Ross has been working on conditioning and was hoping to take batting practice Sunday before the Reds' game against Philadelphia at Ed Smith Stadium. But hours before the game, Ross said he is still unable to run.
"I can't run or do some of the things I need to be able to do," he said. "I want to get back out there, but you can't rush these things."
Ross had never had back problems until this spring. He's tried twice this spring to resume hitting and throwing but suffered setbacks each time.
With Opening Day just two weeks from Monday, Ross may not have enough time to get ready for the season opener.
"That's going to be a little tough, I think," Reds manager Dusty Baker said. "I hope so, but he's got to get his at-bats and time, and he's also got to get his time catching. I would like to get him in there to catch the guys he hasn't caught before. There's a bunch of guys he hasn't caught before."
Ross, who turns 31 on March 19, hit .203 with 17 home runs and 39 RBIs in 112 games last season.
The Reds also have veteran Javier Valentin and non-roster invitee Paul Bako to handle the catching.
Jim Molony is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.