What would be the first thought to pop into your mind if you were asked to describe the leading cause of musculoskeletal injuries? If you answered "repetitive motion," that would be incorrect.
While repetitive motion and resulting injuries such as carpal tunnel syndrome garner much of the attention, it's overexertion that is exacting the heaviest toll on workers.
A recent study by the Liberty Mutual Group listed overexertion, defined as working beyond one's physical capabilities, as the overwhelmingly No. 1 cause of workplace injuries nationwide. The Liberty Mutual Workplace Safety Index -- compiled using Bureau of Labor Statistics (BLS) data, workers' compensation claims reported to the National Academy of Social Insurance and comp benefits paid by Liberty Mutual -- indicated that overexertion accounted for more than 25 percent of direct workers' comp costs paid in 1998.
The estimated cost of overexertion that year, $9.8 billion, was more than double the second-highest accident cause on the list, falls on the same level ($4.4 billion), and four times costlier than repetitive motion ($2.3 billion).
Several ergonomists interviewed believe overexertion warrants more attention in the workplace. The significance of BLS injury rates (overexertion caused 28 percent of nonfatal occupational injuries and illnesses involving lost workdays in 1998) and workers' comp costs alone indicate not enough is being done.
Additionally, because it may be impossible to factor in every individual's physiological makeup, there is a perception that overexertion will happen no matter what preventive steps a company takes. As a result, many employers are puzzled about how to reduce or prevent overexertion injuries, especially those involving the back, and conclude that there are few solutions, said Thomas R. Waters, Ph.D., CPE, chief of the Human Factors and Ergonomics Research Section at the National Institute for Occupational Safety and Health (NIOSH).
"They think that back pain is going to happen anyway, so it's probably not the job causing it but something else," said Waters, the primary author of the revised version of the NIOSH Lifting Equation. "A lot of companies don't want to accept the fact that it may be the work that's causing it."
Ergonomists, however, believe there are solutions to costly injuries resulting from overexertion. For starters, employers need to have a better understanding of why overexertion occurs. Then they can learn what steps to take to reduce or prevent its occurrence.
Why Overexertion Occurs
According to BLS, workplace overexertion is an event or an exposure that leads to an injury due to excessive physical effort such as lifting, pulling, pushing, turning, wielding, holding, carrying or throwing. Determining excessive physical effort for each worker is what makes overexertion such a tough problem to tackle, said Jeffrey E. Fernandez, Ph.D., CPE, PE, senior managing engineer for Exponent Failure Analysis Associates in Alexandria, Va. "Each person has a different point at which overexertion occurs."
An overexertion injury happens when a worker becomes fatigued or performs a job where the human body's capacity to complete the task was not sufficiently considered. Both can cause a mismatch between the physical capacity of workers and the physical demands of their jobs.
When muscles become fatigued, muscular capacity is reduced and puts a worker at risk for an overexertion injury, Waters said. Because about 60 percent of overexertion injuries affect the back, he adds, apparently not enough companies use engineering controls to reduce or eliminate tasks such as lifting.
"When the physical demands are too high, the risk of back pain goes way up," Waters said. "Whether you call it low-back pain or an overexertion injury, a lot of it can be prevented if companies will redesign their jobs."
Jobs often are redesigned because employers did not initially take into account physiological capabilities of workers, said Tycho Fredericks, Ph.D., associate professor of industrial and manufacturing engineering at Western Michigan University. If worker capacities are factored in, he added, the need to justify the cost of redesigning a job or a piece of equipment to remove ergonomic hazards is moot.
When a task is not ergonomically designed, workers become prime candidates for overexertion injuries such as a muscle strain in the back, shoulders or abdomen.
Workers also may become overexerted when asked to perform jobs in which they are not properly trained. For example, a worker who is asked to help with an unfamiliar job tries to pick up a 100-pound stack of machine parts and injures his back. An investigation may reveal that the worker did not read the job instruction sheet, which would have told him to make several lifts of less weight. In addition, workers often overestimate how much they can lift.
Many overexertion injuries occur during maintenance, construction and other nonroutine tasks because it often is not practical to design special equipment or tools for a one-time job.
When a company calls in ergonomist Robert O. Andres, Ph.D., CPE, to help with an overexertion problem, he first determines what types of strains and sprains are occurring. Andres, president of Ergonomic Engineering in Pelham, Mass., then looks at what workers were doing when the injuries occurred.
Are there obvious jobs that demand high levels of strength, such as those requiring lifting? If so, Andres recommends engineering controls such as mechanical lift assists, overhead hoists and other controls to improve positioning of products.
Another step would be to reduce the amount of weight lifted. The NIOSH Lifting Equation can help determine what part of a job is causing the problem, such as size of the load, vertical height of the lift, or the lift's frequency and duration. All factors are entered into the equation to determine a recommended weight limit for the job.
If high-strength jobs are not the problem, Andres will determine whether fatigue is a factor by asking workers what they do throughout their day, such as how often they take breaks. Short, more frequent breaks help prevent fatigue better than longer, less frequent breaks, he said. Persuading a company to take that advice, however, is not always easy.
"Quite often, you find in a production facility that, right away when you talk about doing a five-minute break every hour instead of waiting two hours for a 15-minute break, somebody can calculate exactly how many pieces of lost production you have over that five minutes," he said. "Given more frequent breaks, you can actually move production speed up a little bit and compensate. People become more productive if they're not fatigued."
When investigating an overexertion injury, ensure that complete information is recorded, said Fredericks, who also is director of the Human Performance Institute at Western Michigan.
"I've seen many accident reports that say nothing more than, 'Bob got hurt. Talked to Bob about the incident. Told Bob to be careful,'" he said. Instead, ask the injured worker for more helpful information. How many hours did Bob work that day? How much weight was he lifting? How many repetitions was he doing?
NIOSH's Waters said it's important to realize that successful intervention programs may result in increased injury rates initially because workers are encouraged to report all overexertion injuries instead of trying to "tough it out." The severity of injuries, however, will drop quickly, with lower injury rates soon to follow.
Even after a company has done all it can to eliminate overexertion, injuries still may occur. When a body suffers an overexertion injury, it experiences inflammation, explains Stephen A. Dawkins, M.D., MPH, BSHS, FACOEM, medical director of Caduceus Occupational Medicine in Hapeville, Ga. Inflammation results in soft-tissue swelling, limited range of motion or erythema (skin redness).
Dawkins recommends a three-step process to reduce inflammation:
1. Use anti-inflammatory medicine, such as Motrin, which chemically blocks inflammation. He cautions patients to not mistake anti-inflammatory medicine for a pain killer and stop using it when the pain goes away. When that happens, the inflammation will return.
2. Rest the injured body area through work restriction or time off.
3. Use minor physical therapy such as ice or heat.
If the worker does not respond to initial treatment, Dawkins may prescribe a stronger anti-inflammatory medicine. If the injury is isolated, like a shoulder tendon, a cortisone injection may be appropriate to accelerate healing. If the injury is in a broad area, such as pulled back muscles, a pill may be more effective.
Further treatment, Dawkins said, might include complete rest (i.e., no work); advanced physical therapy, such as time in a whirlpool; or a series of cortisone injections.
The last resort, after all other treatments have failed, would be surgery, most often seen with tendon injuries, Dawkins said. Surgery usually is not used for back injuries unless a bone or disc is involved, he added.
Workers should take preventive steps to reduce the occurrence of overexertion injuries. These steps should include exercise and proper work techniques.
Dawkins lists two types of exercises to prepare a worker for the workday. The first is warm-up exercises to increase the blood flow and prepare the body for vigorous work. The second is stretching exercises to maximize the range of motion for muscle groups or tendons. Long-term efforts should include exercises that strengthen the muscles.
Once muscles are loosened, workers should use proper task techniques. When lifting, for example, they should bend their knees, keep the back bowed in, align the vertebrae vertically, hold up their chin and keep their feet on a diagonal.
Avoid twisting the body, which can cause muscle strains. For example, a production line worker should rotate his or her body when moving a product instead of relying mostly on arm motions.
Because the U.S. population is aging, overexertion likely will continue to top the list of workplace injury causes. By taking steps to reduce the problem, employers will keep a handle on their workers' comp costs and injury rates, and fewer workers will have to suffer debilitating muscle injuries.