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 Biomechanics Laboratory, School of Human Kinetcs

Forces during Walking vs. Running 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 active peaks Biomechanics Laboratory, School of Human Kinetcs

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 Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs 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 Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs 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? Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs Cut of Uppers low cut greatest mobility mid cut high cut may help to control ankle sprains Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs 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 Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs 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 Biomechanics Laboratory, School of Human Kinetcs

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 Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs 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 Biomechanics Laboratory, School of Human Kinetcs

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 Biomechanics Laboratory, School of Human Kinetcs

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) Biomechanics Laboratory, School of Human Kinetcs

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 Biomechanics Laboratory, School of Human Kinetcs

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 Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs 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. Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs 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 Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs Knee (Genu) Varus inward angulation of the distal segment “bowlegged” common in horse riders Biomechanics Laboratory, School of Human Kinetcs

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. Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs 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 Biomechanics Laboratory, School of Human Kinetcs

Biomechanics Laboratory, School of Human Kinetcs 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 Biomechanics Laboratory, School of Human Kinetcs