Recently, Chris Borland, a promising linebacker for the San Francisco 49ers just coming out of his rookie season, announced that he was retiring from football. He retired because he was concerned about chronic traumatic encephalopathy (CTE), a poorly understood neurodegenerative disease associated with head trauma. Over the last several years, concerns about damage from head trauma related to professional football have gotten increasing news coverage. During an interview concerning Borland's retirement, Dr. Joseph Maroon, a neurosurgeon and sports medicine expert who is the team neurosurgeon for the Pittsburgh Steelers, said that it is more dangerous for a child to ride a bike than it is for a child to play football. Hmm. Let's take a closer look.
First, here is a link to Dr. Maroon's complete interview so that you can consider his claim in context. For now, let's pull out some highlights that are relevant to our discussion. Dr. Maroon says:
- There have been 63 cases of CTE from 1954 until 2013.
- There have been 30 to 40 million kids who have played football in that time period.
- There are many more injuries to kids from falling off of bikes and skateboards than there are to kids from playing youth football.
- It is much more dangerous for a kid to ride a bike or a skateboard than it is to play youth football.
Dr. Maroon's comments are very interesting from the perspective of a person studying for the LSAT. Significantly, notice how Dr. Maroon shifts the argument from incidents of CTE to "injuries," generally. This shift is so stark, I originally thought I imagined it and had to go back to the audio to be sure I wasn't just making it up. I wasn't. That transition renders his comparison between football and cycling meaningless. Still, let's give Dr. Maroon the benefit of the doubt and assume that he meant to say that there are more "brain-related injuries" involved in riding bicycles or skateboards than there are involved with children playing youth football.
In 2011 the Centers for Disease Control and Prevention (CDC) put out a report entitled "Nonfatal Traumatic Brain Injuries Related to Sports and Recreation Activities Among Persons Aged ≤19 Years --- United States, 2001--2009." This report actually looked at the numbers relevant to Dr. Maroon's claims and broke them down into a very helpful level of detail. In fact, the detail provided by this report clues us into another issue with Dr. Maroon's position: to which age groups and genders is he referring?
The CDC first looked at all nonfatal traumatic brain injuries (TBIs) for people aged 19 years old and younger, regardless of gender. Given that broad group, it is true that there were more TBIs associated with bicycling (26,212) than with football (25,376). However, consider the rankings when the data is broken down by age and gender:
Source: Centers for Disease Control
As you might expect, football doesn't even make the top five list of activities related to TBIs in girls. When it comes to boys, bicycling and that ever-dangerous "playground" activity top the list of TBI-associated activities for boys nine years old and younger. However, for boys aged 10 to 19, football actually tops the list, followed by bicycling. That holds true for boys aged 19 and under overall. So, for boys aged 19 and younger, according to the CDC, the activity most associated with TBIs is football.
Now, there just aren't many kids younger than four years of age playing football. The youngest age for Pop Warner football is five years old. So, assuming that the CDC data is correct, let's narrow Dr. Maroon's claim to this statement: for boys between the ages of five and nine years old, bicycling is more dangerous than football.
At first glance, that might seem to be a valid statement. But we have to look a bit closer at the data. What the CDC is reporting is the estimated number of emergency room visits associated with each activity. When Dr. Maroon talks about the relative danger associated with bicycling and playing football, he is talking about risk. Essentially he is saying that a child is more likely to suffer a TBI riding a bicycle than he is to suffer one while playing football. However, before we can reach that determination of comparative risk, which is always a complicated subject, we have to know much more information.
At very least, we need to know the numbers involved. During the relevant period, how many times did a boy between the ages of 5 and 9 years old ride a bike, and how many times did a boy in that age range play football? Without that data, we cannot come to any conclusions about the activities' comparative risks.
Interestingly, in Question 22 of the second logical reasoning section of the September 2006 LSAT (PT 50), LSAC tested a data-related flaw very similar to that committed by Dr. Maroon. In that Flaw in the Reasoning question, the stimulus gave just one fact, that more pedestrians in the United States die each year while crossing the street with the light than when crossing the street against the light. Based on this evidence, the stimulus concluded that crossing the street with the light is more dangerous than crossing the street against the light.
The problem with this argument is that we don't have enough context. We need to know how many times people crossed with the light and how many times they crossed against the light. To assess Dr. Maroon's claim, we need to know how many times kids played football and how many times they rode bicycles. Without this statistical context, we can't come up with any reasonable conclusions about risk, let alone comparative risk.
A separate issue is that the CDC data focuses on emergency room visits, situations in which a serious brain injury is suspected. It does not address sub-concussive head contact, in which a player sustains head impact that is below the threshold for being categorized as a concussion, but still has a negative physical impact on the player. These smaller impacts often occur several times throughout a single football game, and the effects are now thought to add up over a player's career. You just don't see repeated sub-concussive impacts in bicycling.
Apart from the mere numbers, the football versus bicycling argument ignores the inherent differences in the two activities. The whole point of football is that players collide with each other. When the game is played as designed, you get violent impacts between players that can result in various injuries, including TBIs.
Bicycling is a very different activity. When done properly, no potentially harmful contact occurs. The point is to get from Point A to Point B as quickly as possible, without falling or coming into contact with anyone or anything. As far as I know, although professional cycling teams have a team doctor, they don't have a team neurosurgeon. It would seem that Dr. Maroon's own employment as the Pittsburgh Steeler's team neurosurgeon is some indication that there is a special relationship between football and brain injury.
There is no denying that the risk of TBI is inherent in children riding bicycles, especially when those children do not wear helmets. But for Dr. Maroon to make the unqualified claim that it is more dangerous for children to ride bicycles than it is for them to play football seems fairly absurd.
By the way, for those tempted to put faith in Dr. Maroon's statistical analysis because he is a neurosurgeon, just know that temptation is an improper appeal to authority, another reasoning error. And let's not go too far and question whether the doctor is intentionally spinning the data because of his professional and financial associations with the NFL. That would be a source argument, or ad hominem attack, which is beneath us as LSAT superstars.
So, what are your thoughts? Do you agree with Dr. Maroon? Have I got it wrong? Weigh in and let me know.
Image: "IMG_6698" by John Martinez Pavliga.