Jackson joined his teammates outside for the first time since spraining his medial collateral ligament on Saturday. But he was only able to ride a bicycle, do some light jogging and watch practice while wearing a sleeve on his knee. He still walked with a slight limp.
Coach Brad Childress said he does not have a timetable for Jackson's return but is confident he will be just fine. Childress said Jackson will return "when he can protect himself."
Jackson is in a competition with Sage Rosenfels for the starting job. After looking shaky in the first three days of camp, Rosenfels had his best practice of the day on Monday as he continues to get familiar with the offense.
The Vikings have no plans at this point to bring in another quarterback to handle the many throws of a typical practice, preferring to give Rosenfels and third-stringer John David Booty as many repetitions as possible to help their development.
Rosenfels arrived in a trade from Houston in the offseason and is still trying to get comfortable in a new system. That gave Jackson, who is in his fourth season with the Vikings, a slight edge initially in the competition.
Rosenfels said he steadily is growing more comfortable with his teammates and the playbook.
"Practice and reps, you need to have those," he said. "[Offensive coordinator] Darrell Bevell can't teach you that one guy is faster than the other. You need to see that."
"That's the natural evolution as you go through camp," Childress said. "There's a different urgency. You're getting a lot of repetitions of the same plays."