Musculoskeletal Disorder (MSD)

There are many hazards associated with musculoskeletal disorders including:

Awkward Postures  •  Static Postures  •  Force  •  Repetition  •  Vibration

Learn more about each of these hazards below and access tools and resources that can help you to minimize or eliminate the hazard.


Posture is a term used for the position of various parts of the body during an activity.

Awkward Postures

For most joints, a good or “neutral” posture means that the joints are being used near the middle of their full range of motion.

The further a joint moves towards either end of its range of motion, or the further away from neutral, the more awkward or poor the posture becomes and the more strain is put on the muscles, tendons and ligaments around the joint.

For example, when arms are fully outstretched, the elbow and shoulder joints are at the end of their range of motion.

If an individual pulls or lifts repeatedly in this position, there is a higher risk of injury.

Static Postures

Static postures are defined by those which are held for a long period of time and may result in fatigue and injury.

Oxygen is delivered to the muscles and joints by blood.
When a posture is held for a prolonged period of time there is a reduction in blood flow to the tissues.
This results in a reduction of nutrient and oxygen supply with lactic acid and other metabolites accumulating, which can  result in pain and tissue damage.

Researchers have found that even 30 degrees of forward shoulder flexion or abduction can cause a significant impairment in blood circulation within the shoulder / neck region.

Statically holding postures requiring greater than 50% of the body’s musculature to contract can result in increased muscular effort which can lead to muscle overload, decreased blood flow and increased pressure on muscles and joints.


Force refers to the amount of effort created by the muscles as well as the amount of pressure placed upon a body part.

All tasks require workers to use their muscles to exert some level of force, however, when a task requires them to exert a level that is too high for a particular muscle, it can damage the muscle or related tendons or joints and/or other soft tissue.

An example of a gripping task requiring high force application could be holding small instruments for a prolonged period of time.
This task is commonly performed with a pinched grip where the fingers are on one side of the object and the thumb is on the other.
This form of gripping is undesirable as it requires a much greater force application than a power grip (object in the palm of the hand).


Repetitive motions are extremely prevalent in many of today’s professions
(e.g. dental work, computer work, assembly work, etc.).

The risk of developing an MSD increases when same or similar parts of the body are used continuously, with few breaks or chances for rest.

Highly repetitive tasks can lead to fatigue, tissue damage, discomfort, and, eventually injury.
This can occur even if the level of force is low and the work postures are not awkward.

High usage of wrist and forearm musculature has been linked to an increased risk of fatigue and overuse.

Three critical components to consider include:


How many times an action is repeated (e.g. repetitive wrist motions, the number of related duties performed in a day, the number of tools/instruments gripped by one hand


How long an action is performed (e.g. length of time spent holding a tool/ instrument, length of time sitting in a static posture, the total length of a work day)

Recovery Time

The time which breaks a repetitive cycle (e.g. time between duties, scheduled breaks, time spent stretching, time in meetings, time spent performing other tasks, etc.)


Occupational vibration occurs when a person comes in direct contact with a vibrating source which transmits energy to the human body, typically through hands, feet, or buttock. The risk of injury is dependent upon the frequency and magnitude of the vibration, and the length of time a person is exposed to it.

There are two types of vibration: Whole Body Vibration (WBV) and Hand-Arm Vibration (HAV).

Hand-Arm Vibration Syndrome is transmitted to the hands and arms when working with or holding: hand-help power tools (I.e. jack hammer); hand-guided equipment (i.e. floor buffer, lawnmower); materials being processed by machines (i.e. pedestal grinder). Workers who are regularly exposed to HAV are at risk of damaging the soft tissues of the fingers, hands, and arms.

Whole Body Vibration is transmitted to a person typically through a seat or a platform. Common occupational sources include construction and mining vehicles, lift trucks, buses, and trucks. Studies have shown strong evidence that long-term exposure can result in increased risk of disorders to the lumbar spine (such as low back pain, herniated disc and early degeneration of the spine), neck and shoulders (


Manual Material Handling (MMH) is an important component of workplace ergonomics
as many of the actions involved can lead to musculoskeletal disorders (MSD).

Manual Materials Handling (MMH) refers to the moving or handling of items by:

Icon showing a figure lifting or lowering a box

Lifting or Lowering

Icon showing a figure pushing and pulling an object

Pushing or Pulling

Icon showing a figure walking while carrying an object


Icon depicting the action of holding or gripping and object

Holding or Gripping

Manual material handling is also the most common cause of occupational fatigue, low back pain and lower back injuries.

The following resources are related to manual material handling:

Physical Demands Description

A document used by employers to objectively capture and describe the physical demands that are required to perform a particular job or role.
A PDD can be used by a wide range of individuals within different organizations.

PDD Handbook
PDD Template

NIOSH Lifting Equation

An Online Tool for Calculating Recommended Weight Limit (RWL)

Online Tool
(on the CCOHS website)

Ergonomics and Manual Materials Handling

A Presentation by OHCOW Ergonomist, Melissa Statham, MHK, CCPE