"He's moving around a lot better," Baker said before Saturday night's game against the Mets at Citi Field.
Heisey said he felt tightness when he crossed the plate in the fourth inning of Cincinnati's win against the Indians on Thursday, and has not played since he was removed from the game shortly thereafter.
"If he was playing first base or something, it'd be a different thing," Baker said. "But he's an outfielder and he's got to run. He depends on running. Definitely another day and maybe more. We'll see."
Heisey, who is the Reds' second center fielder sidelined (Drew Stubbs is on the 15-day disabled list with an oblique injury), is batting .275 with a homer and 12 RBIs in 53 games this year.