San Francisco 49ers linebacker Chris Borland shocked the football world last week by announcing that he was retiring from the sport after only one year in the NFL. His announcement stirred controversy among the media, athletes, football fans and parents of young football players. Riding a bike (horizontal)_BPMany predicted Borland’s retirement would become a watershed moment for the NFL, where countless other players would ultimately make the same decision. Others speculated that little would change, as many players would step up to take his place and accept the same risks.

Regardless of how you feel about the decision of a professional athlete choosing to leave while he is still healthy, the debate has introduced a controversial talking point.

Safer than riding a bike?

Last Tuesday, Dr. Joseph Maroon, a neurosurgeon for the Pittsburgh Steelers and a consultant to the NFL’s Head, Neck and Spine Committee, gave an interview to the NFL Network. He discussed efforts the league has made to decrease the risk of head injuries in football. He pointed out that we don’t know the true incidence of chronic traumatic encephalopathy (CTE) and argued that the problem “is being over-exaggerated.”

It was his comparison of the risk of head injuries in football to those from riding a bicycle, however, which drew the most attention.

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“There are more injuries to kids from falling off of bikes, scooters, falling in playgrounds than there are in youth football,” Dr. Maroon stated. “I think again it’s never been safer. Can we improve? Yes. We have to do better all the time to make it safer. I think if a kid is physically able to do it and wants to do it, I think our job is to continue to make it safer. But it’s much more dangerous riding a bike or a skateboard than playing youth football.”

Is this a “smoke and mirrors” comparison?

The comparisons of the dangers of football to those from riding a bicycle are not new. In a 2012 interview with ESPN’s Steve Fainaru and Mark Fainaru-Wada, Dr. Richard Ellenbogen, co-chair of the NFL’s Head, Neck and Spine Committee, made the same comparison.Young football player helmet

“For me it’s all about the kids,” Ellenbogen argued. “Do we tell kids not to play sports any more? What we know from the (Centers for Disease Control) is kids are more likely to get hurt riding a bike or falling down while running. There’s nothing critical in saying that, I’m just putting it in perspective. What are the true risks?”

Chris Nowinski, the co-founder and executive director of the Sports Legacy Institute, a research institute dedicated to advancing the understanding of concussions, criticized the bike riding comparison by Dr. Maroon in The Huffington Post. He had previously responded to Ellenbogen’s comments to Fainaru and Fainaru-Wada, saying, “I think that’s smoke and mirrors; I mean, it’s night and day.”

Problems with the comparison

There are several problems with comparing football to riding a bicycle.

Look at data for boys only. Using the CDC data for nonfatal traumatic brain injuries related to sports and recreation activities between 2001 and 2009 among children 19 years old and younger, bicycling did cause a slightly greater number of estimated annual number of emergency department visits compared to football overall. However, when you look at males only – very few girls play tackle football – the numbers reverse. In the 10- to 14-year-old age group, boys suffered more traumatic brain injuries in football than bicycling. The numbers in football were significantly greater in the 15- to 19-year-old boys compared to riding a bike.

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True incidence rates are hard to calculate without knowing numbers of participants, especially in bicycle riding. These are absolute numbers of injuries, not incidence rates. While we have fairly good estimates of the number of children who play tackle football from high school data and youth leagues, we have little data to determine how many kids ride bicycles. In its 2014 Bicycle, Skate and Skateboard Safety Fact Sheet, Safe Kids Worldwide noted that each month three out of four children in the U.S. ride a bicycle. Given the likely dramatically higher number of kids who ride bikes rather than play tackle football, the incidence rate of traumatic brain injuries from riding a bike is probably much lower than football.

Riding a bicycle does not cause repetitive subconcussive impacts. This data does not account for head trauma not severe enough to cause acute injuries. We are starting to question the effects of repetitive blows to the head in football, like those impacts where offensive and defensive linemen collide during each play. Scientists have not determined the true long-term significance of those blows, but there is growing concern that they could at least play some role in the development of later cognitive impairment. Bicycle riding has no similar repetitive head trauma.

The player whose retirement provoked these arguments, Chris Borland, made this point in an interview on “CBS This Morning.” The former linebacker observed, “You can ride a bicycle and the act of riding a bicycle isn’t causing brain trauma. Yeah, you could fall, but that’s if Youth football linemensomething goes wrong. Everything could go right in football and it’s still dangerous.”

Still much to learn

In his interview with the NFL Network, Dr. Maroon discussed his belief that football is working to become a safer sport. “Having been associated with concussions over many years, I really believe that it’s never been safer before in terms of the sport. The rules changes, the safer tackling techniques, the medical management of concussions is so much better than it ever has been in the history of the sport.”

I truly hope he is correct. I agree with many of the prominent concussion experts who feel that while CTE is real, we do not know its true significance. We cannot conclusively claim that football causes CTE. We need more time and far more research.

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To claim that football is safer than riding a bicycle is misleading, though. And even if kids do suffer head injuries riding a bike, that fact alone does not make football a safe sport.

How do you feel about the football-to-bicycle comparison? Are we overreacting to the risks of head injuries in football? Was Chris Borland’s retirement an impactful moment for the NFL? Share your thoughts below!


Bicycle, Skate and Skateboard Safety Fact Sheet (2014). Safe Kids Worldwide.

Concussion Experts Pick Apart The Myth That Cycling Is More Dangerous Than Football. By Maxwell Strachan. The Huffington Post. March 20, 2015.

Nonfatal Traumatic Brain Injuries Related to Sports and Recreation Activities Among Persons Aged ≤19 Years — United States, 2001–2009. Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report. October 7, 2011.

Study: New cases of CTE in players. By Steve Fainaru and Mark Fainaru-Wada. December 2012.

Note: A modified version of this post appears as my sports medicine column in the March 26, 2015 issue of The Post and Courier.