Kinesiology of the Musculoskeletal System

1
Kinesiology of the Musculoskeletal System

• Chapter 15
• Kinesiology of Walking

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Gait Terminology

• Gait Cycle the fundamental unit of walking
  measurement in time or , from initial contact
  (aka. heel strike or heel contact) of one foot
  through the point when that same foot makes
  contact with the ground again
• Stride sequence of events taking place between
  successive heel contacts of the same foot
• Step sequence of events that occurs within
  successive heel contacts of opposite feet

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Gait Terminology (cont.)

• Stride length distance between two successive
  heel contacts of the same foot
• Step length distance between successive heel
  contacts of the two different feet
• Step width lateral distance between the heel
  centers of two consecutive foot contacts
  (normally 7-9 cm)
• Foot angle degree of toe-in or toe-out
  (about 7 degrees of toe out is normal)

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The Gait Cycle

• Stance Phase (60 of gait cycle) from initial
  contact to toe off of the same foot
• i.e. Right stance phase is when right foot
  is in contact with the ground and is supporting
  weight
• Swing Phase (40 of gait cycle) from toe off
  to initial contact of the same foot

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Subdivision of the Gait Cycle

• Divided into phases of stance and swing, and into
  periods of single and double-limb support
• 80 of the stance phase is taken up by single
  limb support
• 20 by double limb support

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Subdivision of the Gait Cycle
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Stance Phase Events

• Initial Contact (heel contact heel strike)
• Foot Flat marked by the instant the striking
  foot lies flat (approximately 8 into gait cycle)
• Mid-stance point where the bodys weight passes
  directly over the supporting lower extremity
  occurs during mid point of stance phase
• Heel off (heel rise)- marked by the heel of the
  stance foot leaving the ground (approximately 10
  into gait cycle)
• Toe off approximately 60 into stance phase
  10 of the phase after double limb support

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Swing Phase

• Early Swing from toe off to mid swing
• Mid Swing corresponds to mid stance of support
  leg feet pass next to each other
• Late Swing from mid swing to initial contact

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Time Periods of Gait Cycle

• Stance Phase
• Loading Response
• Mid Stance
• Terminal Stance
• Pre Swing
• Swing Phase
• Initial Swing
• Mid Swing
• Terminal Swing

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C of M Displacement

• Despite all of the lower extremity movement,
• C of M is only displaced, on average, 5 cm
  vertically and 2 cm horizontally
• The less the displacement, the more economical
  the gait cycle

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Sagittal Plane Kinematics

• Hip sagittal plane ROM is from -10 degrees
  extension to 30 degrees of flexion
• Knee joint flexion peaks after toe off full
  extension never occurs in the normal gait cycle
• Plantar flexion peaks at
• toe off

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Horizontal Plane KinematicsInternal/External
Rotation
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Walking Speed

• Walking speed may be the best and most functional
  measure of an individuals walking ability speed
  can be raised by either increasing stride or step
  length, and increasing cadence
• Normal Values
• Gait speed 1.37m/s or 3 mph
• Step rate 1.87steps/s or 110 steps/min
• Step length 72cm (28 inches)

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Energy Expenditure of Walking

• The body attempts to conserve energy expenditure
  by minimizing excursion of C of M, controlling
  body momentum taking advantage of
  intersegmental transfers of energy

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Muscular Activity During the Walking Gait Cycle
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Ground Reaction Forces
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Path of Center of Pressure

• Initial Contact (heel contact) occurs at the
  posterior or posterolateral aspect of the heel in
  most walkers
• IC can also occur at the midfoot or forefoot,
  but less commonly
• Following IC, the path of center of pressure
  travels through the midline of the midfoot and
  then deviates medially, towards the 1st or 2nd
  toe
• Toe Off can occur from the 1st or 2nd toe,
  depending on anatomical or biomechanical
  individualities
• Variations of the path of C of P do occur,
  possibly suggesting significant biomechanical
  deviations
• Variations of the path of C of P lend to
  biomechanical inefficiency

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Over Pronation
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Gait Analysis Lab