Don't let it show. This is what Raiders OT Lincoln Kennedy is thinking as he goes about the gradual process of reducing his life expectancy in the season opener at Kansas City. The Raiders have had the ball for nearly 11 minutes in the first quarter, and Kennedy's legs, which appear too spindly to hold up his 350-pound body, are rubbery with exhaustion. His lungs are having serious trouble drawing sufficient air. His field of vision narrows to pinpoints surrounded by a head-rush swirl of Chief Red and Raider Silver and Black. Don't let it show. His world is reduced to an instruction manual: One task at a time. Get to the huddle. Get the play. Get to the line. Do the job.

His body is working on muscle memory. Ten plays into the 13-play drive -- the fourth Raider possession of the quarter -- his body's heat is buzzing through his head, his helmet is serving as an enormous, echoing seashell, and all he can think is: Don't let it show.

A run for eight, a run for one, a pass for 15, no gain, a pass for three -- it's the kind of clock-chewing drive coaches love and 6'6", 350-pounders like Kennedy hate. The snarling, unbroken-colt defensive ends shuttle in and out, a different guy in front of him every two or three plays, but Kennedy stays out there, the collisions as insistent as the slap of wave against shore. He appears unaffected, standing upright between plays, regulating his breathing, taking deliberate, hide-the-pain breaths and staring straight through infinity.

Kennedy can't let his teammates see him struggle. They'll look at him and realize, Damn, I'm tired too, and the whole drive might fall apart. He can't let his opponent see it, either. That's even worse. The past and the future have drifted away, gone with his peripheral vision. The present is the only truth. Get to the line, throw the body at the guy across it. Forward, forward, forward. This is the life of the offensive tackle, the biggest, strongest category of men in professional sports. Don't let it show. He's in the trades -- and his trade is to move men.

Kennedy is an intelligent, thoughtful 30-year-old giant, a behemoth who reads Toni Morrison, plays chess and adores Bugs Bunny. He gets ready for a game not by banging his head against a wall but by sitting in the locker room eating half a party-size bag of peanut M&Ms, methodically separating the coating from the chocolate and the chocolate from the peanut.

But there's something inside him that undergoes an organic change when he's on the field. It's not unchecked aggression -- he's too smart a businessman for that -- but a complete willingness to subjugate, even harm himself for the common good. It's not unique to him; the entire league runs on this current. When he thinks about it later, he'll call the feeling "terrifying," but while it's happening there is no perspective. There is only the job, and the willingness to do it, to do it no matter what.

In some part of his brain, Kennedy knows the pain in his strained right shoulder means he won't be able to take off his pads after the game, or put on a shirt, or brush his teeth.

The heat prickling up and down his legs is masking an ache in his knees he knows he'll feel when he boards the plane for Oakland, and even more when he tries to fold himself into the Cadillac Eldorado waiting for him in the parking lot at team headquarters.

Somewhere deep inside, he knows exactly what he's doing. He knows he will awaken on Monday morning, click on the television from bed, take inventory of the pain and wonder why.

"You always question yourself on Monday morning," he says. "Why am I doing this? What am I doing to my body? This hurts too much." He knows what he's doing is nothing short of killing himself -- gradually, systematically, insidiously. He's been killing himself this way for nine years in the NFL, putting his enormous body and its 206 bones through collisions and stresses that have inflicted damage he won't know about for years. According to the NFL Players Association, it's common for a 40-year-old former NFL lineman to have the degenerative arthritis more familiar to an 80-year-old. "Later on, we're all going to pay," Kennedy says. "It's the deal you make."

He is one of 290 players in the NFL who "officially" weigh more than 300 pounds. There were just 83 such players 10 years ago. The Raiders' offensive linemen, based on listed weights, average 316 pounds. (Kennedy's actual weight is 15-20 pounds more than his listed weight of 335, so digest the average accordingly.) Is there a limit? How big is too big?

"I used to think the limit was me," Kennedy says. Leonard Davis, the Cardinals' first-round pick, is viewed as a significant notch on the evolutionary time line. Davis is listed at 370 pounds, and he runs the 40 in 5.1 seconds. "There are 400-pounders out there, trust me," says Raider guard Mo Collins, who's listed at 335. "And there will be more."

"There are contradictions," says Kennedy. "There's no question I need my size and strength to be successful. Unfortunately, the bigger guys get, the more coaches are saying, 'You can't play unless you lose weight.' The minute you tell an athlete that, he'll do whatever it takes. That leads to all kinds of problems, with people not drinking water at practice, taking supplements that speed up their heart rate. The next thing you know, we've got people falling."

His wife, Crystal, had the television on in their Atlanta home on Aug. 2 when it was reported that a huge NFL lineman had died after pushing himself too hard in training camp. She knows how strange this sounds, but when she turned to look at the screen, she swears there was a split second when she saw Lincoln's face on Viking Korey Stringer's body.

Every big man in the NFL places extreme demands on his body, and every big man knows the inherent risks. In 1994, after his rookie season with the Falcons, Lincoln arrived for camp weighing 405 pounds. "To be honest, it was the first time in my life I had enough money in my pocket to eat out every night," he says. "So I did." The Falcons, upset that their first-round pick out of Washington had allowed himself to get this far out of shape, sent him to the Rice Diet Clinic at Duke University.

But Lincoln went a step beyond nutrition: To control his weight and stay on the field, he put a plastic sweat-top under his pads, even on the hottest and most humid Georgia days. He stopped drinking water at practice. "We've all done things we're not proud of," he says, shaking his head. "I'm sure it did damage I haven't been able to catch up on."

Kennedy has a weight clause requiring him to pay a fine every time his weight climbs above 333: $50 per pound for a first offense, rising another $50 per pound for every subsequent offense. He's been fined twice this year. He says, "You fine me with the understanding that I'm not going to kill myself to get to a certain weight."

Of course, Kennedy is well compensated for his efforts. He makes more than $1 million a year, and he has entered the stage of his career when he looks at the numbers and, like an overstressed Wall Street trader, calculates how many more years he'll be willing to let the game chip away at his future. "Sometimes I look at his salary and realize it might take an average person a lifetime to make what Lincoln makes in a year," says Crystal. "My job is to make sure he can walk away whenever he wants."

Says Kennedy: "I used to think I'd play 12 years no matter what, but every day it gets less and less. I'm 30, but I'm an old 30. When you look through the eyes of your family and friends -- the people who care about you -- there's no way you can say it's a fair trade-off."

For the rest of the story, get the October 29 issue of ESPN The Magazine.