THIBODAUX, La. -- It was evident Thursday when Peyton Manning took the field with a number of college quarterbacks for a traditional workout session at his family passing camp that something wasn't right.

For the first time in 16 years of the Manning Passing Academy, the Indianapolis Colts' quarterback did not physically participate with the others on the campus of Nicholls State University and served only as a verbal instructor.

Manning conceded that the neck surgery he had May 23 to correct a bulging disk and the NFL lockout rules have put him in a "cautious" mode on being physically active.

"The lockout didn't allow me to work my (Colts) therapist, Erin Barill, and I'm just not comfortable taking any chances with this thing," Manning said. "Erin knows me. He's rehabbed me through two other surgeries (neck and knee) and I think most people understand that once you build up a trust with your therapist, that's the guy you want and need to work with."

Manning said he had "no idea" when he will be able to participate in training camp until he gets an assessment from Barill. He has been rehabbing with other therapists.

Manning, 35, is rehabbing from his second neck-related surgery in 15 months.

The two procedures were not related, according to Manning. The March 2010 surgery eradicated a buildup of calcium in his neck. This year's surgery corrected the disk problem.

Manning has done some light throwing but his cautious approach during his six weeks of current rehab has left him frustrated with the prohibitions imposed by the NFL during the owners' lockout.

While NFL commissioner Roger Goodell has stated he still expects to discipline players who violate the league's personal conduct policy during the lockout, the league has cut off health-care benefits and imposed strict limits on communication between clubs and injured players.

Team medical personnel are allowed to communicate with outside doctors and therapists, but are not allowed to interact with players, let alone participate in the rehab process.

Manning's May 23 surgery occurred after he experienced pain and discomfort that he says are unquestionable remnants of the 2010 football season. He said it was not an elective procedure after sending MRI results to a number of "top specialists," all of whom agreed surgery was required.