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PubMed1995

A mathematical lifting model of the lumbar spine.

The objective of this study was to develop a comprehensive mathematical lifting model which takes into account both task and personal factors. The outcome measure of this model was compared to that of the 1981 and 1991 NIOSH lifting equations as well as the model reported by Drury and Pfeil (Int J Prod Res 13:137, 1975). The model was developed in two stages. In the first stage, the complete model was derived from the psychophysical data. In the second stage, the discounting factors of the various parameters included in the model were tested and adjusted using the physiological and biomechanical data. The rationale for building the model in two stages was based upon the hypothesis proposed and tested by Karwowski (Proc Ergon Soc Conf 95, 1983), which, combining the acceptability of physiological and biomechanical stresses, should lead to an overall measure of lifting task acceptability--namely, the acceptability of psychophysical stress. The following input parameters were incorporated into the model: (a) horizontal distance in the sagittal plane, (b) vertical distance between the origin of lift and the floor, (c) vertical travel distance, (d) lifting frequency, (e) task duration, (f) twisting angle, (g) coupling, (h) heat stress, (i) gender, (j) age, (k) body weight, and (l) percentage of worker population. The lifting capacity values predicted from the present study are consistently lower than the values generated from prior research. This can largely be explained by the incorporation of new biomechanical and physiological guidelines for lifting tasks.

Aging↗
PubMed1995

A test to measure lift capacity of physically impaired adults. Part 2--Reactivity in a patient sample.

STUDY DESIGN: Test reactivity is the based on the idea that experience with a test may affect performance on subsequent tests, independent of what the test purports to measure. The reactivity of a test of lift capacity was studied in a single-blind randomized clinical trial was studied in a single-blind randomized clinical trial in which subjects were assigned to one or two groups. One group received lift testing before and after a therapeutic trial, while the other group received lift testing only at the conclusion of the therapeutic trial. OBJECTIVE: To measure the reactivity of a lift capacity test over the course of treatment. SUMMARY OF BACKGROUND DATA: The reactivity of a test is an important criterion by which an outcome measure must be judged. Change in response to treatment is assumed to be independent of changes resulting from the evaluee's experience with the test, although this is rarely addressed. METHODS: The EPIC Lift Capacity test was administered to 55 patients with low back pain in a treatment program after they were randomized into a pre-test/post-test and a post-test only group. Additional measures were taken on a pre-test/post-test basis for all subjects. RESULTS: Analyses of variance demonstrated no difference between the randomized groups after treatment. However, the pre-test/post-test group demonstrated significant improvement over the course of treatment. Other measures of outcome were similarly affected. CONCLUSION: The reactivity of the EPIC Lift Capacity test was negligible over an 8-week treatment regimen that did not include lifting tasks.

Adult↗
PubMed1999

The effect of industrial back belts and breathing technique on trunk and pelvic coordination during a lifting task.

STUDY DESIGN: Relative phase angle was used to study segmental motion patterns during a lifting and lowering task. OBJECTIVES: To investigate the effect of back belts, breathing technique, and their interaction on lumbar and pelvic motion patterns. SUMMARY OF BACKGROUND DATA: Trunk and pelvic coordination has been investigated in healthy and low back pain populations. Back belts have been shown to alter range of motion and intra-abdominal pressure. Little has been reported about belts and coordination during lifting and lowering. Phase angle has been used for quantifying segmental coordination. METHODS: Six individuals performed lifting/lowering tasks with a 23-kg load under elastic, rigid, and no belt conditions. During a second session, individuals were trained in Valsalva's maneuver and repeated the protocol. Cinematography was used to track trunk and pelvis displacements. RESULTS: Segmental coordination during lowering generally was found to be the inverse of lifting. Significant differences in the relation between lumbar and pelvis phase angles were found during the initial stage of lifting because of the interaction of belt use and breathing. Lumbar range of motion decreased significantly with belt use during lifting and lowering. No significant change in pelvis range of motion was observed. CONCLUSIONS: Back belt use and breathing technique interacted during the initial stage of lifting to significantly alter the lumbar and pelvis phase angles. The change in segmental kinematics was similar to that previously reported for patients with a history of low back pain. Lumbar range of motion significantly decreased with belt use during both lifting and lowering.

Adolescent↗
PubMed2001

A randomized controlled trial to prevent patient lift and transfer injuries of health care workers.

STUDY DESIGN: Randomized controlled trial (RCT). OBJECTIVES: To compare the effectiveness of training and equipment to reduce musculoskeletal injuries, increase comfort, and reduce physical demands on staff performing patient lifts and transfers at a large acute care hospital. SUMMARY OF BACKGROUND DATA: Back injury to nursing staff during patient handling tasks is a major issue in health care. The value of mechanical assistive devices in reducing injuries to these workers is unclear. METHODS: This three-armed RCT consisted of a "control arm," a "safe lifting" arm, and a "no strenuous lifting" arm. A medical, surgical, and rehabilitation ward were each randomly assigned to each arm. Both intervention arms received intensive training in back care, patient assessment, and handling techniques. Hence, the "safe lifting" arm used improved patient handling techniques using manual equipment, whereas the "no strenuous lifting" arm aimed to eliminate manual patient handling through use of additional mechanical and other assistive equipment. RESULTS: Frequency of manual patient handling tasks was significantly decreased on the "no strenuous lifting" arm. Self-perceived work fatigue, back and shoulder pain, safety, and frequency and intensity of physical discomfort associated with patient handling tasks were improved on both intervention arms, but staff on the mechanical equipment arm showed greater improvements. Musculoskeletal injury rates were not significantly altered. CONCLUSIONS: The "no strenuous lifting" program, which combined training with assured availability of mechanical and other assistive patient handling equipment, most effectively improved comfort with patient handling, decreased staff fatigue, and decreased physical demands. The fact that injury rates were not statistically significantly reduced may reflect the less sensitive nature of this indicator compared with the subjective indicators.

Back Injuries↗
PubMed2002

Human muscular and postural responses in unstable load lifting.

STUDY DESIGN: Most studies of manual material handling have focused on stable (fixed) loads. The muscular response during unstable load handling deserves more investigative attention. OBJECTIVES: To investigate muscular and postural responses during unstable load lifting, and to quantify the threat posed by such loads in the workplace. SUMMARY OF BACKGROUND DATA: Accurate assessment of load weight is important for lifters. Unfortunately, this information is not always available to individuals handling containers of liquids or shifting loads, or those encountering impact loading or a sudden unexpected load. METHODS: In this study, 12 subjects were subjected to time-variant loads, in which a box weighing 18 kg was used to generate a sudden 12 (kg. m)/second load impact internally during the lifting process. Responses were investigated as a function of different load-shift conditions (anterior-to-posterior and posterior-to-anterior rolling loads and stable load), two foot placements (wide and narrow stance), and two lifting techniques (stoop and squat). Normalized electromyography signals, joint angles, and total linear length for center of pressure (COP-length) were investigated. RESULTS: Lifting an unstable load significantly increases total lifting time, COP-length, and muscular contraction levels. When responding to impact momentum, subjects attempted to lift with greater elbow extension and shoulder and trunk flexion. A more flexed knee joint (approximately an additional 5 degrees ) was observed during preparation for load impact in the anterior-to-posterior rolling task, allowing the formation of a more stable platform to compensate for the load variation. The largest erector spinae contraction for unstable lifting was approximately 12% to 25% greater maximal voluntary contraction than for the stable analog. CONCLUSIONS: The normalized electromyography data demonstrate that the central nervous system detects and responds to the need to stabilize the joints closest to the location of load-shift perturbation.

Acceleration↗
PubMed2002

Factors in breathing maneuvers that affect trunk electromyogram during manual lifting.

STUDY DESIGN: A fully randomized experiment was conducted in a laboratory with a breath-by-breath monitor to control accurately the two factors of breathing maneuvers: breathholding duration and air volume within the thoracic cavity. OBJECTIVES: To resolve the controversy in previous reports about the effect of breathholding on the trunk electromyogram, and to verify the hypothesis that not only the factor of glottis closure, but also that of the air volume inside the thoracic cavity affects the trunk muscular activities during lifting. SUMMARY OF BACKGROUND DATA: Breathing was shown to affect spinal loading. However, there still is a debate about the effect of breathholding on trunk muscular activation during activities. It is possible that variations in air volume influence this effect. METHODS: Seven healthy, volunteer men participated in lifting tasks, in which lifting moment was standardized. Three breathing maneuvers were used: sustained breathholding with tidal volume of air, sustained breathholding with functional residual volume, and intended breath-nonholding involving inspiration within tidal capacity. Data on the surface electromyographic activation of the external oblique muscle, rectus abdominis, erector spinae, latissimus dorsi, air volume inside the cavity, and the duration of the one breath held in the last lift were collected and analyzed. RESULTS: Of the four muscles investigated, the breathing maneuvers affected only the external oblique muscle. The effect of sustained breathhold during lifting was the significantly increased activation of this muscle (P < 0.05). The effect of decreased air volume held was further increased activation. Intention to inspire normally during lifting decreased external oblique activation, but increased compensatory diaphragmatic effort, measured as inspiratory flow acceleration. CONCLUSIONS: Both the factors of the breathheld state and sustained air volume were verified to affect the external oblique activation during lifting. The current study emphasizes that both factors should be controlled in studies analyzing trunk electromyogram during activities. Otherwise, these breathing variations will be a confounding factor on electromyogram results.

Abdominal Muscles↗
PubMed2005

The use of splines to calculate jerk for a lifting task involving chronic lower back pain patients.

Motion differences in a repetitive lifting task have been described previously using differences in the timing of body angle changes during the lift. These timing changes relied on small differences of motion and are difficult to measure. The purpose of this study was to evaluate shoulder jerk (rate of change of acceleration) in a repetitive lifting task as an alternative parameter to detect differences of motion between controls and chronic lower back pain (CLBP) patients and to measure the impact of a rehabilitation program on jerk. The jerk calculation was a noisy measure, since jerk is the third derivative of position; consequently a simulation was performed to evaluate smoothing methods. Woltring's generalized cross-validation spline produced the best estimates of the third derivative and was fit to subject data. The root mean square (rms) amplitude of jerk was used for comparison. Significant group differences were found. CLBP patients performed lifts with lower jerk values than controls and, as the task progressed, both groups increased jerk. After completion of a rehabilitation program, CLBP patients performed lifts with greater rms jerk. In general, patients performed lifts with lower jerk values than controls, suggesting that pain impacts lifting style.

Acceleration↗
PubMed2004

The size-weight illusion in team lifting.

The purpose of these studies was to examine whether or not there is a size-weight illusion when participants lift containers as a team. In Experiment 1, teams of participants lifted a set of 16 containers that varied in mass and size and reported their perceptions of heaviness and volume. In Experiment 2, participants lifted the same containers individually. A size-weight illusion was demonstrated in each experiment: Reports of perceived heaviness decreased substantially as the volumes of the containers increased for both styles of lifting. However, both the magnitude of the illusion and mean perceived heaviness were greater in the team lift. Actual or potential applications of this research include the development of safe lifting guidelines for team lifting.

Female↗
PubMed1994

Therapists' ability to identify safe maximum lifting in low back pain patients during functional capacity evaluation.

Functional capacity evaluation (FCE) of an injured worker's ability to lift weight guides the determination of whether he or she is capable of handling the physical demands of a job. The purpose of this study was to examine the interrater and intrarater reliability in determining the safe maximum floor-to-waist lift for patients with low back pain during FCE testing. Twenty-one patients with low back pain were evaluated. Patients were videotaped lifting weight in progressive increments using a kinesiophysical approach. Five experienced physical therapists viewed the videotape and judged the lifts for body mechanics safety. Safety reliability was high, indicating that therapists can accurately judge safe lifting methods during FCE. As lifting loads increased, body mechanics deteriorated, indicating the patient was approaching or had reached a biomechanical end point. Clinical information is needed, in addition to visual observations, to accurately determine when maximum lift capacity is reached.

Adult↗
PubMed1998

Lifting patients in bed with and without a drawsheet: a comparative ergonomics study.

Two techniques for lifting a patient in bed, namely with and without the use of a drawsheet, have been compared from an ergonomics point of view. Forty-two nurses of a Thai university hospital were studied before and after using each method by measuring back strengths and by using a questionnaire for feelings of fatigue and for musculoskeletal fatigue and pain. Decreases in back strength 10 minutes after and immediately after lifting with each method were found to be significant (90% confidence). The decrease 10 minutes after lifting was found to be significantly smaller with a drawsheet than without one (98% confidence). Immediately after lifting there was less difference between the two methods, which indicates that the use of a drawsheet reduced the recovery time and the decrease in back strength. Increases in feelings of fatigue from lifting with each method were also found to be significant (90% confidence), and the results indicate that the increase was lower with a drawsheet than without one. Musculoskeletal fatigue and pain immediately after lifting were more common without a drawsheet than with one. In conclusion, the lifting technique with a drawsheet is ergonomically superior and should be used by nursing personnel.

Adult↗
PubMed1995

[Lifting and blepharoplasty].

The term face lifting enconpasses a variety of surgical procedures. Their goal is to obtain a rejuvenated look: frontal lift, temporal lift, cervico facial lift. The mask lift tends to a more radical modification of the upper third and mind third of the face. Its indications, with the psychological counterpart must be cautiously decided. The video endoscopy has recently modified and reduced the importance of the incision in frontal and mask lift. The blepharoplasties may be performed separately or, in combination with a face lift. The upper blepharoplasties rejunevate the look. The lower blepharoplasties are mostly indicated in baggy eyelids.

Blepharoptosis↗
PubMed1996

Effect of body position on isometric arm lifting strength.

The purpose of this study was to examine the influence of three different body positions on isometric arm lifting strength. Thirty students aged between 20 and 27 years volunteered as subjects for the study. A force Evaluation and Testing System (FET 5000) was used to measure the arm lifting strength in the supine, sitting, and standing positions. Average force of each body position was determined by the mean of two trials. At the same time, electromyographic activity of bilateral biceps brachii muscles was measured during maximal voluntary isometric arm lifting. Repeated measures analysis of variance was used to analyze the effects of body positions on the amount of average force value and integrated electromyographic (IEMG) values during isometric arm lifting. The results showed that the highest mean lifting strength was recorded in the sitting position for both males and females. Significant difference in arm lifting strength was found between each body position. Differences in force were elicited more easily between the female and male subjects. However, the average IEMG values were not significantly correlated with the force produced in arm lifting. Nevertheless, this study supports the conclusion that body position did influence the production of isometric elbow flexors strength. We conclude, therefore, that body position must be considered during rehabilitation of upper extremities.

Adult↗
PubMedDate not supplied

A retrospective comparison of open and endoscopic brow-lifts.

OBJECTIVES: To measure and compare surgical brow elevation with open and endoscopic techniques; to compare patients who did and did not undergo an eyelid procedure in the same setting as the brow-lift; and to determine whether a learning curve exists for a successful endoscopic brow-lift procedure. DESIGN: A retrospective review of patients who underwent coronal, trichophytic, and endoscopic brow-lift surgery from January 1, 1993, to December 31, 1997 (performed by K.A.L.). We analyzed preoperative and postoperative photographs obtained from 10 to 56 months after surgery while masked to the surgical technique used. Measurements included a horizontal baseline drawn through the midpoint of the right and left medial canthi, and extended laterally across the face; the distance from the baseline to the superior border of the medial eyebrow on the right and left sides; and the distance from the baseline to the highest point of the brow on the right and left sides. A second, nonbiased observer analyzed a random sampling of patient photographs to determine the degree of interobserver variation. SETTING: Private facial plastic and reconstructive surgery practice. All procedures were performed in an ambulatory surgery setting. PARTICIPANTS: We identified 125 patients (average age, 54 years) with greater than 10 months of postoperative photographic documentation. We excluded 41 patients owing to several inconsistencies between their preoperative and postoperative photographs and included 84. These patients were divided into 3 groups: those undergoing coronal, trichophytic, and endoscopic procedures. Of the patients undergoing concomitant eyelid procedures, 12 underwent upper lid blepharoplasties; 15, lower lid blepharoplasties; 16, bilateral upper and lower lid blepharoplasties; 6, periorbital laser resurfacing or chemical peel; 1, canthoplasty; and 1, ptosis repair. The endoscopic brow-lift procedure was not performed in this facial plastic surgery practice until 1995. To determine whether better results were obtained in the later half of the study, when the surgeon had more experience, this group was divided between the 14 patients who underwent the procedure from January 1, 1995, to June 30, 1996, and the 20 who did from July 1, 1996, to December 31,1997. MAIN OUTCOME MEASURE: Comparison of preoperative photographs with postoperative 10- to 32-month follow-up photographs and with final 35- to 56-month follow-up photographs. RESULTS: We found no statistically significant difference in: the distance of the medial brow (P =.89) or highest elevated point of the brow (P =.93) between the coronal, trichophytic, and endoscopic groups; the distance that the medial brow (P =.15) or the highest point of the brow (P =.11) was raised for those patients undergoing concomitant eyelid procedures; and the distance that the medial brow (P =.80) or highest point of the brow (P =.79) was raised between the 2 endoscopic brow-lift groups. Interobserver variation in brow measurements was 0.1 cm or less in more than 90% of cases. CONCLUSIONS: Both open and endoscopic brow-lift techniques described herein elevate the entire brow successfully. We found no statistical difference in patients undergoing concomitant eyelid procedures, and there was no identification of a "learning curve" for a successful endoscopic brow-lift with the surgical technique described.

Endoscopy↗
PubMedDate not supplied

The evolution of midface rejuvenation: combining the midface-lift and fat transfer.

OBJECTIVE: To evaluate the aesthetic results in our initial group of patients treated with a combination of a midface-lift and fat transfer compared with a randomly selected group of patients who underwent a midface-lift without concurrent fat transfer by one of us. METHODS: The setting was a private, ambulatory, surgical center. The design was a comparative study between patients who did or did not receive fat transfer in addition to a midface-lift to determine if the addition of fat transfer to the midface-lift resulted in an improved aesthetic outcome. A total of 40 patients with complete photographic and medical records and a minimum of 6 months of follow-up were included in the study. Group 1 consisted of 30 patients randomly selected (from >650 potential patients) who underwent a midface-lift without fat transfer to serve as a control group. Group 2 consisted of our initial 10 patients who underwent fat transfer in addition to a midface-lift at the same setting. The degree of aesthetic improvement in 4 facial zones was assessed by 3 independent blinded evaluators. Zone 1 represents the tear trough/infraorbital rim; zone 2, the malar eminence; zone 3, the submalar region; and zone 4, the nasolabial crease. Each zone was given a rating from 0 to 2 (0 for no improvement; 1, mild improvement; and 2, marked improvement). The 2 groups were compared with 4 chi(2) tests of independence. RESULTS: Four chi(2) tests of independence were conducted to compare the findings between group 1 and group 2. One hundred twenty ratings were conducted; group 1 consisted of 90 total ratings on 30 patients and group 2 consisted of 30 total ratings on 10 patients. The first chi(2) (tear trough/infraorbital rim) test revealed a significant difference on tear trough ratings by group (chi(2)(2) = 73.59, P<.01). The second chi(2) test (malar eminence) did not reveal a significant difference on malar eminence ratings by group (chi(2)(2) = 3.10, P = .21). The third chi(2) test (submalar region) failed to reveal a significant difference on submalar region by group (chi(2)(2) = 4.01, P = .13). The final chi(2) test (nasolabial crease) revealed a significant difference on nasolabial ratings by group (chi(2)(2) = 14.28, P<.01). CONCLUSIONS: Our findings revealed a statistically significant difference between group 1 (no fat transfer) and group 2 (fat transfer) in the tear trough region (P<.01) and the nasolabial crease (P<.01). The fat transfer technique in combination with a midface-lift is a safe and effective means to provide more complete facial rejuvenation, especially in the regions of the tear trough and nasolabial crease.

Adipose Tissue↗
PubMed2005

[Limitations of blood supply to the skin flap in face lift surgery].

BACKGROUND: Besides nerve injuries or hematomas, one of the main risks of face lift surgery is the development of skin necrosis. We therefore investigated which arteries contribute to the blood supply of the face lift skin flap and how extensively mobilization can be performed before arterial cutaneous circulation is endangered. MATERIAL AND METHOD: In six cadavers, selective dye injections into the branches of the carotid external artery were performed to determine the location of their vascular territories in relation to the face lift region. In another 12 cadavers, face lift flaps were raised with different extension of the undermined skin area before dye injections were performed. RESULTS: It was shown that the facial artery provides blood supply to the area of the face lift flap by perforating vessels in the paranasal, perioral and submental regions and the transverse facial artery by a perforating vessel below the malar bone prominence. Although the perforating vessel of the transverse facial artery was transected by standard mobilization, the face lift flaps were sufficiently perfused via the paranasal and perioral perforating vessels of the facial artery alone. CONCLUSION: We conclude that undermining of the face lift flap should not exceed the nasolabial fold to preserve the perforating vessels of the facial artery in the centrofacial region.

Arteries↗
PubMed1987

Maximum acceptable lifting loads during seated and standing work positions.

The psychophysical method was used to determine the maximal acceptable load that eight males (age 22-30 years) would lift in each of four different positions: (1) seated, two-handed, symmetrical lift from a table, to a position 38 cm forward of the edge, (2) a seated lift from a position at the subject's side, on to a table in front of the subject involving a 90 degree twist of the torso, (3) standing, two-handed, symmetrical lift from the table, to a position 38 cm forward of the edge, and (4) standing, vertical lift from 86 above the floor. Subsequent to a training period, subjects lifted a tray with slotted handles at the rate of 1 or 4 lifts/min. Each subject chose the weight of the tray which was acceptable to him by adding or removing flat pieces of lead over a 45 min period. The weight of the tray, heart rate, and the perceived exertion were measured at 15, 30 and 45 min. Oxygen consumption was measured during the last 5 min of the 45 min experiment. Statistical analysis revealed a significant frequency and position effect. An increase in frequency from 1 to 4 lifts/min resulted in a decrease of 1.6 to 2.1 kg in the maximum acceptable weight for the various tasks. On average, the maximum acceptable weight of lift for standing positions was 16% greater than for sitting positions. Oxygen consumption and heart rate were significantly higher for 4 lifts/min than for 1 lift/min; however, the rating of perceived exertion did not differ for any factor.

Journal Article↗
PubMed1985

Dynamically and statically determined low back moments during lifting.

Assessment of the effects of lifting on the low back has most frequently been done with the aid of static models. Many lifting movements appear to have substantial inertial components. It was of interest, therefore, to determine the size of the difference between statically and dynamically calculated lumbar moments during a demanding but not unusual manual lift observed in a metal fabrication industry. The results of several trials by four young men showed that the dynamic model resulted in peak L4/L5 moments 19% higher on average, with a maximum difference of 52%, than those determined from the static model. The technique adopted in the lift could minimize the difference. When the inertial forces of the load itself and the load weight were incorporated into an otherwise static model (quasi-dynamic) then the resulting L4/L5 moments exceeded those of the fully dynamic model by 25%. In many industrial tasks static analyses may severely underestimate the demands of dynamic lifts. These results show that a reasonably inexpensive approach in lifting task analysis is to measure the dynamic forces of the load on the hands and to use these in an otherwise static model. This results in a conservative assessment of the injury risk of lifts at least of the type reported in this study.

Adult↗
PubMed1995

Correlations of isokinetic and psychophysical back lift and static back extensor endurance tests in men.

Isokinetic lift, psychophysical lift, and static back endurance tests are among the most widely used measurements of muscle function for determining risk for, and recovery from, back problems. After determining test repeatability we examined the degree of association between these test measures in 100 men selected to represent a variety of occupations and lifestyles. Isokinetic lifting had low correlations with test results for psychophysical lifting (r = 0.28) and static back endurance (r = 0.24). Static back endurance and psychophysical lift test results were not at all correlated (r = 0.03). RELEVANCE--:Muscle function measurements for back problems are sometimes arbitrarily selected due to health practioners' beliefs and preferences or practical reasons such as the availability of equipment. Yet little is known about the associations of these tests with one another or with anthropometric factors. The data presented in this study document that isokinetic lift, psychophysical lift, and static back endurance tests appear to measure very different aspects of muscle function, and comparing studies using these different test methods should be approached with these low inter-test correlations in mind.

Journal Article↗