Running Shoes

Selecting Running Shoes

Injury Prevention and Performance Enhancement

Biomechanics Laboratory, School of Human Kinetcs

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


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

Vertical ground reaction forces

1xBW

0

2xBW

3xBW

walking

running

Time (s)

active peaks


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 people’s 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


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


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?


Cut of Uppers

• low cut– greatest mobility

• mid cut

• high cut– may help to control ankle sprains


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


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


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


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


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


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)


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


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


References

• Bates B et al. Amer J Sports Med 7:338-342,1979.• Huberti HH & Hayes WC. J Bone Jnt Surg 66A:715-724,1984.• Insall J, Falvo KA & Wise DW. J Bone Jnt Surg 58A:1-8,1976.• MacLean C, McClay Davis, I & Hamill J. Clin Biomech 21:623-

630,2006.• Mündermann A et al. Clin Biomech 18:254-262,2003.• Stackhouse CL, McClay Davis, I & Hamill J. Clin Biomech

19:64-70,2004.


Knee (Genu) Valgus

• valgus: outward angulation of the distal segment– distal segment is rotated

Laterally– distal means farther away from

the body’s centre– “knock-kneed”– common in women


Knee (Genu) Varus

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


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.


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


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

Documents

Running Shoes