By: Amanda Wach
A new study may help to shed some light on the cost of using (certain) football cleats. The type you choose may affect where and how badly you injure your ankles – this is a breakdown of a newly published paper.
Rotational Stiffness of American Football Shoes Affects Ankle Biomechanics and Injury Severity by K.D. Button, J.E. Braman, M.A. Davison, F. Wei, M.C. Schaeffer, and R.C. Haut from Michigan State University. Published in Journal of Biomechanical Engineering, June 2015, vol. 137. 
Translation: The type of football cleats you wear can affect where and how badly you injure your ankles, based on research from the Orthopaedic Biomechanics Laboratories at MSU.
Why did they choose to focus on this? Ankle injuries account for 10-30% of all sports injuries , and this study focused on one mechanism of injury, external rotation of the foot. It’s an easy scenario to imagine, you plant your outside foot as you change direction, rotating your upper body into the turn, leaving your foot rotating away from your body. This external rotation results in syndesmotic and medical ankle injuries (high ankle sprains and ankle ligament injuries), which make up 10-15% of ankle injuries [3,4]. While this doesn’t sound like a pressing concern, these particular injuries have a long recovery time and can lead to chronic ankle problems [2,3].
This study looked to see if the type of football cleat you wear can change how ankles “fail” with experimental (cadaver) and computational modeling tests. The cleats used, Nike Flyposite and Nike Zoom Air, were chosen for their differences in rotational stiffness. Think of planting your cleat firmly in the ground and trying to rotate your foot (and shoe) from side to side. The cleat with a higher stiffness (Flyposite) would not allow much movement, while the flexible cleat (Zoom Air) allows some wiggling. The experiment externally rotated the foot, while keeping the cleats fixed, until a failure occurred. Motion analysis cameras were used to track motion of bones involved with ankle rotation (the talus and tibia). This data served as an input for the computational model, which computed the forces experienced by ankle ligaments and the resulting stretching and/or failure.
The results suggest that more flexible cleats may result in less severe ankle injuries. The specimen with stiff cleats experienced more bone fractures or ligament ruptures, and at lower torque. The study reasons that by having a lower constraint on ankle motion (i.e. allowing more external rotation) the ankle can respond naturally and absorb the torque. The ligaments in the ankle are allowed to stretch more, which means they can take on higher loads and share them across multiple ligaments.
What does this mean for ultimate players? Well, as a biomechanical engineer, the first thing I’d like ultimate players to take away from this is that science is cool. There are tons of studies being done on sports and injuries, not to mention the work going in behind equipment design, and it is all cool. Second, is that there are more things to consider when purchasing cleats than just the functional performance. Especially if you’ve had previous ankle injuries, you may want to think about how your cleats can help protect you. Maybe next time you try on cleats, internally and externally rotate your foot to see how the shoe reacts, how the upper leather/cloth part of the shoe moves with respect to the plastic sole/cleats.
As with all research results, take these conclusions with a grain of salt. As someone who has injured both ankles, it is important to note that these results only address external rotation injuries. This doesn’t consider what to look for in cleats to prevent lateral ankle injuries or rolling your ankles on uneven ground. Also, these tests were performed on older cadaver specimens, which may have different limitations than athletes. I’m looking forward to studies investigating the performance characteristics of different cleats in a variety of circumstances, an overall approach to the best recommended cleats that may prevent injury.
For those of you who are scientifically inclined, I’ve included the link to this a few other interesting papers on cleat mechanical testing and performance. (You may need to have a subscription to the journal to view the full article for free. Most universities have subscriptions, so try accessing these from a university network.)
 Button, K.D., Braman, J.E., Davison, M.A., Wei, F., Schaeffer, M.C., and Haut, R.C., 2015, “Rotational Stiffness of American Football Shoes Affects Ankle Biomechanics and Injury Severity,” ASME J. Biomech. Eng., 137(7).
 Waterman, B.R., Belmont, P.J., Jr., Cameron, K.L., Svoboda, S.J., Alitz, C.J., and Owens, B.D., 2011, “Risk Factors for Syndesmotic and Medial Ankle Sprain Role of Sex, Sport, and Level of Competition,” Am. J. Sports Med., 39(5).
 Gerber, J.P., Williams, G.N., Scoville, C.R., Arciero, R.A., and Taylor D.C., 1998, “Persistent Disability Associated with Ankle Sprains: A Prospective Examination of an Athletic Population,” Foot Ankle Int., 19A(4).
 Fallat, L., Grimm, D.J., and Saracco, J.A., 1998 “Sprained Ankle Syndrome: Prevalence and Analysis of 639 Acute Injuries,” J. Foot Ankle Surg., 37(4).
 Wei, F., Meyer, E.G., Braman, J.E., Powell, J.W., and Haut, R.C., 2012, “Rotational Stiffness of Football Shoes Influences Talus Motion During External Rotation of the Foot,” ASME J. Biomech. Eng., 134(4).
 Hennig, E.M., 2011, “The Influence of Soccer Shoe Design on Player Performance and Injuries,” Res. Sports Med., 19(3).