Your Job and Low Back Pain: The Occupational Factors Affecting Your Health

A common misconception about work-related injury is that it only happens in jobs that require heavy manual labor, like construction and freight handling. The truth is that there are so many factors affecting the musculoskeletal system that nearly every occupation poses some risk of injury. The correlation between musculoskeletal disorders (MSDs) and the workplace is so significant that the National Institute for Occupational Safety and Health (NIOSH) devoted nearly 600 pages to examine the epidemiologic evidence of this relationship. According to the Bureau of Labor Statistics, most non-fatal injuries are a result of overexertion (pushing, pulling, lifting, holding, carrying, turning) and/or repetitive motion. These injuries occur in several body structures. Here we'll focus on the low back: what occupational factors contribute to the risk of low back injury?

The most frequently reported back injuries are strains, sprains, disc herniation, joint inflammation, contusions, and sciatic issues. Low back pain can be chronic or acute and may be felt in the lumbar, gluteal, upper leg, or sciatic regions. MSDs may originate in the muscle, ligament, joint, disc, or nerve. These injuries are not always the result of one specific incident; commonly, the body wears down from physical factors over time, creating weakness and vulnerability in the structures of the body. Activity at home contributes to this wearing; however, physical factors on the job make the most significant impact on structural health.

Specifically, back pain and injury from occupational stress are a result of different "forces" applied to the spine. These include bending (or rotation), compression (stress applied perpendicular to the spine), or shear force (stress applied parallel to spine.) The amount of stress imposed on the spine depends on the weight of the object lifted, how the worker handles his body, and how the spine moves during activity. Injury occurs when these factors create forces that surpass capabilities of the discs and supporting tissues recruited to counteract these movements.

NIOSH's study focused on 5 common factors that create these loading forces on the spine. They found significant associations between injury and all of the following occupational elements amongst many jobs:

• Heavy physical work - nursing, personal care, air transportation, construction, etc. This is the most obvious correlation between work and injury. Note that disc degeneration happens at an earlier age in people who engage in regular heavy physical work.


• Lifting and forceful movements - auto workers, electronics manufacturing, hospital employees, nursing aids, baggage handlers, manual materials handlers, etc. Industries that rank the highest in time-loss injuries here are nursing and personal care facilities.


• Bending and twisting (awkward postures) - jobs identified include those listed previously. These movements are closely related to sciatic pain symptoms and slipped discs, especially when combined with lifting.


• Whole body vibration (WBV) - bus drivers, tractor drivers, fork-lift operators, etc. These vibrations fatigue the tissues around the spine and may cause disc fiber strain and disc herniation amongst other problems. WBV may cause lower back instability that can make the body more prone to other injury.


• Static work postures - crane operators, etc. This is experienced in jobs where workers sustain cramped or inactive postures. It is found that disc pressure is greater in unsupported seated positions than in standing.

Looking at the factors contributing to back pain, it is clear that a huge variety of workers are incurring some kind of physical trauma every day. By compromising the structure of the body, not only is injury more likely, but also product damage and other costly consequences of time-loss MSDs. Understanding spinal loading can improve work conditions by allowing a true assessment of what can be done to minimize risk of injury. Whether this involves ergonomic restructuring, manual handling aids, safety training, or any other form of prevention, minimizing MSDs benefits both company and employee. For more information on self care to prevent injury on the job, see the article, "Preventing Injury in Manual Material Handling: Uncommon Common Sense."