Is the Rise in NFL Injuries Caused by Improper Footwear?

Picture this: It’s Sunday in Green Bay, Wisconsin and you’re a faithful Packers fan wearing your infamous cheesehead awaiting a sure to be frigid game at Lambeau Field. You check the lineup and wonder what is causing the sudden onslaught of injured players like wide receiver Jordy Nelson (knee), linebacker Sam Barrington (foot), defensive end Josh Boyd (ankle), tight end Andrew Quarless (knee), safety Morgan Burnett (calf), wide receiver Davante Adams (ankle), linebacker Clay Matthews (ankle)…you get the point. All player injuries listed were lower extremity non contact injuries. What is causing this upward swing of lower extremity injuries that has plagued every team in the NFL for seasons? Could it be the playing surface? The new NFL tackling rules? The footwear? Or is there no answer as Walter Thurmond of the Philadelphia Eagles puts it, “You can’t make a vicious game safe at the end of the day.” The graph below, provided by Zachary O. Binney of Footballoutsiders.com illustrates the upward swing in overall NFL injuries from 2002-2014. As you can see, all three categories have steadily increased with a large continual spike around 2012.

# of injuries + weeks missed due to injury 2002-2014

Other Possible Causes Affecting the statistics

What about other possible causes affecting the injury statistics? In 2013, Pat Kirwan, an NFL insider and writer for CBS sports interviewed numerous podiatrists and NFL team doctors. The purpose of their study was to determine whether footwear or playing surface contributed to more injuries. Regarding artificial turf fields, an NFL team doctor stated, “the new synthetic field surfaces create too much traction, especially when players wear traditional screw-in spikes to dig in deeper on those fields.” While this is a valid claim, there is not enough recorded data to prove the correlation between field surface and the lack of specialized turf field equipment as the combined cause.

Another possibility is the NFL’s recent emphasis on tackling lower towards the legs instead of the upper body with the intent of reducing concussions. However, players like Miami Dolphin’s tight end Dustin Keller who explained to Bleacher Report that a common theme among players in the NFL is the desire to be tackled high because even if they receive a concussion, their season is not likely over. If they tear an ACL or rupture an Achilles as a result of a low tackle, then their livelihood is taken away for at least one season. A concussion Is essentially an opportunity cost that they’re willing to pay.

# of NFL regular season weeks missed

 Focusing On Lower Extremity Injuries

According to the graph on the left provided by Zachary O. Binney of Footballoutsiders.com, 63% of the top 11 most common injuries in the NFL over the past 15 seasons occurred to the lower extremities. From 2000 to 2014 (15 seasons), 30,186 injury reports have been filed, leading to 51,596 regular-season weeks missed, an average of 1.71 weeks missed per injury. In such a brutal sport you’d think wearing the most protective equipment money can buy would be the goal, but these days’ football requires even the biggest players to be agile and explosive while the most protective equipment tends to be cumbersome and bulky. As stated in an article on footballbyfootball.com, “Football cleats have become much lighter, yet less durable; more attractive, yet less supportive.” which is somewhat ironic since the ‘sole’ purpose of shoes is for protection. We have 33 joints and 52 bones, or 25% of the total bones that make up the human skeleton in your feet and ankles. When you run, the pressure on your feet can be 3-4 times that of your body weight. Without healthy feet how can we ever expect to perform at our highest level?

Let’s examine the cleats on the bottom of every shoe in the NFL

Cleats are applied to shoes to prevent slipping and falling but are in no way performance enhancing, but this is how they are being marketed to football players of all ages. The formula looks something like this: lighter cleats = faster player = better football player. However, what truly makes a player better is repetition which is impossible for a player to gain if they’re constantly sidelined with injuries.

According to Dr. Wannop of the Human Performance Lab in Calgary, AB, “Each cleat has two type of traction: translational traction keeps you from slipping as you move forward and the other, called rotational traction factors in when you shift direction. The amount of cleats on each shoe is determined by the shoe’s material, the size of cleats and the positioning of cleats on the shoe.”

In Dr. Wannop’s recent case study at the Human Performance Lab at the University of Calgary, his team of researchers wanted to test whether different degrees of traction would affect whether players got hurt in real life playing conditions. The researchers created a shoe wearing robot mounted on rails that can move in any direction while the feet stay in contact with the ground. By utilizing various sensors, they were able to determine distinctions between forward and rotational traction. The consensus among the researchers was that forward moving traction, or translational traction has no effect on injury risk while rotational traction does. However, this has been difficult for researchers to study as it cannot be done in an ethical way: you can’t ask athletes to wear faulty shoes with hopes of them injuring themselves for the sake of the study.

Dr. Wannop’s Case Study Details

Over the span of three years the researchers recruited 555 of the top high school football players and borrowed their shoes- most of which are the exact same shoes used by top NFL players. Many of the high school players had experienced non contact injuries to their lower extremities, but frequency and severity of the injuries were among those players whose shoes provided the most rotational traction. In addition, players whose shoes provided the most forward traction developed the fewest injuries. Dr. Wannop, the primary researcher on this study stated that “the finding was unexpected because it had been thought that any shoe with high forward-motion traction would also automatically have high rotational traction and so would increase injury risk.” But this was not the case; some shoes gripped the surface as players ran forward but didn’t stick when they cut sideways and those shoes were the safest. Dr. Wannop stated that “for the ideal mix of athletic performance and reduced injury risk in sports, a shoe should have high translational traction values and relatively low rotational traction values.” What this looks like is a shoe that has groupings of shorter cleats in the forefoot and doesn’t have large toothy cleats or rubbery nodules along the outside of the sole since those cleats create too much rotational traction.

Dr. Wannop stated, “Cleats with too much rotational traction produced injuries at a rate 3.4 times higher than that of all other designs combined because when there is too much rotational traction the shoe sticks in place causing increased stress without additional support around the ankles and knees.” Many of the football shoes worn today resemble ballerina shoes rather than football cleats and any athlete knows once you injure a part of your body the risk of reinjuring the same body part increases.

Jeff Hall’s Opinion

In a different article, Jeff Hall, editor in chief of podiatrytoday.com claims that football cleats lack necessary arch support that many athletes need to remain stable. He also claims that most NFL teams lack necessary preseason foot and ankle screenings and should seek more input from podiatrists when selecting appropriate footwear for their athletes as this would likely have a favorable impact on reducing the number of lower extremity injuries at all levels of the sport.

Majority of Opinion

While there is no clear cut answer for the specific cause of increased injuries, it’s safe to say that improper or inadequate football cleats does in fact have a substantial influence on the likelihood of incurring a non contact injury to your lower extremities.

Please click on these resources for more in depth analysis on this topic:

Bumps, Bruises & Breaks

The above image provides an alternate view of NFL injuries from the 2014 NFL season prior to the Super Bowl courtesy of the Wall Street Journal.

Individual Case Studies

Zachary O. Binney

Pat Kirwan

Jeff Hall

Dr. John Wannop