1. Sports Medicine II SECTA
UNDERSTANDING GAIT
Sports Medicine II
SECTA

2. Gait Cycle - Definitions:
Normal Gait =
Series of rhythmical , alternating movements of the trunk & limbs which result in the forward progression of the center of gravity
series of ‘controlled falls’

3. Gait Cycle - Definitions:
Single sequence of functions by one limb
Begins when reference foot contacts the ground
Ends with subsequent floor contact of the same foot

4. Gait Cycle - Definitions:
Step Length =
Distance between corresponding successive points of heel contact of the opposite feet
Rt step length = Lt step length (in normal gait)

5. Gait Cycle - Definitions:
Stride Length =
Distance between successive points of heel contact of the same foot
Double the step length (in normal gait)

6. Gait Cycle - Definitions:
Walking Base =
Side-to-side distance between the line of the two feet
Also known as ‘stride width’

7. Gait Cycle - Definitions:
Cadence =
Number of steps per unit time
Normal: 100 – 115 steps/min
Cultural/social variations

8. Gait Cycle - Definitions:
Velocity =
Distance covered by the body in unit time
Usually measured in m/s
Instantaneous velocity varies during the gait cycle
Average velocity (m/min) = step length (m) x cadence (steps/min)
Comfortable Walking Speed (CWS) =
Least energy consumption per unit distance
Average= 80 m/min (~ 5 km/h , ~ 3 mph)

9. Gait Cycle - Components:
Phases:
Stance Phase: (2) Swing Phase:
reference limb reference limb
in contact not in contact
with the floor with the floor

10. Gait Cycle - Components:
Support:
(1) Single Support: only one foot in contact with the floor
(2) Double Support: both feet in contact with floor

11. Gait Cycle - Subdivisions:
A. Stance phase:
1. Heel contact: ‘Initial contact’
2. Foot-flat: ‘Loading response’, initial contact of forefoot w. ground
3. Midstance: greater trochanter in alignment w. vertical bisector of foot
4. Heel-off: ‘Terminal stance’
5. Toe-off: ‘Pre-swing’

12. Gait Cycle - Subdivisions:
B. Swing phase:
1. Acceleration: ‘Initial swing’
2. Midswing: swinging limb overtakes the limb in stance
3. Deceleration: ‘Terminal swing’

13. Gait Cycle

14. Stance phase = 60% of gait cycle Swing phase = 40%
Time Frame:
A. Stance vs. Swing:
Stance phase = 60% of gait cycle
Swing phase = 40%
B. Single vs. Double support:
Single support= 40% of gait cycle
Double support= 20%

15. With increasing walking speeds:
Stance phase: decreases
Swing phase: increases
Double support: decreases
Running:
By definition: walking without double support
Ratio stance/swing reverses
Double support disappears. ‘Double swing’ develops

16. Path of Center of Gravity
Center of Gravity (CG):
midway between the hips
Few cm in front of S2
Least energy consumption if CG travels in straight line

17. CG

19. Path of Center of Gravity
A. Vertical displacement:
Rhythmic up & down movement
Highest point: midstance
Lowest point: double support
Average displacement: 5cm
Path: extremely smooth sinusoidal curve

20. Path of Center of Gravity
B. Lateral displacement:
Rhythmic side-to-side movement
Lateral limit: midstance
Average displacement: 5cm
Path: extremely smooth sinusoidal curve

21. Path of Center of Gravity
C. Overall displacement:
Sum of vertical & horizontal displacement
Figure ‘8’ movement of CG as seen from AP view
Horizontal
plane
Vertical
plane

22. Determinants of Gait :
Six optimizations used to minimize excursion of CG in vertical & horizontal planes
Reduce significantly energy consumption of ambulation

23. Determinants of Gait : (1) Pelvic rotation:
Forward rotation of the pelvis in the horizontal plane approx. 8o on the swing-phase side
Reduces the angle of hip flexion & extension
Enables a slightly longer step-length w/o further lowering of CG

24. Determinants of Gait : (2) Pelvic tilt:
5o dip of the swinging side (i.e. hip adduction)
Reduces the height of the apex of the curve of CG

25. Determinants of Gait : (3) Knee flexion in stance phase:
Approx. 20o dip
Shortens the leg in the middle of stance phase
Reduces the height of the apex of the curve of CG

26. Determinants of Gait : (4) Ankle mechanism:
Lengthens the leg at heel contact
Smoothens the curve of CG
Reduces the lowering of CG

27. Determinants of Gait : (5) Foot mechanism:
Lengthens the leg at toe-off as ankle moves from dorsiflexion to plantarflexion
Smoothens the curve of CG
Reduces the lowering of CG

28. Determinants of Gait : (6) Lateral displacement of body:
The normally narrow width of the walking base minimizes the lateral displacement of CG
Reduced muscular energy consumption due to reduced lateral acceleration & deceleration

29. Gait Analysis – Forces:
Forces which have the most significant Influence are due to:
(1) gravity
(2) muscular contraction
(3) inertia
(4) floor reaction

30. Gait Analysis – Forces:
The force that the foot exerts on the floor due to gravity & inertia is opposed by the ground reaction force
Ground reaction force (RF) may be resolved into horizontal (HF) & vertical (VF) components.
Understanding joint position & RF leads to understanding of muscle activity during gait

31. Gait Analysis: At initial heel-contact: ‘heel transient’
At heel-contact:
Ankle: DF
Knee: Quad
Hip: Glut. Max&Hamstrings

32. Gait HC
Initial HC
‘Heel transient’
Foot-Flat
Mid-stance

33. Gait HC
Initial HC
‘Heel transient’
Heel-off
Toe-off

34. GAIT
Low muscular demand:
~ 20-25% max. muscle strength

35. COMMON GAIT ABNORMALITIES
Antalgic Gait
Lateral Trunk bending
Functional Leg-Length Discrepancy
Increased Walking Base
Inadequate Dorsiflexion Control
Excessive Knee Extension

36. “ Don’t walk behind me, I may not lead.
Don’t walk ahead of me, I may not follow.
Walk next to me and be my friend.”
Albert Camus

37. COMMON GAIT ABNORMALITIES: A. Antalgic Gait
Gait pattern in which stance phase on affected side is shortened
Corresponding increase in stance on unaffected side
Common causes: OA, Fx, tendinitis

38. COMMON GAIT ABNORMALITIES: B. Lateral Trunk bending
Trendelenberg gait
Usually unilateral
Bilateral = waddling gait
Common causes:
A. Painful hip
B. Hip abductor weakness
C. Leg-length discrepancy
D. Abnormal hip joint

39. Ex. 2: Hip abductor load & hip joint reaction force

40. Ex. 2: Hip abductor load & hip joint reaction force

41. COMMON GAIT ABNORMALITIES: C. Functional Leg-Length Discrepancy
Swing leg: longer than stance leg
4 common compensations:
A. Circumduction
B. Hip hiking
C. Steppage
D. Vaulting

42. COMMON GAIT ABNORMALITIES: D. Increased Walking Base
Normal walking base: 5-10 cm
Common causes:
Deformities
Abducted hip
Valgus knee
Instability
Cerebellar ataxia
Proprioception deficits

43. COMMON GAIT ABNORMALITIES: E. Inadequate Dorsiflexion Control
In stance phase (Heel contact – Foot flat):
Foot slap
In swing phase (mid-swing):
Toe drag
Causes:
Weak Tibialis Ant.
Spastic plantarflexors

44. COMMON GAIT ABNORMALITIES: F. Excessive knee extension
Loss of normal knee flexion during stance phase
Knee may go into hyperextension
Genu recurvatum: hyperextension deformity of knee
Common causes:
Quadriceps weakness (mid-stance)
Quadriceps spasticity (mid-stance)
Knee flexor weakness (end-stance)
* * *

45. Other Abnormalities: Overpronation
Pronation is the movement of the subtalar joint (between the talus and calcaneus) into:
Eversion (turning the sole outwards)
Dorsiflexion (pointing the toes upwards) and
Abduction (pointing the toes out to the side
Overpronation is often recognized as a flattening or rolling in of the foot

46. Other Abnormalities: Overpronation
Shin Splints
Anterior Compartment Syndrome
Patello-femoral Pain Sydrome
Plantar Fasciitis
Tarsal tunnel Syndrome
Bunions (Hallux Valgus)
Achilles Tendonitis

47. Other Abnormalities Oversupination
Supination is a movement at the foot which is a necessary movement for walking and running amongst other activities
Supination is the movement of the subtalar joint (between the talus and calcaneus) into:
Inversion (turning the sole inwards)
Plantarflexion (pointing the toes away from you) and
Adduction (pointing the toes across your body).

48. Other Abnormalities Oversupination
Oversupination (hyper-supination) is far more rare than overpronation and causes problems for runners and other athletes, as in this position the foot is less able to provide shock absorption.
Shin Splints
Plantar Fasciitis
Ankle Sprains
Stress fractures of the tibia, calcaneus and metatarsals

49. Other Abnormalities
Propulsive gait -- a stooped, stiff posture with the head and neck bent forward
Carbon monoxide poisoning
Manganese poisoning
Parkinson’s disease
Use of certain drugs including phenothiazines, haloperidol, thiothixene, loxapine, and metoclopramide (usually drug effects are temporary)

50. Other Abnormalities
Scissors gait -- legs flexed slightly at the hips and knees like crouching, with the knees and thighs hitting or crossing in a scissors-like movement
Brain abscess
Brain or head trauma
Brain tumor
Cerebrovascular accident
Cerebral palsy
Cervical spondylosis
Liver failure
Multiple sclerosis
Spinal cord trauma
Spinal cord tumor

51. Other Abnormalities
Spastic gait -- a stiff, foot-dragging walk caused by a long muscle contraction on one side
Brain abscess
Brain or head trauma
Brain tumor
Cerebrovascular accident
Cerebral palsy
Cervical spondylosis
Liver failure
Multiple sclerosis
Spinal cord trauma
Spinal cord tumor

52. Other Abnormalities
Steppage gait -- foot drop where the foot hangs with the toes pointing down, causing the toes to scrape the ground while walking, requiring someone to lift the leg higher than normal when walking
Herniated lumbar disk
Multiple sclerosis
Muscle weakness of the tibia
Spinal cord injury

53. Other Abnormalities
Waddling gait -- a duck-like walk that may appear in childhood or later in life
Muscle disease (myopathy)
Spinal muscle atrophy
Muscular dystropy
Congenital hip dysplasia

54. Other Abnormalities Ataxic or broad-based gait Alcohol intoxication
Brain injury
Damage to nerve cells in the cerebellum of the brain (cerebellar degeneration)
Medications (phenytoin and other seizure medications)
Polyneuropathy (damage to many nerves, as occurs with diabetes)
Stroke