EFFECT OF WALKING SPEED ON GAIT VARIABLES

1
EFFECT OF WALKING SPEED ON GAIT VARIABLES

• By
• Sheetal Pinjarkar
• Brian Meyer
• HUMAN LOCOMOTION (BE522)

 

B


Sprinting
Running
Walking
Stand Still
B
A
Maximum Speed
2
Topics of Discussion

• Effect of speed on Gait Variables namely Speed,
  Cadence and Stride Length.
• Effect on Angles, Moments and Powers with change
  in speed
• Electromyography.
• Measure energy consumption.(PCI)
• Maximum Walking Speed.
• Race walking and Furlong shoe.

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EFFECT OF SPEED ON CADENCE

• There are three ways to increase speed-
• (i) Increase in stride length.
• (ii)Increase in Cadence
• (iii) Decrease in the time taken to cover a
  particular distance.
• All the three parameters are interrelated
• Natural Cadence 120 Steps/min, Stride length
  1.5m and natural velocity is 1.5 m/s

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EFFECT OF SPEED ON CADENCE STRIDE LENGTH

• VelocityStride Length X Cadence
• 120
• Velocity Distance Covered
• Unit time

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CHANGES IN GAIT CYCLE WITH SPEED
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CHANGE INSTANCE, SWING AND DOUBLE SUPPORT
DURATION WITH SPEED
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PEAK KNEE STANCE SWING PHASE ANGLES

• Stance phase Knee flexion for shock absorption
• Knee extension for power generation.
• Swing phase knee flexion increases with speed

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ANKLE ANGLE, MOMENT POWERS

• Running eccentric power generated by plantar
  flexors.
• Sprinting No dorsiflexors acting in the start
  as forefoot striking takes place. (5- 10 )
• Total energy absorbed by ankle in sprinting is
  more than running.
• Mag. of ankle power generation by plantar flexors
  for forward propulsion depends on atheletes
  speed.

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KNEE ANGLE, MOMENT POWERS

• Peak knee extensor moment is more for running
  than for sprinting because in sprinting the ankle
  plantar flexors absorbs much of the shock than
  knee extensors.
• As knee flexes following IC, eccentric power by
  knee extensors.
• Power generation is by knee extensors

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HIP ANGLE, MOMENT POWERS

• Both Hip flexors and extensors resposible for
  power generation.

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ENERGY SOURCES

• Amount of power generated increases as the speed
  increases
• Power generators stretches eccentrically just
  prior to generating their burst of the power.
  Convert their potential energy into kinetic
  energy.

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ELECTROMYOGRAPHY

• EMG activities are greater at the transition
  from swing to stance phase than from stance to
  swing.
• Muscles are more active just after IC than after
  TO.

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CHANGES IN ENERGY CONSUMPTION WITH SPEED
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MEASUREMENT OF OXYGEN UPTAKE

• Gait efficiency is defined as energy cost per
  distance traveled.
• 1. Indirect Calorimetry
• (a) Douglas Bas Method-Waters 1983
• (b) Breath by Breath Mode-Corry, 1996
• (c) Dilution ModeBranson, 1990
• 2. Heart Rate
• (a) Energy Expenditure Index-Rose 1991
• (b) Energy Cost Index-Rose 1985
• (c) Physiologic Cost Index (PCI)-Butler 1994

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LIMITATIONS OF THE MEASUREMENT TECHNIQUES

• Indirect Calorimetry
• ADVDirect measurement of O2 and CO2
• LIM Expensive cumbersome equipment
• Heart rate
• ADVData is easy to obtain
• LIM- Data influenced by anxiety, medication,
  illness, exercise, walking.
•          - Lacks sensitivity to detect change
  with age.
• - Assumes linear relationship between
  the heart rate and oxygen
  consumption .

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Physiological Cost Index (PCI)

• PCI in heart beats / meter is equal to working
  heart rate minus resting heart rate divided by
  speed in meter per minute
• A simple measurement of the energy demands of
  walking

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MAXIMUM WALKING SPEED

• Rate of O2 consumption at rest, standing,
  Customary walking speed (CWS) and fast walking
  speed (FWS) .
• Rate of O2 consumption- Speed relationship in
  children, teens and adults. Rate of O2 the
  milliliters of O2 consumed per kilogram body
  weight VO2/Kg

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Maximum Walking Speed

• It has been assumed that there is an optimum
  speed at which metabolic cost, or rate of oxygen
  consumption (VO2) is at a minimum
• Ralston, derived the relationship to confirm
  this
• VO2avc
• With a minimum
• v(c/a)0.5

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Race Walking

• A progression of steps so taken that the walker
  makes contact with the ground so that no visible
  (to the human eye) loss of contact occurs

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Race Walking Objective

• To maintain a constant velocity of the bodys
  center of gravity without excessive vertical or
  side to side displacement
• Race walking technique includes correct posture,
  proper hip motion and knee/foot action, and using
  your arms efficiently

21
Hip Motion

• Primary source of forward locomotion provided by
  the body
• Watch for
• Excessive hip drop
• Excessive lateral hip motion

22
Increased Stride Length

• Correct hip action leads to increased stride
  length
• Right Foot Placement along a straight line
• Wrong Insufficient hip rotation in pelvis may
  lead to foot placement on either side of straight
  line

23
Knee Action

• The knee must be straight from moment of heel
  contact until the support leg is in the vertical
  position
• Watch for
• Lead knee swinging through high
• Bent knee on heel contact
• (illegal)
• Lead knee bending before the leg is vertically
  upright (illegal)

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Foot Action

• The heel strikes the ground first with the toes
  elevated, not flat footed
• Once the foot had made contact, it rolls forward,
  keeping the toes off the ground until the leg is
  supporting the bodys weight
• Watch for
• Landing flat footed or with the foot slapping too
  soon

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Arms/Hand Position

• Arms
• -Elbows of a race walker are bent at an angle
  between 90 degrees and 45 degrees
• -Elbow must be fixed, but the muscles relaxed,
  throughout the arm swing
• -Arm movement is backwards forwards, not from
  side to side
• -Hands should not cross the centerline of the
  body

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Arms/Hand Position

• -A race walkers hand should be relaxed
• -Should not dangle or flop with the arm swing
• -The wrist should be a straight line while the
  hand should be held in a loose fist with the
  fingertips facing the hips as the arm swings past

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Furlong Shoe Sydney Olympics

• With a 14-second lead and only steps from the
  finish line, Australia's Jane Saville was
  disqualified from the women's 20K racewalking
  event for lifting her foot a centimeter off the
  ground
• Saville was actually in the Stadium Australia
  tunnel with a winning advantage in the 20km walk
  when she was shown the red card for her third
  offence of 'lifting'

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Furlong Shoe

• Former race walker, Dr. Dennis Furlong, invented
  an shoe that would take such controversial
  officiating out of the sport
• The Furlong Shoe, an electronic shoe, sounds
  an alarm when neither foot is touching the ground
• This intelligent shoe consists of a 90 gram
  capsule attached to both sides that would
  immediately detect a loss of contact with the
  ground
• It would then emit a red light and trigger a beep
  after a certain number of faults

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ACKNOWLEDGEMENTS

• We would like to acknowledge Dr. Chris Kirtley
  for his diligent support and guidance and in
  helping me in getting insight of this topic. I
  would also like to express my sincere vote of
  thanks to the library members who helped me in
  tracking the journals at the soonest.

THANK YOU