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Running Shoes? - enhance performance? - prevent injury Craig Payne
Running Shoes Do they prevent injury? Do they enhance performance?
Paradigm Motion Control Stability Cushioning Minimalist Does getting it right mean less injury?
Overpronation
The truth about
Rationale overpronation bad control it with design features in running shoes Part of the pronation paradigm for prescribing running shoes
History Grew out of running boom in late 70 s As a category it has declined in share Minimalist trend Feel Ride Responsiveness Research Laboratory Outcome Category name? Bad name use design features
Lots of throw away lines BBS They don t control motion You can t control motion They are dead
Design Features Not one design feature Many different design features Different shoes in this category have different features
Minimalist Index
Multi-Density Midsole
Thermoplastic Medial Post
Rigid Heel Counter
Elevated Medial Insole
Supportive Tensioned Upper
Medial Heel Flare
Others Medial wedging Midsole geometries and torsional links Windlass enhancing Proprietary features Eg Asics Space Trusstic Eg Hoka J-Frame
Do they work at controlling motion? The research: Shoe vs foot movement Skin vs bone movement Lump all the design features into one category What measure? Calcaneal eversion Tibial rotation What was actually causing the overpronation? Never taken into account
Research Mixed They do control motion They do not control motion Can cherry pick evidence to support your argument Mean vs subject specific responses
Do shoes control motion? 2011 All three interventions were effective in reducing calcaneal eversion (p<0.001) Motion control footwear with heel flare or wedge design was less effective than those with dual midsole materials.
Depends on cause: Tight calf muscles Forefoot varus Weak gluteal muscle Never taken into account in the research
Outcome Studies Do they make a difference in the field
This study is unable to provide support for the convention that highly pronated runners should wear motion control shoes. Current conventions for assigning stability categories for women's running shoes do not appear appropriate based on the risk of experiencing pain when training for a half marathon.
Knapps Mallisoux - meta-analysis of 3 studies - Military population - Allegations from a participant
The overall injury risk was lower in participants who had received motion control shoes. Based on secondary analysis, those with pronated feet may benefit most from this shoe type.
Aside: Funding source
Conclusion for outcomes Depends on how much weight you want to give to each study and preconceived biases: Ryan et al Fragility analysis might show weak Funded by Nike Knapik et al Soldiers allegedly did not wear much Malisoux et al Funded by Decathlon
What next Did not account for the cause of overpronation Analogous with dose-response in drug trials Tuning running shoes Vibration dampening
Enhance Performance Is it legal?
International Amateur Athletic Association (IAAF) Rules (Old) Rule 143.2: Athletes may compete barefoot or with footwear on one or both feet. The purpose of shoes for competition is to give protection and stability to the feet and a firm grip on the ground. Such shoes, however, must not be constructed so as to give an athlete any unfair additional assistance, including by the incorporation of any technology which will give the wearer any unfair advantage. A shoe strap over the instep is permitted. All types of competition shoes must be approved by IAAF.
New rule 143.2: (1 Nov 2017) Athletes may compete barefoot or with footwear on one or both feet. The purpose of shoes for competition is to give protection and stability to the feet and a firm grip on the ground. Such shoes, however, must not be constructed so as to give athletes any unfair assistance. Any type of shoe used must be reasonably available to all in the spirit of the universality of athletics. Note (i): Adaption of a shoe to suit the characteristic of a particular athlete s foot is permitted if made in accordance with the general principles of these Rules. Note (ii): Where evidence is provided to the IAAF that a type of shoe being used in competition does not comply with the Rules or the spirit of them, it may refer the shoe for study and if there is non-compliance may prohibit such shoes from being used in competition.
Study
A spokesman for Nike has told the Guardian the shoe, which the company believes makes runners 4% more efficient compared to its previous fastest marathon trainer, adheres to the specifications of the International Association of Athletics Federations. When the Guardian contacted the IAAF to ask whether Nike s carbon fibre plate was legal, a spokesman said it was interested in its technical advances but wanted to make sure they and shoes from other manufacturers conformed to its rules.
We are aware of the speculation around the shoe and have received inquiries about new designs of shoes currently being worn by elite athletes, said a spokesman. However, this is not linked to just one manufacturer. There is development in shoe tech across the board. Because of this speculation and the increased interest in the development in this area the IAAF is going to discuss shoe approval processes as defined by the competition rules as part of the agenda at the IAAF Technical Committee in two weeks time in Zaragoza, Spain, to see if we need to change or review approvals.
Is the VaporFly 4% compliant with 143.2? Evidence is they help Words used in Nike s patent "In conventional footwear, little or none of this mechanical energy is recovered to contribute back to ongoing movement. Reducing this energy expenditure and/or improving the energy recovery can potentially improve locomotion efficiency Ross Tucker: To sum my position up, I think the addition of any device that purports to act as a spring (and the Vaporfly Elite clearly has this) should be banned for the credibility of performances both now and into the future.
Old 143.2 Such shoes, however, must not be constructed so as to give an athlete any unfair additional assistance, including by the incorporation of any technology which will give the wearer any unfair advantage. New 143.2 Such shoes, however, must not be constructed so as to give athletes any unfair assistance
Timelines Nike Patent published (Oct 2016) Nike press release re Breaking2 (Dec 2016) Working on a shoe IAAF Technical Committee meets (late March 2017) Amends rules Appears to have taken no action Nike announce the Nike VaporFly 4% (May 3 2017) Breaking2 (May 6, 2017) Nike VaporFly 4% comes to market (August 2017) New IAAF rules come into effect (1 Nov 2017) Nothing happened yet
Line in the sand Yes, the VaporFly does return energy So does the Adidas Boost, Brooks Levitate, etc But VaporFly (carbon plate) and Spira (springs) have inserts in addition to the energy return from the foam midsole.
Spira (~2007-2008) Wanted to be banned USATF PR blitz Offered big money to anyone to wear and win Spira had filed suit against USATF and IAAF alleging the two groups had violated the Sherman Anti-Trust Act and restricted trade by banning Spira's shoes. USATF: "confirming that USATF has not examined or 'banned' the shoe, as we have publicly stated multiple times over the last year-plus. Spira believed they banned as they broke rule 143.2
What will happen? Need a ruling by the IAAF and not by armchair lawyers
Conclusion Injury prevention? Enhance performance? legalities