The NFL’s chief medical officer became the latest expert to downplay the notion that the rash of injuries suffered by the San Francisco 49ers over the past two seasons is due to the team’s practice fields being close to an electrical substation.
“Listen, I would say we look at injury causation across the board,” Dr. Allen Sills said Friday during the league’s health and safety call. “We consult with experts throughout sports medicine and other industries to try to understand and gain as comprehensive an understanding of injury causation as we can.”
He continued, “I would tell you that I’m not familiar with anything in the sports medicine literature that supports those associations, but I would also tell you that injury causation is really complex.”
The 49ers have been practicing at the same facility in Santa Clara, Calif., since 1988. It is next to Levi’s Stadium and adjacent to the Silicon Valley Power Mission Substation. The team has struggled with injuries in recent seasons, with fantasy football website Rotowire ranking them fourth worst in the league in injuries in both 2024 and 2025, and a viral conspiracy theory posits the injuries could be linked to excessive exposure to electromotive force (EMF), the invisible electricity from power lines and other electrical equipment.
“If you think about biology and medicine, you don’t have usually one single factor that drives biological systems. And so when we think about injury causation, whether it’s lower extremity strains or ACL or concussion, you know, as we’ve already talked about on this call today, it’s equipment, it’s training, it’s prior injury history, it’s exposure, it’s play type. There’s so many things that go into that. And so, I think it’s very rare in a biological system that you’ll see one factor that really drives an injury risk,” Dr. Sills said.
“So with that being said, we look at all factors. We look at it very comprehensively. I think it’s also important … to say that we have seen significant erroneous conclusions drawn from people using publicly available data sources. And what I mean by that is there’s research that often gets published where people take injury reports that are distributed media and use that to try to assess an injury burden. And those are almost universally wrong because they’re just not complete, and they’re not complete because they don’t have all the data because not everything gets put into those disclosure systems.”
Still, while some may give little weight to the idea that electromagnetic waves can increase the risk of injury, 49ers general manager John Lynch would not dismiss it publicly when asked during the team’s season wrap-up media session.
“Because it deals with, allegedly, the health and safety of our players, I think you have to look into everything,” Lynch said when asked about it. “So, our guys have been — we’ve been reaching out to anyone and everyone to see, does a study exist other than a guy sticking an apparatus underneath the fence and coming up with a number that I have no idea what that means? That’s what we know exists. We’ve heard that debunked.”
Despite the spread of the conspiracy theories, Frank de Vocht, a professor of epidemiology and public health at Bristol Medical School in England, previously told The Washington Post that attempts to link the power station to the 49ers’ injury woes were “nonsense.”
Another expert, Hans Kromhout, a Utrecht University professor of exposure assessment and occupational hygiene, told The Post that it’s “quite unlikely” that EMFs could cause the kinds of tendon and ligament injuries that have plagued the 49ers for years.