The NFL Players Association took action Monday on behalf of Adrian Peterson, who remains on the commissioner's exempt list despite reaching a plea deal on an injury-to-a-child charge in Texas.

The NFLPA filed an expedited, noninjury grievance to seek reinstatement of the Vikings running back, who has missed eight games after he was charged on Sept. 12.

The NFLPA said in the statement the move was made "based on the explicit language in a signed agreement dated September 18, 2014. We asked the NFL to honor the terms of that agreement last week and as of now, they have failed to respond or comply."

Peterson, who pleaded no contest on Nov. 4 to a misdemeanor charge of injuring his 4-year-old son with a switch, can't return to the Vikings until the NFL reviews the case. The Vikings have deferred to the league in the matter, noting in a statement Monday that "at this time his potential reinstatement is under NFL guidelines."

Under terms of the collective bargaining agreement, an expedited grievance must be heard within seven days, and a ruling must be issued within five days following the hearing.

The NFL responded Monday night with a statement of its own.

"We have received the NFLPA's grievance on behalf of Adrian Peterson,'' the NFL statement read. "We have honored our commitment to Mr. Peterson and the NFLPA not to process or impose any discipline until the criminal charges pending in Texas were resolved.

"When Mr. Peterson decided not to contest criminal charges, we promptly advised both him and the NFLPA that we were prepared to consider what, if any, discipline should now be imposed under the Personal Conduct Policy. We asked Mr. Peterson and his representatives, including the NFLPA, for relevant information. We have not received any of the requested information, but remain prepared to schedule a hearing and make a determination as quickly as possible based on as much information as available.''

The Vikings initially deactivated Peterson against the Patriots during Week 2 just before he flew to Houston and was booked in Montgomery County. They reinstated Peterson the following week, only to place him on the exempt list after public backlash.

"When those decisions are made [by the NFL], we can make decisions," Vikings coach Mike Zimmer said. "Until then, really our hands are tied. There's nothing we can do about it other than what I've said all along. We love the kid. He's done everything I've asked him to do. And we support him. We want him to get through this for him, for him. Then we'll worry about all the other things we have to deal with at the time."

The Vikings are 3-5 in the 2012 NFL MVP's absence and have relied on Jerick McKinnon and Matt Asiata in the backfield.

"If he walks through those doors, we'll be excited," wide receiver Greg Jennings said. "If he's not, he hasn't been here so this is the expectation that we have. We have to move on without him. If he does come, he's here but right now our focus is winning ballgames."

Rudolph close

Tight end Kyle Rudolph inched closer to returning to the field. The Vikings didn't release a practice report, but Rudolph participated throughout the open portion of practice to the media.

Rudolph worked with the tight ends individually and then caught passes from rookie quarterback Teddy Bridgewater.

"He ran routes and did more than individual [work]," Zimmer said. "… We're hopeful, but we'll see as the week goes on."

Rudolph has missed the past six games while recovering from sports hernia surgery.

Bubble coming

The Vikings practiced indoors due to the wintry conditions, but that won't be common this season. Zimmer said the team has purchased a heating device for the outdoor practice fields to keep them from freezing, but it hasn't arrived from Europe. The Vikings weren't anticipating snow this early, but they plan to practice outdoors as often as possible once the heating bubble arrives.