"I wasn't able to finish the trip with the team," Martinez said. "I've been bored going crazy with nothing to do, just sitting around when I'm not working out. It's nice to shoot the crap and catch up with everybody."
Manager Bo Porter said Martinez will do his rehab in Houston, but it's unclear if the 25-year-old will need a Minor League rehab stint before coming off the disabled list for a second time this season.
"I haven't had time to sit down with [trainer] Nate [Lucero} and map out his progress, but I know J.D.'s working hard and he'll be around the park while we're here," Porter said.
Martinez said the team's medical staff is playing the injury "by ear" and gave a rough timetable for dealing with the sprain.
"They said if you have to put a time frame on it, usually you can start swinging the bat after two weeks and then maybe be game ready two weeks after that," Martinez said. "The day I'll be able to do my exercises without pain is when I'll know I'm ready to swing."
According to that progression, Martinez would be taking batting practice by this weekend and potentially be ready for game action by late August.
However, Martinez could find himself part of a suddenly crowded Astros outfield when he returns to health despite Justin Maxwell's recent departure via trade.
Robbie Grossman is hitting almost .500 since being called up in Martinez's place, Trevor Crowe is nearly finished with his rehab stint after a shoulder injury in late June, Brandon Barnes is entrenched in center and Chris Carter is the team's best power bat.
Chris Abshire is an associate reporter for MLB.com.