Selection Running Shoes

Running Injuries and Shoes

Injury Prevention and Performance Enhancement

Biomechanics Laboratory, School of Human Kinetcs

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

• jump landings:– brief duration– up to 10+ times BW– forefoot landing

Vertical ground reaction forces

1xBW

0

2xBW

3xBW

walking

running

Time (s)

active peaks


Running Forces• Visual3D animation of walking,

jogging and running.• 4 force platforms• 10 Motion Analysis infrared

cameras

centre of gravity

ground reaction force

centre of pressure

force platforms

line of gravity


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, hard surfaces, old/poor footwear, poor prep.• knee/hip/back pain

– anatomical (leg length, abnormal Q-angle, supinated foot)• shin splints

– mechanically caused by rapid changes in training surfaces and overuse

• heel contusion (bruise) – poor heel protection, heavy landings


Anatomical Indicators of Running Knee Pain

• femoral neck anteversion• excessive Q-angle• knee (genu) varum (bowlegged)• squinting patellae• functional equinus• pronated feet (valgus) in weight-bearing

Ref. • S L James, BT Bates, LR Osternig, Injuries to runners, Amer J

Sport Med, 6(2):40-50,1978.


Q-angle or Quadriceps-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.


Pronation versus Supination

• of hand:– one-dimensional rotation– turning palm upwards is supination, downwards is pronation

• of foot– three-dimensional motion

• supination = inversion, plantiflexion and internal rotation• pronation = eversion, dorsiflexion and external 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


Knee (Genu) Varus or Varum

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

and infants


Knee (Genu) 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


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; Undermanned et al., 2003; Stackhouse et al., 2004) but it is unclear how they affect the kinetics (MacLean et al., 2006)


Foot Orthotic Appliances

• orthotic with medial forefoot postfor forefoot supination (varum)

• orthotic with lateral forefoot post for forefoot pronation (valgus or plantiflexed first ray)

• orthotic with medial heel post forsubtalar varum


Heel Protection

• heel cup– rigid material that doesn’t “absorb”

impact but does spread impact over larger area

• heel cups with gel cells– attenuates peak forces by “spreading”

impact over time • “doughnut” (cushion with hole under

calcaneus)– same as gel cells but also transfers

impact forces to wider area


Impact Protection

• object is to reduce peak forces especially at weak areas• reduction can be done by spreading impact forces over a wider

area• distributing the forces to the strongest structures or away from

damaged structures• delaying the forces by gradually “absorbing” the impact (you

cannot actually decrease the total impact (impulse)• run on softer surfaces• decease amount of exposure• reduce duty cycle (avoid high-impact aerobic dance, i.e., use

step aerobics)• use appropriate footwear


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


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 varum/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


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


Orthoses and Orthotics

• orthosis (singular of orthoses)– 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


Prostheses

• prosthesis (singular of prostheses)– 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 and can compete for a place in the Beijing Olympics.

• IAAF Rule 144.2: 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


Sprinting Prostheses

Disadvantages

• very stiff in torsional rotation therefore difficult in bends

• passive spring therefore cannot add energy

• slower to accelerate

Advantages

• lighter therefore lower locomotor energy cost

• may increase stride length on straight-aways


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.

Selection Running Shoes

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