Running Injuries and Shoes

1. Running Injuries and Shoes Injury Prevention and Performance Enhancement

2. active peaks 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 Biomechanics Laboratory, School of Human Kinetcs

3. ground reaction force centre of gravity force platforms centre of pressure line of gravity Running Forces • Visual3D animation of walking, jogging and running. • 4 force platforms • 10 Motion Analysis infrared cameras Biomechanics Laboratory, School of Human Kinetcs

4. 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 Biomechanics Laboratory, School of Human Kinetcs

5. 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. Biomechanics Laboratory, School of Human Kinetcs

6. 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. Biomechanics Laboratory, School of Human Kinetcs

7. 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 Biomechanics Laboratory, School of Human Kinetcs

8. Knee (Genu) Varus or Varum • inward angulation of the distal segment • “bowlegged” • common in horse riders and infants Biomechanics Laboratory, School of Human Kinetcs

9. 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 Biomechanics Laboratory, School of Human Kinetcs

10. 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) Biomechanics Laboratory, School of Human Kinetcs

11. Foot Orthotic Appliances • orthotic with medial forefoot post for forefoot supination (varum) • orthotic with lateral forefoot post for forefoot pronation (valgus or plantiflexed first ray) • orthotic with medial heel post for subtalar varum Biomechanics Laboratory, School of Human Kinetcs

12. 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 Biomechanics Laboratory, School of Human Kinetcs

13. 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 Biomechanics Laboratory, School of Human Kinetcs

14. 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

15. 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 Biomechanics Laboratory, School of Human Kinetcs

16. 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

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

18. 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

19. 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

20. 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

21. 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

22. 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 Biomechanics Laboratory, School of Human Kinetcs

23. 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 Biomechanics Laboratory, School of Human Kinetcs

24. 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. Sprinting Prostheses 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

25. Disadvantages very stiff in torsional rotation therefore difficult in bends passive spring therefore cannot add energy slower to accelerate Sprinting Prostheses Advantages • lighter therefore lower locomotor energy cost • may increase stride length on straight-aways Biomechanics Laboratory, School of Human Kinetcs

26. 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