Selecting the right footwear to minimise injury risk and increase performance

What impact can selecting the “wrong” football boots have on injury risk?

It’s hard to define what the “wrong” boot is for a player. Like everything in sport, context matters.

Ideally, the boot should match the surface type, weather conditions, positional demands (e.g., strikers and goalkeepers look for different things in their boots), the level of traction or grip that feels good, and, last but not least, each player’s unique foot shape.

Modern football boots are the Swiss Army knife of sports equipment. Think of all the tasks players perform: shooting the ball, jumping, accelerations and decelerations, dribbling, curved runs, walking, changing direction… One pair of boots has to handle all of these (and many more) with a sufficient level of comfort, on top of which we can layer performance, injury prevention and healthy movement.

Just consider how a boot fits your foot. There are huge variations between individuals in foot anatomy and, subsequently, foot shape. Football boots should mirror a player’s unique foot shape and feel comfortable for the whole match.

Players frequently wear boots a few sizes too small so they can get a better “feel” for the ball. But this tendency can lead to decreased performance and increased injury risk.

Comfort is important to performance and an indicator that something is going wrong.

Ill-fitting boots commonly lead to cramping or numbness at the forefoot, blisters, or damaged or bruised toenails. Boots that are too stiff or too flexible, or that bend at the wrong place, can cause or contribute to plantar fascia and metatarsal issues. Suboptimal traction at the shoe-surface interface can lead to decreased performance via slippage (too little traction), or increased chance of injury due to the boot / foot getting trapped on the playing surface with too much traction.^[5]

Of course, there will always be those players who can put almost anything on their feet and do just fine. They are the lucky ones, not the ones we should be basing best practices on!

What would your checklist be for players when selecting boots? How do you navigate the conversation with so many players being “a Nike guy” or “an adidas girl?”

Individual football boot preference is complex and contextual. If you have a particularly strong experience – say, scoring a hat trick in your first game with new boots or, on the other side, rupturing your ACL after feeling your foot get “stuck” on the surface – it will likely drive how you approach that boot or brand going forward.

Because individual preference and context is paramount, generalizations are difficult, but here are some basic tips or starting points:

• Choose a boot that best mirrors your individual foot shape. Comfort goes above all things. Poor foot or lower limb comfort is linked to increased injury risk ^[1] and decreased performance ^[3]. One simple fit test is to compare the shape of the removable sock liner or insole to your foot shape. Take the insole out and stand on it with your heel at the appropriate place and your normal football or grip socks on. Check the length, width and general shape. If your foot is “spilling” over the insole at the 5^th metatarsal area, for example, then try some other boots on until you find a better fit.      
  • There is an individual “sweet spot” for bending stiffness, i.e., how much force is required to bend the shoe along the long axis. Too much or too little bending stiffness can affect performance and injury risk. Too much stiffness may increase calf muscle demand, while too much flexibility may increase the demands on the 1^st metatarsal-phalangeal joint and plantar fascia.Match the outsole type (studs / cleats) to the weather and pitch conditions. AG for artificial pitch, SG for soft wet pitch, etc.
  • Women’s specific football boot designs are finally on the way! Until recently, most football boots have been based on male foot lasts. With large running shoe brands now making shoes from millions of 3D foot scans of womens’ feet, it makes sense that football boots will be next to follow.

Dr. Katrine Okholm Krgyer from St Mary’s University in London has research coming out very soon on foot shape in professional and international women’s football players, and it will be a must read for anyone working in the sport.

Each brand produces so many different boot models that it’s more about finding the one that suits each player best rather than trying to talk a player out of a certain brand that they like. 

Should young athletes be looking for anything different when it comes to boots? If so, why?

Yes. Young players might benefit from some key characteristics.

We conducted a study asking male Academy football players what they wanted from their boots. We also asked medical and performance staff about their experiences with how adolescent players select or alter their boots, and where the players suffer discomfort or issues related to boot fit.

Over 76% of Academy players reported issues at the heel area, followed by 50% at the hallux and 33% at the 5^th metatarsal.

Blisters were the greatest issue, which is understandable given the rapid growth rates and changing foot morphology of this age group. Fit is therefore very important, especially around the heel. Buying boots that are already a tight fit for “feel” means the boot is unlikely to fit well for long.

The 5^th metatarsal should not hang over the lateral edge of the outsole plate. Boots need to be wide enough to support this area.  Encourage the use of boots with a removable insole in case you need to replace it with an orthotic to help manage heel pain.

Generally, some kids’ boots or youth boots are made with inferior materials to keep the costs low. Try to find last season’s colour at a reduced price. Often the boot is exactly the same as the full price version currently available, just with a different colour scheme.

Are there any considerations around what boots to wear (or avoid) during and after certain injuries?

High rotational traction (grip) between the shoe and surface increases lower extremity injury risk ^[2,8]. High rotational forces can be problematic for players returning from an injury that has a rotational mechanism, such as anterior cruciate ligament trauma or ankle syndesmosis sprain.

During the early on-field rehabilitation phase, it’s best to use an outsole that has good straight line (translational) traction but allows the boot to release from the surface easily when rotated.

A few of our studies at Aspetar showed large variation in the magnitude of rotational traction (torque) when testing how boots release from the playing surface. Outsoles that have short, round moulded studs tend to release easier than longer metal screw-in studs or large bladed cleats (Figure 2).

After bone stress injuries such as a metatarsal stress fracture, it’s important to keep plantar pressure evenly distributed. This can be done with many shorter, moulded round studs instead of a few longer studs or blades that are further apart. Studs should match the surface hardness and soil moisture to ensure there is penetration all the way to the sole plate. Some boots also are starting to incorporate cushioning at the forefoot or metatarsals.

Do you have any recommendations for practitioners to help players make the most appropriate boot selection on a daily basis? I heard of one club testing the surface daily to get a gauge on how soft the ground was so they could inform the players which stud fit the conditions best. Would you recommend this approach?

Objective data can be useful. FIFA, UEFA and other governing bodies set windows or thresholds for pitch surface conditions to make sure there is good playability and minimise the risk of injury. Ground staff often measure properties such as hardness or soil moisture using specialized tools. Along with weather conditions, this can help players make more objective decisions about which outsole to use for that training session or match.

The key is to never match a high traction surface to a high traction outsole group (or the reverse, low to low).

If there isn’t pitch data available, players can use their intuition by running a short “traction” course in a few pairs of boots to see what feels right for them that day. This could be crucial for those returning from a career threatening injury.

What are the biggest mistakes you see young practitioners / clinicians make, and what advice would you give them to help?

During my Ph.D. studies I was part time in the clinic seeing players with foot and ankle issues, part time at a turf research and development centre, and part time using equipment that mechanical engineers would construct to measure how football boots interact with different playing surfaces.

Developing “range” (as author David Eptein calls it) across these multiple disciplines or interests has been incredibly useful as my career has progressed. Now, when I meet a football player returning from a career threatening injury, I can speak to the ground staff and understand that side of things, along with the boot manufacturers, and the medical, sports science and strength & conditioning team.

I would say don’t be afraid to respectfully reach out to colleagues whose work might seem a little far from what you do day-to-day. The “stay In your lane” mindset doesn’t apply to all things, especially learning.