Injuries will always be present in sport, especially those as physical as American football. However, that hasn’t stopped the NFL from passing new or updating old rules in an attempt to cut down on injury occurrence and make the game safer for its athletes.
But have the league’s various rule changes over the years actually reduced injury trends?
A new study published in BMJ Open Sport & Exercise Medicine argues that they haven’t. “Our data support the argument that new, well-intentioned rules adopted every season by the NFL have been proven to be too weak to make the NFL game safer,” writes the research team out of the University of California – Irvine, the University of Houston, and the Baylor College of Medicine.
The research team scoured publicly available injury reports (including the postseason, but excluding the preseason) and included every injury that caused an athlete to miss at least one game over the course of the past 10 NFL seasons (2010-19) in their analysis. The team also looked at how many games each individual athlete ultimately sat out due to their specific injury. Each injury was categorized as occurring at the leg, arm, back, or head.
Additionally, the research team looked at each rule change that was designed to improve player safety and adopted by the NFL before every season and determined which specific body region – leg, arm, back, head, or whole body – the rule was aimed at protecting. Injury occurrence in each body region was then compared between the season the rule was adopted and the season previous to determine the acute impact of the rule change. A correlation between number of injuries and number of rule changes adopted prior to each season was also calculated.
The researchers discovered a few notable trends in the data over the 10-year timeframe:
- There was no statistically significant* change – positive nor negative – in the number of NFL athletes who suffered leg, back, or head injuries.
- “A small but statistically significant increasing trend” in the number of arm injuries was noted.
- There was no statistically significant change in the amount of games missed due to injury of the leg, back, or arm.
- There was a “strong increase” in the number of games missed due to head injury (i.e. concussion).
- Rule changes adopted for protecting the arm and head were correlated with a decrease in games missed due to arm and head injuries; however, this correlation lasted only one season.
- There was no correlation between number of rules adopted and games missed year-to-year.
(*Statistical significance is defined as the likelihood that the data discovered is produced by something other than chance. Usually if the p-value – the term used to define statistical significance – is smaller than 0.05, it is determined that the data was unlikely to be produced by change alone.)
The findings of the research study may come across as eyebrow raising. After all, one would assume that changes to the rules aimed at protecting players would have a positive impact on athlete health.
The research team made no assumptions when beginning their research, however. “We really had no preconceptions [about what the results would be] going in,” wrote Dr. Bhavin Sheth, one of the co-authors of the research article and Associate Professor within the University of Houston Cullen College of Engineering, in an email correspondence with me. “What really guided us was that the NFL provides statistics on season-to-season changes, but information on trends over longer time spans was not easily available, at least to us. Moreover, the NFL focused on a single measure: number of injuries. However, whenever a single measure is provided of anything, it is human nature to game it. We are not saying that is what is happening in the NFL, but it has been a common undercurrent through nearly all of human enterprise over generations.” (Click here for NFL player health and safety reports for the 2012-2019 seasons.)
The research team used the example of concussions within their research article to demonstrate the point of the NFL potentially being able to “game” their data. They write, “According to the NFL, a lower number of diagnosed concussions is a sign of progress, but so is a higher number, because the NFL claims that a higher number points to a sign of ‘culture change’, a point that was made in 2016 and again, back in 2010 when the number of concussions first showed an uptick compared with the year before.”
An example of rule adoptions that recently generated buzz within the football community was the XFL’s unique kickoff rules directed at reducing high-speed collisions and athlete injuries. The rules are backed by sound logic – high-speed collisions are a major source of injury, particularly concussions, and the NFL has adopted rules in the past aimed at reducing their frequency during kickoffs; however, Dr. Sheth is unsure if the NFL adopting similar rules would improve player safety. “Kickoffs are but one part of the game where players get injured. More pertinent to our findings, what we find puzzling is that the NFL has adopted a lot of new rules and whereas there is a correlation in the short-term (i.e. in the season immediately following the rule change(s)) between rule changes tailored to protect a specific part of the body and a reduction in time missed due to injuries to those specific parts, the reductions do not appear to persist over subsequent seasons. This would mean that while rigorous rules (e.g. during kickoffs) may work to help the numbers in the short run, it may not matter over the long run.”
As for what the NFL can do to help improve the health and safety of its athletes, Dr. Sheth argues that the answer is a simple, yet difficult, one. “Figure out why rule changes to protect the player only appear, at best, to work for one season but not over subsequent seasons. I have no idea [why this] could be happening – maybe the teams learn to work around the new rules with new plays or schemes or just learn to conceal the infractions better, or the new rules are not as strictly enforced over subsequent seasons, or any number of other reasons.”
Or to put it more simply, “More rigorous rules, in general, sounds like a good idea.”
