Running Back Injuries: Injury Rate Increases in High Leverage Situations Show Why Committees Have Become Popular

By Jason Lisk
Aug 24, 2011, 2:00 PM EDT

I’ve spent a fair amount of time over the years looking at running back workload issues and trying to measure injury rates, many of which are linked in the piece I wrote on the Curse of 370 and injury rates. I also talked about why I thought rush attempts mattered more than receptions.

"High rush attempt games are highly correlated with teams that won the game. Why should that matter? Because teams that are winning tend to run the ball heavily late. The distribution of runs is not uniform throughout the game. The difference between a 20 carry back and a 28 carry back may be 8 carries, but it’s probably not 2 carries every quarter. The 28 carry back probably has a quarterly distribution more like 7-5-6-10, while the 20 carry back is more uniform. The high workload rushing attempt guy, then, is getting a greater percentage of carries in the fourth quarter, when he may be tired. Those carries are more likely to come consecutively, when his team wants to run clock, and the other team knows they are going to run the ball. Running the ball is a risk every time, running the ball fatigued, though, is a greater risk to cause damage that will show up in the near future."

Today, I’m going to look at it a little differently. That was some theory as to why serious injury rates were higher in the immediate aftermath of high carry games. Now, I’m going to hold the total touches constant, irregardless of the distribution between rushes and receptions, and look at injury rates in backs who had the same amount, dependent on the score margin in the game. Using the pro-football-reference game finder, I used all backs who had exactly 30 official touches in a game since 1990, and recorded the final score margin, as well as whether the back showed up with an injury causing missed games before they got to an additional 40 touches after that game. Here are the results:


Just so you are reading that correctly, there were 18 backs who had exactly 30 touches when their team won in a blowout by 22 or more points. Only one got hurt soon after (Travis Henry in 2003 following the 31-0 opening week win over New England). 15 of the 69 players who had exactly 30 touches in a close victory turned up with an injury soon afterwards (21.7%), the highest of the group.

Though there are exceptions, I think this speaks fairly well for coaches that they have some sense of where players’ thresholds are. You are not going to give 30 carries to a guy who can handle only 10 touches and watch him literally disintegrate on the field. If you are going to overdo it with a player, it will be just barely, with an extra few touches late. The fact that the injury rates are directly related to the leverage of a particular situation, with close victories being the highest, shows that coaches are taking risks when they are more valuable to the team. Even in those close loss situations, more than half of the injuries involved games where the player’s team had the lead or was tied late (or lost in overtime).

While it speaks to coaches having some general understanding of how much they can use a player, I also think it is further evidence of why committees have become more en vogue in the last four seasons. At the outset of a game, a coach doesn’t know how high leverage the situations later in the game will be, so he must plan for contingencies. Even though wins are important, an injury rate around 20% for leading backs used in these situations, particularly when they tend to be costly injuries that can alter careers and cause significant missed time is too heavy to risk tacking those extra carries late. The solution: more cases where the lead back splits time early, so that he is fresh when needed in high leverage situations, or where a different back operates as the “closer” late in games to take those punishing hits where the defense knows what is coming.

[photo via Getty]