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• Office Ergonomics

  • Human
  • Task or Machine
  • Environment
• Basic Requirements of Office Ergonomics

  Meets anthropometric measures

  have a workstation and job tasks designed to allow a person to remain in a balanced position

  or neutral posture, regardless of the work being done.

  The CSA Standard Z412-17 Office ergonomics
•  The body position that has the highest strength to handle the pressure felt by the supporting structure, while causing the least amount of strain on the muscles, tendons, and ligaments, is called the neutral or balanced body position.
• Important factors in review of sitting work posture

  1. Anthropometry
  2. Biomechanics
• 1. Anthropometry measurements in sitting posture:

   The person sits erect and look straight ahead

   The sitting surface is adjusted so that the person’s thighs are parallel to the floor and the knees are bent to a 90 degrees angle with the feet fiat on the floor
• 1. Anthropometry measurements in sitting posture:

   The upper arm is relaxed and perpendicular to the horizontal plane, and the forearm is at a right angle to the upper arm and thus also parallel to the floor

   Measurement is sitting are made using a horizontal reference point, either the ground or the seat, and vertical reference pint in an imaginary line that touches the back of the uncompressed buttocks and shoulder blades of the subject.
•  When sit upright, approximately two thirds of body weight is distributed to the chair seat, with the backrest, armrest, and floor supporting the remainder.
• When sitting, the pressure fall on to the two small “sit bone” or ischia tuberosity.
• Depending on chair and posture, some proportion of total body weight is transferred to the floor via the seat pan and feet, armrests, and backrest.
• Musculoskeletal Network: Internal joint reaction forces in form of shear and compression when the body moves, like bending
• The sacrum is fixed to the pelvis, so rotational movement of the pelvis affects lumbar vertebrae.
• Forward rotation of the pelvis leads to increased lordosis of the lumber spine
• Backward rotation of the pelvis leads to increased flattening of the lumbar spine and eventually increases kyphosis
• Sitting with the straight spine puts additional pressure on the front of the spinal disks and creates additional strain on ligaments.
• A job design should allow the worker to work in a variety of balanced positions.
• Avoid an excessive range of movement by:

   providing all materials at working level

   positioning tasks within easy reach

   avoiding lifting and transferring loads while sitting
• Design the lighting system to:

   provide good general lighting.

   provide task lighting where necessary.

   avoid glare.
• Sit stand stools are used in workplaces to accommodate sitting and standing postures
• Mats do not seem to reduce lower leg fatigue (reduce discomfort in lower leg)
• Wearing of compression stockings reduces the leg swelling
• A workstation should allow the worker to sit in a balanced body position
• Lumbar forces Top is highest and bottom is lowest

  • Sitting relaxed
  • Relaxed, feet unsupported
  • Relaxed, arms supported
  • Straight
  • Standing at ease
• Lumbar forces Top is highest and bottom is lowest these are tasks while sitting

  • Lifting weight
  • Typewriting
  • arms hanging
  • Depression of pedal
  • Writing
  • relaxed
• -        Standing has less forces on the lumbar than the sitting positions

  -        This is because the pelvis having to move while sitting removes the curve causing it to be straight and causes compression
• -        When the feet are not supported it creates more load on the spine
• -        Kyphotic is the worst way to sit for you
• -        When you lean back on the chair the weight of your body is going to your chair instead of your spine and is the best way to sit
• -        As long as feet are not severely engaged in an activity it does not affect the spinal loading