The Gait Cycle

isotonic contraction

• muscle changes in length to produce movement

  • concentric→ muscle shortens

  • eccentric→ eccentric

isometric contraction

• increase in tension of muscle→ does not change in length and there is no movement

• good for endurance, rehab, stability

rules of the gait cycle

1. muscles can contract concentrically to create a movement

2. muscles can contract eccentrically to slow down movement

3. muscles can contract isometrically to stabilise a body part

phases of the gait cycle

1. stance phase→ foot in contact with ground

2. swing phase→ foot in air

stance phase

1. heel strike

2. loading response

3. mid stance

4. terminal stance

5. pre-swing

swing phase

1. initial swing

2. mid swing

3. terminal swing

heel strike

• begins when heel strikes the ground

• eccentric contraction of dorsiflexors (tib. anterior) to lower forefoot to ground in controlled manner

dorsiflexors

• mainly tibialis anterior

• also extensor hallucis longus and ext. digitorum longus

loading response

• foot comes into full contact with ground and body weight transferred to stance limb

• concentric contraction of quadriceps femoris to extend knee to reach midstance

quadriceps femoris

• all 4 heads insert into patell

• stabilises knee

mid stance

• opposite limb swings past stance limbs

• requires stabilisation of the pelvis to keep it level

• achieved by isometric contraction of hip abductors of hip on stance side

hip abductors

• hip abductors on standing side prevents pelvis tilting downwards on swing side

  • gluteus medius

  • gluteus minimus

terminal stance

• heel of stance limb starts to lift off the ground

• achieved by concentric contraction of plantar flexors

  • soleus

  • gastrocnemius

• accelerates mass froward

pre-swing (toe-off)

• final stage of stance phase→ preparation for moving into swing phase e.g. prep for this limb leaving ground and swinging forward

• powerful concentric contraction of flexors of digits to push off the ground and accelerate mass forward

initial and mid-swing

• starts with toe off and ends at heel strike

  • concentric contraction of hip flexors create forward swing of lower limb

  • concentric contraction of knee flexors to shorten limb and prevent foot from dragging on floor

hip flexors

• iliopsoas

  • iliacus

  • psoas major

terminal swing

• in preparation for landing the foot on the ground for heel strike, foot is positioned to land foot on the ground

  • concentric contraction of dorsiflexors ensures toes clear the ground

  • concentric contraction of quadriceps extend knee

position of body’s COG during walking

• kep tfairly constant

• vertical shift minimised by hip abductors

• minimises energy expenditure and makes walking energy efficient

lateral shift and hip adductors

• adductors active with every step→ pull lower limbs back in towards midline

• limits lateral shifts of CoG which would make walking much less efficient