Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Lifting”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2003

Workers' assessments of manual lifting tasks: cognitive strategies and validation with respect to objective indices and musculoskeletal symptoms.

OBJECTIVES: To determine the different cognitive strategies adopted by workers in assessing the effects of lifting-task parameters on effort, and to validate workers' assessments. METHODS: Questionnaires were administered to 217 male workers with varied levels of experience in manual handling. Workers were asked to assess the effects of lifting on perceived effort, using linguistic descriptors (e.g., light, heavy), and to determine the physical meaning of such descriptors. In addition, each worker assessed on-the-job effort, perceived risk of injury and work dissatisfaction, and musculoskeletal outcomes in a cross-sectional design. RESULTS: Perceived physical effort was significantly associated with lifting variables. Results indicated that the three-cluster strategy is the best performer. Weight of load emerged as the most influential factor that impacted on effort in the most dominant cluster (close to 50% of the observations). The second cluster (25% of the observations) demonstrated that weight, horizontal distance, and twisting angle, contributed equally to effort, and the third cluster had weight and vertical travel distance as the most important variables (with travel distance being more important). Perceived effort was significantly associated with objective indices (i.e., biomechanical lifting equivalent and NIOSH lifting index), and musculoskeletal symptoms in eight body parts. CONCLUSIONS: Cognitive reasoning of experienced workers may be used as an active device for the evaluation of strenuous physical activities such as lifting tasks. Lifting activities are significantly associated with musculoskeletal symptoms, not only in the lower-back region, but also in seven other body parts; and effort may integrate the effects of both physical (lifting tasks) and non-physical (i.e., work dissatisfaction) factors, as well as perception of risk.

Cognition↗
PubMed2005

The prediction of safe lifting behavior: an application of the theory of planned behavior.

PROBLEM: Injuries resulting from lifting are costly, and create significant pain and discomfort. While engineering controls are the most effective means of reducing risks, most organizations continue to rely on manual lifting techniques. The problem, however, is that the use of safe-lifting techniques is inconsistent and managers have a difficult time motivating use of these techniques. Consequently, it is important to understand the factors driving safe-lifting behaviors. METHODS: This study used a survey to apply the theory of planned behavior (Ajzen., I., 1991. The theory of planned behavior. Organization Behavior and Human Processes, 50, 179-211) to safe-lifting among 136 materials management employees at a heavy manufacturing organization. Structural equation modeling and factor analysis were employed to analyze relationships among constructs. RESULTS: Results revealed that perceived behavioral control and intention were the strongest predictors of safe-lifting behavior. Subjective norms, to a lesser degree, were also important influences on intention. Attitudes did not surface as effective direct predictors of safe-lifting behavior, but did affect behavior and intent via mediating factors (subjective norms and perceived behavioral control). Finally, the theory of planned behavior was supported as an effective model explaining safe-lifting behavior, and had potential application for many other safety-related behaviors. IMPACT ON INDUSTRY: Results from this study emphasize the importance of perceived behavioral control as a factor associated with safety-related behavior.

Attitude to Health↗
PubMed2000

Lifting an unexpectedly heavy object: the effects on low-back loading and balance loss.

OBJECTIVE: This study evaluates the effects of lifting an unexpectedly heavy object on low-back loading and loss of balance. BACKGROUND: It is often suggested that lifting an unexpectedly heavy object may be a major risk factor for low-back pain. This may lead to an increase in muscle activation, stretch of ligaments and posterior disc, and loss of balance.METHODS. Nine healthy male subjects were asked to pick up and lift a box as quickly as possible. The weight of the box was unexpectedly increased by 5 or 10 kg. Kinematics and force data were recorded throughout the experiment. RESULTS: Lifting of an unexpectedly heavy box led to a decrease in maximum torque of the low back compared to lifting the same box mass with correct expectation. The maximum lumbar angle did not increase compared to the light box condition. Only the threat to balance appeared to be somewhat increased.CONCLUSIONS. The lifting of an unexpectedly heavier box appeared not to lead to an increased balance loss or a clearly increased stress of the structures of the low back, although a burst of abdominal muscle activity was found in one condition. These results do not fully clarify the assumed relation between lifting unexpectedly heavy objects and low-back injury. RelevanceA commonly cited cause of low-back pain is the lifting of an unexpectedly heavy object. A study of the responses to such perturbation is important to an understanding of spine mechanics and the etiology of low-back injury.

Adult↗
PubMed2005

Effectiveness of overhead lifting devices in reducing the risk of injury to care staff in extended care facilities.

Patient and/or resident handling is a major cause of injury to healthcare workers. The effectiveness of an overhead ceiling lift programme at mitigating the risk of injury from resident handling was evaluated by comparing injury data and staff perceptions before and after implementation of the programme, and by comparison with a similar unit that did not implement an overhead ceiling lift programme. A questionnaire was used to assess perceived risk of injury and discomfort, preferred resident handling methods, frequency of performing designated resident handling tasks, perceived physical demands, work organization, and staff satisfaction. Staff preferred overhead ceiling lifts to other methods of transfer (manual or floor lifts) when lifting or transferring residents. A significant reduction was observed in the perceived risk of injury and discomfort to the neck, shoulders, back, hands, and arms of care staff. Compensation costs due to lifting and transferring tasks were reduced by 68% for the intervention unit and increased by 68% for the comparison unit. Overhead ceiling lifts were not beneficial in reducing the perceived risk of injury, pain or discomfort, or compensation costs when used to reposition residents. The study demonstrated an overall cost-savings associated with the installation of the overhead lifts, and highlighted areas for further improvement.

Accidents, Occupational↗
PubMed2005

Postural perturbation and muscular response following sudden release during symmetric squat and stoop lifting.

Squat and stoop lifting have been examined in some detail, but limited data exist regarding the sudden release of load during such lifting. Ten participants performed squat and stoop lifting trials with loads of 20, 40, 60 and 80N, and sudden release was randomly included in one of the lifting cycles. Postural perturbation was recorded via centre of pressure displacement using a force platform and the electromyographic response of trunk and lower limb muscles was recorded. Results indicated that irrespective of lifting posture, an 'ankle' response strategy to sudden release was elicited, where the anterior muscles of the lower limb contracted first, followed by the anterior trunk muscles, relaxation of the posterior trunk muscles and, finally, relaxation of the posterior lower limb muscles. The latency of muscles responding by contraction tended to decrease slightly with increasing load for both postures, while the latency of muscles responding by relaxation increased, resulting in increased trunk muscle co-contraction durations. The postural disturbance appeared to be greater for squat lifting than stoop lifting at the higher loads of 60 and 80N, as the centre of pressure moves significantly closer to the posterior limit of static stability (the line joining the heels).In terms of stability and muscular response, squat lifting may not be the most appropriate strategy if a sudden release of loads greater than approximately 50N is likely.

Adult↗
PubMed1999

Significance of biomechanical and physiological variables during the determination of maximum acceptable weight of lift.

The aim was to identify which biomechanical and physiological variables were associated with the decision to change the weight of lift during the determination of the maximum acceptable weight of lift (MAWL) in a psychophysical study. Fifteen male college students lifted a box of unknown weight at 4.3 lifts/min, and adjusted the weight until their MAWL was reached. Variables such as heart rate, trunk positions, velocities and accelerations were measured during the lifting, as well as estimated spinal loading in terms of moments and spinal forces in three dimensions using an EMG-assisted biomechanical model. Multiple logistic regression techniques identified variables associated with the decision to change the weights up and down prior to a subsequent lift. Results indicated that heart rate, predicted sagittal lift moment and low back disorder (LBD) risk index were associated with decreases in the weight prior to the next lift. Thus, historical measures of LBD risk (e.g. compression, shear force) were not associated with decreases in weight prior to the next lift. Additionally, the magnitudes of the predicted spinal forces and LBD risk were all very high at the MAWL when compared with literature sources of tolerance as well as observational studies on LBD risk. Our findings indicate that the psychophysical methodology may be useful for the decision to lower the weight of loads that may present extreme levels of risk of LBD; however, the psychophysical methodology does not seem to help in the decision to stop changing the weight at a safe load weight.

Adult↗
PubMed1999

Determination of the effect of lift characteristics on dynamic performance profiles during manual materials handling tasks.

In any quantitative gait or occupational biomechanics investigation, the quantification of the different kinematic, kinetic, and electromyographic parameters is essential towards assessment of functional capacity and development of a biomechanical profile of the task demands. In the current study, the authors presented a methodology for using inferential statistics to evaluate the effect of lift characteristics on phase-dependent and phase-independent variability in performance. Using a database of kinematic and kinetic profiles obtained from a manual lifting study, the phase-dependent effects of lift characteristics: box mass (load), mode (technique of lift), and speed (frequency of lift) were investigated through the use of analysis of variance (ANOVA) techniques, which recognize the vectorial constitution of the profiles. In addition, the Karhunen-Loeve Expansion (KLE) feature extraction method was used for representing the lifting patterns of measured joint angular position, velocity, acceleration, and net muscular torque profiles obtained from a 2-D biomechanical lifting model in order to study the phase-independent effects. In comparison to traditional descriptive statistical analyses currently used in various occupational biomechanics experimental investigations, this method allows the significant information content of the time varying signal to be captured, enhancing the sensitivity of subsequent hypothesis testing procedures. The application of this technique to MMH investigations allows identification of the lift characteristics that dominate the variability of task demands, hence aiding in the design and assessment of ergonomic solutions.

Biomechanical Phenomena↗
PubMed2000

Middle cerebral artery blood flow velocity in elite power athletes during maximal weight-lifting.

Cerebral blood flow velocity (CBFV) has been shown to significantly increase during dynamic exercise (running) secondary to increases in cardiac output. Static exercise (weight-lifting) induces supraphysiological arterial pressures up to 450/380 mmHg, and thus may alter CBFV. Catastrophic brain injuries such as stroke, cerebral hemorrhage, subarachnoid hemorrhage, retinal hemorrhage and retinal detachment have been associated with weight-lifting. A recent study has shown that intra-ocular pressure (IOP), which is an indirect measure of intracranial pressure, elevates to pathophysiologic levels during weight-lifting. Recent CBFV studies instituting Valsalva have demonstrated decreases in CBFV from 21%-52%. To date, no studies have examined CBFV during maximal weight-lifting to elucidate the cerebrovascular responses to extreme pressure alterations. We recruited nine elite power athletes, including a multi-world record holder in powerlifting, for a transcranial Doppler study of middle cerebral artery blood flow velocity at rest and during maximal weight-lifting. All subjects' resting blood flow velocities were within normal ranges (mean 64.4 +/- 9.5 cm sec2). Blood flow velocities were significantly (p < 0.0001) decreased in all subjects during maximal lifting (mean 48.4 +/- 10.1 cm sec2). Linear regression analysis demonstrated a significant inverse linear relationship in the net change of blood velocities from rest to maximal lift for each subject (r = 0.8585, p < 0.001). This study demonstrates that blood flow velocities are significantly decreased during heavy resistance training. The drop in CBFV during weight-lifting was significantly less than previous Valsalva studies, which likely reveals the cardiovascular, baroreflex, and cerebrovascular system adaptations occurring in these elite power athletes.

Adult↗
PubMed1985

Physiological limits in lifting.

Two different experiments were conducted to study the effects of frequency, height and load of lift on computed maximal oxygen uptake and to compare the data obtained to a standard bicycle ergometer. A progressive submaximal technique was used to predict maximal oxygen uptake. The results of the present study revealed that across all heights, an increase in either the frequency of lift or load of lift was accompanied by an increase in computed maximal oxygen uptake; however, all maximal oxygen uptake values reported showed a tendency to level off beyond the frequency of five lifts/min. The results also showed that combined arm and leg lifting recorded the highest maximal oxygen uptake followed by leg lifting then arm lifting, respectively. Maximal oxygen uptake values obtained for lifting tasks were much lower than those obtained for a bicycle ergometer. It is therefore recommended that limits for continuous work for a lifting task be based on the attainable maximal oxygen uptake for that particular task and not on a maximal oxygen uptake obtained from another task such as a bicycle ergometer test.

Adult↗
PubMed1988

Influence of dynamic factors and external loads on the moment at the lumbar spine in lifting.

Flexion-extension moments occurring at the L5-S1 level of the spine were calculated when subjects lifted a box weighing from 50 to 250 N. Lifting was performed at normal and fast speed, and the lifts were performed using a freestyle and a leglifting technique. The peak moment increased linearly with increasing load. The moment/load relationship was significantly influenced by lifting speed, and a higher moment occurred at each load level when lifting fast. Lifting speed was reduced when the external load was increased, particularly when the load was 150 N and higher. Moments when lifting using the leglifting technique were lower than when lifting freestyle.

Adult↗
PubMed1994

Functional assessment for prediction of lifting capacity.

OBJECTIVE: This study investigated the ability to predict maximal functional lifting capacity from peak isometric lumbar extension torque and submaximal lifting mechanics. METHODS: Peak isometric lumbar extension torques were measured on 26 healthy men and women, ages 18 to 39 years. In addition, their lifting mechanics were evaluated while they lifted a submaximal load. Each subject's maximal lifting capacity (kg) then was predicted from the peak torque and submaximal kinetic analysis using a linear regression model. RESULTS: Mean values for the predicted and actual maximum weight the subjects lifted were not significantly different (50.3 +/- 15.6 kg and 48.5 +/- 17.0 kg, respectively, P > or = 0.05). The correlation between predicted and criterion values was high (r = 0.96), and the total error of the prediction was 5.1 kg, which represented 10.5% of the actual maximum value. CONCLUSIONS: This multi-faceted functional assessment model involving biomechanical analysis of a submaximal lift and maximal isometric lumbar extension strength accurately predicted a subject's maximum functional lifting capacity.

Adult↗
PubMed2004

The effects of breath control on intra-abdominal pressure during lifting tasks.

STUDY DESIGN: This was a repeated measures study examining 11 asymptomatic subjects while performing dynamic lifting using various postures, loads, and breath control methods. OBJECTIVES: To examine the effects of breath control on magnitude and timing of intra-abdominal pressure during dynamic lifting. SUMMARY OF BACKGROUND DATA: Intra-abdominal pressure has been shown to increase consistently during static and dynamic lifting tasks. The relationship between breath control and intra-abdominal pressure during lifting is not clear. METHODS: Eleven healthy subjects were tested using lifting trials consisting of two levels of posture and load and four levels of breath control (natural breathing, inhalation-hold, exhalation-hold, inhalation-exhalation). Intra-abdominal pressure was measured using a microtip pressure transducer placed within the stomach through the nose. Timing of intra-abdominal pressure was determined relative to lift-off of the weights. Repeated measures analysis of variance was used to determine the effect of breath control, posture, and load on intra-abdominal pressure magnitude and timing. RESULTS: There was a significant effect of breath control (P < 0.018) and load (P < 0.002), but not of posture (P < 0.434), on intra-abdominal pressure magnitude. The inhalation-hold form of breath control produced significantly greater peak intra-abdominal pressure than all other forms of breath control (P < 0.000 for all comparisons). No other comparisons among levels of breath were significantly different. No significant main effects of breath control were found relative to intra-abdominal pressure timing. CONCLUSIONS: Breath control is a significant factor in the generation of intra-abdominal pressure magnitude during lifting tasks. The effects of respiration should be controlled in studies analyzing intra-abdominal pressure during lifting.

Abdomen↗
PubMed1994

Neuromuscular control of lifting in the elderly.

The aim of this investigation was to determine, utilising an electromyographic (EMG) technique, the influence of the ageing process on the neuromotor control of the stoop-lift. Seven elderly (60-75 years) and seven young (18-25 years) subjects completed a series of ten unresisted (no weight) stoop-lifts. EMG potentials were recorded with 4-mm bipolar surface electrodes from the erector spinae and medial hamstring muscle groups. The temporal features of the stoop-lift itself were recorded with an electrogoniometer. The results of this investigation showed that the elderly subjects had a significantly (p < 0.05) earlier onset of the erector spinae muscle during the up-phase of the stoop-lift compared to the younger subjects. In addition, reactivation of the erector spinae muscle in the up-phase occurred at hand positions significantly (p < 0.05) closer to the floor in the elderly group indicating more stooped postures. Thus the EMG profiles of the erector spinae within the elderly subjects performing unresisted stoop-lifts approximated those previously reported in younger subjects performing resisted (with a weight) lifting. The earlier onset of the erector spinae in the up-phase of the stoop-lift was partially explained by a significant (p < 0.05) reduction in flexibility (sit and reach test) associated with the elderly subjects. The results further stress the potential for injury associated with the utilisation of the stoop-lift, particularly by elderly populations.

Adolescent↗
PubMed1997

Toward a quantitative definition of manual lifting postures.

Manual lifting techniques are commonly defined in terms of the postures adopted at the start of the lift. Quantitative definition is problematic, however, because the absolute joint angles adopted to lift an object are influenced by task parameters, such as the initial height of the load. We present an argument for the use of a postural index (the ratio of knee flexion from normal standing to the sum of ankle, hip, and lumbar vertebral flexion) to define the postures adopted at the start of lifting. Stooped postures adopted at the start of a lift correspond to postural indices close to 0, whereas full squat postures correspond to postural indices close to 1. We use angular kinematic data gathered from 71 individuals lifting loads of varying mass from a range of starting heights to illustrate the utility of this index. Although average absolute joint angles were influenced by load mass and initial load height, the average postural index remained unchanged. For example, changes in starting height from 9 cm to 63 cm accounted for between 19% and 67% of the variance in joint positions at the start of the lift but only 1% of the variance in average postural index. This suggests that the postural index provides a method of defining lifting posture that is independent of specific joint positions.

Adolescent↗
PubMed2005

Role of the primary motor and dorsal premotor cortices in the anticipation of forces during object lifting.

When lifting small objects, people apply forces that match the expected weight of the object. This expectation relies in part on information acquired during a previous lift and on associating a certain weight with a particular object. Our study examined the role of the primary motor and dorsal premotor cortices in predicting weight based either on information acquired during a previous lift (no-cue experiment) or on arbitrary color cues associated with a particular weight (cue experiment). In the two experiments, subjects used precision grip to lift two different weights in a series of trials both before and after we applied low-frequency repetitive transcranial magnetic stimulation over the primary motor and dorsal premotor cortices. In the no-cue experiment, subjects did not receive any previous information about which of two weights they would have to lift. In the cue experiment, a color cue provided information about which of the two weights subjects would have to lift. Our results demonstrate a double dissociation in the effects induced by repetitive stimulation. When applied over the primary motor cortex, repetitive stimulation disrupted the scaling of forces based on information acquired during a previous lift. In contrast, when applied over the dorsal premotor cortex, repetitive stimulation disrupted the scaling of forces based on arbitrary color cues. We conclude that the primary motor and dorsal premotor cortices have unique roles during the anticipatory scaling of forces associated with the lifting of different weights.

Adult↗
PubMed2004

Prevention of disabling back injuries in nurses by the use of mechanical patient lift systems.

Occupational back pain in nurses (OBPN) constitutes a major source of morbidity in the health care environment. According to the National Institute for Occupational Safety and Health (NIOSH), occupational back injury is the second leading occupational injury in the United States. Among health care personnel, nurses have the highest rate of back pain, with an annual prevalence of 40-50% and a lifetime prevalence of 35-80%. The American Nursing Association believes that manual patient handling is unsafe and is directly responsible for musculoskeletal disorders encountered in nurses. It has been well documented that patient handling can be done safely with the use of assistive equipment and devices that eliminate these hazards to nurses that invite serious back injuries. The benefit of assistive patient handling equipment is characterized by the simultaneous reduction of the risk of musculoskeletal injury to the nursing staff and improvement in the quality of care for patient populations. To understand the cause of disabling injuries in health care workers, several factors must be considered, including the following: (1) anatomy/physiology of the back, (2) risk factors, (3) medical legal implications, and (4) prevention. Among nurses, back, neck, and shoulder injuries are commonly noted as the most prevalent and debilitating. While mostly associated with dependant patient care, the risk for musculoskeletal injury secondary to manual patient handling crosses all specialty areas of nursing. The skeletal defects of an abnormal back make the back more susceptible to occupational injury, even under normal stress conditions. Workers compensation guidelines for occupational back injury differ in public and private health care sectors from state to state. Nursing personnel should be reminded that the development of back pain following occupational activities in the hospital should be reported immediately to the Occupational Health Department. A nurse's failure to report OBPN immediately has resulted in numerous denials of claims for rehabilitation and compensation that nurses deserve. Experts believe that training in proper body mechanics does not prevent back injury. Consequently, focus has been placed on other innovative injury prevention programs, including the use of engineering controls as well as the "lift team" method. Ergonomics involves the use of mechanical devices (e.g., walking belt and mechanical hoist) to aid in patient lifting and transferring tasks. Guldmann Inc. has devised ceiling lift systems and slings during the past 20 years. They have successfully completed thousands of installations worldwide, covering a wide range of challenging conditions and complex environments. The Guldmann ceiling-mounted hoist system consists of a wide range of lifting units, rail components, and a complete assortment of lifting slings and accessories. Its sling is made of polyester, which is characterized by its strength and elasticity. It retains its shape and is dirt repellent and easy to maintain. The Guldmann network has one of the largest and indisputably most experienced group of certified installers in the United States. The "lift team" method was devised to remove nursing personnel from the everyday task of moving patients. This type of intervention assumes that lifting is a specialized skill to be performed only by expert professional patient movers who have been thoroughly trained in the latest lifting device techniques.

Back Injuries↗
PubMedDate not supplied

Lower-limb extensor power and lifting characteristics in disabled elders.

Few reports address lifting in disabled elders. Resistance training may facilitate function by improving coordination and muscular recruitment in common lifting tasks. Subjects were considered "functionally limited" if they reported a limitation in at least 1 of 9 possible functional areas listed on the Short-Form Health Survey physical function scale (SF-36), excluding the vigorous activity item. Eighty-nine functionally limited elders (60.3 to 89.8 years old) consented to participate in an intervention trial consisting of a 6-month in-home video-facilitated resistance exercise program using elastic bands. Biomechanical variables (leg extensor power, work, squared jerk), temporal outcomes (lift time and time to peak leg powers), and leg extensor strength were analyzed with the use of analysis of variance (ANOVA) between the (1) experimental group versus control group and the (2) subgroup of the weakest third of subjects (pretest leg extensor strength as percent of body weight [BW]). The experimental group had significant improvements in strength in knee extension (16.7%) and hip extension (20.5%). Resistance-trained weak subjects significantly increased hip extension strength compared to controls. A trend toward improved performance in lifting--decreased total lift time--was noted in the resistance-trained subjects. Significant correlations were found between total leg extension power, total leg extension strength, total work, and lift time. Resistance-trained disabled elders demonstrated strength benefits and several trends consistent with improved coordination and more efficient lifting. Leg-muscle power was related to better functional performance in lifting.

Aged↗
PubMedDate not supplied

Effects of body mechanics training on performance of repetitive lifting.

OBJECTIVE: To measure the efficacy of body mechanics instruction (BMI) in patients with low back pain. METHOD: The effect of BMI was measured in four participants with back injuries using a standardized lifting protocol. Static strength, weight lifted, number of lifts completed, and motion analysis data to describe the body mechanics were measured before and after work hardening to evaluate treatment effects. The participants' performances were compared with 52 controls from an earlier study. RESULTS: Starting postures, characterized by degrees of hip and knee flexion, varied by participant but favored a squat lift in three participants when compared with the controls. Dynamic motion synchrony of the hip and knee joints was similar to controls in three of the four participants. Posttest data revealed significant changes in static strength, dynamic endurance, and lifting speed. CONCLUSION: Intensive instruction in body mechanics provided during the work-hardening treatment produced major changes in lifting styles, in terms of both starting postures and dynamic aspects of repetitive lifting. The computerized measurement procedures used in this study permitted more careful and detailed analyses of body mechanics, particularly dynamic aspects, than is possible with observational methods. This study demonstrated some of the inherent intricacies in isodynamic lifting and suggests additional areas of performance that may be important to address in BMI.

Adult↗