Breaking the cycle of repetitive strain injuries

Repetitive gripping, holding, bending, twisting, clenching, reaching all cause RSIs

Whether you work on an assembly line, at a computer, or even butchering meat, your job likely requires you to perform the same task or movement over and over again, which puts you at risk of developing a repetitive strain injury (RSI).

RSIs, also known as musculoskeletal disorders (MSDs), are serious workplace concerns that cause pain and suffering for many workers and are the most frequent type of lost-time injury and the single largest source of lost-time cost in Canada.

RSI causes

Many work tasks require repetitive movements. These can be particularly hazardous when they involve the same joints and muscle groups over and over, and when you perform the same motion too often, too quickly, and for too long. Gripping, holding, bending, twisting, clenching, and reaching are ordinary movements that we make naturally every day. What can make them hazardous is the continual repetition of the movements, especially when done in awkward or fixed positions or with excessive force.

Work involving movement repeated over and over is very tiring because you don’t have time to fully recover in the short periods between movements. Eventually it takes more effort to perform the same repetitive movements. When the work activity continues in spite of pain or fatigue, injuries can occur.

Work pace determines the amount of time available for rest and recovery of the body between cycles of a particular task. The faster the pace, the less time is available for rest and the higher the risk for developing RSI.

Stress levels also increase when you have no control over the timing and speed of work because of external factors like assembly line speed or quota systems. With higher stress levels comes muscle tension causing fatigue and, again, increased risk for RSI.

When you cannot control your own work speed, it goes against a natural human characteristic to work at varying rates at different times of the day.

The effects of force

Force is the amount of effort our bodies must use to move, lift objects, and use tools. More force equals more muscular effort, and consequently, a longer time is needed to recover between tasks. Because repetitive work, as a rule, does not allow sufficient time for recovery, these more forceful movements create fatigue much faster.

Although no one really knows when MSDs will develop, workers performing forceful movements are at risk.

Exerting force in certain fixed or awkward hand positions is particularly hazardous. Different hand positions will require different amounts of force, and in general, pinching and pressing require more effort. In addition, the weight and shape of tools or objects will add to the amount of force needed.

Tools that do not use the most neutral position of the wrist, elbow, and shoulder also substantially increase the force required.

RSI prevention

Prevention and control measures established with the participation of both employees and employers are most likely to be effective. These include providing a well-designed and comfortable workstation, adequate job design, training in proper lifting procedures, well-suited adjustable chairs, and scheduled breaks.

It’s important to eliminate hazards at the source.

Employers should focus on avoiding repetitive patterns of work through job design changes, such as mechanizing tasks, where possible. Additionally, structuring jobs so that workers can rotate between various tasks in which they do something completely different allows them to use different muscle groups.

When it isn’t practical to eliminate the repetitive patterns of work, a well-designed workstation that is adjusted to fit the worker’s body size and shape can help. Workers should be provided with appropriate, carefully maintained tools and equipment to reduce the force needed to complete tasks and prevent muscle strain.

Because RSIs develop slowly, workers should be trained to understand what causes these injuries, how best to prevent them, and how to recognize the early signs and symptoms. Workers need to know how to adjust workstations to fit their tasks and individual needs. Besides providing training, employers also should encourage employees to take short, frequent rest breaks to allow their muscles to relax and to consciously control muscle tension throughout the work shift.

RSIs can improve once the source is eliminated. However, if nothing is done to address the injury or remove its cause, the damage can become permanent.

This article was written by the Canadian Centre for Occupational Health and Safety (CCOHS), 135 Hunter St. E., Hamilton, Ont. L8N 1M5, 800-668-4284, www.ccohs.ca