NFL players more likely to injure knee after shorter rest period

Knee injuries are the most common in the NFL, though this study looked specifically at a rupture or tear of the extensor mechanism, the combination of muscles and tendons that allow the knee to straighten.

"The extensor mechanism is critical for knee stability and joint extension, and such an injury could threaten an athlete's career," study author Dr. Steven DeFroda said. "Damage can make it very painful to walk, let alone play."

Using publicly available data from the 2009-2023 seasons, researchers determined that players were 3.7 times more likely to suffer a tear during a short rest week than a long rest week or resting less than seven days versus a period of over seven days.

Players were also 4.7 times more likely to suffer a tear during a normal rest week, or for exactly seven days, than long rest weeks. DeFroda and his team found no meaningful difference when comparing injury risks after short and normal rest weeks.

"This does highlight that certain injuries likely occur because of 'microtrauma' that accumulates over a long season, and that longer periods of rest could be warranted for athletes, especially if they are showing signs of fatigue or an inability to recovery between games," DeFroda said.

They also found no association between player position, age or weight -- however, there was an increased risk of ruptures for players when playing on artificial turf versus playing on grass. This corresponds with other research that suggests more injuries occur on turf, since rubber and synthetic fibers don't absorb as much impact force.

"Studies like these can help us think about how athletes get injured and work on strategies to prevent some of these injuries from occurring," DeFroda said. "Recovery time and the cumulative effects of injury are crucial to monitor, especially as athletes play more games and in a shorter time span than ever before."

Steven DeFroda, MD is an orthopaedic surgeon at MU Health Care and an assistant professor of orthopedic surgery at the MU School of Medicine. He also serves as an official team doctor for the Mizzou Athletics volleyball, baseball and softball teams, and has served as an assistant team physician for the Chicago White Sox, Chicago Bulls and Chicago Fire.