Lecture 7a: Sit/Stand Ergonomics & Workstation Design

Question 1

the spine

Answer 1

• provides flexibility and support
• cervical and lumbar are mobile
• thoracic relatively immobile
• 3 curves in the spine
• vertebral bodies support weight
• vertebral spine for muscle attachment

Question 2

why do humans have lordotic-shaped spines?

Answer 2

• necessary for bipedal gait
• allows more mass to be centred anteriorly over the pelvis (energy-efficient gait)
• reduces pressure between vertebrae

Question 3

thigh posture and lumbar curve

Answer 3

• when the thigh angle goes from 135-90 degrees it causes the lumbar spine to flatten
• sitting changes the curvature of the lumbar spine

Question 4

advantages of sitting

Answer 4

• reduced energy consumption
• better for circulation
• reduces stress on lower extremities
• better for fine control
• increased stability
• reduces hydrostatic pressure on limbs

Question 5

risk factors of prolonged sitting

Answer 5

• low back pain
• disc herniation
• disc degeneration
• spondylolisthesis

Question 6

viscoelastic creep

Answer 6

time-dependent increase in strain

can occur in spine discs with prolonged sitting

Question 7

disadvantages of sitting

Answer 7

-restricted mobility
- not suitable for producing large forces
- vibrating spaces are dangerous when seated
- promotes abdominal weakness
- induces an abnormal spinal curve
- compresses internal organs

Question 8

sit - stand ratios

Answer 8

3:1

• decreases lower back pain
• cyclic loading

Question 9

lumbar spine movement promotes:

Answer 9

• improved disc nutrition
• disc pressure flucuations
• spine creep recovery
• varied muscle activity
• reduced muscle fatigue
• increased blood flow to muscles