EDEN PRAIRIE, Minn. (AP) - The Minnesota Vikings were running sprints during one of their workouts a couple of weeks ago, and Adrian Peterson was watching off to the side.
Salivating like a kid asking his dad if they can stop for ice cream on the drive home, Peterson turned to head athletic trainer Eric Sugarman.
"He had a look on his face like, `I know what you want to do,"' Peterson said.
Permission granted, Peterson took the brace off his left knee and jumped in line with the rest of the running backs and wide receivers.
"I finished in first place," he said.
Roughly four months into his post-surgical rehabilitation from the torn anterior cruciate and medial collateral ligaments he suffered in a game last Dec. 24, Peterson is still plenty fast. He's exercising without pain or problems and ahead of the average pace for this injury recovery.
That doesn't mean he's assured of being in the backfield when the Vikings start the regular season Sept. 9, no matter how determined his mind or how supernatural his body might be.
"I'm not going to say with certainty that Adrian is going to play in our first game," Sugarman said. "That wouldn't be fair to me to him or to this organization. That's a long way off from now, and we certainly have a long road to get to that point."
Peterson, though, left no doubt. One of the most optimistic and confident players in the NFL, Peterson said he's set on playing from the start - and not in a limited role. "Full throttle," was his prediction.
"I'll be disappointed if I'm not," Peterson said.
So the Vikings must be able to find the balance between caution toward their franchise player's long-term health and acknowledgment of Peterson's unique healing ability and physical skill.
"My whole life, I've been setting my goals and pushing forward. I've been successful with doing that. I've been smart. Don't get me wrong. I've been smart about the process," Peterson said.
Said Sugarman: "He realizes now that there's too much to lose by doing something foolish."
The Vikings opened part of Peterson's regular rehab drills to the media on Wednesday, with more than three-dozen reporters and photographers watching him run around at the indoor field at Winter Park. Peterson had the operation Dec. 30, and Sugarman said he's now safe for any activity. The current goal is to restore function, comfort and confidence in the knee and to bring his conditioning back to normal.
Peterson estimated his explosiveness is at about 50 percent. His ability to change direction and speed ahead out of a cut will be the last and most critical piece of his recovery. For now, at least, he said his confidence is "light years" ahead of where it was four months ago.
There's no plan for exactly when he can put pads on and practice with the team once formal practices begin later this summer and, Sugarman said, no point in putting a timetable on how long he'll need between his first practice and clearance to play in a real game.
They're not wasting any time, though, as evidenced by Wednesday's drills.
Sugarman rolled him a soccer ball as he shuffled from side to side in a basketball defense pose and tossed it back. Then Peterson ran around in a circle before practicing his explosion out of a pivot. He ran with a slight limp the width of the field. Then he high-jumped onto stacks of boxes. The rapid-fire pace of the activities left Peterson needing a rest, and Sugarman teased him about stalling.
If there's any let up, well, the return to elite running back status can only take longer.
"Those guys know my limit, and they push me to it," Peterson said.
Notes: Vikings general manager Rick Spielman said the decision to release veteran kicker Ryan Longwell dated to the team's postseason roster evaluation in January. After drafting Blair Walsh last month, the Vikings let Longwell go to give him as much time as possible to find another team. ... Free agent LB Rocky McIntosh worked out for the team on Tuesday but didn't sign. Spielman said he'll continue to monitor McIntosh, who spent the last six seasons with the Washington Redskins. ... Asked for his reaction to the stiff punishment levied by the league on members of the New Orleans Saints who took part in the illegal cash-for-hits program: "Bet it won't happen again," Peterson said.
Follow Dave Campbell on Twitter: http://www.twitter.com/DaveCampbellAP