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.

SourceResearch connectionFrom yearThrough year

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

At least 865 records · Page 48Linked to original sources

PubMedDate not supplied

Compulsive weight lifting and anabolic drug abuse among women rape victims.

In the course of a study of 75 female weight lifters, we encountered 10 (13%) who reported that they were raped as teenagers or adults. Nine of these women began or greatly increased their weight lifting activities after the assault to be better able to defend themselves against men. Seven began abusing anabolic steroids and/or clenbuterol to gain muscle mass. Compulsive weight lifting and anabolic substance abuse may represent another form of response to the trauma of sexual assault.

Adolescent↗

PubMed1999

Development of a set of equations describing joint trajectories during para-sagittal lifting.

Given a lifting task with predetermined starting and ending positions, the angular trajectories are usually very consistent with a distinctive pattern. This paper derives a set of equations that can describe the joint trajectories during a para-sagittal lifting task. Three optimal motion patterns were also expressed by the polynomials: minimal hand jerk, minimal center of gravity (CG) jerk, and minimal muscle utilization rate (MUR). The variability of the joint movements were synthesized by overlapping the optimal patterns.

Adult↗

PubMed2000

Regressionally determined vertebral inclination angles of the lumbar spine in static lifts.

OBJECTIVE: Our previous study has developed the non-invasive models to predict the vertebral inclination angles by relating the external stick marker angles and radiographic measurements during trunk flexion. Based on these models, the present study attempted to further predict the inclination angles using externally measured body posture (i.e., lumbar posture, trunk flexion angle, knee angle) as well as load handling. DESIGN: Prediction models of the vertebral inclination angles were developed with a stepwise regression technique. This was done by selecting related postural variables as well as load handling as predictors. BACKGROUND: The technique of skin-surface stick marker has been investigated for measuring vertebral inclination angles. This technique, however, is rarely systematically validated by radiographic measurement because of concerns over radiation exposure, especially for ergonomical purposes. METHODS: Twelve healthy men aged 22-31 years were recruited in the experiment. The angles of the vertebral markers and subject's posture were recorded videographically as the subject performed a given task. Prediction models were then developed to express the relationships between the vertebral inclinations and the lifting postures. RESULTS: The prediction models revealed that the lumbar posture (lordosis or kyphosis) had a statistically significant effect on these inclination angles. Non-linear first-order regression models of the torso angle and the pelvic angle were fit to the transformed vertebral inclination angles (transformed from external stick marker angle), with resulting R(2) values between 0. 86 and 0.92. CONCLUSIONS: These findings indicate that the vertebral inclination angles can be calculated easily and with relative accuracy on the basis of the externally measured torso and pelvis angles. RELEVANCE: Measurements of lumbosacral vertebral inclination angles are important in assessing low back stress during lifting. In this study, we used a regression approach to model these angles of the lumbar/sacrum spine in different lumbar postures in the sagittal plane. Our data suggest that the vertebral inclination angles can be calculated easily. These models may be useful to the low back stress evaluation and job design through a biomechanical analysis.

Adult↗

PubMed2002

Effect of center of pressure and trunk center of mass optimization methods on the analysis of whole body lifting mechanics.

OBJECTIVE: This study evaluates methods to optimize the trunk center of mass position, the center of pressure position, or both to minimize the difference between horizontal location of the whole body center of mass estimated by the model and center of pressure measured during static postures. DESIGN: Within subjects repeated measures. BACKGROUND: Methods to optimize the trunk center of mass position have been proposed in the past, but have not been fully evaluated nor have accounted for errors in the location of the center of pressure. Accurately determining these locations affects the understanding of the control of balance. METHODS: Six methods were compared using kinematic and force plate data from 22 subjects. Static postures resembling both leg and back lifting techniques were used to optimize the center of mass. A typical lifting movement was used to evaluate the effectiveness of the methods in reducing the difference between external moment and time derivative of the angular momentum. RESULTS: Optimization of the center of pressure had a statistically significant effect on reducing errors (P<0.05), whereas optimization of the trunk center of mass alone had not (P>0.05). CONCLUSIONS: Optimizing the center of pressure was simple and compensated for systematic errors introduced from the model and instrumentation. The addition of the center of mass optimization improved some results but added much complexity to the experimental procedures. RELEVANCE: Reducing errors in determining the relative position of the center of pressure and center of mass enhances the understanding of balance control as this relationship reflects the dynamic stability of the system.

Adult↗

PubMed1989

Effects of running or weight lifting on self-concept in clinically depressed women.

Forty clinically depressed women were randomized to a running, weight lifting, or delayed treatment condition. Self-concept was assessed at baseline, pre-, mid-, and posttreatment for all subjects and at 1, 7, and 12 months for exercise groups. Significant improvements in self-concept were found for exercise groups relative to control groups. No significant differences between exercise groups were found, and improvements were reasonably well-maintained over time. Differential changes on dimensions of self-concept were not demonstrated. These results suggest that both running and weight lifting exercise programs improve self-concept in clinically depressed women.

Adult↗

PubMed2003

Predictive and reactive co-ordination of grip and load forces in bimanual lifting in man.

We investigated the intra- and inter-manual coordination of grip force (GF) and load force (LF) during bimanual lifting and holding of a single object. In a voluntary task involving lifting a predictable load (Experiment 1), we showed scaling of GF to LF generated by either hand, similar to effects seen in previous unimanual studies. Moreover, the GF rates generated by the two hands were correlated. In part this correlation was due to the correlation between the LF rates. However, the GF rates remained correlated when the effects of the correlation in LF rates were partialled out. This novel finding suggests an additional co-ordinative constraint at the level of specification of GFs. As a contrast to the predictable loading in the first experiment, in the second experiment loading was temporally unpredictable and elicited reactive increases in GF. In Experiment 2, the intermanual correlation of GF rates was stronger than in Experiment 1. We speculate that this result reflects greater degrees of co-ordinative constraint at lower levels in the motor control hierarchy.

Adolescent↗

PubMed2001

Rescue lifting system (RLS) might help to prevent death after rescue from immersion in cold water.

OBJECTIVE: In order to prevent sudden death after rescue from immersion in cold water, victims should be handled carefully avoiding additional cardiovascular stress. In this study we investigated if a new double-sling rescue system ("Rescue Lifting System-RLS) was superior to conventional single-sling techniques. METHODS: We studied 14 healthy male subjects in good physical condition aged 21 to 40 years. They were lifted up from the ground with the new RLS and two conventional techniques ("Lifesling" and a navy rescue system used in SAR helicopters). Heart rate was determined by QRS detection (Polar Precision Performance device; Polar Electro Oy, Kempele, Finland) and blood pressure by sphygmomanometry. RLS and "Lifesling" were tested under conditions of dry land and immersion in 18 degrees C water. RESULTS: Rescue with RLS induced only moderate heart rate changes which were significantly lower (about 30 bpm) than with conventional techniques. These findings could be reproduced under "wet" condition. DISCUSSION: RLS enables rescue in a supine position avoiding extensive orthostatic stress. It might therefore be favourable in preventing sudden death after rescue from immersion in cold water.

Adult↗

PubMed1995

Salivary cortisol and testosterone variations during an official and a simulated weight-lifting competition.

This study was undertaken to compare salivary levels of cortisol (C), testosterone (T) and T/C ratio during an official and a simulated weight-lifting competition. Thirteen top-level weight-lifters (French team) including 7 national level athletes (NG) and 6 international level athletes (IG) entered the study. The performance levels corrected with the IWF index (an index which relates the performance to body weight) obtained during the competition were higher than those obtained during the simulation and were higher in IG than in NG. Salivary samples were collected for each session after weighing, snatch and clean-and-jerk. The mean T-levels of these athletes were the same as those obtained in the laboratory on sedentary adults; they did not vary throughout the competition, nor between the competition and the simulation. Conversely the C-levels were statistically higher in the competition than in the simulation (p < 0.05). These C-levels are correlated with the performance levels corrected with the IWF index obtained during the competition (r = 0.67; p < 0.05; n = 13). Moreover, C-levels noted at the time of the competition were higher in the international athletes than in the national ones. Therefore, we concluded that the cortisol level may be considered as a performance factor in weight-lifting.

Adult↗

PubMed1986

Hormone and metabolite response to weight-lifting training sessions.

Eleven weight-trained athletes (age X +/- SD = 33 +/- 5 yrs, weight = 72 +/- 10 kg) with a maximal performance in bench press at the beginning of the study (116 +/- 19 kg) were studied at rest, after a standardized submaximal training session, and after a maximal session once a month for 4 months to study the blood metabolites and hormonal changes during weight lifting. The submaximal load was six series of eight bench presses at 70% of maximal performance presses, and the maximal load was the maximal number of repetitions at the same work load. The levels of several metabolites (lactate, glycerol, triglycerides, beta-OH-butyrate) and hormones (norepinephrine and epinephrine) increased (P less than 0.05) after submaximal work and more after maximal work. Glucose, FFA, acetoacetate, insulin, testosterone, and cortisol did not change significantly or consistently. Lactate after maximal work was higher after the 4th training month (P less than 0.05). Other variables did not change much with training while the maximal number of repetitions in the last series increased slightly (P less than 0.05). In general, the changes observed were smaller than the ones reported for endurance or interval running, which use larger muscle groups. Nevertheless, weight lifting induced changes in blood metabolites which reflect a mobilization of both carbohydrates and lipids stores for energy.

Adult↗

PubMed2002

Usability of the revised NIOSH lifting equation.

Following the revision of the 1981 National Institute for Occupational Safety and Health (NIOSH) lifting equation, research needs related to the new equation were outlined. Aside from epidemiological studies, the need to evaluate the usability of the 1991 NIOSH equation in realistic work environments was expressed. This paper reports on extensive experiences with training users and application of the equation in varied work settings. Qualitative results from training sessions indicated that frequency, asymmetry and duration were the parameters that required relatively longer instruction periods and resulted in the most questions. Field applications indicated that the variable nature of lifting/lowering demands found in many jobs resulted in difficulty applying the equation. Approximately 35% of 1103 lifting and lowering tasks had at least one parameter outside of acceptable ranges, while a majority of workers (62.8%) reported other manual handling tasks that are counter to assumptions made in the development of the equation. The practical implications of the findings are discussed.

Guideline Adherence↗

PubMed1997

Learning versus correct models: influence of model type on the learning of a free-weight squat lift.

It has been assumed that demonstrating the correct movement is the best way to impart task-relevant information. However, empirical verification with simple laboratory skills has shown that using a learning model (showing an individual in the process of acquiring the skill to be learned) may accelerate skill acquisition and increase retention more than using a correct model. The purpose of the present study was to compare the effectiveness of viewing correct versus learning models on the acquisition of a sport skill (free-weight squat lift). Forty female participants were assigned to four learning conditions: physical practice receiving feedback, learning model with model feedback, correct model with model feedback, and learning model without model feedback. Results indicated that viewing either a correct or learning model was equally effective in learning correct form in the squat lift.

Analysis of Variance↗

PubMed1995

Lifting Belts: A Review.

This article reviews and evaluates the literature related to the effectiveness of protective restraints on abdominal strength, lower back injuries, and workers' discomfort. The studies indicate that back belts have potential disadvantages as well as advantages. Belts seem to reduce lifting stress. They may, however, lead to a false sense of security while being worn and may also weaken the body, so injury occurs when they are not being worn. There also seems to be comfort problems with some belts. More scientific research is needed before any conclusions can be drawn about positive, negative, or long-term effects of lifting belts.

abdominal supports↗

PubMed2001

A biomechanical analysis of manual lifting tasks performed in restricted workspaces.

This paper describes the results of an experimental study aimed at evaluating the biomechanical effects of working in a spatially restricted environment on manual lifting tasks. The main objective of the study is to estimate the biomechanical loading (in terms of peak compression and shear forces) on the lumbar spine for the selected combinations of limited headroom heights and twisting angles. A three-dimensional dynamic biomechanical model was utilized to assess peak compression and shear forces at the L5/S1 lumbosacral joint. The results indicated that by reducing the headroom height, the participants were forced to stand with their trunks fully flexed forward which, by increasing the mechanical disadvantage at the lumbosacral disc, increased the compression forces. Both compression and shear forces were affected by the increase in twisting angle. The greater the twisting angle, the higher the compression and shear forces. Regression models were developed and validated, which demonstrated high accuracy of predicting the psychophysical and biomechanical lifting capacities.

Adult↗

PubMed1997

Do standing, lifting, climbing, or long hours of work during pregnancy have an effect on fetal growth?

We assessed prospectively the impact of length of the work week and job activity on fetal growth. Among 575 women who worked during pregnancy, neither prolonged standing, frequent lifting, or climbing at work, nor a high composite activity score showed an association with fetal growth, as measured by birthweight for gestational age. Long hours of work, however, did reduce fetal growth. Infants of women working long hours late in pregnancy showed decreases in gestation-adjusted birthweight of about 80 gm (95% confidence limits = -238, +74 gm), compared with women working 20 hours or less. When long hours (> 40 hours per week) were combined with job activity, the estimated reductions ranged up to 350 gm. At lower weights (< or = 3,000 gm), categorical analyses showed elevated odds ratios (1.1-1.8) for climbing, lifting, and long hours and for the combination of prolonged standing with a lengthy work week. These results indicate that long weeks of physically demanding work could lead to fetal growth reductions that may be clinically significant. Consistent with this suggestion, infants of women who worked part-time had the highest mean birthweights. Hours of work, not only job tasks, may be important for pregnant workers.

Adult↗

PubMed1988

Progressive isoinertial lifting evaluation. I. A standardized protocol and normative database.

Dynamic tests of trunk strength and lifting capacity have become more popular in recent years, offering certain advantages over static isometric tests in measuring patient progress in functional restoration programs for spinal disorders. However, equipment for performing such tests is expensive to buy, complex to run, and requires technical expertise and clinical volume unavailable in most physician offices. In this study, a new dynamic test known as Progressive Isoinertial Lifting Evaluation (PILE) is described, which draws upon prior psychophysical and isoinertial methods. An industrial sample of 61 male and 31 female incumbent workers were tested using the PILE, and a variety of anthropometric normalizing factors were evaluated. The isolation of an "Adjusted Weight" (AW) normalizing factor is documented, after which normative data are presented for male and female workers utilizing lumbar (0-30 inches) and cervical (30-54 inches) dynamic protocols.

Adult↗

PubMed2003

Effects of unexpected lateral mass placement on trunk loading in lifting.

STUDY DESIGN: A repeated measurements experiment of spinal loading in healthy subjects. OBJECTIVES: To test whether unexpected lateral mass placement increases low back loading and trunk movement when subjects are lifting a mass in upright posture. SUMMARY OF BACKGROUND DATA: Epidemiologic studies suggest that sudden, unexpected loading will lead to low back pain. Also, asymmetric loading is considered to be harmful to the spine. It can be anticipated that unexpected asymmetric loading will increase the risk of injury even more. METHODS: Ten subjects lifted in an upright posture a crate, in which a mass of 10 kg was placed laterally at the left side either expectedly or unexpectedly. The crate reaction forces, body movements, and trunk muscle activity were measured. From these, the L5-S1 net moments and muscle forces were estimated. RESULTS: Unexpected lateral placement of the mass caused no clear increase in peak low back loading. The stiffness of the trunk was lower in the unexpected condition, which, in combination with inadequate net moments produced, resulted in movement of the trunk to the side of the displaced mass. CONCLUSIONS: Unexpected lateral mass placement does not increase the compression force. Perturbed trunk movement and lower muscle forces indicated a decreased stability of the spine, which may imply an injury risk.

Adult↗

PubMed2005

Test-retest reliability of the Progressive Isoinertial Lifting Evaluation (PILE).

STUDY DESIGN: A repeated measures single group design. OBJECTIVES: To investigate test-retest reliability of Progressive Isoinertial Lifting Evaluation on patients with long lasting musculoskeletal problems related to the lumbar spine. SUMMARY OF BACKGROUND DATA: Test-retest reliability has been satisfactory in healthy men. Test-retest reliability for clinical populations has not been reported. METHODS: A total of 31 patients (17 women and 14 men) with long lasting low back pain participated in the study. The patients were tested twice at an interval of 2 days and at the same time of the day. The heaviest load that the patient could lift 4 times was used as outcome measure. RESULTS: The error of measurement indicates that the true result in 95% of cases will be within +/-4.5 kg from the measured value, while the difference between 2 measurements in 95% of cases will be less than 6.4 kg. Intra-class correlation (1,1) was 0.91. CONCLUSIONS: Relative test-retest reliability was high assessed by intra-class correlation, but absolute measurement variability reported as the smallest detectable difference has relevance for the interpretation of clinical test results and should also be considered.

Adult↗

PubMed2002

Changes in the surface EMG signal and the biomechanics of motion during a repetitive lifting task.

The analysis of surface electromyographic (EMG) data recorded from the muscles of the back during isometric constant-force contractions has been a useful tool for assessing muscle deficits in patients with lower back pain (LBP). Until recently, extending the technique to dynamic tasks, such as lifting, has not been possible due to the nonstationarity of the EMG signals. Recent developments in time-frequency analysis procedures to compute the instantaneous median frequency (IMDF) were utilized in this study to overcome these limitations. Healthy control subjects with no history of LBP (n = 9; mean age 26.3 +/- 6.7) were instrumented for acquisition of surface EMG data from six electrodes on the thoraco-lumbar region and whole-body kinematic data from a stereo-photogrammetric system. Data were recorded during a standardized repetitive lifting task (load = 15% body mass; 12 lifts/min; 5-min duration). The task resulted in significant decreases in IMDF for six of the nine subjects, with a symmetrical pattern of fatigue among contralateral muscles and greater decrements in the lower lumbar region. For those subjects with a significant decrease in IMDF, a lower limb and/or upper limb biomechanical adaptation to fatigue was observed during the task. Increases in the peak box acceleration were documented. In two subjects, the acceleration doubled its value from the beginning to the end of the exercise, which lead to a significant increase in the torque at L4/L5. This observation suggests an association between muscle fatigue at the lumbar region and the way the subject manipulates the box during the exercise. Fatigue-related biomechanical adaptations are discussed as a possible supplement to functional capacity assessments among patients with LBP.

Adaptation, Biological↗