provide for a more flexible and efficient prediction of the lifting motion.

Adult↗
PubMed2001

Underestimation of object mass in lifting does not increase the load on the low back.

Sudden, unexpected loading on the low back is associated with a high incidence of low back pain. Experiments in which sudden loading was applied during standing revealed increased compression forces on the spine and increased trunk angle, which may cause injury to the spine and hence explain this association. During a more dynamic daily activity, i.e. lifting, this could not be demonstrated, which may be due to experimental constraints. We therefore reinvestigated the loading of the low back when subjects were lifting an unexpectedly heavy object. Ten males lifted boxes, weighing 1.6 or 6.6 kg, at a self-selected lifting velocity. In some trials the mass of these boxes was unexpectedly increased by 10 kg. The ground reaction forces, body movements and trunk muscle activity were measured and from these, the L5/S1 torques and compression forces were estimated. Underestimation of the mass did not lead to an increase in low back loading. This finding was independent of the mass the subjects were expecting to lift. In conclusion, no evidence was found to support inference regarding causality of the association between sudden loading and low back pain during whole body lifting movements.

Adult↗
PubMed1998

Repetitive lifting tasks fatigue the back muscles and increase the bending moment acting on the lumbar spine.

During manual handling, the back muscles protect the spine from excessive flexion, but in doing so impose a high compressive force on it. Epidemiological links between back pain and repetitive lifting suggest that fatigued muscles may adversely affect the balance between bending and compression. Fifteen volunteers lifted and lowered a 10 kg weight from floor to waist height 100 times. Throughout this task, the bending moment acting on the osteoligamentous lumbar spine was estimated from continuous measurements of lumbar flexion, obtained using the 3-Space Isotrak. Spinal compression was estimated from the electromyographic (EMG) activity of the erector spinae muscles, recorded from skin-surface electrodes at the levels of T10 and L3. EMG signals were calibrated against force when subjects pulled up on a load cell, and correction factors were applied to account for changes in muscle length and contraction velocity. Fatigue in the erector spinae muscles was quantified by comparing the frequency content of their EMG signal during static contractions performed before, and immediately after, the 100 lifts. Results showed that peak lumbar flexion increased during the 100 lifts from 83.3 +/- 14.8% to 90.4 +/- 14.3%, resulting in a 36% increase in estimated peak bending moment acting on the lumbar spine (P = 0.008). Peak spinal compression fell by 11% (p = 0.007). The median frequency of the EMG signal at L3 decreased by 5.5% following the 100 lifts (p = 0.042) confirming that the erector spinae were fatigued, but measures of fatigue showed no significant correlation with increased bending. We conclude that repetitive lifting induces measurable fatigue in the erector spinae muscles, and substantially increases the bending moment acting on the lumbar spine.

Adult↗
PubMed2000

Arm motion and load analysis of sit-to-stand, stand-to-sit, cane walking and lifting.

OBJECTIVE: To conduct a pilot study to characterize the hand loads, arm joint angles and external moments corresponding to five activities of daily living demanding of the shoulder, for healthy subjects over 50 years of age. DESIGN: The tasks were sit-to-stand, stand-to-sit, cane walking, lifting a 5 kg box with both hands, and lifting a 10 kg suitcase. BACKGROUND: Arm motion and loading have not been previously studied for functional daily-living tasks involving substantial external loads.Methods. Motion was tracked using an optoelectronic system. Loads were measured using an instrumented chair arm, a force plate, and gravitational and acceleration loads. Six healthy volunteers (3 male, 3 female), mean age 55, with no history of shoulder problems participated in the study. RESULTS: Average peak external moments ranged from 12.3 N m for sitting down into a chair to 27.9 N m for lifting a suitcase. Except for lifting the box, which had much lower loads, average peak hand loads varied from 16% to 19% of body weight (114-134 N). The arcs of motion were larger than for seated activities of daily-living studied previously. CONCLUSIONS: The five tasks studied are commonly performed, yet involve large external moments. Lifting represents the greatest potential loading at the shoulder as it resulted in the highest external moments; furthermore, loads larger than those used in this study might be commonly lifted. RELEVANCE: External moments at the shoulder should not be underestimated, even for activities of daily living.

Activities of Daily Living↗
PubMed2000

Trunk muscle activation and low back loading in lifting in the absence of load knowledge.

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 range within which the mass lay. Nine males lifted boxes weighing 6.5 or 16.5 kg under the condition in which they knew the actual mass before attempting a lift (the 'known' condition) and the condition in which they only had the information that the mass would be within the range of 6.5-16.5 kg (the 'unknown' condition). The ground reaction forces and body movements were measured in the trials and, from these, the L5/S1 torques were calculated. The activation of back and abdominal muscles was also measured. For the 6.5 kg weight, a higher (16%) back muscle activation in grasping the box and a higher (10%) peak L5/S1 torque in actual lifting were observed in the 'unknown' compared with the 'known' weight condition. For the 16.5 kg weight, the back muscle activation was lower (10%) during grasping, and higher (10%) during lifting in the 'unknown' compared with the 'known' weight condition. Knowledge of the load had no effect on the activation of the abdominal muscles. It was concluded that in the so-called 'unknown' conditions, the risks of low back injury were increased in comparison with the conditions where the actual weight was known in advance.

Abdominal Muscles↗
PubMed1994

Lumbosacral compression in maximal lifting efforts in sagittal plane with varying mechanical disadvantage in isometric and isokinetic modes.

Nine normal male subjects (mean age 28.2 years and mean weight 72.6 kg) performed 20 standardized maximal effort lifting tasks. They were asked to perform stoop and squat lifts at half, three-quarters and full individual horizontal reach distances in mid-sagittal plane in isometric and isokinetic modes (fixed velocity 60 cm/s). Both stoop and squat lifts were initiated at the floor level and terminated at the individual's knuckle height keeping the horizontal distance constant throughout the lift. The isometric stoop lifts were performed with hip at 60 degrees and 90 degrees of flexion with hands at preselected reach distances. The isometric squat lifts were performed with knees at 90 degrees and 135 degrees of flexion with hands at similarly preselected reach distances. The force was measured using a Static Dynamic Strength Tester with load cell (SM 1000). The postures were recorded using a two-dimensional Peak Performance System with an event synchronizing unit. The load cell was sampled at 60 Hz and the video filming was done at 60 frames per second. The force and postural data were fed to a biomechanical model (Cheng and Kumar 1991) to extract external moment and lumbosacral compression. The strengths generated in different conditions were significantly different (p < 0.01). The strength variation ranged by up to 73% whereas the lumbosacral compression varied by only up to 15%. A high level of lumbosacral compression was maintained in all conditions.

Adult↗
PubMed1998

Pulling force in lateral lifting and lowering.

This work investigated maximal voluntary lateral hand pulling force in 18 healthy, habitually active men. Measurements were made in standing at different static angles of lateral trunk flexion, as well as at different constant lifting and lowering velocities. Movement was constrained to the frontal plane, velocity was controlled by an isokinetic dynamometer, pulling force was measured with a strain gauge and overall lateral angular displacement of the trunk by an electrogoniometer. Mean peak pulling force values ranged from 478 to 658 N (static), 291 to 528 N (lifting), and 801 to 911 N (lowering), respectively. The static pulling forces were the highest in flexed positions to the loaded side (10 degrees and 20 degrees trunk angles). In lifting, peak and position-specific pulling force decreased with increasing velocity. Peak lifting force occurred in a flexed trunk position of 7 to 9 degrees to the loaded side. In lowering, pulling forces were significantly higher than during lifting at corresponding velocities and showed less changes with velocity. Peak lowering force occurred at a trunk angle of -7 to -11 degrees, that is towards the unloaded side. In conclusion, maximal voluntary pulling force in the frontal plane was found to be task dependent. Lowering was accompanied by higher forces and a different velocity and position dependency than lifting which, in addition to the fact that the trunk muscles act predominantly eccentrically during the lowering task, may impose an increased risk of injury.

Adult↗
PubMed1997

Perception of Kinematic Characteristics in the Motion of Lifted Weight.

It has been widely shown that human observers are able to perceive lifted weight from the observation of a point-light display of the lifter's action. In the experiments reported here, the kinematic information used by observers to perceive a lifted weight was determined. In Experiment 1, observers (N = 30) were able to identify weights (5, 10, 15, 20, and 25 kg) successfully by observing only the lift phase of the action. Other procedures, such as walking while holding the weight and placing the weight on a table, did not result in significantly improved estimations. In Experiment 2, the kinematic patterns used by 4 lifters with weights varying from 5 to 25 kg were examined. Changes in weight lifted resulted in changes in lift velocity, hip angle, and dwell time. In Experiment 3, in which 15 observers participated, these 3 kinematic variables were experimentally manipulated. The results indicated that observation was most significantly influenced by variations in lift velocity. The results are discussed in relation to kinematic specification of dynamics and heuristic approaches.

kinematics↗
PubMed2002

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.

Biomechanical Phenomena↗