Core Principles
What is body mechanics?
The proper use of the body to move, lift, carry, and perform tasks safely and efficiently to prevent injury.
What is your base of support?
The area between your feet that supports your body.
Name two common musculoskeletal injuries in healthcare.
Back strain
Herniated disc
Muscle strain
Tendonitis
What is ergonomics?
Designing work/tasks to fit the body to reduce strain and injury.
What is a synovial joint?
A freely movable joint with a fluid-filled capsule.
Name three reasons why good body mechanics are important.
Prevents injury
Reduces strain on muscles and joints
Protects patients
Increases efficiency
Reduces fatigue
Demonstration: Show a wide stance vs narrow stance and explain which is safer.
Wide stance = more stable
Narrow stance = less stable and easier to lose balance
What are repetitive stress injuries?
Injuries caused by repeated movements over time (e.g., carpal tunnel, tendonitis).
Give one example of poor posture you see in daily life.
Slouching
Looking down at phone
Leaning forward at desk
Name 2 examples of hinge joints.
Elbow, knee.
Demonstration: Show how to lift a box safely using your legs.
Bend knees
Keep back straight
Keep chest up
Hold object close
Lift with legs
Avoid twisting
Why does lowering your center of gravity help with balance?
Improves balance and stability; reduces risk of falling.
Scenario: A CNA lifts a patient repeatedly without bending knees. What injuries could occur?
Lower back strain, disc injury, muscle tear.
Demonstration: Show correct posture while sitting at a desk or using a phone.
Back straight
Shoulders relaxed
Feet flat
Screen at eye level
Demonstration: Act out a ball-and-socket joint movement.
Shoulder or hip — circular motion.
Why is twisting while lifting dangerous?
Twisting puts excessive stress on the spine and discs, increasing risk of muscle strain or herniated discs.
Scenario: You are helping a patient stand. How would you position yourself to avoid losing balance?
Feet shoulder-width apart
One foot slightly forward
Knees bent
Keep patient close
Avoid twisting
Demonstration: Show “safe pivot” when moving a patient instead of twisting the back.
Keep back straight
Turn entire body
Move feet
Do NOT twist spine
Scenario: You have a workstation with your monitor too low and supplies far away. How can you fix it?
Raise monitor to eye level
Move supplies within reach
Adjust chair height
Scenario: Describe which bones, joints, and muscles you use to pick up a backpack.
Bones: femur, tibia, spine
Joints: hip (ball-and-socket), knee (hinge)
Muscles: quadriceps, hamstrings, glutes
Scenario: You must carry a heavy backpack across the room. Describe 3 key body mechanics principles to follow.
Use both straps
Keep load close to body
Maintain upright posture
Bend knees if lifting from floor
What might happen if you lift a heavy object with your feet together and your back bent?
Loss of balance, increased spinal strain, higher risk of back injury.
List 4 strategies to prevent workplace injuries while lifting, reaching, or bending.
Bend knees
Keep load close
Ask for help
Adjust bed height
Use assistive devices
Avoid twisting
Explain why carrying a backpack on one shoulder is harmful.
Causes uneven weight distribution → shoulder, neck, and spine strain.
Why does greater joint mobility often mean less stability? Give an example.
More mobility = less stability (e.g., shoulder more flexible but easier to injure than elbow).