The goal of this project is to identify how workplace factors (lifted load, posture) and gender influence the loading tolerance of the spine during lifting exertions. Spinal buckling tolerance describes the loading tolerance at the threshold of instability and subsequent tissue injury. Buckling tolerance is controlled by neuromuscular control of spinal stability. The proposed research is a continuation of R01 AR46111 where we demonstrated: 1) stiffness of active muscles and reflexes are both necessary to maintain spinal stability;and 2) these factors are influenced by trunk extension force, posture, and gender. These indicate that gender and workplace factors influence injury tolerance (stability and associated buckling tolerance). To understand how workplace factors influence spinal stability and buckling load we will complete three specific aims.
SPECIFIC AIM 1 will measure how reflex force and stiffness of active muscles are modified by load, posture and gender during voluntary trunk extension exertions to simulate manual materials handling / lifting tasks. These data will be used to calibrate a subject-specific biomechanical analysis of spinal buckling load (calibrated parameters of intrinsic muscle stiffness gain and reflex gain).
SPECIFIC AIM 2 will measure the torso kinetics, kinematics and EMG in separate dynamic lifting exertions to simulate low- risk and high-risk manual materials handling / lifting tasks. These data will be analyzed using the calibrated, subject-specific biomechanical analysis of stability to output buckling tolerance of the spine as a function of lifted load, posture and gender.
SPECIFIC AIM 3 will compare empirically measured torso stability with the data computed in specific Aim 2. Nonlinear dynamic analyses (Floquet multipliers) will be determined from data recorded during small torso disturbances applied during trunk extension exertions similar to conditions recorded in Specific Aim 2. The roles of intrinsic muscle stiffness and reflex contributes to spinal stability will be investigated separately. Effects of load, posture and gender will be examined. This research is designed to provide insight into the underlying pathophysiology of lifting-related musculoskeletal injury that can be used by ergonomic experts to investigate improved MMH task design and safer gender inclusion in the workplace.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
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Musculoskeletal Rehabilitation Sciences Study Section (MRS)
Program Officer
Panagis, James S
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Virginia Polytechnic Institute and State University
Engineering (All Types)
Schools of Engineering
United States
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Miller, Emily M; Bazrgari, Babak; Nussbaum, Maury A et al. (2013) Effects of exercise-induced low back pain on intrinsic trunk stiffness and paraspinal muscle reflexes. J Biomech 46:801-5
Miller, Emily M; Slota, Gregory P; Agnew, Michael J et al. (2010) Females exhibit shorter paraspinal reflex latencies than males in response to sudden trunk flexion perturbations. Clin Biomech (Bristol, Avon) 25:541-5
Groth, Kevin M; Granata, Kevin P (2008) The viscoelastic standard nonlinear solid model: predicting the response of the lumbar intervertebral disk to low-frequency vibrations. J Biomech Eng 130:031005
Granata, K P; Gottipati, P (2008) Fatigue influences the dynamic stability of the torso. Ergonomics 51:1258-71
Franklin, Timothy C; Granata, Kevin P; Madigan, Michael L et al. (2008) Linear time delay methods and stability analyses of the human spine. Effects of neuromuscular reflex response. IEEE Trans Neural Syst Rehabil Eng 16:353-9
Moorhouse, Kevin M; Granata, Kevin P (2007) Role of reflex dynamics in spinal stability: intrinsic muscle stiffness alone is insufficient for stability. J Biomech 40:1058-65
Granata, K P; Rogers, E (2007) Torso flexion modulates stiffness and reflex response. J Electromyogr Kinesiol 17:384-92
Franklin, Timothy C; Granata, Kevin P (2007) Role of reflex gain and reflex delay in spinal stability--a dynamic simulation. J Biomech 40:1762-7
Rogers, Ellen L; Granata, Kevin P (2006) Disturbed paraspinal reflex following prolonged flexion-relaxation and recovery. Spine (Phila Pa 1976) 31:839-45
Granata, Kevin P; England, Scott A (2006) Stability of dynamic trunk movement. Spine 31:E271-6

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