There remains no timetable for a return, but Heisey is eligible for activation on May 13.
"I'm optimistic that I will be ready to go," Heisey said.
Heisey hurt himself on April 27 at Washington trying to beat out a double play. He was struggling at the time, batting .173 with two home runs and five RBIs in 23 games.
With the team on a road trip, Heisey has been running on the field and pushing himself on the exercise bike inside the visitor's clubhouse at Wrigley Field.
"The only thing I haven't really done is sprinting. I've jogged and done a hard jog, but I haven't wanted to test it yet. I've been hitting and swinging feels great."
Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon This story was not subject to the approval of Major League Baseball or its clubs.