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PubMed2002

Biomechanical comparison of isokinetic lifting and free lifting when applied to chronic low back pain rehabilitation.

The study compares free and isokinetic lifting using a multivariate statistical analysis. Each of the 13 male subjects performed three free lifts and three isokinetic lifts using a CYBEX LIFTASK. The measurement variables were obtained from a 3D video system, two force plates and two strain-gauge transducers. Coupling of fuzzy space-time windowing and multiple correspondence analysis was used to show the links between the variables and the differences between the experimental situations. Isokinetic lifting had almost no points in common with free-lifting, but there was a similar range of extension for the different joints. Most free-lifting strategies could not be used in isokinetic lifting, as constraints between the subject and his environment were different. The main drawback of the isokinetic lifting was due to the necessity for individuals to reach the machine speed, yielding high transient efforts. The maximum vertical effort at the L5/S1 joint was about 1600, 1500 and 1400N for low, medium and high speed, whereas it was lower than 1300N, irrespective of the load, during free lifting. In the context of chronic low back pain rehabilitation, movement strategies used in free lifting could not be relearnt using an isokinetic machine. A better understanding of the common points and differences between isokinetic movement and free movement could help rehabilitation physicians to plan rehabilitation programmes, taking advantage of each kind of movement.

Adult↗
PubMed2002

A biomechanical comparison of lifting techniques between subjects with and without chronic low back pain during freestyle lifting and lowering tasks.

OBJECTIVE: To evaluate if chronic low back pain patients perform manual material handling tasks differently from control subjects. DESIGN: Comparative study using a repeated measures design. BACKGROUND: No study evaluated the lifting technique of back pain patients relative to control subjects during free style lifting and lowering tasks. Previous findings suggest that lowering would be more hazardous than lifting to the low back. It would be interesting to evaluate if chronic low back pain patients behave differently than controls when lifting and lowering. METHODS: Thirty-three male subjects (18 controls, 15 suffering from non-specific chronic low back pain) participated. A 12-kg box was lifted (freestyle) from the floor to the hips (1) in front (symmetric task) or (2) to a shelf located at 90 degree on the right (asymmetric task) and was lowered back to the floor. A 3D biomechanical analysis involving the assessment of L5/S1 loading, posture of segments, inertial parameters, and EMG was performed. RESULTS: There was no difference between the groups for postural (trunk and lower limb angles), inertial (trunk velocity and acceleration), and L5/S1 loading (moments and compression) variables. The patients showed abnormally low left lumbar erector spinae (symmetric task, lowering) or high left thoracic erector spinae (all tasks) EMG activation. Significant Group x Action (lifting vs. lowering) interactions were also observed for some inertial and L5/S1 loading variables suggesting that the biomechanical differences detected between lifting and lowering may have a differential influence on the technique used by back pain patients and control subjects. CONCLUSIONS: The gross lifting technique of back pain patients was unaltered relative to controls but the activation of paraspinal muscles differed, suggesting that a more detailed biomechanical analysis, such as the use of EMG driven models, might be required to reveal lumbar impairments during lifting. RELEVANCE: To evaluate if chronic low back pain patients use naturally different lifting techniques to prevent pain exacerbation and damaged lumbar tissue overloading.

Adult↗
PubMed2006

Can low back loading during lifting be reduced by placing one leg beside the object to be lifted?

BACKGROUND AND PURPOSE: Lifting technique could, through its effect on low back loading, affect the risk of developing low back pain. In this study, 2 lifting techniques (a straddle technique and a 1-leg kneeling technique), which aimed to reduce low back loading by placing one leg beside a load, were compared with stoop lifting and squat lifting with respect to their effect on low back loading. SUBJECTS: Twelve men with no history of low back pain participated in the study. METHODS: The subjects lifted wide and narrow 20-kg boxes from 2 initial hand heights. With measured kinematics, ground reaction forces, and electromyography, 3-dimensional spinal forces were calculated. RESULTS: When the subjects lifted a narrow box from a 290-mm height, peak L5-S1 compression forces were 5,060 (SD = 827), 3,980 (SD = 701), 4,208 (SD = 762), and 4,719 (SD = 1,015) N for the stoop, squat, straddle, and kneeling techniques, respectively. When the subjects lifted a wide box from 50 mm, spinal compression forces were much higher and distributed differently over lifting techniques: 5,926 (SD = 610), 6,868 (SD = 924), 6,472 (SD = 1,042), and 6,064 (SD = 968) N, respectively. DISCUSSION AND CONCLUSION: The authors conclude that no single lifting technique can be advised for all lifting conditions.

Adult↗
PubMed2000

Effects of squat lift training and free weight muscle training on maximum lifting load and isolinetic peak torque of young adults without impairments.

BACKGROUND AND PURPOSE: Manual lifting is a frequent cause of back injury, and there is no evidence as to which training mode can provide the best training effect for lifting performance and muscle force. The purpose of this study was to examine the effects of a squat lift training and a free weight muscle training program on the maximum lifting load and isokinetic peak torque in subjects without known neuromuscular or musculoskeletal impairments. SUBJECTS: Thirty-six adults (20 male, 16 female) without known neuromuscular or musculoskeletal impairments participated. The subjects' mean age was 21.25 years (SD=1.16, range=20-24). METHODS: Subjects were divided into 3 groups. Subjects in group 1 (n=12) performed squat lift training. Subjects in group 2 (n=12) participated in free weight resistance training of their shoulder abductors, elbow flexors, knee extensors and trunk extensors. Subjects in group 3 (n=12) served as controls. The maximum lifting load and isokinetic peak torques of the trunk extensors, knee extensors, elbow flexors, and shoulder abductors of each subject were measured before and after the study. Training was conducted on alternate days for 4 weeks, with an initial load of 80% of each subject's maximum capacity and with the load increased by 5% weekly. RESULTS: All groups were comparable for all measured variables before the study. After 4 weeks, subjects in groups 1 and 2 demonstrated more improvement in maximum lifting load and isokinetic peak torque of the back extensors compared with the subjects in group 3, but the 2 training groups were not different. CONCLUSION AND DISCUSSION: The findings demonstrate that both squat lift and free weight resistance training are equally effective in improving the lifting load and isokinetic back extension performance of individuals without impairments.

Adult↗
PubMed2004

Lifting over an obstacle: effects of one-handed lifting and hand support on trunk kinematics and low back loading.

Mechanical loading of the low back during lifting is a common cause of low back pain. In this study two-handed lifting is compared to one-handed lifting (with and without supporting the upper body with the free hand) while lifting over an obstacle. A 3-D linked segment model was combined with an EMG-assisted trunk muscle model to quantify kinematics and joint loads at the L5S1 joint. Peak total net moments (i.e., the net moment effect of all muscles and soft tissue spanning the joint) were found to be 10+/-3% lower in unsupported one-handed lifting compared to two-handed lifting, and 30+/-8% lower in supported compared to unsupported one-handed lifting. L5S1 joint forces also showed reductions, but not of the same magnitude (18+/-8% and 15+/-10%, respectively, for compression forces, and 15+/-17% and 11+/-14% respectively, for shear forces). Those reductions of low back load were mainly caused by a reduction of trunk and load moment arms relative to the L5S1 joint during peak loading, and, in the case of hand support, by a support force of about 250 N. Stretching one leg backward did not further reduce low back load estimates. Furthermore, one-handed lifting caused an 6+/-8 degrees increase in lateral flexion, a 9+/-5 degrees increase in twist and a 6+/-6 degrees decrease in flexion. Support with the free hand caused a small further increase in lumbar twisting. It is concluded that one-handed lifting, especially with hand support, reduces L5S1 loading but increases asymmetry in movements and moments about the lumbar spine.

Abdomen↗
PubMed2002

Balance loss when lifting a heavier-than-expected load: effects of lifting technique.

OBJECTIVES: To compare the lifting techniques of subjects who did and did not maintain their balance with an unexpectedly heavy load, and to examine whether the balance loss increased low back loading. DESIGN: Repeated-measures design. SETTING: A research laboratory. PARTICIPANTS: Fourteen healthy volunteers were assigned to 2 groups in the post hoc analysis. Group 1 (7 men; mean age, 25.6 +/- 4.2yr; height, 1.78 +/-.08m; weight, 83.0 +/- 8.5kg; lifting capacity, 63.2 +/- 8.0kg) maintained balance and was matched to group 2 (7 men; mean age, 26.3 +/- 4.1yr; height, 1.75 +/-.06m; weight, 78.2 +/- 5.3kg; lifting capacity, 64.7 +/- 4.9kg) who lost balance. INTERVENTIONS: Subjects lifted boxes of 5%, 20%, and 35% of their lifting capacity. Load magnitude was expected or unexpected. MAIN OUTCOME MEASURES: Center of mass (COM), lower body mechanics, ground reaction forces, and angular and horizontal momentum. RESULTS: Group 1 consistently showed greater lumbar flexion, less knee flexion, and a higher COM just before and after load liftoff. During the heavier-than-expected 35% lift, the trunk angular velocities lifts indicated that both groups experienced eccentric trunk extensor muscle contractions. CONCLUSIONS: The semisquat technique may protect against balance loss when lifting unexpectedly heavy loads. Eccentric muscle contractions and rapid increases in lumbar joint reaction moments may increase the risk of low back injury when there is a large, unexpected increase in the weight of the lifted load.

Adult↗
PubMed2006

An on-body personal lift augmentation device (PLAD) reduces EMG amplitude of erector spinae during lifting tasks.

BACKGROUND: A new on-body personal lift augmentation device was developed to support the back muscles during the repetitive lifting task. METHODS: Nine male subjects participated in the study. Three Fastrak units were used to record positions and rotations of the segments. Trunk muscle normalized and integrated electromyography of the left and right thoracic erector spinae, lumbar erector spinae, external obliques, and rectus abdominis, as well as the kinematic variables of peak lumbar angle, peak pelvis angle, peak trunk acceleration, peak load acceleration were compared in symmetrical lifting for three different loads (5 kg, 15 kg, 25 kg) with three different styles (stooped, squat, free) under two conditions of with and without personal lift assist device. FINDINGS: The lift assist device significantly reduced the required muscular effort of the lumbar (p = 0.001) and thoracic erector spinae with no significant differences in the level of abdominal muscle activity. The amount of integrated electromyography reduction ranged from 14.4% to 27.6% for the lumbar and thoracic erector spinae respectively. Simple measures of trunk posture and accelerations confirmed that there were no differences in lifting technique that would cause the integrated electromyography activity to be reduced. No major kinematic differences were found when the lift assist device was worn indicating that it did not alter these specific technique variables. INTERPRETATION: The lift assist device did reduce the required muscular effort of the lumbar and thoracic erector spinae without adversely affecting the level of abdominal muscle activity. This reduction may help reduce the risk of recurring back injuries or assist in the return to work phase, especially in repetitive tasks.

Adult↗
PubMed2005

The effect of asymmetry on psychophysical lifting capacity for three lifting types.

The effect of asymmetry on a person's lifting capacity was investigated using the psychophysical approach. Ten male college students lifted a box from pallet height (15 cm) to conveyor height (75 cm) at a frequency of one and five lifts/min. Three types of asymmetric lifting tasks (step-turn, middle twist and twist) were studied using 90 and 180 degrees task angles. Lifting capacity reductions for middle twist and twist at a 90 degrees asymmetric angle were about one-half of the 30% reduction that would be calculated by the 1991 National Institute for Occupational Safety & Health (NIOSH) lifting equation. The lifting capacity reduction for step-turn at 180 degrees was 14.9%, although that reduction cannot be calculated in the NIOSH equation. The middle twist lifting capacity was greatest among the three types at a 90 degrees task angle. The reductions for the middle twist and step-turn were not proportional to the task angle. This is contrary to the proportional reduction in the NIOSH lifting equation. Heart rate did not increase with an increase in task angle. Based on the results of this research, a different approach to assigning the asymmetric multiplier is proposed. This approach includes a task angle (as opposed to asymmetric angle) of up to 180 degrees.

Adult↗
PubMedDate not supplied

Optimal lifting techniques adopted by Chinese men when determining their maximum acceptable weight of lift.

The purpose of this study was to identify biomechanically the mechanisms adopted by Chinese men when they psychophysically determined their MAWLs (maximum acceptable weights of lift) in different tasks. Twenty-two healthy Chinese men determined their MAWLs at two lifting vertical ranges and three lifting frequencies. Peak L5/S1 compressive forces, elbow and shoulder peak reactive moments, acceleration effects, and postures were analyzed throughout the lifting acts. The results showed that different lifting techniques were adopted when determining the MAWL at different vertical ranges and frequencies of lifting. Posture analyses showed that a more stooped technique was used in frequent tasks, which would minimize the metabolic cost. For infrequent tasks, subjects accelerated and lifted the load upward and then shortened the moment arm by flexing the elbow and shoulder joints during landing, to compensate for weakness of the upper extremities. The high prelifting acceleration used during the infrequent tasks caused high compressive forces on the L5/S1 disc. These results emphasize the importance of considering the roles of upper extremity strength when designing lifting tasks for Chinese workers.

Acceleration↗
PubMed1990

The effect of lifting protocol on comparisons with isoinertial lifting performance.

The purpose of the study was threefold: (1) to determine if protocol constraints affected scores on a box-lifting task; (2) to identify any differences in impact of protocol changes on male and female scores; and (3) to determine if these protocol changes affected correlations between maximal box-lifting scores and maximal scores obtained on isoinertial lifting tests. Two hundred and sixty nine participants (143 males and 126 females) completed maximal isoinertial lifting tests to 1.50 m and 1.80 m using a constrained protocol on an Incremental Lifting Machine (ILM). Participants were divided into three samples for completion of a maximal box-lifting task, with each sample using one of the following task protocols: (1) set style; (2) free style; and (3) ergonomically redesigned. Statistical analyses using general linear models procedures revealed that changes in protocol constraints significantly affected scores on lifting tasks. Removal of protocol constraints resulted in greater percentage increases in task scores for females than for males. Furthermore, disparate patterns between genders in task-test correlations were observed. It was concluded that the ILM was unable to predict female lifting capabilities accurately using any of the three protocols.

Anthropometry↗
PubMed1988

Effects of psychophysical lifting training on maximal repetitive lifting capacity.

The purpose of this investigation was to determine the effectiveness of psychophysical lifting training on maximal repetitive lifting capacity. Maximal repetitive lifting capacity was defined as the maximum box mass that could be lifted for 1 hr to a height of 132 cm at a rate of 6 lifts/min. Eight male subjects participated in five psychophysical lifting training sessions each week for 4 weeks. During each session subjects were presented with one empty and one heavily loaded box and asked to adjust the box mass to the maximum load they felt capable of lifting for 1 hr. This load was lifted at a rate of 6 lifts/min to a height of 132 cm for two 15-min periods each session. Heart rate was recorded, and subjects were asked to provide a rating of their perceived exertion. At the end of 4 weeks of training, subjects did not select a heavier training load, exhibit a decreased training heart rate, or report a decreased rating of perceived exertion. The training program did produce a significant increase in 1-hr maximal repetitive lifting capacity, as indicated by a greater box mass selected, but there was no concomitant change in VO2, heart rate, or rating of perceived exertion. It can be concluded that 4 weeks of psychophysical training of inexperienced lifters can produce a substantial increase in work output for a given energy expenditure. These increases are attributed to neural factors (skill, neuromuscular coordination) and to possible increases in the muscular endurance of specific muscle groups occurring with practice.

Adult↗
PubMed1988

Comparison of isokinetic and isoinertial lifting tests as predictors of maximal lifting capacity.

This study compared the relationship between isokinetic lifting test (ILT) performance and a maximal operational lifting test (OLT) with that between an isoinertial progressive lifting test (PLT) and OLT. Fifty subjects performed the ILT, PLT and OLT after familiarization trials. OLT was defined as the weight of the heaviest crate that could be lifted to 1.34 m with a progressive, incremental test. ILT performance was the force generated during a single maximal simulated lift on an isokinetic dynamometer. PLT performance was the maximal weight lifted to 1.52 m with a progressive, incremental protocol on a weight stack. OLT was highly correlated with ILT (r = 0.96) and PLT (r = 0.97); the standard error was similar for both linear regression equations. The results demonstrate that a single maximal voluntary lift on an isokinetic dynamometer is as good a predictor of OLT as in the PLT presently used in military recruit centers.

Female↗
PubMed2006

Effects of a new industrial lifting belt on back muscular activity, hand force, and body stability during symmetric lifting.

This work investigated how wearing a new design of back belt affects erector spinae activity, hand force, and body stability. The belt was first tested with static holding tasks and found to significantly decrease the back muscle activity. Actual lifting tasks were further carried out to test the effect of the belt. Ten male subjects performed a symmetric lifting task of low-lying loads (11 and 16 kg) at natural toting velocity, using either a squat or stoop lifting posture, both with and without a belt. The study measured various independent variables using electromyography (EMG), load cells, and motion capture device. The results demonstrated that the belt reduced the load on the erector spinae, as well as the triceps brachii and biceps brachii. The overall mean values of the peak (hand) force did not appear significantly affected while wearing the belt, but the force peaks appeared postponed. The belt did not alter body stability while lifting. From the present findings, the belt effectively changed the force distribution during lifting, at least reducing the muscle load on the back. The belt may be a potentially useful device for symmetric industrial lifting tasks.

Adult↗
PubMed1988

Progressive isoinertial lifting evaluation. II. A comparison with isokinetic lifting in a disabled chronic low-back pain industrial population.

The Progressive Isoinertial Lifting Evaluation (PILE), as described in Part I of this series of articles, is a simplified test combining psychophysical and isoinertial protocols to provide an unconstrained lifting assessment. In the second part of this study, 100 chronically disabled low-back pain patients (57 men and 43 women) were studied at two points: 1) at initial evaluation, when referred for possible entry into a comprehensive Functional Restoration treatment program; and 2) at the conclusion of the treatment (an average 7 weeks later). Results of simultaneous lumbar PILE and Cybex Liftask (Lumex, Ronkonkoma, NY) tests are presented, showing that patients may frequently double or triple initial lifting capacity after undergoing the functional restoration training program, achieving lifting levels at or above normal for incumbent industrial workers. Overall, results demonstrate that the PILE test can be an effective baseline screening test for lifting capacity under certain circumstances. Although several drawbacks affecting the PILE as an isolated test are discussed, its usefulness as part of a battery of physical capacity tests making up a quantitative functional evaluation is clearly demonstrated. Finally, the potential use of PILE as a safe, inexpensive, simple, and relevant screening test for frequent lifting capacity in worker selection is discussed.

Back Pain↗
PubMed1994

[Frontal face lift. Temporal face lift. Extraperiosteal face lift].

The author describes the anatomical structures and various incisions responsible for progress in frontal facelift. He describes the technique currently adopted by the majority of authors to perform this operation. The incision has been the site of the greatest progress and the use of myoplasties remains a controversial issue. Possible combinations with blepharoplasty and with procedures used to complete the facelift at various levels are discussed. These procedures may consist of bone remodelling performed in combination with the operation or osteotomies to modify bony contours, or the use of various filling materials with their respective advantages and disadvantages. The author then describes a temporal facelift technique, which has fallen out of use, under the name of "mannequin facelift" and which, as a result of a better understanding of the planes of dissection has a renewed value in certain indications. It is an incision rather than a technique, but it should also be used with the development of endoscopy. The extraperiostal masklift is a technique which treats the middle part of the face. Its extraperiostal approach, in contrast with the subperiosteal masklift, can be used to release soft tissues and to act more precisely than by raising the periosteum which is considered to be inextensible. Its rejuvenating effect is dramatic, but it does not allow the bony appositions which can be performed via a subperiosteal approach. This technique is very well defined and allows easy progression to a complementary cervicofacial facelift.

Biocompatible Materials↗
PubMed1992

["Total SMAS lift" or deep facial lift by temporal approach. Initial report].

The authors present a new technique of face lift via a temporal approach which allows them to perform a "Total SMAS Lift" of the supra- and infra-zygomatic region. They use the passage on the deep side of the superficial layer of the temporal fascia, which avoids damage to the frontal branch of the facial nerve. Undermining of the periorbital area is performed under the muscle, but above the periosteum of the malar bone. This technique is situated between the subcutaneous face lift and the superiostal mask-lift. This technique can also be combined with a frontal or cervico-facial lift. This "Total SMAS Lift" is essentially indicated in patients with early ptosis of the cheek, the peri-orbital area ant the naso-labial folds and the aesthetic results are gratifying.

Face↗
PubMed1997

A comprehensive lifting model: beyond the NIOSH lifting equation.

A comprehensive lifting model (CLM) for the evaluation and design of manual tasks was developed in two stages using 11 task, personal and environmental variables. In the first stage, the model was built using the psychophysical data. In the second stage, discounting factors of various variables were tested and adjusted using the physiological and biomechanical data. Two lifting indices are proposed to evaluate lifting tasks for a group of workers (relative lifting safety index or RLSI) and for an individual worker (personal lifting safety index or PLSI).

Energy Metabolism↗
PubMed1998

The effect of lifting belt use on multijoint motion and load bearing during repetitive and asymmetric lifting.

The evaluation of the effect of lifting belts on multijoint coordinated lifting performance has been limited. Thirteen subjects participated in two experiments: (a) fatiguing repetitive sagittal lifting and (b) asymmetric lifting. Both experiments were performed with and without the use of a common flexible lifting belt to determine the effect of belt use on the trunk and lower extremity motion and load sharing. During both tests, the use of the belt was observed to restrict the sagittal trunk range of motion and velocity, while the hip motion and velocity increased. Although one of the risk factors for acquisition of low back pain may be reduced while wearing the belt, the results also demonstrate a need for greater study of the consequences on the risk of injury to the other joints. More laboratory experiments and prospective epidemiological studies are needed before a conclusive recommendation could be made in favor of using the belt as a valid preventive measure.

Adult↗