9.4 Kinematics- Sagittal

Question 1

Where is the body’s center of mass located in an adult?

Answer 1

Just anterior to the S2 vertebra.

Question 2

In which plane do the largest and easiest-to-measure gait movements occur?

Answer 2

The sagittal plane.

Question 3

Why is gait research often focused on the sagittal plane?

Answer 3

Because flexion and extension movements at the hip, knee, and ankle are largest and most consistent.

Question 4

How does the center of mass move during walking?

Answer 4

It oscillates up and down in the sagittal plane and side-to-side in the frontal plane.

Question 5

When is the center of mass highest during gait?

Answer 5

At midstance.

Question 6

When is the center of mass lowest during gait?

Answer 6

During double-limb support.

Question 7

How much vertical displacement of the center of mass occurs during walking?

Answer 7

Approximately 2–5 cm.

Question 8

How much lateral (side-to-side) displacement occurs in the center of mass during walking?

Answer 8

About 4–7 cm depending on speed.

Question 9

How does walking speed affect center of mass displacement?

Answer 9

Slower walking increases displacement, while faster walking decreases it.

Question 10

How much does the pelvis tilt during walking in the sagittal plane?

Answer 10

About 2–4 degrees (small, subtle movement).

Question 11

How does pelvic tilt change with walking speed?

Answer 11

It increases slightly as walking speed increases.

Question 12

How much total hip motion occurs in the sagittal plane during a gait cycle?

Answer 12

Approximately 40–50 degrees.

Question 13

What is the typical hip angle at initial contact?

Answer 13

About 25–30 degrees of flexion.

Question 14

What is the maximum hip extension reached during terminal stance?

Answer 14

About 10–20 degrees of extension.

Question 15

When does the hip begin flexing again during gait?

Answer 15

During preswing, continuing into midswing.

Question 16

What is the maximum hip flexion during midswing?

Answer 16

Slightly over 30 degrees.

Question 17

What is the typical hip range of motion required for walking?

Answer 17

About 10 degrees of extension to 30 degrees of flexion.

Question 18

What is the knee position at initial contact?

Answer 18

Nearly full extension (about 3–5 degrees of flexion).

Question 19

How much does the knee flex during loading response?

Answer 19

About 15–20 degrees to absorb shock.

Question 20

When does maximum knee extension occur?

Answer 20

During terminal stance.

Question 21

How much knee flexion occurs at preswing?

Answer 21

About 30–40 degrees.

Question 22

What is the maximum knee flexion during midswing?

Answer 22

About 60–65 degrees for foot clearance.

Question 23

What happens to the knee during terminal swing?

Answer 23

It extends again in preparation for initial contact.

Question 24

What is the overall functional role of knee motion during gait?

Answer 24

To alternate between shock absorption, limb clearance, and efficient weight transfer.

Question 25

What is the ankle position at initial contact?

Answer 25

Neutral (0° dorsiflexion/plantar flexion).

Question 26

What happens at the ankle during loading response?

Answer 26

It plantar flexes to allow the foot to fully contact the floor and absorb impact.

Question 27

How much dorsiflexion occurs during midstance?

Answer 27

About 10 degrees.

Question 28

When does plantar flexion peak and to what degree?

Answer 28

At preswing (toe-off) reaching about 20 degrees of plantar flexion.

Question 29

Why is 10 degrees of dorsiflexion during midstance significant?

Answer 29

It represents the closed-packed, most stable position of the ankle joint.

Question 30

What happens to the ankle during swing phase?

Answer 30

It dorsiflexes back to neutral to ensure toe clearance.

Question 31

Is there more plantar flexion or dorsiflexion during gait?

Answer 31

More plantar flexion (≈20°) than dorsiflexion (≈10°).

Question 32

What is the overall range of motion needed for normal gait?

Answer 32

Hip: 30° flexion and 10° extension; Knee: 60° flexion and full extension; Ankle: 20° plantar flexion and 10° dorsiflexion.