"I just have to let it calm down," Shields said of the forearm stiffness that surfaced after a camp game effort on Wednesday. "I'll be ready on the 31st. Nothing to worry about. It's fine."
Shields came to camp in good shape, but a bout of shoulder soreness set him back about a week. He appeared in two Cactus League games, giving up four runs and four hits in two innings, then worked two innings in the camp game before stiffness infiltrated an unfamiliar location.
"Any time this time of spring," Scioscia said, "anything that comes up heightens your awareness to make sure it calms down and you take care of it.
"We're not really concerned. We're confident he'll be where he needs to be. We're looking at the timeline, but he's gotten out there enough where he's feeling [comfortable], getting stamina back up. We're not seeing it as an issue right now."
Shields, the American League leader in holds with 31 each of the past two seasons, has been the game's most durable reliever over the past four seasons, with 361 2/3 innings. His 368 strikeouts over that span are third most in the Majors among relievers.
His second-half struggles in 2007, however, raised red flags over concern about possible wear and tear. Dominant in the first half with a 1.70 ERA in 40 appearances, he had a 7.36 second-half ERA, finishing with the highest ERA (3.86) of his career.
"Now's the time to ease back and let it heal a little bit," Shields said of the forearm. "It was the same thing with the shoulder. I know [the season] is getting closer, but now's the time to let it heal.
"There have been past springs where I've gone into the season not throwing all that well. When the lights come on ... you try to make it as much like the season as you can [during the spring], but it's not the same. When those lights turn on, I'll be ready."
The forearm will be monitored by the medical staff "on a day-by-day basis," Shields said, adding that in seasons past, he's pitched through discomfort, but not in the forearm area.
Lyle Spencer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.