Despite their victory over the Arizona Cardinals last night, the Seattle Seahawks were ravaged by injuries. Because the game came four days after Seattle’s last game, it is tempting to blame the short week for the injuries. Indeed, this seemed to be the sentiment after the game, with Doug Baldwin and Richard Sherman, among others, voicing strong displeasure with playing on a short week.
While the medical literature has consistently found an association between muscle fatigue and the rate of muscle strains, it is not clear the extent to which the difference between 3 days off (playing on Sunday and then on Thursday) and 5-6 days off (playing on Sunday or Monday and then on Sunday) translates to higher injury rates.
I have been looking around for studies that measure whether playing on Thursday is associated with an increase in injuries and found three pieces of evidence.
Measuring the association between Thursday games and injuries
First, in 2013, NFL spokesman Brian McCarthy wrote the following:
In 2012, the injury rate for Thursday games was 5.2 per game versus 5.3 in games played on Saturday, Sunday and Monday. Concussion rates for games played on Thursday were also similar to games played on other days. A comparison of injury information between Thursday games and games played on other days dating back to 2009 provided similar results. The information showed that there is no greater injury risk playing on Thursday than on Saturday, Sunday or Monday.
Of course, the NFL has shown that it is hardly a reliable source when it comes to being honest on player safety issues (see: the past few decades of concussion denial). So let’s move on.
My results indicated nothing exceptional about games played with less than a week of rest. Injuries occurred at almost exactly the same rate in Thursday night games and post-Monday night games (31 injuries in 30 team-games, for a rate of 1.03 per team-game) as they did on regular Sunday games (204 in 202 team-games, 1.01 per team-game).
When I limited the sample to just Thursday games, which have two fewer days of rest than post-Monday night games, the injury rate did increase slightly to 20 in 16 team-games. However, a binomial test revealed that this rate is still not significantly different from the proportion of injuries that occur on Sundays. It appears that Thursday night games pose no added danger to players after all.
Third, there is a forthcoming piece on footballoutsiders.com that also does not find an increase in injuries after Thursday Night Football:
I trust players who tell me they're more hurt w/ just 4 days rest. But the numbers DON'T show an increase in injuries (per injury report) during TNF. Article coming later this month @fboutsiders!https://t.co/3M3wq3U2PS— Zachary Binney (@zbinney_NFLinj) November 10, 2017
Richard Sherman’s injury
While the above studies fail to find an association between Thursday games and injuries, what about the specific case of Richard Sherman, the most damaging injury that Seattle sustained last night?
Dr. David Chao, former team doctor for the San Diego Chargers, does not believe that Sherman’s injury was caused by the short turnaround:
Would Richard Sherman’s Achilles injury have happened on seven days rest? Probably. Three more days of rest/healing would be unlikely to prevent the rupture. The injury happens with an eccentric load where the muscle overpowers the elasticity of the tendon.
Tendons don’t heal in three extra days.
After the game, Sherman revealed that his achilles had been bothering him since the game against the Los Angeles Rams, making it sound like a rupture was inevitable.
Thursday Night Football going forward
This is not an argument that Thursday Night Football is good or should continue: even if it were the case that Thursday night games don’t cause excess injury rates, that doesn’t mean that Thursday Night Football is a good thing. Asking players to play two games within five days is unreasonable, and I completely understand why the players don’t like it. Proposals to remove one preseason game and replace it with a second bye week that teams would have before Thursday games seem like a good step forward.
However, football is a violent, brutal sport. We may notice injuries more on Thursdays, but thinking that getting rid of Thursday games will bring an end to games like yesterday is wishful thinking. Games like yesterday happen on Sundays, too:
Earl Thomas, C.J. Prosise, Ryan Mathews and Darren Sproles all could be out for multiple weeks after getting hurt in a punishing contest [...] In total, 17 players left the game for at least one play due to injury. For Seattle, that included strong safety Kam Chancellor, left tackle George Fant and linebacker Brock Coyle, all of whom returned. Starting cornerback DeShawn Shead felt something in his hamstring during Saturday’s walkthrough and could not get loose on Sunday, playing just sparingly in the first half. His replacement, Neiko Thorpe, had to leave in the fourth quarter due to cramps.