Lions quarterback Daunte Culpepper practiced Friday after sitting out drills Thursday.
Those who did not participate in Friday's practice included Matthew Stafford, Calvin Johnson and Larry Foote.
DeAndre Levy also sat out, but Lions coach Jim Schwartz would not go into detail about what prevented the rookie linebacker from participating.
"We had a lot of guys that were held out for various reasons," Schwartz said.
Stafford was not present on the field or the sidelines during the early portion of practice that is open to the media, and he turned down interview requests following practice.
Schwartz said Stafford would test his injured right knee as soon as he is able to, but he refused to speculate when that would be.