Starting running backs Arian Foster of Houston, Matt Forte of Chicago and Trent Richardson of Cleveland were sidelined for part of their games Sunday.
With one week remaining in the regular season, the Texans will be monitoring Foster's heart after he was removed from a loss to Minnesota with an irregular heartbeat.
"I'll be OK," Foster said. "It's a very minor situation, so I'll be OK."
Foster, the team's leading rusher, left the game after gaining 15 yards on 10 carries. He also had two catches for 14 yards. His last play came with about nine minutes left in the third quarter.
Coach Gary Kubiak said Foster had experienced the problem once before in practice.
"He calms down and he's fine," Kubiak said.
The medical staff told Kubiak that Foster was OK late in Sunday's game and could return. But Kubiak thought it best to give him the rest of the game off.
"I know they're on top of it and he's feeling fine," Kubiak said.
Forte gained 88 yards in 12 carries, including a 4-yard TD run in a win at Arizona before leaving with a right ankle injury early in the second half.
Chicago safety Chris Conti left the game in the first half with a hamstring injury.
Late in the fourth quarter of a loss at Denver, Richardson was carted off the field with a left ankle injury; the Browns offered no report on the injury.
Earlier, fellow rookie Brandon Weeden hurt his right shoulder when Von Miller crashed into the quarterback.
Weeden slammed his helmet to the ground on the sideline and walked slowly to the locker room.
Earlier in the game, cornerback Sheldon Brown left with a head injury after colliding with Broncos receiver Brandon Stokley. Brown was trying to cover Demaryius Thomas over the middle of the field when he bumped into Stokley.
Broncos cornerback Tracy Porter left with a concussion in the first quarter.
Oakland quarterback Carson Palmer hurt his back in a loss at Carolina.
Palmer was flushed from the pocket late in the first quarter, rolled right and stopped to set up. That's when defensive end Greg Hardy came in from behind and hit Palmer in his lower back with the crown of his helmet. Officials flagged Hardy for unnecessary roughness because he led with his helmet, resulting in a 15-yard penalty and an automatic first down.
X-rays on Palmer were negative.
Also, Raiders DB Phillip Adams (groin) and safety Tyvon Branch (foot) were sidelined.
San Francisco tight end Vernon Davis sustained a concussion against Seattle after getting hit along the sideline by Seahawks safety Kam Chancellor.
Davis was attempting to haul in a pass deep in Seattle's end late in the first quarter. Davis caught the pass but was immediately knocked off his feet by Chancellor, jarring the ball loose. Davis was slow to get up, was examined by doctors on the sideline and eventually taken to the locker room for further evaluation.
Pittsburgh TE Heath Miller left in the fourth quarter of a loss to Cincinnati with a right knee injury.
Chiefs WR Terrance Copper (left knee) and DT Tyson Jackson (left foot) left a loss to Indianapolis.
Jaguars WR Cecil Shorts III and guard Uche Nwaneri left the loss to New England with concussions.
Chargers rookie safety Brandon Taylor was carted off the field in the third quarter against the Jets after injuring his right knee. Jets DB Ellis Lankster left in the second half with a concussion.
The Bucs lost CB E.J. Biggers to a groin injury in a loss to St. Louis.
Giants DL Marvin Austin and Chris Canty both left a loss at Baltimore with knee injuries. Ravens WR Anquan Boldin hurt his shoulder in the third quarter and did not return.