Trunk stability and spinal load during MMH lifting.
NIOSH 2001 Apr; :1-6
Occupationally related low back disorders (LBDs) are the leading cause of lost work days and the most costly occupational safety and health problem facing industry today. It is well known that LBD risk is associated with manual materials handling (MMH) and are influenced by MMH lifting parameters, specifically trunk posture and lifting task design. However, a major limitation in controlling the incidence of occupational LBDs is the inability to explain the injury mechanism to the lumbar spine (the most common type of injury). The scientific community has overlooked the influence of trunk and spinal stability as a cause of occupational LDD. When the trunk / spine is unstable, the tolerance to compressive forces on the spine is dramatically reduced. Therefore, an unstable spine may fail even if the applied load is a mere fraction of the recommended limits. The goals of this research were to evaluate whether the neuromuscular system attempts to control stability of the spine, and whether trunk posture during MMH lifting influences the stability of the spine. It was hypothesized that the risk of LBD in asymmetric and flexed postures is partially related to reduced spinal stability in these postures. Results confirmed that the neuromotor system actively modifies muscle recruitment patterns in response to stability requirements. Results also demonstrate the spine is less stable in assymetric postures. In trunk flexed postures, physiological constraints limit the ability to achieve spinal stability. Thus, the risk of LBDs may be related to spinal stability.
Back-injuries; Musculoskeletal-system; Musculoskeletal-system-disorders; Posture; Spine; Spinal-disorders; Spinal-stability; Muscular-disorders; Neuromuscular-system; Neuromuscular-system-disorders; Manual-lifting; Manual-materials-handling;
Author Keywords: Low-Back pain; Lifting; Stability; Muscle; Coactivation
Kevin P Granata, PhD, Motion Analysis and Motor Performance Laboratory, Kluge Children's Rehabilitation Center, University of Virginia, 2270 Ivy Road, Charlottesville, VA 22903
Final Grant Report
Disease and Injury: Low Back Disorders
National Institute for Occupational Safety and Health
Motion Analysis and Motor Performance Laboratory, Kluge Children's Rehabilitation Center, University of Virginia, Charlottesville VA