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Reducing MSD's through Ergonomics

Musculoskeletal Disorders or MSDs are injuries and disorders that affect the human body’s movement or musculoskeletal system (i.e. muscles, tendons, ligaments, nerves, discs, blood vessels, etc.).


There are three primary ergonomic risk factors: HIGH TASK REPETITION, FORCEFUL EXERTIONS, REPETITIVE / SUSTAINED AWKWARD POSTURES.


The primary occupational risk factors for MSDs include:


Repetition: Repetition rate is defined as the average number of movements or exertions performed by a joint or a body link within a unit of time. 5 Repeated identical or similar motions performed over a period of time could cause over-extension and overuse of certain muscle groups, which could lead to muscular fatigue. Interestingly, symptoms often relate not to the tendon and muscle groups involved in repetitive motions, but to the stabilizing or antagonistic tendon and muscle groups used to position and stabilize the extremity in space.


Force: is the mechanical or physical effort to accomplish a specific movement or exertion.

mechanical stresses


Posture and positioning: profile factors such as torso twist, tipped shoulders, head tilt/rotation, raised elbows (either dominant , non-dominant, or both) and operating with hands close to the face are associated with increased risk of musculoskeletal symptoms.

Vibration, posture and positioning profile factors such as torso twist, tipped shoulders, head tilt/rotation, raised elbows (either dominant , non-dominant, or both) and operating with hands close to the face are associated with increased risk of musculoskeletal symptoms.


Cold temperature: Low temperatures reduce manual dexterity and accentuate nerve-end impairment


The individual worker also contribute to MDS injuries. Risk factors include: Poor work practices - Workers who use poor work practices, body mechanics and lifting techniques are introducing unnecessary risk factors that can contribute to MSDs. Individual risk factors include:

  • Poor work practices. Workers who use poor work practices, body mechanics and lifting techniques are introducing unnecessary risk factors that can contribute to MSDs. These poor practices create unnecessary stress on their bodies that increases fatigue and decreases their body’s ability to properly recover.

  • Poor overall health habits. Workers who smoke, drink excessively, are obese, or exhibit numerous other poor health habits are putting themselves at risk for not only musculoskeletal disorders, but also for other chronic diseases that will shorten their life and health span

  • Cold Temps - Low temperatures reduce manual dexterity and accentuate the symptoms of nerve-end impairment

  • Low temperatures reduce manual dexterity and accentuate the symptoms of nerve-end impairment

Extrinsic Stress: Extrinsic stress, or sometimes called organizational factors, can be defined as the way in which work is structured, supervised and processed. 4 Extrinsic stress reflects the objective nature of the work process. It may include such variables as job variety, job control, workload, time pressure, and financial constraints.


In general manufacturing, some studies show a relationship between extrinsic stress factors and a higher incidence of MSDs


Factors to reduce MSD's through three main controls:

  • Ergonomic Controls: Engineering controls eliminate/reduce awkward postures

  • PPE: Provide PPE to minimize the risk.

  • Administrative Controls: Administrative controls establish processes and procedures that can reduce injury risk including job rotation, Team stretching exercises, proper training for material handling/use devices

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