Gait Cycle

Question 1

Locomotion

Answer 1

Variety of movements or methods that animals use to move from one place to another.
Crutches, walking sticks etc. is equipment helping with locomotion.

Question 2

Walking

Answer 2

Primary form of locomotion, most efficient form of energy consumption.
Doesn’t require voluntary control (not thinking about hip flexion and contraction of muscles while walking).
Automatic in normal circumstances.
Repetitive gait cycle, moving the same muscles and stance.

Question 3

Human Gait

Answer 3

Type of locomotion that uses sequences of movements of several body segments, to propel the body forward, with the lease energy expenditure (most efficient).

• Kinetics (force)
• Kinematics (movement)
• Posture analysis
• Clinical/functional assessment
• Research
• Motor control (needs to be optimal for normal gait cycle)

Question 4

Characteristics of Human Gait

Answer 4

Spatial: 
- Stride length 
- Step length
- Stride width
- Angle of progression 
Temporal (time, quantitative):
- Speed
- Cadence

Question 5

Stride Length

Answer 5

Distance (cm) between the initial contact (heal) of the same foot: right foot - right foot (2 steps).

Question 6

Step Length

Answer 6

Distance (cm) between the initial contact (heal) of the left and right foot.

Question 7

Stride Width

Answer 7

Width between the midpoints of the left and right foot.

Question 8

Angle of Progression

Answer 8

How much the foot is out of alignment with the sagittal plane.
Shows rotation of the hip.
Usually a slight external rotation (calcaneus closer together)

Question 9

Speed

Answer 9

Average 4.5 km/h approximately.

Question 10

Cadence

Answer 10

Frequency: how many steps per minute.

60 - 120 steps/minute

Question 11

Requirements for Normal Gait

Answer 11

Body in upright position, body weight equally supported by lower limbs
Symmetric weight transfer; erect bipedal stance
Center of mass projection within the base of support.
Constant sensorial information: visual, proprioceptive (gives constant info on joint position and muscle tendon length, to plan and correct movement).

Question 12

Gait Cycle

Answer 12

Time from the point when one foot touches the ground to the time it touches the ground again.
Two phases (at average walking speed):
- Stance phase: contact with the ground - 60%
- Swing phase: Foot is in the air - 40%
Speed of gait can change the proportion.
Increase (running): swing phase longer, stance shorter.

Question 13

Phases of the Gait Cycle

Answer 13

Stance:
- Initial contact 
- Loading response
- Mid stance 
- Terminal stance
- Pre-swing
Swing:
- Initial swing
- Mid swing
- Terminal swing

Question 14

Limb Progression

Answer 14

Takes place in swing phase.
Need to complete the body weight transfer.
- Stability during stance phase 
- Opposite plantar flexors
- Hip extensors

Question 15

Stability During Stance Phase

Answer 15

• Motor control (gluteus medius: stable pelvis, Soleus: ankle and entire lower limb stable).
• Proper plantar function/structure: base of foot, arch (defined by head of metatarsal) allows adaptation to any obstacle.
• Proper strength levels

Question 16

Foot Rockers

Answer 16

3 movements/actions involving foot articulations in the stance phase: fundamental for progression in the stance phase.

• First rocker
• Second rocker
• Third rocker

Question 17

First Rocker

Answer 17

Ankle plantar flexion.

Dorsiflexors working eccentrically, OKC - tibialis anterior, extensor digitorum longus, extensor hallucis longus.

Question 18

Second Rocker

Answer 18

Tibial motion over the foot - ankle dorsiflexion.
Midstance CKC, foot fixed to the ground, longest phase.
Plantar flexors working eccentrically.
Distal extremity flexed.

Question 19

Third Rocker

Answer 19

Forefoot rocker during heel-off.
Transfer of body weight. 
Extension of the metatarsophalangeal joint.
CKC.
Distal extremity flexed.

Question 20

Foot Clearance

Answer 20

Happens in early moments of swing phase: Hip, knee, ankle articulations of the lower limb flex.
Involuntary motion. Defense mechanism: maintains distance between foot and walking surface.
- Dorsiflexors: primary. Tibialis anterior, extensor digitorum longus: work concentrically to bring foot up, then isometrically to keep foot in dorsiflexion.
- Hip flexors.
- Knee flexion control, from toe-off.

Question 21

Heal strike in Initial Contact

Answer 21

Phase 1: calcaneus in contact with the ground.
Knee has to be fully extended.
Proper shock absorption (ground reaction forces).
- Dorsiflexors work isometrically to maintain the position.
- Knee extensors/flexors coordination.

Question 22

Joint Kinematics - Initial Contact (Heal Stance)

Answer 22

Double support
Hip flexed (20°-30°)
Knee close to full extension (0°-5°)
Ankle in neutral position (0°)

Question 23

Joint Kinematics - Loading Response (Flat foot)

Answer 23

Last moment of double support
Hip remains flexed
Knee flexion with the purpose of load absorption (eccentric) (Knee flexes to respond to load: reaction of weight transfer)
Ankle plantarflexion, allowing for full foot
contact - First ankle rocker

Question 24

Joint Kinematics - Midstance

Answer 24

Single support
Momentum acquired by the opposite limb propulsion
Hip extension
Knee resumes extension
Ankle dorsiflexion - Second ankle rocker (moves the least)
Contralateral foot in swing phase.

Question 25

Importance of Hip Abductors and triceps surae during single leg stance (midstance)

Answer 25

``` Hip abductors (gluteus medius) provide pelvic stability, preventing contralateral pelvic tilt. Gastrocnemius control knee position: in full extension, due to it's proximal attachment, pushes femoral condyle posteriorly. Controls ankle dorsiflexion. ```

Question 26

Joint Kinematics - Terminal Stance (Heel off)

Answer 26

Third rocker Hip in extension (20°) - eccentric, adductor longus, gives transverse stability to pelvis. Knee kept close to full extension Heel rise Beginning of weight transfer to opposite limb Gastrocnemius limits dorsiflexion and stabilizes knee.

Question 27

Joint Kinematics - Pre swing (toe off)

Answer 27

Hip and knee start to flex (eccentric rectus femoris, controls flexion)(concentric soleus for heel rise) Maximal plantar flexion, with toe-off propulsion End of stance phase* Weight transferred: Leg is weight free Contralateral leg: Loading response

Question 28

Joint Kinematics - Initial Swing (Acceleration)

Answer 28

Hip, knee, and ankle flexion, concentric. Sartorius: flexes knee and hip(synergist) Foot clearance mechanisms

Question 29

Joint Kinematics - Mid Swing

Answer 29

``` Hip flexion (concentric) Start of knee extension (eccentric by hamstrings) Foot in neutral position (dorsiflexors isometric, plantarflexors eccentric) ```

Question 30

Joint Kinematics - Terminal Swing (Decleration)

Answer 30

Preparation for new Heel-strike (especially knee in proper position: extension) Hip flexion motion decelerates (hamstrings) Knee almost fully extended (co-contraction: hamstrings and quadriceps) Ankle stabilized in neutral position

Question 31

Inverted Pendulum

Answer 31

A pendulum that has its center of mass above its pivot point. It is unstable and without additional help will fall over.

Question 32

Plantar Loading Progression During Stance Phase

Answer 32

Posterior to anterior 1. Initial contact (heel strike) 2. Loading response (foot flat) (stability by plantar fascia) 3. Midstance 4. Terminal stance (heel-off) highest pressure (entire body mass) on head of metatarsals 5. Pre-swing (toe-off) pressure on hallux but less because load is transferred to other foot.

Question 33

Propulsion

Answer 33

The action of driving or pushing forwards.

Question 34

Importance of bi-articular muscles

Answer 34

- Biceps femoris (hamstrings): initial stance, elongate proximally and shorten distally. Hip flexion and knee extension in final deceleration. - Rectus femoris: initial stance, shorten at hip (flexion). Pre-swing, eccentric control of knee/hip flexion. - Sartorius: Initial swing, knee/hip flexion concentric - Gastroc: Proximal - static, help keep knee extended. Distal - elongate, dorsiflexion eccentrically.

Question 35

Which phases have double support?

Answer 35

Initial contact Loading response Pre-swing

Question 36

What is the main characteristic of the terminal stance phase of the gait cycle?

Answer 36

Moment of weight transfer from one leg to the other.

Question 37

Who is responsible for the hip motion, in the sagittal plane, during Midstance phase?

Answer 37

No muscle activity at this point! Momentum acquired during loading response is responsible. Body weight accepted + contraction of gluteus maximus in the start of the gait cycle.

Question 38

Describe the center of motion and the phase of gait cycle that corresponds to the first foot rocker.

Answer 38

Ankle/tibiotalar articulation. | Loading response.

Question 39

When one limb is in initial contact phase, which phase is the other limb in?

Answer 39

Terminal stance. In pre-swing the body weight is already on the other leg.

Question 40

Give an example of a muscle that is simultaneously shortening and stretching and identify the phase.

Answer 40

Rectus femoris. Initial swing. Flexing both knee and hip. Proximal head shortening (concentric hip flexion) Distal head lengthening (eccentric knee flexion)