Transcript Gait Analysis (1) - Kansas State University

Analysis of a continuous skill –
walking and running (gait)
• Reading assignment:
• Jones & Barker, Ch 15; McNeil, Ch 5
• Outline
– Walking
• Gait cycle
• Kinematics and ground reaction forces
– Running
• Gait cycle
• Kinematics and ground reaction forces
– Methods of studying gait
– Gait changes with children and ageing
Walking Analysis … the process
• A gait cycle consists of “the activities that occur
from the point of initial contact of one lower
extremity to the point at which the same extremity
contacts the ground again”
• During one gait cycle, each extremity passes
through two phases, a single stance phase and a
single swing phase.
The Gait Cycle:
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
Walking – The Stance Phase
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
Walking – The Swing Phase
GRF while walking
GRF while walking
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 (Note:
Frankel and Nordin state that normal values are + 4 cm
bilatgerally and +3 cm vertically)
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
Running – A Gait Cycle
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
part of stance phase
Methods of Studying Gait
• Observational techniques (use checklist, and videotape
when possible)(Slide 18)
• Quantitative analysis
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time-distance measurements (stop watch, footswitches) (Slide 19)
Kinetic techniques (Slide 20)
Kinematic analysis
Videotaping, semi-automated imaging (Slides 21 & 22)
Combined kinematic and kinetic (Slides 20 & 21)
Sample gait
checklist
Analysis aids: Pressure
on bottom of feet
Force Plates –
Measurement of ground
reaction forces
Optoelectric system - Vicon
Vicon
System:
Gait changes with normal ageing
• Generally, they try to improve stability by
the following adjustments:
• Shorter step and stride lengths
• lower walking speeds
• greater variation in stride width
• wider base of support
Gait in children
• base is wider until 4 yrs
• no heel strike until 2 yrs - contact is made with a
flat foot
• stride length and velocity is less
• cadence is greater
• reduced knee flexion in stance phase until 2 yrs of
age
• no reciprocal arm swing until 4 yrs
• adult stride length, velocity & cadence are
obtained around 15 yrs of age
Scientific Method of Problem Solving
• Develop (define and delimit) the problem
• Formulate the general hypothesis:
– Overload training improves strength
– (e.g., 3 sets of bp 3 d/w will improve bp strength)
• Formulate the specific hypothesis:
– If A (general) is true, then B (specific) will be true
– (e.g., if the general hyp is true, then posttest > pretest)
• Gather , analyze, and interpret the data
– If B is true (significant difference), what about A?
– If B is not true (no sig diff), what about A?
• Discuss the results
– Is B without A very unlikely, or are there alternative
explanations?