Transcript Part IV Lower Extremities

The Gait Cycle:
1
Walking – The Stance Phase
2
Components of the Stance Phase
• Stance phase comprises 60% of the gait cycle
• Heel strike – moment when the heel first strikes
the ground
• Foot flat – from heel strike to when the full foot is
in contact with the ground
• Midstance – body weight is directly over the
stance leg
• Heel off – moment the heel of the stance leg
leaves the ground
• Toe off – when only the toe of the stance leg is in
contact with the ground
3
Walking – The Swing Phase
4
Components of the Swing Phase
• Swing phase comprises 40% of the gait cycle
• Acceleration – the toe of the stance leg leaves the
ground and begins to swing forward
• Midswing – the swinging leg is directly beneath
the body
• Deceleration – the swinging leg continues forward
towards knee extension but is slowing down as it
travels, stopping just prior to full knee extension
and heel contact with the ground
5
Range of motion at the joints
• Trunk - As left leg moves forward, pelvis rotates clockwise
as viewed from above 7 deg
• Hip Joint (30 deg flex at HS strike, 180 deg at TO)
– Stance - extension, adduction, internal rotation
– Swing - flexion/extension, abduction, ext rotation
• Knee joint - 180 deg at HS, 160 deg at mid-stance
• Ankle joint - Neutral at HS, hinges down during support,
and plantar flexes at TO . ROM 30 deg
• COM displacement +5 cm bilaterally and vertically (Fig
15.3)
6
7
Running Analysis…...
• Running is similar to walking BUT, it differs
significantly in a number of ways, for example:
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No period of “double support”
Float periods (both feet airborne)
Requires greater balance
Requires greater strength
Requires greater ROM at hip, knee, and ankle joints
Involves greater excursion of center of mass
Involves greater ground reaction forces
8
Running – A Gait Cycle
9
Muscle Activity in Running...
• Glut. Max. & med. -- active at the beginning of the stance
phase (concentrically) and again at the end of the swing
phase (eccentrically).
• Iliopsoas -- active during a portion of the swing phase
(concentrically).
• Quadriceps -- 1st 10% of the stance phase (eccentrically)
and last 20% of the swing phase (concentrically).
• Hamstrings -- initial portion of the swing phase
(concentric) and at the end of the swing phase
(eccentric).
• Plantar flexors (gastrocnemius & soleus) – Mid and latter
10
part of stance phase