4.3 Stance and Refinement

Question 1

Why is independent stance more difficult than sitting?

Answer 1

Requires finer balance within smaller stability limits, more joints to control (legs, thighs, trunk, head), and recalibration of sensory + motor systems.

Question 2

By what age can infants generate forces exceeding body weight? What does this show?

Answer 2

By ~6 months; muscle strength isn’t the limiting factor, sensory integration and postural control are.

Question 3

Which system contributes earlier to standing posture: vision or somatosensory?

Answer 3

Vision maps onto posture control by ~5–6 months, earlier than somatosensory.

Question 4

What is the ‘rate-limiting factor’ in postural development?

Answer 4

The slowest maturing sensory/motor system needed for balance.

Question 5

Why do children sway more than adults during stance?

Answer 5

They are ‘top heavy’ (center of mass ~T12) and shorter, leading to faster sway velocities.

Question 6

At what age do structural growth factors (height, mass) stop correlating with sway?

Answer 6

Around 7 years, signaling maturation of postural control mechanisms.

Question 7

How do muscle responses refine with age?

Answer 7

Faster onset, better timing/amplitude, less variability → improved stability.

Question 8

How do toddlers (15 mo) compare to older kids in postural responses?

Answer 8

Toddlers: slow, variable responses. By 7–10 years: adult-like responses. Ages 4–6: temporary regression with slower/more variable responses.

Question 9

When does balance control shift from vision-dominant to somatosensory-dominant?

Answer 9

Around 3 years old.

Question 10

What happens to sensory adaptation abilities by age 7+?

Answer 10

Children adapt better to conflicting sensory inputs and handle dual tasks more effectively.

Question 11

When do anticipatory postural adjustments begin to appear?

Answer 11

By ~10 months (postural muscles activate before voluntary arm movements). Fully mature by ~4–6 years.

Question 12

When do children struggle most with vestibular-only balance?

Answer 12

Before 7–8 years; they cannot rely well on vestibular input when other senses are inaccurate.

Question 13

Until what age does postural control continue refining?

Answer 13

Through adolescence, up to ~14 years.

Question 14

What do dual-task studies show about posture + cognition?

Answer 14

Younger children sacrifice cognitive performance; older children and adults maintain it, as postural control becomes more automatic with age.