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Gait Cycle

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Topic updated on 10/15/14 4:57pm
Overview
  • One gait cycle is measured from heel-strike to heel-strike 
    • consists of 
      • stance phase
        • period of time that the foot is on the ground
        • ~60% of one gait cycle is spent in stance
        • during stance, the leg accepts body weight and provides single limb support
      • swing phase
        • period of time that the foot is off the ground moving forward
        • ~40% of one gait cycle is spent in swing
        • the limb advances
  • Stride
    • is the distance between consecutive inital contacts of the same foot with the ground
  • Step
    • is the distance between initial contacts of the alternating feet
Stance Phase
  • Initial contact (heel strike)  
    • definition
      • occurs when foot contacts the ground
    • muscular contractions
      • hip extensors contract to stabilize the hip 
      • quadriceps contract eccentrically
      • tibialis anterior contracts eccentrically 
  • Loading response (initial double limb support)
    • marks the beginning of the initial double limb stance
    • definition
      • occurs after initial contact until elevation of opposite limb
      • bodyweight is transferred on to the supporting limb
    • muscular contractions
      • ankle dorsiflexors (tibialis anterior) contract eccentrically to control plantar flexion moment
      • quads contract to stabilize knee and counteract the flexion moment (about the knee)
  • Mid-stance (single limb support)
    • initial period of single leg support
    • definition
      • from elevation of opposite limb until both ankles are aligned in coronal plane
    • muscular contractions
      • hip extensors and quads undergo concentric contraction 
  • Terminal stance (single limb support)
    • definition
      • begins when the supporting heel rises from the ground and continues until the opposite heel touches the ground
    • muscular contractions
      • toe flexors contract and are the most active during this phase
  • Pre-swing (second double limb support)
    • is the start of the second double limb stance in the gait cycle
    • definition
      • from initial contact of opposite limb to just prior to elevation of ipsilateral limb
    • muscular contractions
      • hip flexors contract to propel advancing limb
Swing Phase
  • Initial swing (toe off)  
    • start of single limb support for opposite limb
    • definition
      • from elevation of limb to point of maximal knee flexion
    • muscular contractions
      • hip flexors concentrically contract to advance the swingiing leg
  • Mid-swing (foot clearance)
    • definition
      • following knee flexion to point where tibia is vertical
    • muscular contractions
      • ankle dorsiflexors contract to ensure foot clearance
  • Terminal swing (tibia vertical)
    • definition
      • from point where tibia is vertical to just prior to initial contact
    • muscular contractions
      • hamstring muscles decelerate forward motion of thigh
Variables Affected During Gait Cycle
  • Pelvic rotation
    • pelvis rotates 4 degrees medially (anteriorly) on swing side
      • lengthens the limb as it prepares to accept weight
  • Pelvic tilt
    • pelvis drops 4 degrees on swing side
      • lowers COG at midstance
  • Knee flexion in stance
    • early knee flexion (15 degrees) at heel strike 
      • lowers COG, decreasing energy expenditure
      • also absorbs shock of heel strike
  • Foot mechanisms
    • ankle plantar flexion at heel strike and first part of stance
  • Knee mechanisms
    • at midstance, the knee extends as the ankle plantar flexes and foot supinates
    • restores leg to original length
    • reduces fall of pelvis at opposite heel strike
  • Lateral displacement of pelvis
    • pelvis shifts over stance limb 
      • COG must lie over base of support (stance limb)
  • Center of gravity (COG)
    • in standing position is 5cm anterior to S2 vertebral body
    • vertical displacement
      • during gait cycle COG displaces vertically in a rhythmic pattern
        • the highest point is during midstance phase
        • lowest point occurs at the time of double limb support
    • horizontal displacement
      • COG displaces 5cm horizontally during adult male step

 

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Qbank (4 Questions)

TAG
(OBQ12.237) Which phase of gait is affected most in a patient with quadriceps atrophy? Topic Review Topic

1. Terminal swing
2. Preswing
3. Initial swing
4. Midstance
5. Midswing

PREFERRED RESPONSE ▶
TAG
(OBQ10.123) Which of the following descriptions of muscle activity during normal gait is correct? Topic Review Topic

1. Gastrocnemius-soleus contracts eccentrically during heel strike
2. Gastrocnemius-soleus contracts concentrically during heel strike
3. Gastrocnemius-soleus contracts concentrically during swing phase
4. Tibialis anterior contracts concentrically during toe-off
5. Tibialis anterior contracts eccentrically at heel strike

PREFERRED RESPONSE ▶
TAG
(OBQ06.222) The primary antagonist of the anterior tibial tendon is innervated by which of the following nerves? Topic Review Topic

1. Superficial peroneal nerve
2. Deep peroneal nerve
3. Tibial nerve
4. Posterior tibial nerve
5. Sural nerve

PREFERRED RESPONSE ▶
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