Transcript Foot-Ground Interfaces

Plan for This week (8/31/04)
and next (9/7/04)

Tuesday 8/31/04:
- Website homework due
- Complete perspectives and Ex Equip Evaluation Article
- Begin Biomech considerations for ground-foot interfaces

Thursday 9/02/04:
- Complete Biomech ground-foot interfaces
- Read Ch 2 for next class and submit 2 questions

Tuesday 9/07/04
- Review Ch 2 and PowerPoint on Running and Court Shoes

Thursday 9/09/04
- Guest speaker on pedorthics: Eddie Olson and Johanna,
Olson Shoe Shop in Aggieville
Biomechanical Considerations for
Foot-Ground Interfaces
Mechanical Aspects of foot-ground interfaces
 Anatomical aspects of foot-ground interfaces
 Question for next class:

-
What masters should a foot-ground interface serve,
or what is (are) the functions of a foot-ground
interface?
Mechanical Aspects

Friction ( Fig 1.1, p. 5)
-

depends on normal force and nature of surfaces
Ground reaction forces (GRF)
-
magnitude and rate of increase of vertical GRF
are most important (round off the peaks)
Pressure (round off the peaks)
 Weight of shoe – MOI
 Stability

Coefficient of Sliding
Friction
Force Plates – Measurement of
ground reaction forces
Force Vectors
on different
parts of the
foot:
GRF While Walking
GRF while
Running
Foot pressures
while walking:
Foot pressures
while running
Other Mechanical Factors

Moment of Inertia (MOI)
- With a shoe, MOI about knee or hip axis increases directly
with weight
Stability is directional and can be increased by
increasing shoe sole in direction of desired stability
 Stability decreases
with height of foot &
Increases with
distance from COM
to edge of base of
support

Anatomical Aspects



Foot structure
Foot misalignments
Leg and thigh misalignments (Fig 1.6, p.10)
-
Lateral deviations
•
•
•
-
Valgus - segment goes outward from prox to distal
Varus - segment goes inward from prox to distal
Genu varus at knee - bowlegged
Torsional deviations
Tibial torsion - tibia rotated outward (toe out)
•
femoral torsion - femur rotated in relative to tibia
Foot
Bones
Foot misalignments
Subtalar Axis:
Types of foot arches – the “Wet
test”
Foot Pronation and Tibial
Torsion:
Tibial
torsion
Rearfoot Movement During
Running:
Plantar Fascium

What is the plantar fascium? - attaches
to calcaneus posteriorly and to the first row of
phalanges anteriorly

What is its function?
- passive intertarsal stabilization
Arches
of the
Foot:
Plantar Fascium:
Plantar fascitis is 4th
most common cause of
pain among runners
(1st – knee pain, 2nd – shin
splints, 3rd- achilles tendonitis)
Plantar Fascitis – 4th leading cause of
pain
in
runners
 What causes plantar fascitis(inflamation of plantar
fascium)?
- anatomic anomalies
•
•
•
•
microtears in fascium and bone spurs
inadequate flexibility of plantar flexors
inadequate strength of plantar flexors
functional pronation (eversion and abduction)
- overuse
•
•
•
•

overweight
poorly designed and poorly fitted shoes
running and jumping on hard surfaces
sudden increase in stress
Treatment
- remove the cause(s)
- Therapeutic treatment to promote body’s natural healing
• NSAIDS
• Intermittent ice and heat
• Ultrasound, diathermy, massage
Applications to shoe design

First, ask the question: What functional
masters must the shoe/boot/skate serve
-
Friction?
Spread pressure over large area?
Force management?
Stability – which direction?
Protection from elements (e.g., cold, wet, rocks)
Other?
Assignment for next class
- Read Chapter 2 of Kreighbaum book on
running and court shoes
- Submit 2 questions from your reading on
running and court shoes that could be used
as exam questions, or about concepts you
don’t understand or want to know more
about.
Plan for This week (8/31/04)
and next (9/7/04) (revised)

Tuesday 8/31/04:
- Website homework due
- Complete perspectives and Ex Equip Evaluation Article
- Begin Biomech considerations for ground-foot interfaces

Thursday 9/02/04:
- Complete Biomech ground-foot interfaces
- Begin unit on running and court shoes
- Read Ch 2 for next class and submit 2 questions

Tuesday 9/07/04
- Complete Unit on Running and Court Shoes
- Begin Unit on Hiking Boots and Shoes
- Read Ch 3 and submit 2 questions for discussion

Thursday 9/09/04
- Guest speaker on pedorthics: Eddie Olson and Johanna, Olson Shoe
Shop in Aggieville