Selecting Running Shoes

1
Selecting Running Shoes

• Injury Prevention and Performance Enhancement

2
Shoe Anatomy

• sole bottom of shoe
• insole interior bottom of a shoe
• some models have removable insoles
• outsole material in direct contact with ground
  (tread)
• midsole material between insole and outsole
  (made of EVA or PU)
• upper top of shoe that holds shoe to foot
• Low-cut, mid-cut and high-cut uppers
• toe box area that holds toes and heads of
  metatarsals
• vamp material over the instep
• heel counter specialized area at heel that is
  relatively rigid in running shoes
• last form for shaping shoe (straight,
  semicurved, curved) and footprint

3
Forces during Walking vs. Running

• walking
• long duration
• double active peaks
• /-20 body weight
• running/sprinting/jumping
• brief durations
• single active peak
• 3 times BW
• heel-toe landing
• landings
• brief duration
• up to 10 times BW
• forefoot landing

4
Why Does Running Cause Injuries?

• ground reaction forces are high (3x body weight)
• impact is brief therefore little time for muscles
  to dissipate forces
• some peoples anatomy may predispose injury (leg
  length discrepancy, excessively
  pronated/supinated feet or varus/valgus knees)
• running surfaces are rigid (roads, sidewalks,
  frozen earth)
• people tend to over-train (amount per day, no
  recovery days)
• warm-up and stretching are often neglected

5
Running Injuries

• plantar fasciitis
• anatomical, excessive heel impacts, poor running
  mechanics
• heel spur, hammer toes, bunions
• poor shoe fit
• ankle and foot sprains
• mechanically caused by landing off balance or on
  an obstacle
• tibial stress syndrome/fracture
• overuse injury, training on hard surfaces, old or
  poor footwear
• knee/back pain
• anatomical differences (leg length, abnormal
  Q-angle)
• shin splints
• mechanically caused by rapid changes in training
  surfaces and overuse

6
Purposes of Shoes

• protection from
• sprains (high cut shoes may help but reduce
  flexibility)
• cuts and abrasions (strong uppers may increase
  weight and decrease mobility)
• punctures from nails, rocks, slivers etc.
  especially for road running (thick soles help but
  reduce efficiency)
• traction or prevent slippage
• tread helps especially on wet surfaces
• spikes and studs (check rule books)
• cushioning
• in midsoles (reduces efficiency)
• ventilation
• air circulation, water drainage or waterproof?

7
Cut of Uppers

• low cut
• greatest mobility
• mid cut
• high cut
• may help to control ankle sprains

8
Running Shoe Types

• Cushion
• for high-arch feet, underpronator
• extra cushioning in the midsoles to help absorb
  shocks their soles have a curved or semicurved
  shape (last) that promotes a normal running
  motion
• Motion control
• for flat feet or feet that pronate after landing
• straight last and a more rigid midsole than other
  running shoes, these help keep your feet properly
  aligned.
• Stability
• for normal or neutral feet
• semicurved last, but the less rigid midsoles
  allow feet to strike the ground naturally

9
Cushioning

• measured by durometer (hardness)
• mainly in midsole
• cushioning is helpful for hard surfaces
• especially as muscles start to fatigue
• greater cushioning means less efficiency
• may cause ankle instability and sprains
• gel or air cushions cause landing instability
• cushioning columns are better
• breaks down over time
• impact testing for endurance

10
Biomechanical Efficiency?

• all shoes absorb and dissipate energy
• cushioned running shoes absorb the most energy
• the greater the cushioning the more lost energy
• sprinters shoes have the least cushioning and
  are therefore the more efficient
• bare feet are most efficient but traction may be
  compromised and they offer little protection from
  stones, heat or sharp objects

11
Athletic Shoe Types

• basketball/volleyball
• sturdiest with thick midsole cushioning
• for wooden floors and high impacts
• cross-trainers
• most versatile athletic shoes available
• less cushioning
• spiked for track field
• greatest traction on rubberized tracks
• lightest and fastest
• studded for soccer or rugby etc.
• greatest traction of grass or artificial turf

12
Pronation versus Supination

• of hand
• one-dimensional rotation
• turning palm upwards is supination, downwards is
  pronation
• of foot
• three-dimensional motion
• inversion, plantiflexion and internal rotation
• supination is turning foot so that plantar
  surface (bottom of foot) is directed medially
  (towards midline)
• pronation is turning foot so that plantar surface
  (bottom of foot) is directed laterally (away from
  midline), this is most common motion when a foot
  lands during running

13
Supinated Foot Pronates during Landings

• foot is supinated at landing pronates during
  loading
• orthotics help to reduce rates of pronation
  during landings (Bates et al. 1979 Mündermann et
  al., 2003 Stackhouse et al., 2004) but it is
  unclear how they affect the kinetics (MacLean et
  al., 2006)

14
Orthoses and Orthotics

• orthosis
• device added to support an anatomical structure
• i.e., brace or wedge
• e.g., custom foot orthotic (CFO) appliances
  (orthotics), ankle-foot orthoses (AFO) and knee
  braces

15
Foot Orthotic Appliances

• orthotic with medial forefoot post
• for forefoot supination (varus)
• orthotic with lateral forefoot post
• for forefoot pronation (valgus or
• plantiflexed first ray)
• orthotic with medial heel post for
• subtalar varus

16
References

• Bates B et al. Amer J Sports Med 7338-342,1979.
• Huberti HH Hayes WC. J Bone Jnt Surg
  66A715-724,1984.
• Insall J, Falvo KA Wise DW. J Bone Jnt Surg
  58A1-8,1976.
• MacLean C, McClay Davis, I Hamill J. Clin
  Biomech 21623- 630,2006.
• Mündermann A et al. Clin Biomech 18254-262,2003.
• Stackhouse CL, McClay Davis, I Hamill J. Clin
  Biomech 1964-70,2004.

17
Knee (Genu) Valgus

• valgus outward angulation of the distal segment
• distal segment is rotated Laterally
• distal means farther away from the bodys centre
• knock-kneed
• common in women

18
Knee (Genu) Varus

• inward angulation of the distal segment
• bowlegged
• common in horse riders

19
Quadriceps-angle or Q-angle

• quadriceps-angle is formed in the frontal plane
  by two line segments
• from tibial tubercle to the middle of the patella
  
• from the middle of the patella to the anterior
  superior iliac sine (ASIS)
• in adults is typically 15 degrees
• Increases or decreases in the Q-angles are
  associated with increased peak patellofemoral
  contact pressures (Huberti Hayes, 1984).
• Insall, Falvo, Wise (1976) implicated increased
  Q-angle in a prospective study of patellofemoral
  pain.

20
Prostheses

• prosthesis
• device that replaces an anatomical structure
• i.e., an artificial limb
• e.g., solid-ankle, cushioned-foot (SACH) foot,
  FlexFoot, C-knee, Mauch leg

21
Sprinting Prostheses

• LAUSANNE, Switzerland -- Double-amputee sprinter
  Oscar Pistorius won his appeal Friday and can
  compete for a place in the Beijing Olympics.
• Olympic Rule For the purpose of this Rule the
  following shall be considered assistance, and are
  therefore not allowed
• e) use of any technical device that incorporates
  springs, wheels or any other element that
  provides the user with an advantage over another
  athlete not using such a device.

It's a great day for sport. I think this day is
going to go down in history for the equality of
disabled people. -- Oscar Pistorius