Pk:gait1

Front 1

Spatial Descriptors of Gait & Values for a Normal Right Gait Cycle (3)

Back 1

1. A typical gait cadence in younger to middle aged adults is 110-120 steps/min, while a typical gait cycle time (time to complete one complete stride) is approximately 1 s
2. If a subject is videotaped perpendicular to the direction they walk, and the subject passes two lines (at least 10 m apart) while walking at a normal cadence, the following gait parameters can easily be calculated by counting the total steps taken between the two lines and using a stopwatch to record the total time:
3. Cycle time (s) = [(time (s) x 2)/(steps counted)]Cadence (steps/min) = [(steps counted x 60)/(time (s)]Average Stride Length (m) = [(distance covered (m) x 2)/(steps counted)]Average Speed (m/s) = [distance covered (m)/time (s)]

Front 2

Gait Cycle (4)

Back 2

1. Both “heel strike” & “initial contact” are often used interchangeably as events, as are “foot flat” & “opposite toe off”
2. The percentages shown above for the events listed are approximations only. For example, heel rise (also called heel off) typically occurs between 30-40% of the gait cycle
3. The event “feet adjacent” can be used in place of “heel rise” at the end of mid stance
4. During the gait cycle, 60% is stance (20% is double-limb support & 40% is single-limb support) & 40% is swing.
5. Conventionally the Right Gait Cycle

Front 3

Center of Mass Displacement During Gait Cycle (2)

Back 3

1. Vertical displacement of center of mass
- Lowest at 5% (Loading response) and 55% (Preswing)
- Highest at 30% (Feet adjacent1), and 80% (Midswing)
2. Medial-lateral displacement of center of mass
- Right foot FWB at 30% (Feet adjacent1)
- Left foot FWB at 80% (Mid swing)

Front 4

Transfer Between Potential & Kinetic Energy During Gait Cycle (3)

Back 4

1. PE highest at 30% (Feet adjacent) and 80% (Midswing)
2. KE highest at 5% (Loading response) and 55% (Pre-swing)
3. PE and KE are inversely related to one another (i.e. high point for PE is low point for KE and vice versa)

Front 5

Energy Expenditure During Walking (2)

Back 5

1. Energy expenditure during walking is lowest at 80 m/min (approximately 1.3 m/s or 3 mi/h), which is normal walking speed
2. This implies that normal walking speed is very efficient, whereas walking faster or slower than normal walking speed decreases walking efficiency and increases energy expenditure

Front 6

Sagittal Plane Lower Extremity Kinematics During Gait Cycle: Pelvic motion (4)

Back 6

1. Pelvic motion
- posterior tilt at 0-25%: Loading response to end of mid-stance
- anterior tilt at 25-50%: End of midstance to opposite heel strike
- posterior tilt at 50-75%: opposite heel stike to Feet adjacent2
- anterior tilt at 75-100%: Feet adjacent2 to heel strike of next cycle

Front 7

Pelvic and Hip Frontal Plane Kinematics During R Gait Cycle: Pelvic obliquity

Back 7

Pelvic Obliquity: Height of the left iliac crest relative the right
Down (0-40%)
- From heel strike to Terminal stance
- Down 3 degrees at 15% of cycle: Early midstance
Up (40-87%)
- From terminal stance to tibia vertical
- Up 3 degrees at 65% of cycle: Early initial swing

Front 8

Gait Cycle Cycle: Events (8)

Back 8

0% - Initial contact: Heel Strike
10% - Opposite foot toe off: Foot flat
30% - Heel Rise: feet adjacent
50% - Opposite Initial contact: Opposite heel srike
60% - Toe off: opposite foot flat
73% - Feet adjacent
87% - Tibia vertical
100% - Next initial contact

Front 9

Gait Cycle: Tasks (3)

Back 9

1. Weight acceptance: 0-10%
- Heel strike to Opposite toe off
2. Single-limb support: 10-60%
- Opposite toe off to Toe off
3. Limb advancement: 60-100%
- Toe off to heel strike

Front 10

Gait Cycle: Phases (2)

Back 10

1. Stance Phase 0-60%
- Double support at 0-10%: Loading response
- Single support at 10-50%: Mid/ Terminal stance
- Double support at 50-60%: Preswing
2. Swing Phase 60-100%
- Initial swing (60-73%)
- Mid swing (73-87%)
- Terminal swing (87-100%(

Front 11

Frontal Plane Subtalar Joint Motions During Stance Phase of Gait (5)

Back 11

1.
Inversion (0%-10%)
- 2 degrees inversion at 0% (Heel contact)
- From heel strike to opposite toe off
Eversion (10%-45%)
- From opposite toe off to late terminal stance
- 2 degrees of eversion at 30% : feet adjacent1
Inversion 45%-60%
- From late terminal stance to toe off
- 6 degrees of inversion at 55%: mid pre-swing
2. Lowering of arch
- rearfoot eversion
- tibial internal rotation
3. Raising of arch
- rearfoot inversion
- tibial external rotation
4. 40-60% is the push-off phase of the gait cycle
- mid terminal stance to toe off

Front 12

Associated Movements as the Tibia Internally Rotates over a Fixed Foot During Loading Response & Mid Stance. (3)

Back 12

1. Rearfoot Pronation
2. Forefoot/Midfoot supination
3. More flexibility and pliability in the foot

Front 13

Associated Movements as the Tibia Externally Rotates over a Fixed Foot During Terminal Stance (3)

Back 13

1. Rearfoot Supination
2. Forefoot/Midfoot Pronation
3. A More Rigid Foot

Front 14

Actions at Ankle during stance phase

Back 14

1. Representative Joint
- Talocrural
2. Loading Response
- Plantarflexion
- Allows rapid foot contact
3. Mid to Terminal Stance
- Dorsiflexion followed by rapid plantarflexion
- Produces a stable joint to accept body weight,
followed by thrust needed for push off

Front 15

Actions at Rearfoot during stance phase (3)

Back 15

1. Representative Joint
- Subtalar
2. Loading Response
- Pronation and lowering of the medial longitudinal arch
- Permits internal rotation of lower limb
- Allows the foot to function as a shock absorber
- Produces a pliable midfoot
3. Mid to Terminal Stance
- Continued pronation changing to supination, followed by a raising of the medial longitudinal arch
- Permits external rotation of lower limb
- Coverts the midfoot to a rigid lever for push off

Front 16

Actions at Midfoot during Stance Phase (3)

Back 16

1. Representative Joint
- Transverse tarsal joint
2. Loading Response
- Relative inversion as a response to counterforce from the ground
- Allow full extent of subtalar joint pronation
3. Mid to Terminal Stance
- Relative eversion
- Allows the midfoot and forefoot to maintain firm contact with the ground

Front 17

Actions at Forefoot during stance phase (3)

Back 17

1. Representative Joint
- Metatarsalphalangeal
2. Loading Response
- Insignificant
3. Mid to Terminal Stance
- Hyperextension
- Increases tension in the plantar fascia
- Through the windlass effect, raises the medial longitudinal arch and stabilizes the midfoot and forefoot for pushoff

Front 18

Horizontal Plane Lower Extremity Kinematics During R Gait Cycle: General (4)

Back 18

1. Subtalar pronation & tibial IR unlocks knee & facilitates knee flexion & shock absorption
2. Subtalar supination & tibial ER locks knee & facilitates knee extension & stance stability
3. Both the femur & tibia rotates 5-10° in both directions, while the pelvis rotates 3-4° in both directions
4. By convention, IR & ER of pelvis is defined in the same direction as IR & ER of femur, which implies if femoral IR > pelvis IR, the net result is hip IR. HOWEVER, if femoral IR < pelvis IR, the net result is hip ER, so femur & pelvis are both IR but the hip joint is ER (think about this!!).

Front 19

Center of Pressure of Ground Reaction Force During Gait Cycle (4)

Back 19

1. (a) At heel strike
2. (b) At foot flat
3. (c) At the end of midstance
4. (d) At toe off
5. Center of pressure (COP) path may vary among subjects and may be altered by different footwear

Front 20

Ground Reaction Forces During Gait Cycle: Vertical GRF (3)

Back 20

1. Vertical GRF
1. Right Foot
- 120% bodyweight at 10% of cycle: opposite toe off
- Dips to 80% BW at 30% of cycle: feet adjacent1
- Rises back to 120% BW at 45% of cycle: pre-swing
2. Left foot
- 120% of BW at 50%: opposite heel strike
- Dips to 80% of BW at 78%: Midswing
- Back to 120% at 95%:late terminal swing
3. When downward dip in GRF occurs, the center of mass is accelerating downwards and must be subtracted from weight when calculating the GRF
- Fgr = W + May

Front 21

Compressive Forces at the Talocrural Joint During the Stance Phase of Gait (3)

Back 21

1. Compression forces act during entirety of Stance Phase (0-60%)
2. Peak ankle compression forces (500%BW) at 40% of gait cycle: Terminal stance
3. Forces are high due to the action of muscles/tendons counteracting the GRF

Front 22

Torques Generated by Ground Reaction Forces at R Heel Contact (2)

Back 22

1. Plantarflexion torque
- must be resisted by dorsiflexors
2. Eversion torque
- must be resisted by inverters

Front 23

Flexor Torque Generated at Knee by Ground Reaction Force at Initial Foot Contact (2)

Back 23

1. Force is posterior to ankle and knee
Ankle: plantarflexor torque
Knee: flexor torque
2. Force is anterior to hip
- Flexor torque

Front 24

Timing of Muscle Activation During Gait Cycle: Leg Muscles: General (3)

Back 24

1. The ankle dorsiflexors control ankle plantar flexion & initiate ankle dorsiflexion
2. The ankle plantar flexors control ankle dorsiflexion and initiate ankle plantar flexion
3. The ankle supinators control ankle pronation (especially when excessive pronation occurs), while the ankle pronators control ankle supination

Front 25

Normative Values during Gait Cycle (4)

Back 25

1. Step Length:
- 72 degrees
2. Foot Angle
- 7 degrees
3. Normal Gait Speed
- 1.37 m/s
- 3 miles an hour
4. Step width
- 7-9 cm

Front 26

Sagittal Plane Lower Extremity Kinematics During Gait Cycle: Hip (3)

Back 26

Flexion (0-35%)
- From loading response to beginning of terminal stance.
- Starts at 30 degrees
Extension (35%-60%)
- From early terminal stance to toe off
- 10 degrees at heel strike
Flexion (60%-100% and on)
- From toe off to heel strike (and beyond)
- 35 degrees at midswing)
- From toe off to loading response
- 35 degrees at 80%: midswing
- 30 degrees at 100%: next heel strike

Front 27

Sagittal Plane Lower Extremity Kinematics During Gait Cycle: Knee (2)

Back 27

Small Flexion (0-40%)
- From Heel strike (5 degrees) to terminal stance (5 degrees)
- 20 degrees at 15%: Early midstance
Large Flexion (40%-95%)
- From terminal stance (5 degrees) to late terminal swing (5 degrees)
- 60 degrees at 75%; Early midswing

Front 28

Sagittal Plane Lower Extremity Kinematics During Gait Cycle: Ankle (3)

Back 28

Plantar flexion (0-10%)
- From heel strike to opposite toe off
- 10 degrees 5%: Loading response
Dorsiflexion (10%-55%)
- From opposite toe off (foot flat) to Preswing
- 10 degrees at Terminal stance
Plantarflexion (55%- 100%)
- From preswing to heelstrike
- 20 degrees at 65%: Initial string
- Just below neutral at midswing/ terminal swing

Front 29

Gait Cycle: Periods (7)

Back 29

1. Loading Response (0-10%)
- From Heel strike to Opposite toe off
2. Mid stance (10-30%)
- From Opposite toe off to Feet adjacent1)
3. Terminal stance (30-50%)
- From feet adjacent to Preswing
4. Pre-swing (50-60%)
- From opposite heel strike to toe off
5. Initial swing (60-73%)
- From Toe off to feet adjacent
6. Mid-swing (73-87%)
- From feet adjacent to tibia vertical
7. Terminal swing (87-100%)
- From tibia vertical to next initial contact

Front 30

Pelvic and Hip Frontal Plane Kinematics During R Gait Cycle: Right Hip Joint motion (2)

Back 30

Adduction (0-45%)
- From heel strike to late terminal stance
- At 5 degrees at 20% of cycle: Midstance
Abduction (45-100%)
- From late terminal stance to heel strike
- At 5 degrees at 65%: Initial swing



- Abduction at 5 degrees at 65% of cycle

Front 31

Change in Medial Arch Height During Stance Phase of Gait (5)

Back 31

1. Height of medial arch (%)
- 95% at start of gait cycle
- 87% at 50% gait cycle:opposite heel strike
- 100% at 58% of gait cycle: right before toe off

Front 32

Horizontal Plane Lower Extremity Kinematics During R Gait Cycle: Phases (3)

Back 32

1. Pelvis/Femur/Tibia
- internally rotating during 0-15/20%: heelstrike to midstance
- externally rotating from 15/20%-60%:midstance to toe off
- internally rotating form 60-100%: swing phase
2. Subtalar joint
- everting from 0-30%: heel strike to feet adjacent1
- inverting from 30-55%: feet adjacent1 to pre-swing
- everting from 55%-100: pre-swing to heel strike
3. Midfoot
- increasing pliability from 0-30%: heel strike to feet adjacent1
- increasing stability from 30-55%: feet adjacent1 to pre-swing
- increasing pliability from 55%-100: pre-swing to heel strike

Front 33

Ground Reaction Forces During Gait Cycle: Anterior-Posterior GRF in % Bodyweight (2)

Back 33

1. RIght Foot
Posterior (0-30%)
- From heel strike to feet adjacent1
- 15% Posterior at 10% of cycle:
Anterior (30%-60%)
- 20% Anterior at 50% cycle:opposite heel strike
2. Left
Posterior (50-80%)
- From opposite heel strike to midswing
3. Friction force is causing the posterior ground reaction force since foot is pushing anteriorly at heelstrike
- 15% Posterior at 60% of cycle: Toe off
Anterior (80-100)
- 20% Anterior at 100% cycle: heel strike

Front 34

Ground Reaction Forces During Gait Cycle: Medial-Lateral GRF in % Bodyweight (1)

Back 34

Medial/Lateral GRF are mostly medial throughout gait cycle but approach neutral at
- 30% of gait cycle for Right foot: feet adjacent1
- 80% for left foot: midswing

Front 35

Timing of Muscle Activation During Gait Cycle: Thigh Muscles: Hip Extensors (3)

Back 35

1. Active during:
- 0-10/15% of gait cycle: heel strike to opposite toe of and midstance
- 80-100%: Mid-swing to terminal swing
2. Initiate hip extension and control (eccentric) hip flexion.
3.
- Gluteus maximus
- Hamstrings

Front 36

Timing of Muscle Activation During Gait Cycle: Thigh Muscles: Hip abductors (3)

Back 36

1. Active during
- 0-45% of gait cycle: heel strike to terminal stance
- 90-100% (gluteus medius) terminal stance to heel strike
2. Control frontal plane pelvis movement
3.
- Gluteus medius
- Gluteus minimus
- Tensor fascia lata

Front 37

Timing of Muscle Activation During Gait Cycle: Thigh Muscles: Hip flexors(3)

Back 37

1. Active during
- 50-70% of gait cycle: opposite heel strike to late initial swing
2. Control hip extension and initiate knee flexion
3.
- Iliopsoas
- Sartorious
- Rectus femoris (also does knee extension 90-100%, 0-15%)

Front 38

Timing of Muscle Activation During Gait Cycle: Thigh Muscles: Knee extensors (3)

Back 38

1. Active during
- 0-25% of gait cycle: heel strike to late mid-stance
2. Control knee flexion and initiate knee extension
3.
- Vastus lateralis and medialis
- Rectus femoris (also does hip flexion, 50-70%)

Front 39

Timing of Muscle Activation During Gait Cycle: Thigh Muscles: Hip adductors (3)

Back 39

1. Active during 40-60%
2.
- Adductor magnus
- Adductor longus

Front 40

Timing of Muscle Activation During Gait Cycle: Leg Muscles: Ankle dorsiflexors (2)

Back 40

1. Active during
- 0-15% of gait cycle: heel strike to early midstance
- 50-100%: Limb advancement
2.
- Tibialis anterior
- Extensor digitorum longus
- Extensor hallucis longus

Front 41

Sagittal Plane Hip Motion, Internal Muscle Torque, Power, and Muscle Activity During Gait Cycle (4)

Back 41

1. Joint power = Tω, where ω is hip angular velocity (1st derivative, or slope, of each point on the position-time graph A) and T is torque (graph B).
2. The EMG curves represent relative intensity of muscle activity during the gait cycle, with the dark shaded areas indicating eccentric action, and the hatched area indicating concentric action
3. Energy generation (pos power) is associated with concentric contractions while energy absorption (neg power) is associated with eccentric contraction.
4. Eccentric activity
- Iliopsoas 30-50%
- Gluteus maximus 90-100%

Front 42

Frontal Plane Hip Motion, Torque, Power, and Muscle Activity During Gait Cycle

Back 42

1. Eccentric activity
- Gluteus Medius: 0-15%:Heel strike to early mid-stance

Front 43

Sagittal Plane Knee Motion, Torque, Power, and Muscle Activity During Gait Cycle

Back 43

1. Eccentric activity
- Biceps femoris: 75-100%
- Vastus muscles: 0-15% and 50-60%

Front 44

Sagittal Plane Ankle Motion, Torque, Power, and Muscle Activity During Gait Cycle

Back 44

1. Eccentric Action
- Tibialis anterior: 0-10%
- Soleus: 10-45%