2 Main Gait Cycles

1. stance
2. swing

Stance Phase cycles (60% of the time)

1. Loading response (foot flat)
2. Mid Stance
3. Terminal Stance (heel off)
4. Pre-Swing (toe off)

Swing Phases Cycles (40% if the time)

1. initial swing (acceleration)
2. midswing (toe-off)
3. Terminal swing (deacceleration)

Heel strike -> foot flat (ANKLE)

• Neutral @ ankle joint (no PF/DF)
• => 15* plantarflexion @ankle joint
• movement controlled
• Dorsiflexors(antagonist): eccentric contraction

Flat foot -> mid-stance (KNEE)

• Foot flat: 15* flexion
• Midstance: 5* flexion
  • Net movement: 10* extension
• Mov AGAINST gravity = MOV produced
  • Quadriceps(antagonist): concentric contraction

Heel off -> toe off (KNEE)

• flexion
• quadriceps(eccentric): control movement

Heel off -> toe off (HIP)

• flexion
• Hip flexors (concentric): produce movement

Heel off -> toe off (ANKLE)

• flexion
• plantarflexion (concentric): produce movement

Concentric contractions

• Produces movement
• Moving against gravity

Eccentric contractions

• Control movement
• moving towards gravity

Isometric contraction

• stabilizing movement

Straide

• 0%: (Right heel contact) // 50%: (left heel contact) // 100%: (right heel contact)
• Length: 144 cm
• Average human walking speed: 1.37 meter/sec

Weird pace (walk->fast walk)

• @4-5mph

More speed during walk means(bruce protocol)?

• less time in stance
• transition into running

Stance and swing phase (limb support)

1. double limb support (10%)
2. single limb support on RIGHT (40%)
3. Double limb support (10%)
4. Single limb support on LEFT (40%)

More time on double limb support (slower)?

• helps with balance
• spend more time on swing

Events during stance and swing phases

1. Heel contact (0%)
2. Foot flat (8%)
3. Midstance (30%)
4. Heel off (40%)
   1. PUSH OFF
5. toe-off (60%)
   1. early swing // mid swing // late swing
6. Heel contact (100%)

Periods of stance and Swing

1. loading phase
2. mid-stance
3. terminal stance
4. pre-swing
5. initial swing
6. mid-swing
7. terminal swing

Events during stance and swing phases (SPECIFIC)

1. Initial contact (0%)
2. Opposite toe off (10%)
   1. mid-stance
3. Heel raise (30%)
4. Opposite initial contact (50%)
5. toe-off (60%)
   1. early swing // mid swing // late swing
6. Feet adjacent (73%)
7. Tibial vertical (87%)
8. Next initial contact (100%)

Displacement of COM (vertical)

• 5cm displacement // HIGH BoB
  • Heel raise + midstance// switch to next leg
• 0cm displacement // LOW BOB
  • torque creates unilateral swing self-forward
  • SWING PHASE = NO CHANGE

Displacement of COM(lateral)

• 4cm
  • total displacement (L+R)
• 2cm (each)
  • Right leg @30% (1st heel/switch off)
  • Left leg @80% (2nd heel/switch off)

Joint kinematics: Sagittal Plane (all) PIC

1. Pelvis
2. Hip joint
3. knee joint
4. ankle joint

Joint kinematics: Sagittal Plane (Pelvis) PIC

1. Posterior tilt (tilt back) = -5*
   1. heel strike -> heel plant
2. Anterior tilt (forward) = +*5
   1. heel plant -> heel raise -> knee bend
3. Posterior tilt (tilt back) = -5*
   1. knee bend -> full knee bend -> leg initial swing
4. Anterior tilt (forward) = +*5
   1. initial leg swing -> final swing

Joint kinematics: Sagittal Plane (Hip Joint) PIC

1. Flexion (+30*)
   1. heel strike down
2. Extension (-10*)
   1. heel raise / toe-off
3. Flexion (+30*)
   1. heel raise -> terminal swing

Joint kinematics: Sagittal Plane (Knee Joint) PIC

ALL FLEXION

1. @10*
   1. heel contact/strike
2. @20*
   1. foot flat // shock absorber
3. @2* (lowest)
   1. heel raise (end of stance // pre-swing)
4. @60* (highest)
   1. start of swing (ext->flex) // clear legs
5. @2* lowest
   1. terminal swing

Joint kinematics: Sagittal Plane (Ankle) PIC

1. Plantar flexion (-10*)
   1. toe up // heel strike
2. Dorsiflexion (10*)
   1. heel strike -> foot flat (propelling)
3. Plantarflexion (-20*)
   1. fast transfer of range // initial heel raise
4. Dorsiflexion (1*)
   1. initial knee bend + pre-swing
5. Plantar Flexion (-1*)
   1. leg clears and terminates swing

Kinetic + potential energy

• Inverse relationship
• Potential Energy (HIGH)
  • B4 footplant -> B4 heel raise+knee bend -> heel strike
• Kinetic Energy (HIGH)
  • Foot complete plant -> midswing

Kinetic Kinematics (x2)

• Pelvic + hip
• Subtalar joint

Kinetic Kinematics: Pelvic+Hip

• Pelvic
  • -1.5 // Left side lower (heel contact = drop)
  • zero cm ( midstance, pitch up pelvis)
  • 1.5 // Left side higher (heel raise // pelvis raise)
• Hip
  • LOW Adduction: foot plant (cowboy mini lunge out => absorb weight)
  • HIGH Abduction: pre-swing (raise heel)

Kinetic Kinematics: Subtalar Joint

• Inversion (high)
  • land in lock
• Eversion (low)
  • unlock // pronation // shock absorption // transfer force
• Inversion (HIGH)
  • lock // producing force
  • rigid level for plantar flexion

Joint Kinematics: Horizontal plane // COWBOY BELT BUCKLE

1. Stance Phase (internal rot peak @foot flat)(external rot low @pre-swing)
   1. Pelvis (highest)
   2. Femur (dip @initial heel raise)
   3. Tibia (dip @initial heel raise)
2. Swing Phase (ext. rot low @pre-swing)(internal rot high @terminate swing)
   1. Pelvis (highest)
   2. Femur (dip @initial heel raise)
   3. Tibia (dip @initial heel raise)

Hip kinematics (horizontal plane)

1. LOW internal rot: heel strike
2. HIGH IR: inital knee bend (after foot plant)
3. LOW ER: midswing -> terminal swing
   1. shift weight to opposing foot you're going

Lower extremity kinematics (horizontal plane): graph pic

Energy expenditure graph

• NEED HIGH ENERGY = to go slow
• NEED LOW ENERGY = to go fast

Energy expenditure rank

1. post cerebral accident (mod-severe residual deficits)
2. unilateral transfemoral amputation (w/ prosthesis)
   1. unilateral transtibial amputation (w/ prosthesis)
   2. immobilization 1 knee @45*
3. Immobilization of 1 hip
   1. immobilization of 1 knee @full extension
4. Immobilization of 1 ankle

5 energy saving strategies

1. horizontal plane pelvic rotation
   1. LOW down displacement of COM
2. sagittal plane ankle rotation
   1. LOW down displacement of COM
3. frontal plane pelvic rotation
   1. LOW UP displacement of COM
4. frontal plane hip rotation
   1. LOW s2s of COM

Muscle Activity (Hip/Butt/Thigh)

• Muscles
  • errector spinae // rector abdomins // gluteus maximus // iliopsoas // satorius // gluteus medius // gluteus minimus // tensor fascia lata // adductor magnus // adductor longus
• ON activation in the beginning
  • shock absorbtion
• ON at b4 MIDSTANCE
  
  • preparing to swing leg forward
• ON at terminal swing
  • need high trunk control / not fall foward

Muscle activity (Thigh/Calf/Foot)

Muscle activity: erector spinae

• hip extension: keeps from falling from flexion
• ON = heel contact + swing / heel raise
  • quad turns on // from extensor + flung forward // create flexion torque = need to counteract
  • when trunk control is highest
• OFF = midstance

Muscle activity: rectus abdominus

• flexor
• gravity pulling down but not want flexor
• ON= kee pelvis stable during swing

Muscle activity: gluteus medius

• hip extensor
• need to create hip extension (4 shock absorption)

Muscle activity: tensor fascia

• 30% single-leg stance
• abduction (IT band)(PREVENT TIP OVER)

Muscle activity: Why is soleus and gastric most active at middle phase?

• at midstance -> heel off: needs to turn on calves to propel leg foward

at midstance of gait what does hip abduction doing?

• allowing the swing leg to advance toward the next step
• generating moments of force to control frontal plane movement.

Muscle activity of midstance to heel off

• midstance
  • tibial progression stops // calf turns on + holds tibia stable
• heel off
  • gastrocnemius slows tibia down (tibia thrown forward)