Aaaaand …. here we go! In many ways, the Vikings' 2013 season officially gets underway Friday – first training camp walkthrough at 10:30 a.m., first practice at 2:45 in Mankato. And yes we know a lot can and will happen between now and Sept. 8, the day the Vikings open the regular season at Detroit. But taking the 90 players currently on the roster, we're delivering our in-depth position-by-position report as a primer for the opening of camp.
RUNNING BACKS

Currently on roster: 8

Likely to make opening day roster: 4

Certain to make the team: Adrian Peterson, Toby Gerhart, Jerome Felton

On the bubble: Matt Asiata

Practice squad candidates: Zach Line, Joe Banyard

Camp depth: Jerodis Williams, Bradley Randle

Biggest offseason developments: It was learned that the abdomen injury that "slowed" Peterson down the stretch of last season was a sports hernia injury, an issue that required the MVP to undergo surgery in February. … The Vikings also re-signed Felton, rewarding him for his Pro Bowl efforts in 2012 with a new three-year deal worth a maximum of $7.5 million.

What we'll be watching: Like the Vikings, we'll be keeping a close eye on Peterson's training camp workload. During OTAs and mini-camp, Peterson was given several practices off, a means to keep his body fresh as he overcomes that sports hernia injury and a 2012 MVP season that included 388 touches and probably twice that many collisions.

Peterson, as we all know, can be quite restless. Don't forget that last year he spent the first 11 practice days of training camp on the Physically Unable to Perform list, forced to continue his ACL rehabilitation off to the side. Yet he was so miffed at being placed on the PUP list that he vowed to make his workouts with strength and conditioning coach Tom Kanavy and head athletic trainer Eric Sugarman even more grueling than any practice could be.

Anyway, as superhuman as Peterson seems to be physically, the Vikings will certainly pump the brakes on his preseason workload when they can.

On a side note, color us curious as to whether head coach Leslie Frazier and offensive coordinator Bill Musgrave will find an increased role for Toby Gerhart, who was the forgotten man in the 2012 Peterson Extravaganza. Gerhart finished last season with a career-low 50 carries for 169 yards.

Star Tribune offseason excerpt:

For months, everyone around football marveled about how Peterson bounced back from torn anterior cruciate and medial collateral ligaments to post 2,097 rushing yards, the second most prolific single-season output in NFL history. Peterson was rewarded for his efforts with the league MVP award. And if that wasn't extraordinary enough, then it was learned earlier this month that Peterson played the final six games of the season with a painful sports hernia. That injury caused the Vikings to significantly cut back on his practice time. In December, for example, Peterson essentially only went through practice on Fridays. And yet in the Vikings' five games in the season's final month, Peterson totaled 861 rushing yards and five touchdowns.

-- Feb. 22