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Health & Exercise Forum


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Mar 8, 2009

Dr. Paul MackareyGuest Columnist: Janet M. Caputo, PT, OCS

Ergonomics is the process of changing your environment to encourage good body mechanics. This can be accomplished by a modifying a tool, work station, counter height, task, or job.

Performing tasks within the best work zones encourages safety and decreases risk of injury through facilitating neutral spine postures.

Best work zone

  • As far forward as your wrist when elbows are at the sides and bent to ninety degrees.
  • As wide as the shoulders
  • As high as heart height
  • As low as waist height
  • Perform heavy lifting tasks in this zone

There are four major risk factors for developing a musculoskeletal injury:

  • Force: The amount of physical effort required to form a task.
  • Repetition: Performing the same motion or series of motions continually or frequently for an extended period of time.
  • Awkward or static postures: Assuming positions that place stress on the body such as prolonged or repetitive reaching above shoulder height, kneeling, squatting, leaning, twisting, and using tools with wrists bent.
  • Contact stress: Pressing the body or part of the body (such as the hand) against hard or sharp edges or using the hand as a hammer.

Whether certain activities increase risk of injury, depends on the duration (how long), frequency (how often), and magnitude (how intense) of the exposure to the above mentioned risk factors.

General ergonomic guidelines

  • Posture: Keep elbows close to your body. Keep work at about elbow height. Avoid working with the hands/wrists held in a bent or twisted position. Keep the hands straight and in line with the forearms. Avoid working with wrists pressed against hard or sharp objects.
  • Grasping: When grasping an object, use a power grip (wrap all fingers and thumb around object; make a fist around the object) not a pinch grasp. If the object is heavy or bulky, use a two-handed power grip.
  • Standing: Provide toe space to allow individual to get close to work. This will reduce leaning and reaching. Stand on anti-fatigue mats rather than on bare floors. Work left to right rather than front to back to reduce leaning and reaching.
  • Lifting: Whether a particular lift will require assistance depends on: the weight/size of the object, how frequently the object is lifted, how close the object is to the ground, how high it must be lifted, how far it must be carried, and whether it has handles. Assistance can include a dolly, a cart, or help from another individual. Avoid reaching and twisting with lifting by ensuring adequate room for lifting tasks.
  • Carrying: Use bags with handles and boxes with hand holes. Use carts to transport heavy or multiple items. Carts with larger wheels are easier to push.
  • Kneeling: Use knee pads. Use a kneeler or stool when working at low levels for prolonged periods.
  • Storage: The heaviest and most frequently used items should be stored at waist height. Use smaller containers to reduce the weight that must be handled.
  • Tools: Lightweight, short handled tools reduce stress on the wrist and hand.
  • Equipment maintenance: Keep cart wheels well maintained. Wheels that are in poor condition make cart difficult to push. Keep blades sharp. Dull tools require more force.

Changing bad posture, poor body mechanics, and poor ergonomics is not easy. It takes time to think about using proper body mechanics to prevent injury. The key is perseverance! And remember, practice good body mechanics and ergonomics at all times, not just when you are in pain or recovering from an injury.