The second baseman has been progressing through an upper-body exercise plan that was developed by concussion specialist Dr. Michael Collins. Roberts hasn't reported any ill effects as he has progressed through the plan.
"He's starting to do some more physical things down there," Orioles manager Buck Showalter said. "He's gotten into an exertional program. He's doing light upper-body exercises. He's moving along good."
Roberts hasn't seen the field since May 16 at Fenway Park, when he started getting headaches after a headfirst slide into first base. Up until this point, the concussion-like symptoms had limited Roberts from undergoing most physical activity as he slowly progressed through his rehabilitation.
The team isn't taking any chances with the veteran infielder, who has battled injury in the past. The concussion-like nature of this injury gives the Orioles even more reason to not rush anything with Roberts.
"We already have progressed really slowly and done it the way that the doctors have prescribed," Showalter said. "It's not something that you try to get on a different timetable. You go with the people that are experts at it, and you work within their time frame."
This is the second straight season that Roberts has been bothered with a long-term injury; he missed 59 games in 2010 with a herniated disk in his lower back. The 33-year-old also battled back and neck injuries this Spring Training after another headfirst slide into first base.
For now, the team is hoping that Roberts will be cleared to resume baseball activities on June 21.