by Daniel Matsushita
Ergonomics refers to the science of designing work to meet the needs of workers. The practice of ergonomics aims to reduce cognitive and physical demands, and by extension, the risk of injury or musculoskeletal disorders (MSDs). MSD is a term referring to discomfort or injuries to the human muscular and skeletal systems, including joints, ligaments, muscles, nerves, and tendons. Common examples of MSDs include carpal tunnel syndrome or epicondylitis (tennis elbow). MSDs may occur gradually (developing and worsening over time) or acutely (single occurrence causing injury, such as a back strain).
The importance of good ergonomic practices applies to all jobs. 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 to high forces generated over long duration and is more likely when the body is in an awkward posture.
Static or Awkward Postures
Refers to:
- 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
Refers to:
- 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 risk factors may present in combination. For example:
- Working at an office workstation may include sitting in a static position and sitting awkwardly if the equipment is not adjusted properly. Typing may constitute as a repetitive movement, and force may be required to lift the arms and reach the desk surface.
- Manual material handling tasks, such as moving supplies from one area to another, may include forceful and repetitive lifting and carrying movements. Awkward or static postures may present as lifting a box improperly or carrying an object in your arms.
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)?
The hierarchy of controls should be applied to potential MSD hazards:
- Elimination – the most effective control, removing the hazard entirely.
- Substitution – replacing a hazardous task or object with a safer alternative.
- Engineering controls – Isolating workers from hazard through physical means or new equipment.
- Administrative Controls – Changing how work is performed, implementing procedures, training, etc.
- Personal Protective Equipment – The least effective method of protection.
If you identify concerns or risks in your work, it is vital to share the issues with your direct supervisor and discuss controls to be implemented. Any injuries or discomfort should likewise be reported to your supervisor. Risk factors can often be reduced using low-cost options such as rearranging a workstation or changing work practices.
Trent’s Ergonomics program includes additional training, resources, and in-house ergonomics assessments. To learn more, contact healthandsafety@trentu.ca or visit the Ergonomics page on the Health and Safety website.