Maybe someone smarter than me can interpret this, because I’m not understanding how they came to their conclusion. According to this study, the average number of injuries during Sunday games was 21.4 compared to Thursday games at 21.7 but the difference is “negligible”. I feel like they didn’t take into account the fact only one game is played on fewer Thursdays, as opposed to the majority of games taking place every Sunday.
Link to study: http://www.fortunejournals.com/articles/the-effect-of-thursday-night-football-on-injuries-in.pdf
I think over time, it has actually averaged out, but about 6 years ago, an article came out that Thursday games have the least amount of injuries per game. A Sunday game after a bye, meaning the maximum amount of rest, had the most injuries.