Low-back disorders (LBDs) are the leading cause of lost work days and the most costly occupational safety and health problem facing industry today. The nature of industrial MMH has been rapidly changing from lifting to push-pull exertions. Epidemiological studies identify pushing and pulling as a major LBD risk factor, i.e. 20% of injuries. Unfortunately, little is known regarding biomechanics risks of industrial pushing tasksBiomechanical risk of LBD includes components of spinal load, spinal stability and material tolerances such as disc and vertebral fracture limits. Preliminary calculations suggest spinal stability is severely limited during pushing exertions thereby requiring increased muscle co-contraction. Co-contraction is known to increase spinal loads. Moreover, push forces are expected to introduce increased risk from spinal shear forces. Few published studies have examined spinal load during pushing exertions, NONE have considered the influence of coactivation, few have considered shear load and NONE have considered spinal stability. The goal of this effort is to quantify the biomechanical risk factors imposed by pushing tasksWe will perform a multi-institutional biomechanical analyses of pushing exertions including in-vivo assessment of spinal compression, spinal shear force and spinal stability.
In Specific Aim #1 we will calibrate the EMG-assisted model of spinal load to permit analysis of pushing exertions. Preliminary data indicate large increases in trunk muscle co-contraction during pushing versus lifting tasks. This model accounts for trunk muscle co-contraction in the determination of spinal load and permits estimation of spinal shear force. The calibration and validation procedure will include experimental comparison of trunk flexion versus extension exertions. Increased co-contraction indicates the pushing tasks are associated with reduced spinal stability.
In Specific Aim #2 we will calibrate and further develop the spinal stability model to permit analyses of pushing exertions including assessment of dynamic stability. This process will include experimental measurement of trunk kinematics, kinetics and EMG following sudden perturbations in both flexion and extension moment conditions.
In Specific Aim #3 we will evaluate the influence of workplace factors on spinal compression, shear force and stability. Experimental will record the influence of push force and handle height on spine biomechanics. In a second experiment we will examine how handle stability influences biomechanical risk. A third experiment will evaluate the influence of exertion dynamics on biomechanical risk, i.e. the influence of the inertial mass of the pushed object, the velocity of movement, and compare the spinal loads and stability of pushing a cart versus pushing an overhead lift-assist device.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR049923-04
Application #
6779833
Study Section
Special Emphasis Panel (ZOH1-PCM (04))
Program Officer
Panagis, James S
Project Start
2002-09-15
Project End
2006-07-31
Budget Start
2004-08-01
Budget End
2005-07-31
Support Year
4
Fiscal Year
2004
Total Cost
$332,152
Indirect Cost
Name
Virginia Polytechnic Institute and State University
Department
Engineering (All Types)
Type
Schools of Engineering
DUNS #
003137015
City
Blacksburg
State
VA
Country
United States
Zip Code
24061
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Lee, HyunWook; Granata, Kevin P (2008) Process stationarity and reliability of trunk postural stability. Clin Biomech (Bristol, Avon) 23:735-42
Lee, HyunWook; Granata, Kevin P; Madigan, Michael L (2008) Effects of trunk exertion force and direction on postural control of the trunk during unstable sitting. Clin Biomech (Bristol, Avon) 23:505-9
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Lee, Patrick J; Rogers, Ellen L; Granata, Kevin P (2006) Active trunk stiffness increases with co-contraction. J Electromyogr Kinesiol 16:51-7
Granata, Kevin R; Bennett, Bradford C (2005) Low-back biomechanics and static stability during isometric pushing. Hum Factors 47:536-49
Granata, Kevin P; Lee, Patrick E; Franklin, Timothy C (2005) Co-contraction recruitment and spinal load during isometric trunk flexion and extension. Clin Biomech (Bristol, Avon) 20:1029-37
Moorhouse, Kevin M; Granata, Kevin P (2005) Trunk stiffness and dynamics during active extension exertions. J Biomech 38:2000-7