Zambrano said he had been logging about four hours a day communicating via e-mail with his brother.
"I have to spend one hour and take it easy," Zambrano said.
Zambrano looked fine Saturday, allowing just one hit in seven innings against the White Sox.
"It's not carpal tunnel, but if you don't watch it, who knows what it can lead to? We are trying to alleviate it," Cubs manger Dusty Baker said.
The Cubs were told after Zambrano had to leave his May 14 start against Washington
early with a sore elbow that was the result of a non-pitching condition and activity. So they also told Zambrano to lighten up on his batting practice.
"I feel completely healthy," Zambrano said.