Biomechanics of Walking

Question 1

What is the sole purpose of walking?

Answer 1

To transport the body safely and efficiently over the ground, regardless of the nature of the environment around the body

Question 2

What are the 5 main functions during each stride period?

Answer 2

1. Maintenance of support of the upper body during stance
2. Maintenance of upright posture and balance of the total body
3. Control of the foot trajectory to achieve safe ground clearance and a gentle heel landing
4. Generation of mechanical energy to maintain or increase the present forward velocity
5. Absorption of mechanical energy for shock absorption and stability, or to decrease velocity

Question 3

What is cadence?

Answer 3

Number of steps per minute (usually 101-122 for adults)

Question 4

What is stride length?

Answer 4

Horizontal distance from initial contact to next initial contact of same foot (usually 1.5m)

Question 5

What is velocity equation?

Answer 5

Velocity = (stride length * cadence)/120 m/s

Question 6

What are the phases of the step cycle?

Answer 6

Stance phase: foot is on the ground (divided into early, mid, and late stance)
Swing phase: foot is in the air (divided into early and late swing)

Question 7

How much does the CoM move during walking?

Answer 7

Vertical movement: ~1.7 cm for males, ~1.2 cm for females

Question 8

How does inverse dynamic analysis work?

Answer 8

Calculates joint torques by breaking down the body into segments and analyzing forces and moments, works on each segment upwards

Question 9

What is Support Moment?

Answer 9

Basically an overall extensor moment required during stance to keep the body upright. Hip+Knee+Ankle

There is a trade-off between knee and hip to allow redundancy in the system.
There is a “double hump” feature seen with the vertical ground reaction forces.

Question 10

Types of force plates? (2)

Answer 10

• Four triaxial transducers
• Pedestal

Question 11

How does the CoM trajectory change during walking?

Answer 11

CoM never travels within base of support, only just medial to the inside of the foot.
Movement of CoM is such that while it is behind the foot, the medial-lateral trajectory is towards the stance foot, but as soon as it passes in front of the foot, it is towards the projected placement of the swing foot

Question 12

Muscle activation during walking (4) - see slides 59-65

Answer 12

Multiple muscles are activated at different times during the step cycle.

-Trunk muscles (stabilize spinal column)
-Hip extensor (active during weight acceptance and then also decelerates the forward swing of the thigh)
-Thigh muscles (control knee flexion, pull leg forward and prevent lower leg from swinging back)
-Calf muscles (gastroc is fine control of knee flexion; soleus controls forwardly rotating leg; tibialis anterior controls the rate the foot is lowered to the floor)