Comparison of Spinal Loads in Kneeling and Standing Postures during Manual Materials Handling

2005 ◽  
Vol 49 (14) ◽  
pp. 1320-1324
Author(s):  
Gang Yang ◽  
Riley Splittstoesser ◽  
Gregory Knapik ◽  
David Trippany ◽  
Sahika Vatan Korkmaz ◽  
...  
Keyword(s):  
Biomechanical Model ◽  
Job Design ◽  
Low Back ◽  
Spinal Loading ◽  
Materials Handling ◽  
Spinal Loads ◽  
Increased Risk ◽  
Manual Materials Handling ◽  
Free Dynamic ◽  
Anterior Posterior

Kneeling in a restricted posture during manual materials handling has been associated with increased risk of low back pain. Little is known about the effect of kneeling posture on spinal loads. The purpose of this study was to compare differences in spinal loading between kneeling and standing postures for lifting tasks. Twelve subjects asymmetrically lifted luggage of three weights to three heights from floor while kneeling. Three subjects also performed the same tasks from waist height while standing. An adapted free-dynamic EMG-assisted biomechanical model was used to calculate spinal loads. Statistical analysis showed that there was no difference in compression between kneeling and standing (p=0.9605), but kneeling resulted in increased anterior-posterior and lateral shear forces on the lumbar spine (p =0.0002 and p<0.0001, respectively). Spinal loading changes while kneeling in a restricted posture may increase the risk of low back injury and must be considered in ergonomic job design.

Quantifying the Precision of Biomechanical Calculations using Experimental Data

1987 ◽  
Vol 31 (3) ◽  
pp. 315-317
Author(s):  
M. Tracy ◽  
E.N. Corlett
Keyword(s):  
Standard Deviation ◽  
Biomechanical Model ◽  
Abdominal Pressure ◽  
Low Back ◽  
Mean Values ◽  
Materials Handling ◽  
Optical Scanner ◽  
Number Of Factors ◽  
Manual Materials Handling ◽  
On Line

Biomechanical calculations are a useful tool to evaluate the severity of manual materials handling tasks. The exactness of the calculated forces depends on a number of factors. On one level is the precision of the inputs such as postural data and the force exerted by the operator. At another level is the exactitude of the biomechanical model itself. The effect of the imprecision of each factor upon the final result can be calculated so that on one hand, the range of values within which the final result is likely to fall is known, and on the other hand, the importance of each factor can be assessed, by comparing the standard deviation of one or more factors with the standard deviation of the result. Calculations of forces on the low back have been carried out in the laboratory using an optical scanner (CODA-3) to record posture on-line to a computer, as well as a handle equipped with strain gauges to record the force exerted. The program automatically carries out biomechanical calculations from these inputs. It takes into account the uncertainties on muscle lever arms and intra-abdominal pressure, using mean values for these and estimating the confidence limits within which the calculated low-back forces will lie, given the variance of one or more of the inputs.

scholarly journals Trunk Posture during Manual Materials Handling of Beer Kegs

2021 ◽  
Vol 18 (14) ◽  
pp. 7380
Author(s):  
Colleen Brents ◽  
Molly Hischke ◽  
Raoul Reiser ◽  
John Rosecrance
Keyword(s):  
Small Businesses ◽  
Inertial Measurement Unit ◽  
Measurement Unit ◽  
Low Back ◽  
Inertial Measurement ◽  
Materials Handling ◽  
Kinematic Measurement ◽  
Manual Materials Handling ◽  
Trunk Posture ◽  
Data Design

Craft brewing is a rapidly growing industry in the U.S. Most craft breweries are small businesses with few resources for robotic or other mechanical-assisted equipment, requiring work to be performed manually by employees. Craft brewery workers frequently handle stainless steel half-barrel kegs, which weigh between 13.5 kg (29.7 lbs.) empty and 72.8 kg (161.5 lbs.) full. Moving kegs may be associated with low back pain and even injury. In the present study, researchers performed a quantitative assessment of trunk postures using an inertial measurement unit (IMU)-based kinematic measurement system while workers lifted kegs at a craft brewery. Results of this field-based study indicated that during keg handling, craft brewery workers exhibited awkward and non-neutral trunk postures. Based on the results of the posture data, design recommendations were identified to reduce the hazardous exposure for musculoskeletal disorders among craft brewery workers.

The Effect of Lifting vs. Lowering on Spinal Loading

1996 ◽  
Vol 40 (13) ◽  
pp. 599-603 ◽  
Author(s):  
Kermit G. Davis
Keyword(s):  
Muscle Activity ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Muscle Forces ◽  
Shear Forces ◽  
Spinal Loading ◽  
Spinal Loads ◽  
Trunk Strength ◽  
Anterior Posterior ◽  
Three Dimensional Space

In industry, workers perform tasks requiring both lifting and lowering. During concentric lifting, the muscles are shortening as the force is being generated. Conversely, the muscle lengthens while generating force during eccentric lowering. While research on various lifting tasks is extensive, there has been limited research performed to evaluate the lowering tasks. Most of the research that does exist on lowering has investigated muscle activity and trunk strength. None of these studies have investigated spinal loading. The current study estimated the effects of lifting and lowering on spinal loads and predicted moments imposed on the spine. Ten subjects performed both eccentric and concentric lifts under sagittally symmetric conditions. The tasks were performed under isokinetic trunk velocities of 5, 10, 20, 40, and 80 deg/s while holding a box with weights of 9.1, 18.2, and 27.3 kg. Spinal loads and predicted moments in three dimensional space were estimated by an EMG-assisted model which has been adjusted to incorporate the artifacts of eccentric lifting. Eccentric strength was found to be 56 percent greater than during concentric lifting. The lowering tasks produced significantly higher compression forces but lower anterior-posterior shear forces than the concentric lifting tasks. The differences in the spinal loads between the two lifting tasks were attributed to the internal muscle forces and unequal moments resulting from differences in the lifting path of the box. Thus, the differences between the lifting tasks resulted from different lifting styles associated with eccentric and concentric movements

Co-Contraction Recruitment and Spinal Load during Isometric Pushing Tasks

2005 ◽  
Vol 49 (14) ◽  
pp. 1330-1333 ◽  
Author(s):  
Kevin Granata ◽  
Patrick Lee ◽  
Tim Franklin
Keyword(s):  
Biomechanical Model ◽  
Neuromuscular Control ◽  
Surface Emg ◽  
Trunk Flexion ◽  
Materials Handling ◽  
Manual Materials Handling ◽  
Muscle Groups ◽  
Spinal Load ◽  
Theoretical Analyses ◽  
Flexion And Extension

Pushing and pulling tasks account for 20% of occupational low-back injury claims but few studies have investigated the neuromuscular control of the spine during these tasks. Primary torso muscle groups recruited during pushing tasks include the rectus abdominis and external obliques. However, theoretical analyses suggest that co-contraction of the paraspinal muscles is necessary to stabilize the spine during flexion exertions. A biomechanical model was implemented to estimate co-contraction and spinal load from measured surface EMG and trunk moment data recorded during trunk flexion and extension exertions. Results demonstrate that co-contraction during flexion exertions was approximately twice the value of co-contraction during extension. Co-contraction accounted for up to 47% of the total spinal load during flexion exertions and spinal load attributed to co-contraction was nearly 50% greater during flexion than during extension exertions despite similar levels of trunk moment. Results underscore the need to consider neuromuscular recruitment when evaluating biomechanical risks. Keywords: Spine; Co-contraction; Push; Manual Materials Handling; Biomechanics

Three-Dimensional Spinal Loading during Complex Lifting Tasks

1996 ◽  
Vol 40 (13) ◽  
pp. 661-665
Author(s):  
Fadi A. Fathallah ◽  
William S. Marras ◽  
Mohamad Parnianpour
Keyword(s):  
Three Dimensional ◽  
Comprehensive Treatment ◽  
Shear Forces ◽  
Spinal Loading ◽  
Materials Handling ◽  
Spinal Loads ◽  
Loading Patterns ◽  
Temporal Occurrence ◽  
Asymmetric Lifting

Knowledge of the complex three-dimensional loads imposed on the spine during typical manual materials handling (MMH) tasks could provide more insights about the mechanical etiology of low back injuries in occupational settings. Comprehensive treatment of such information has been lacking. Most previous studies quantified spinal loading in terms of compressive forces alone. However, there is enough empirical and epidemiological evidence to indicate that the shear forces imposed on the spine may be more important than mere compression. Hence, the purpose of this study was to assess, in-vivo, the three-dimensional complex spinal loading associated with lifting tasks. Subjects performed simulated lifting tasks with varying workplace characteristic. An EMG-assisted model provided the continuous three-dimensional spinal loads. Asymmetric (complex) lifting tasks showed distinctive loading patterns from those observed under symmetric conditions. Simultaneous occurrences of spinal loads in all three directions (compression and shear forces) were patterns unique under the “risky” asymmetric lifting conditions. These situations could be identified and abated through proper workplace design. In conclusion, this approach allow the determination of the magnitudes and temporal occurrence(s) of complex spinal loading, and assess the sensitivity of these loading patterns to workplace characteristics.

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