Twins catcher Joe Mauer is still experiencing concussion symptoms and is not close to returning to the lineup.

Mauer worked out at Target Field on Thursday and said he is making progress in his recovery from a concussion suffered on Aug. 19 in a game against the Mets. He's taken batting practice, ran and lifted weights. But he indicated he still has some hurdles to clear before he can play.

``I start feeling symptoms when I start to get my heart rate up," Mauer said between workouts at Target Field on Thursday.

Mauer is determined to return to the Twins lineup before the end of the regular season - but he has to wait until the symptoms go away for good.

``This process has been a little longer than I hoped," Mauer said.

Read tomorrow's Star Tribune for Mauer's thoughts on remaining a catcher and on the trade of Justin Morneau to the Pittsburgh Pirates.