Players will be required to wear thigh and knee pads beginning with the 2013 season, the NFL announced Tuesday.
The players' union could still oppose the move because it wasn't collectively bargained.
"While the NFL is focused on one element of health and safety today, the NFLPA believes that health and safety requires a comprehensive approach and commitment," the NFLPA said in a statement. "We are engaged in and monitor many different issues, such as players' access to medical records, prescription usage and the situation with professional football's first responders, NFL referees. We always look forward to meeting with the NFL to discuss any and all matters related to player health and safety."
Atlanta Falcons president Rich McKay, chairman of the competition committee, said at an owners meeting Tuesday that the league can implement it unilaterally because it is a playing rule, according to multiple reports.
The rule won't go into effect until 2013 to give equipment manufacturers time to work on safety and comfort.
Whether the new rule will help prevent concussions and other injuries was a popular topic at the Broncos' practice Tuesday.
"That's great for high school kids and college kids, but I don't know," said Broncos defensive tackle Justin Bannan. "I think if you're going to have an injury happen, a knee pad or a thigh pad isn't going to save you. I had a thigh pad on and gotten just as deep of a thigh bruise as you can have with the thigh pad on."
Other rules changes intented to reduce concussions include redesigned helmets.
"They're changing a lot of things, helmets. I've been wearing the same helmet for 15 years. Champ (Bailey has) been wearing it longer than me," said Broncos cornerback Drayton Florence, who is also an NFLPA representative. "This year we have to switch to a new helmet because of concussions and things that have been coming up - the thigh pads. My opinion is that I don't want to wear them but you have to follow the rules and policies."
Meanwhile, other players applauded the new rule.
"I'm a believer in it. I've been wearing them since my rookie year," said cornerback Tracy Porter, who joined the Broncos this offseason from the Saints. "Some guys are superstitious to say that wearing the thigh and knee pads slows them down, but for the most part, I think it's a myth. I still feel pretty fast when I'm out there with thigh and knee pads. It's all about what a guy likes."