FOR A HEAVY guy with bad knees, it was a long walk under a scorching sun to watch a drill he almost never pays attention to.
Yesterday, though, Andy Reid needed to see for himself.
He lumbered about 150 yards to see if Jamaal Jackson's left knee would hold up in one-on-one drills.
Jackson even absorbed the impact of a teammate landing on the side of his leg during that drill - the sort of ultimate test that no one plans for, but that, if it happens, provides the most definitive sort of evidence.
Before and after that alarming incident, Jackson glided through his first real practice since he tore his ACL in the next-to-last game of the 2009 regular season. He is far ahead of schedule - the recovery usually requires a full year - but he appears ready to roll.
For the first time in full pads, with full contact, he emerged unaffected.
"Today was a huge step for me," Jackson said.
It would be a huge bonus for the Eagles, who appear desperate for Jackson to return for the season opener Sept. 12 against Green Bay. Given the result of the last two games of last season, their desperation is justified.
The Birds, stifled at the line of scrimmage and in disarray against the Cowboys' pressure, got blown out in back-to-back trips to Dallas in the regular-season finale and the first round of the playoffs. Nick Cole started in place of Jackson.
"Jamaal? It's kind of exciting," said left guard Todd Herremans.
"He looks great. Feels great at center," quarterback Kevin Kolb said. "Jamaal's a huge help. He's definitely a knowledgeable player."
Not to mention, a relieved one.
When Jackson took that sideways hit in one-on-one drills, his heart stopped: "I just died."
That could be big news for an offensive line that should make or break this year's team.
Herremans' preseason work has been limited due to a left foot injury, and he missed yesterday with a right ankle sprain. Right guard Stacy Andrews' play has been sketchy enough to warrant him splitting time with Cole, who just returned Sunday after missing time with a balky knee.
Third-year man Mike McGlynn had been playing center, though he moved to left guard with Herremans out yesterday. So, the line is a work in progress - a work made more stable, it would seem, if Jackson returns to the middle of it.
His return seems imminent. He said he felt fresh after more than 2 hours in 95-degree heat.
"I felt good. From here on out, it's just getting in football shape," Jackson said.
And getting adjusted to wearing a bulky brace on his left leg.
"It'll take a little bit of time getting adjusted to the brace, mobilitywise," Jackson said.
It held up fine.
The Eagles' first team did extensive run-game work yesterday, which meant Jackson firing off into scrums where impact and force come from every angle. He played well . . . though, he allowed, the defensive linemen he faced might be a bit sluggish from the grind of training camp.
"I feel strong. I'm a little fresher than most," he said.
Now 30, he hopes to stay that way, since Reid often eases up on players 30 and older: "Big Red might not be too hard on me."
Certainly not. Jackson said that team doctor Peter DeLuca told him yesterday that the key to continued progress is controlling swelling in the joint.
The next big step, said Jackson, is "seeing how the pain is [today], if I have any swelling . . . You don't want to push it too much . . . A lot can happen between today and Sept. 12."
Reid wants to monitor everything that happens along the way. The one-on-one drills that Reid watched yesterday mainly tested Jackson's strength.
"It was mostly power stuff, seeing if I could sit down on the bull [rush]," Jackson said. "I guess he wanted to see me in live action."
Reid made sure of it.
Kevin Kolb was scathing in his evaluation of his play Friday. He stayed for extra work after yesterday's practice, sharpening his skills and his tongue before addressing his last preseason performance before he officially becomes the club's starting quarterback.
"Obviously, it wasn't as sharp as we wanted. I saw some things I needed to work on," Kolb said. "It wasn't very good by me. And, as a unit, we have to get better. It starts with me."
In three quarters of work, his most extensive use in the exhibition slate, Kolb was 11-for-25 with an interception and no touchdowns. He also was sacked four times.
The starters are not slated to play Thursday against the Jets in the preseason finale, so Kolb will finish his first preseason as Donovan McNabb's successor 28-for-53 for 324 yards, with no touchdowns and the interception.
Yes, he'd like to play Thursday: "You always want to go play and get that bad taste out of your mouth."
That will have to wait a couple of weeks.
Andy Reid was asked by the Daily News about Donovan McNabb's recent comments in GQ, alluding to what McNabb felt was a lack of support from the Eagles' organization, when he was being criticized.
"From the top of the organization on down, I just think everybody loved having Donovan here, respected him and supported him," Reid said. "We'll always have a special place in our heart for Donovan McNabb and the things he's done for this organization."
Eagles offensive coordinator Marty Mornhinweg asserted that tight end Brent Celek, who has just four catches, had been keyed upon by defenses this preseason. However, Kevin Kolb admitted, "We just haven't clicked as well as we'd like to" . . . The Jets will start Mark Brunell at QB and dress only 36 players . . . Wide receiver Santonio Holmes will play extensively in advance of his four-game suspension for violating the league's substance-abuse policy . . . Bobby April said that, considering personnel vagaries and his track record - his special teams have usually improved - he isn't particularly pressured to see better coverage right now . . . April said that he and Andy Reid discussed using running back J.J. Arrington to return kicks now that Arrington is healthy.
Daily News sports writer Les Bowen contributed to this report.