Basics of Musculoskeletal Disorders (MSDs) - Health and Safety

Musculoskeletal Disorders (MSDs) refer to conditions of injury or discomfort that may occur acutely or develop over time, and can affect muscles, tendons, ligaments, joints, and nerves. Common examples of MSDs include carpal tunnel syndrome, tendinitis, muscle strains, and low back injuries.

Understanding the Hazards

There are 3 main risk factors that can contribute to MSDs, including:

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 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, spinal discs, 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.

Monitor for activities in your work that may contribute to these risk factors. Common examples include,

Sitting for long periods of time
Repetitive and/or heavy lifting
Frequent or static twisting of the back or neck
Repetitive or constant elevation of the shoulders and arms

These MSD risk factors can often be reduced using low-cost options such as rearranging a workstation or changing work practices.

Signs and Symptoms

Early identification of MSDs is key to prevention and recovery. Some common signs and symptoms of MSDs may include,

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

If any of these symptoms are experienced, try to identify the cause and implement controls. 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, or recently changed anything else?
Are there any activities or injuries outside of my job that may be contributing (playing sports, poor sleep)?

Stages of MSD Progression

Stage 1	Stage 2	Stage 3
experiencing some signs and symptoms or discomfort job performance is not affected discomfort goes away with rest	frequent signs and symptoms during and away from work job performance may be affected or hindered signs and symptoms do not completely go away with rest	constant signs and symptoms unable to perform job risk of permanent injury

Intervention in stages 1 and 2 is vital to avoiding long-term, permanent, or debilitating issues. Good ergonomic practices help to prevent the development or worsening of MSDs. Additional benefits include improved comfort, job performance, productivity, and morale.

Last Revised: April 15, 2025