3.2 Body Mechanics

Body mechanics involve the coordinated effort of muscles, bones, and the nervous system to maintain balance, posture, and alignment during moving, transferring, and positioning patients. Proper body mechanics allows individuals to carry out activities without excessive use of energy, and it helps prevent injuries for patients and health care providers (Perry, Potter, & Ostendorf, 2018).

Musculoskeletal Injuries

A musculoskeletal injury (MSI) is an injury or disorder of the muscles, tendons, ligaments, joints or nerves, blood vessels, or related soft tissue including sprains, strains, or inflammation related to a work injury. MSIs are the most common health hazard for healthcare providers (WorkSafeBC, 2013). Table 3.1 lists risk factors that contribute to MSI.

When healthcare providers are exposed to ergonomic risk factors, they become fatigued and risk musculoskeletal imbalance. Additional exposure related to individual risk factors puts healthcare providers at increased risk for MSI (WorkSafeBC, 2013). Preventing MSIs is achieved by understanding the elements of body mechanics; applying the principles of body mechanics to all work-related activities; understanding how to assess a patient’s ability to position or transfer; and learning safe handling transfers and positioning techniques.

Elements of Body Mechanics

Body movement requires coordinated muscle activity and neurological integration. It involves the basic elements of body alignment (posture), balance, and coordinated movement. Body alignment and posture bring body parts into position to promote optimal balance and body function. When the body is well aligned, whether standing, sitting, or lying, the strain on the joints, muscles, tendons, and ligaments is minimized (WorkSafeBC, 2013).

Body alignment is achieved by placing one body part in line with another body part in a vertical or horizontal line. Correct alignment contributes to body balance and decreases strain on muscle-skeletal structures. Without this balance, the risk of falls and injuries increases. In the language of body mechanics, the centre of gravity is the centre of the weight of an object or person. A lower centre of gravity increases stability. This can be achieved by bending the knees and bringing the centre of gravity closer to the base of support, keeping the back straight. A wide base of support is the foundation for stability and is achieved by placing feet a comfortable, shoulder-width distance apart. When a vertical line falls from the centre of gravity through the wide base of support, body balance is achieved. If the vertical line moves outside the base of support, the body will lose balance.

The diagram in Figure 3.1 demonstrates: (A) a well-aligned person whose balance is maintained and whose line of gravity falls within the base of support; (B) balance is not maintained when the line of gravity falls outside the base of support; and (C) balance is regained when the line of gravity falls within the base of support.

Principles of Body Mechanics

Table 3.2 describes the principles of body mechanics that should be applied during all patient-handling activities.

Table 3.2 Principles of Body Mechanics
Action		Principle
Assess the environment.		Assess the weight of the load before lifting, and determine if assistance is required.
Plan the move.		Plan the move; gather all supplies; and clear the area of obstacles.
Avoid stretching and twisting.		Avoid stretching, reaching, and twisting, which may place the line of gravity outside the base of support.
Ensure proper body stance.		Keep stance (feet) shoulder-width apart. Tighten abdominal, gluteal, and leg muscles in anticipation of the move. Stand-up straight to protect the back and provide balance.
Stand close to the object being moved.		Place the weight of the object being moved close to your centre of gravity for balance. Remain as  close to the person as possible when you are about to transfer. Use the long and strong muscles of arms and legs, not the back muscles.
Face direction of the movement.		Facing the direction prevents abnormal twisting of the spine.
Avoid lifting.		Turning, rolling, pivoting, and leverage requires less work than lifting. Do not lift if possible; use mechanical lifts as required. Encourage the patient to help as much as possible. Note: Many agencies have “no lift” policies.
Work at waist level.		Keep all work at waist level to avoid stooping. Raise the height of the bed or object if possible. Do not bend at the waist.
Reduce friction between surfaces.		Reduce friction between surfaces, so that less force is required to move the patient. Special sliding sheets can be used to ease patient transfers or positioning.
Bend the knees.		Bending the knees maintains your centre of gravity and lets the strong muscles of your legs do the lifting.
Push the object rather than pull it, and maintain continuous movement.		It is easier to push an object than to pull it. Less energy is required to keep an object moving than to stop and start it.
Use assistive devices.		Use assistive devices (gait belt, slider boards, mechanical lifts) as required to position patients and transfer them from one surface to another.
Work with others.		The person with the heaviest load should coordinate all the effort of the others involved in the handling technique.
Data sources: Berman & Snyder, 2016; Perry et al., 2018; Registered Nursing, n.d.; WorkSafeBC, 2013

Attributions

Figure 3.2 An illustration depicting how to transfer someone using the pivot method by BruceBlaus is used under a CC BY-SA 4.0 license.