Packers’ Davante Adams is hit by Bears’ Adrian Amos and Danny Trevathan during a September game last season (Matt Ludtke/Associated Press)

ORLANDO — The NFL made what it hailed as a significant safety-related rule change Tuesday, making it a penalty for a player to lower his head to initiate a hit with his helmet on an opponent during a game.

“For us, this is a pretty significant change,” said Atlanta Falcons President Rich McKay, the chairman of the league’s rulemaking competition committee. “This is not situational protection. In the past, whether it’s the college targeting rule or whether it’s our defenseless-player rules, which have a lot of similarities, it’s a situational protection. In this, we’re basically getting to a technique that is just too dangerous for both the player doing it and the player who’s getting hit. Both.”

The rule change comes after a 2017 season in which concussions suffered by players were up and in which Pittsburgh Steelers linebacker Ryan Shazier suffered a serious spinal cord injury on a hit.

“I think this is a very proud day for the NFL,” said Allen Sills, the league’s chief medical officer, “and I’m very pleased to see the overwhelming support that the owners and the coaches and general managers and team presidents gave to this idea that we want to make the game safer, particularly with regard to getting the head out of the game. … This was based on the data and research that we’ve been able to do. We spoke previously this year about having an all-time high in concussions and that we thought that wasn’t acceptable and we wanted to respond to that. And this is part of that response.”

League officials said they studied concussion-causing hits and found the technique of a player lowering his head to deliver a hit to be particularly likely to cause a concussion.

“We’ve seen over the last three years that concussions caused by helmet-to-helmet hits have gone up from about one in every three to nearly one out of every two,” said Jeff Miller, the NFL’s executive vice president of health and safety. “And so we’re seeing a greater incidence of this behavior. And we’re seeing the risky behavior of the technique, based on the engineering analysis and based on the medical advice, is putting both the player doing the hitting and the player being hit at risk.”

The new rule strengthens a previous prohibition against a player using the crown of his helmet to deliver a blow to an opponent. That restriction rarely was enforced. The new rule says: “It is a foul if a player lowers his head to initiate and make contact with his helmet against an opponent.”

This rule, like the crown-of-the-helmet rule, could apply to a ballcarrier who initiates a blow on a potential tackler, as well as to a defender making a hit. An infraction would result in a 15-yard penalty.

The rule also says that the offending player may be ejected by the game officials. However, the competition committee found last season — when it declared that players should be ejected by the game officials or suspended by the league for flagrant illegal hits, even on a first offense — that officials are reluctant to issue ejections and potentially affect the outcome of games without the call being subject to review by instant replay.

This rule is not subject, at this point, to replay review. That element could be added later. But if it is, it would go against the competition committee’s long-standing opposition to making judgment calls by the on-field officials reviewable by replay.

“If you do put replay behind them [the officials], then I do think you have the opportunity for them to be able to feel more comfortable in ejecting them,” McKay said. “But in this rule, we just need to do a little work to understand exactly how the mechanism would work. … No, we’re not over it [the reluctance to make a judgment call reviewable]. But it is enough to say that the result is such that maybe that result needs to be reviewed.”

The league announced in January that, according to its preliminary injury data, concussions suffered by players increased by nearly 16 percent last season over the 2016 season.

Shazier is rehabilitating a severe spinal cord injury suffered during a December game. The Steelers have said that Shazier won’t play in the 2018 season.

McKay said the Shazier play alone was not the impetus for this rule.

“The Ryan Shazier play is a play where he ducked his head and was injured,” McKay said. “I think the impetus was research. The more we saw of the concussion plays and the more there was a common technique, it became apparent that, listen, we need to get out of situationally saying if a player is targeted or if a defenseless player is in the air — we need to get to the technique to protect the person doing the hitting also. It could be Ryan Shazier. It could be many others. I don’t think that play was the impetus because I think that the research and the data was there before. I think it is an example, though.”

McKay also mentioned a hit by Chicago Bears linebacker Danny Trevathan last season on Green Bay Packers wide receiver Davante Adams, for which Trevathan was penalized and suspended. The NFL has existing rules protecting players considered defenseless, including a quarterback throwing a pass and a wide receiver making a catch, from being hit in the head or neck area.

League officials said the conversations about the new rule included representatives of the NFL Players Association and college football. But the NFL did not publicly divulge those deliberations or acknowledge any proposal about the new rule until Tuesday.

“It just seems like players at every level are getting more comfortable playing with their helmets as a weapon as opposed to a protective device,” McKay said. “The helmet was designed to be a protective device.”

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