Causes of MSIs

MSIs may be caused or aggravated at work by the following risk factors:

  • repetitive motions
  • forceful exertions
  • awkward or sustained postures
  • sustained pressure on hand, wrist, arm, leg, etc.
  • vibration
  • cold or wet working conditions
  • a machine-controlled work pace (e.g., assembly line)

Some risk factors can occur in leisure activities such as sports and hobbies. MSIs typically occur after weeks, months or years of overusing muscles, tendons and joints. Not all people will be affected in the same way and some will notice problems sooner than others. They usually develop slowly, but sudden events, such as a slip or fall, may also cause an injury to the musculoskeletal system.

Initially MSIs may only last a short time, but repeated overuse can lead to a long term, chronic injury. In some cases the first symptoms may occur at home after waking from sleep. They may even awaken you from sleep.

What are the symptoms of MSIs?

The physical effects of MSIs range from minor discomfort to disability. Symptoms are not always confined to the injury site. Pain is the most common symptom. Other symptoms include:

  • numbness or burning
  • feeling feeling of “pins and needles”
  • joint stiffness
  • muscle weakness or tightness
  • redness or swelling
  • other skin colour changes
  • tired feeling in the MSI area
  • difficulty grasping/holding objects

Always report a suspected MSI to a supervisor and your doctor right away!

MSIs often progress in three stages:

  1. Early Stage: The body hurts or feels tired at work. Symptoms do not interfere with the ability to work and cease away from work.
  2. Intermediate Stage: The injured area hurts or feels weak from the start until well after work has ended. Work is more difficult.
  3. Late Stage: The injured area hurts or feels weak even at rest. Sleep may be affected. At this stage the injury may not heal completely.

Not everyone goes through these stages in the same way. It may be difficult to say when one stage ends and the next begins.