Descending Stairs: Forwards and Backwards - PowerPoint PPT Presentation

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Descending Stairs: Forwards and Backwards

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Title: Kinetics versus kinematics for analyzing coordination during locomotion Author: Authorized User Last modified by: D. Gordon E. Robertson Created Date – PowerPoint PPT presentation

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Title: Descending Stairs: Forwards and Backwards


1
Descending Stairs Forwards and Backwards
  • François D.Beaulieu, MA
  • Lucie Pelland, PhD
  • D. Gordon E. Robertson, PhD
  • Biomechanics, Laboratory,
  • School of Human Kinetics,
  • University of Ottawa, Ottawa, CANADA

ISB XIX New Zealand, 2003
2
Introduction
  • Investigate mechanics of descending stairs in
    forwards and backwards directions compared with
    level walking.
  • Why? Descending stairs is more difficult and
    dangerous than ascending stairs.
  • Falls from stair descent especially in the
    elderly can be fatal (Simoneau, et al., 1991
    Winter, 1995)
  • Macleans 236 Canadians died in 2000 from stair
    falls vs. 404 pedestrian deaths

3
Research Questions
  • How does stair descent differ from level walking?
  • Will peak moment and forces about the ankle, knee
    and hip be reduced in the backward stair descent
    versus forward descent?

4
Methods
Use of 3 stair boxes with
30 cm tread
20 cm rise
Use of 3 Kistler force plates (last two steps
landing)
Use of 2 Panasonic Digital cameras -left and
right side
5
Study Design
6
Results
  • Stance phase was 65-70 of cycle (versus 60 for
    walking)
  • Differences in average cycle duration forward
    (1.13 s) vs. backward (1.35 s) or 20 longer
  • Ground reaction forces were larger than walking
  • Forces were farther from stair edge with backwards

7
Moments of Force (Support)
Support moments larger with similar double peaks
as walking
Forwards Backwards
8
Show Animation Here
9
Moments of Force (Ankle)
Ankle plantar flexor reduced (means /- 95th CI)
Forwards Backwards
10
Moments of Force (Knee)
Knee extensor moment increased
Forwards Backwards
11
Moments of Force (Hip)
Hip moments small and highly variable with little
power
Forwards Backwards
12
Comparison with Walking
Ankle Power
  • No initial dorsiflexor phase

Forwards
13
Comparison with Walking
Knee Power
Little or no concentric extensor phase
Forwards
14
Ankle Moment and Power
Larger peak eccentric power (5) during weight
acceptance
Forwards Backwards
15
Knee Moment and Power
Forwards Backwards
16
Discussion
Benefits of Backwards Stair Descent
  • Centre of pressure and centre of gravity are
    farther from edge of stairs
  • If tripping occurs person falls into stairs not
    down stairs
  • Person will be more inclined to use handrails
  • Moments and powers were smaller than forwards but
    larger than walking
  • No concentric ankle power needed (e.g.,
    B-K amputees)

17
Discussion
Concerns with Backwards Stair Descent
  • Problems with seeing next step and landing
  • Unconventional therefore may affect compliance
  • Does require railings for most people
  • Irregular stairs may be problematic

18
Chichen Itza Il Castillo
19
Thank you
Try it Its safer and easier on the knees and
calf muscles.
Questions?
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