Wood has pitched once, Tuesday against the Houston Astros, since he came off the disabled list after being sidelined for nearly a month with a blister. The back problems occurred Thursday.
"It's just one of those things," Wood said before batting practice for the Cubs' game against the St. Louis Cardinals. "I should be able to go once I get outside and run around and loosen up."
After batting practice, Wood said he was "ready to go." Cubs manager Lou Piniella said he didn't anticipate Wood's back to be a long-term problem.
"Let's hope it's not as long as the finger," Piniella said of the time missed.
The Cubs relied on Carlos Marmol as the substitute closer while Wood healed his hand. When Wood does make his next appearance, he will likely be used as a setup pitcher again to ease him back into the role. He has not picked up a save since July 11.
"The best way to get him some work and get him sharp and get his arm strength up and get him back to pitching shape is by getting him some work in the middle," Piniella said.
"The secret here is to get him healthy entirely and get him pitching and keep him healthy."
Wood has 24 saves in 29 opportunities in his first full season as the Cubs' closer.
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.