As expected, the 49ers today triggered a three-week window for rookie running back Marcus Lattimore to begin practicing with the team. They did the same for undrafted offensive tackle Luke Marquardt, who had been recovering from a broken foot and who, like Lattimore, has yet to practice with his team. Marquardt is intriguing because of his impressive size - 6-8, 315 pounds - and because the 49ers have been without a true "swing" tackle since Alex Boone started playing guard last season. Marquardt played at Azusa Pacific University in Southern California, but his foot injury washed out his senior season. He had a follow-up surgery on the foot in April and was merely an observer during the 49ers offseason sessions. Both Lattimore, who is recovering from a major knee injury suffered last October, and Marquardt remain on the non-football injury list. Neither is expected to be activated to the 49ers' 53-man roster at the end of the three-week practice period.