Stoop Lifting Research Articles

Regression models for the prediction of dynamic L4/L5 compression forces during lifting

The purpose of this study was to determine whether regression equations could be developed, as an alternative to biochemical models, to predict the peak L4(L5 disc compression force during dynamic, sagittal plane lifting. Eighteen male subjects performed a squat and a stoop lift with loads of 6, 14, 22, 29, and 32 kg. Each lift was analysed with a linked segment biomechanical model that output the compression force time history during the lift. The peak compression served as the dependent variable for two regression models. The independent variables in each model were measures which described the subject's body dimensions, body posture, internal lifting mechanics, load location and load effects. A ‘lab’ model was developed (R2=0·93) which required only four inputs and had an RMS error of only 8·3% between the biomechanical model estimate of the peak L4/L5 disc compression force and that predicted from the regression equation. A seven variable ‘field’ model was developed with an R2 of 0·90 and an RMS error of 9·7%. It was concluded that both of the proposed models were potentially useful to the practising ergonomist interested in easily and quickly estimating lumbar compression forces during dynamic sagittal plane lifting.

Dynamic comparison of the two-hand stoop and assisted one-hand lift methods : J of Safety Res, 1990, 21.2, 53–59, 12 refs

Low-back pain arising from repetitive lifting of objects out of deep containers is a significant problem in many industries and results in a great deal of time lost from work. This study measured electromyographic (EMG) activity of the lumbar paraspinal cles, vertical acceleration of three different loads, and the reaction force of the supporting upper extremity to compare the assisted one-hand lift and the two-hand stoop lift techniques. The results of the study indicate thatmus the assisted one-hand lift requires significantly less EMG activity than the two-hand stoop method when lifting loads out of deep containers. The acceleration of the load was not significantly different for three different loads, but the force on the supporting upper extremity was significantly related to the weight of the load lifted. Results of this study seem to indicate that, under certain circumstances, the one-hand lift is a less stressful method of lifting than the two-hand stoop method.

Efficiency and effectiveness of stoop and squat lifting at different frequencies

The study investigated the effects of frequency (10 and 20 lifts/min) and technique (squat and stoop) of repetitive lifting of a barbell (19 kg) on the relationship between mean power output (Pm) and energy cost in 9 male power-lifters. Oxygen uptake (VO2) was measured directly and continuously and power output was deduced from film analysis using an inverse dynamic analysis. Power output and VO2 were significantly greater for squat than for stoop lifting at the same frequency. The mechanical efficiency (ME), defined as Pm divided by the energy equivalence of VO2, increased from 12% at rate 10 to 18.5% at rate 20, but there was no significant difference between the two techniques. The effectiveness (EF), defined as the productive external power output (only work done on the barbell) divided by the energy equivalence of VO2, was significantly higher for the stoop lift than for the squat lift. EF is judged as a more useful measure than ME for characterizing the relative energy cost of a lifting task.

Dynamic comparison of the two-hand stoop and assisted one-hand lift methods

Low-back pain arising from repetitive lifting of objects out of deep containers is a significant problem in many industries and results in a great deal of time lost from work. This study measured electromyographic (EMG) activity of the lumbar paraspinal cles, vertical acceleration of three different loads, and the reaction force of the supporting upper extremity to compare the assisted one-hand lift and the two-hand stoop lift techniques. The results of the study indicate thatmus the assisted one-hand lift requires significantly less EMG activity than the two-hand stoop method when lifting loads out of deep containers. The acceleration of the load was not significantly different for three different loads, but the force on the supporting upper extremity was significantly related to the weight of the load lifted. Results of this study seem to indicate that, under certain circumstances, the one-hand lift is a less stressful method of lifting than the two-hand stoop method.

Spinal loading in static and dynamic postures: EMG and intra-abdominal pressure study.

Abstract The difference in physiological stress between static posture loading and dynamic lift is poorly understood. Therefore, the quantitative pattern of gradual increase and decrease of stress as measured by EMG of erectores spinae at T12 and L3 and intraabdominal pressure (IAP) due to steady progressive loading and unloading in static stooping posture was studied and compared with that of stoop lifting of the same weight. For dynamic loading and unloading a steady flow of 25 kg of water into or out of a plastic tub held in the hand while maintaining a stooping posture was used. The subjects also performed stoop lifting weights of 15 and 25 kg. In static posture loading the mean EMG at T12 was approximately 50% of the L3 level. During unloading in that posture it was reduced to 33%. The level of electromyographic activity at T12 for loading was not significantly different from unloading. At L3 however, the magnitude increased significantly for unloading. The EMG and intraabdominal pressure responses o...

Dynamic Factors in the Analysis of Stoop and Crouch Lifting Methods: A Methodological Approach to the Development of Safe Materials Handling Standards

Dynamic Factors in the Analysis of Stoop and Crouch Lifting Methods: A Methodological Approach to the Development of Safe Materials Handling Standards