Ergonomic Guidelines

Understanding the Hazards

There are 3 main risk factors that can contribute to MSD’s in material handling tasks. They are:

Risk Factors

Force
  • Refers to the amount of effort made by the muscles and the amount of pressure on a body part.
  • All work tasks require some level of force, however if the required force is higher than the capability of the muscle, it can damage muscles or associated tendons, ligaments, and joints.
  • Injury can occur from a single action that requires a very high level of force or more commonly, occurs due to moderate to high forces generated over long duration, and is more likely when the body is in an awkward posture.

Static or awkward postures
  • Is the position of the joints of the body during an activity.
  • “Neutral posture” is when the joints are working near the middle of their normal range of motion.
  • MSD injuries can occur when the joint is not in “neutral posture”, when the joint moves toward the end of the normal range of motion.
  • The more awkward the posture, the more strain on the joints, ligaments, discs (in the spine) and muscles, and the higher the risk of injury.
  • A “fixed posture” refers to staying in the same position for a long period of time, and injuries occur as the tissue fatigues while exerting effort to maintain the posture.

Repetition
  • The risk of MSD increases when the same body parts are used repeatedly with few breaks or chances for rest.
  • High repetition can lead to fatigue and microscopic tissue damage. If no recuperation of the tissues is allowed through rest or task rotation, injury can occur.
  • Rest allows specific body parts to recuperate.
  • If the posture is awkward, fatigue occurs much more quickly.

Look for activities in your work that may include these hazards, such as,

  • Sitting or standing still for long periods of time
  • Repetitive and/or heavy lifting
  • Frequent twisting of the back or neck
  • Elevation of the shoulders and arm

Often, low-cost simple solutions can be used to correct these risk factors, like re-arranging storage shelves, changing the height of work surfaces, or re-organizing tasks to reduce unnecessary manual material handling.

Signs and Symptoms

Early identification of musculoskeletal disorders (MSDs) is the key to prevention and resolution. Some common signs and symptoms of MSDs may include, but are not limited to,

  • swelling
  • redness
  • reduced range of motion
  • reduced strength
  • pain
  • numbness
  • tingling or burning
  • fatigue
  • stiffness

If any symptoms are experienced, try to identify the cause. Ask yourself,

  • Are there any tasks I do repetitively or with high force?
  • Are there any postures or positions I am in for long periods of time?
  • Have I begun any new activities or tasks?
  • Are there any activities outside my job that may be contributing (playing sports, poor sleep)?

Stages of MSD Progression

Stage 1

  • experiencing some signs and symptoms or discomfort
  • job performance is not affected
  • discomfort goes away with rest

Stage 2

  • more frequent signs and symptoms are experienced  during and away from work
  • job performance may be affected
  • signs and symptoms do not completely go away with rest

Stage 3

  • constant signs and symptoms
  • unable to perform job
  • risk of permanent injury

MSD identification and intervention in stages 1 and 2 are vital to avoiding permanent issues. Good ergonomic practices help to prevent the development or worsening of MSDs. Additional benefits include improved comfort, job performance, productivity, and morale.