There will be a fewer chances over the next few weeks to see what speed can do for the Royals.

Outfielder Jarrod Dyson is headed for an extended stretch of limited duty after a magnetic resonance imaging (MRI) exam Friday revealed a strained back muscle – the latissimus dorsi. The typical recovery time is three weeks.

“That means he’s going to be shut down for a while throwing-wise,” manager Ned Yost conceded. “It doesn’t affect his legs. He just can’t throw. He can hit. He can catch balls. And he can run.”

Dyson is hopeful it won’t be that long.

“It’s day to day right now,” he said. “I’ll just be pinch-running and stuff like that. Maybe pinch-hitting if he needs me. We’ll see how I feel.”

The Royals plan to summon an outfielder from the minors prior to today’s first game against Minnesota but will keep Dyson on the active roster. Effective today, rules permit rosters to expand from 25 to 40 players.

The likeliest promotion candidate is David Lough from Class AAA Omaha because he is already on the 40-man roster. Club officials say it won’t be Wil Myers, generally viewed as the organization’s best prospect, because of roster issues.

Myers does not require protection — i.e., being placed on the 40-man roster — to avoid being eligible for selection in the Rule 5 draft. But one club official estimated 12 players are under consideration for protection for what projects to be three or four openings.

Promoting Myers for a handful of games, therefore, would increase the chances of losing another prospect in the Rule 5 draft. They might take that risk if they were in contention but are unlikely to do so in their current circumstances.

Lough, 26, has never played in the majors and is completing his third full season at Omaha. He is batting .275 with 10 homers and 69 RBIs in 130 games. Dyson believes he suffered the injury Monday in Boston when he slammed into the wall at Fenway Park while running down a long fly by Dustin Pedroia.

“With the adrenaline flowing,” he said, “I didn’t feel it at the time. The next day, I had a little soreness, but I didn’t think anything of it.”

The problem became noticeable Wednesday against Detroit on a throw to the infield.

“I could feel something,” Dyson said. “Hopefully, I’ll be all right. There’s no surgery. Nothing like that. I’m just going day to day and getting treatment.”

Dyson is batting .270 with a .333 on-base percentage in 87 games and is likely to serve as the club’s top pinch-running option. He has 25 steals in 28 attempts.

“Nothing wrong with my legs,” he said. “I can use my legs.”