At 10:28 a.m. today, Larry Brown limped off the Dickinson College practice field for the last time. Ninety minutes later, the Redskin running back with the large heart and the wounded knees announced his retirement.

"It is physically impossible for me to endure the stress and strain of another football season," Brown said. "My knees are like my heart, and once they are damaged, there's not much you can do."

Redskin coach George Allen, describing Brown as "the best back I ever coached," said the team would honor the final year of Brown's contract, and the he would now work in a public relations capacity for the organization as a roving good-will ambassador.

"It's for everyone's good," Allen said. "He has played the last couple of years with two bad knees, he has played with a lot of courage and he has been a great back.

"Larry deserves to go out on top and not just hanging on."

Though Brown dressed for today's first practice session, he said he made his final decision known to Allen in an hour-long conversation earlier in the morning.

"I came to camp because I had a contract," Brown said, "and I planned on fulfilling it. But in the back of my mind I had doubts."

Brown said he also had a long talk with team physician Stanford Lavine "and he felt it would have permanently damaged my leg to keep playing on it," Brown said.

Allen said Lavine told him after Saturday's scrimmage against the Colts, "that Larry should not play football."

Brown practiced Monday morning, but pulled up lame halfway through that worked with a sore leftfoot, returned to the trainer's room and missed the afternoon session. This morning, he came out to practice fully dressed but stood around and watched his teammates before walking off the field for the final time.

For the past two years, Brown had been reduced to a reserve role. He had been switched to fullback after an operation on his right knee in 1974 greatly reduced his speed and cutting ability. In 1976, he carried the ball only 20 times for 56 yards.

But in his first five seasons after being taken by the Redskins in the eighth round of the 1969 draft, Brown terrorized defenses around the league from the tailback position with his slashing bursts through the line, his bone-numbing blocking and his clutch pass receiving.

Vince Lombardi was coach his rookie season and Brown believed everything Lombardi ever told him about playing with reckless abandon. "He loved that man," Bobby Mitchell said. "I wanted to be the best," Brown said. "This is what Vince taught me."

Over those five years, he was one of the best, gaining 5,467 yards and becoming the third man in football history to average more than 1,000 yards per year his first five-seasons.

"The first five were my favorite years," Brown said today. "At the time it was just Jim Brown, O.J. Simpson and me. I thought that was pretty good company."

In 1972, Brown was at the peak of his career. "He got us to the Super Bowl," quarterback Billy Kilmer said today. "He was the focal point of our entire offense. When they keyed on him, it opened up the passing game. Nobody could stop him."

In 1972 Brown set a Redskin rushing record of 1,216 yards that still stands and carried the ball 286 times, also a team record. He caught 32 passes for 473 yards, scored 12 touchdowns and was named the NFL's player of the year, even after missing the final two games to rest for the playoffs.

Allen was often criticized for using Brown so frequently, particularly after his knees began to trouble him in the 1973 season who he missed four complete games and still rushed for 860 yards.

And when Brown held out at the beginning of that season's training camp for a new contract, Allen obtained Duane Thomas to run in his place. Brown soon came back to camp and signed a five-year agreement (at about $140,000 for this year) that would have run out after the 1977 season.

But Brown today had nothing but words of praise for Allen and the Redskin organization. "I've been fortunate and I'm proud to have been associated with a great and fine man, a great coach," Brown said of Allen, who was at his side during a news conference.

"I don't think the Washington Redskins and George Allen deserve the kind of criticism we've received. The abuse we've taken is not justified.George Allen will continue to do what he came here for - to win."

Brown's teammates were somewhat surprised over Brown's decision.

"It's kind of shocking to me really, but I think the timing is probably right," said wide receiver Charley Taylor, one of Brown's closest friends on the team. "I'm sure he could still produced, but why should he suffer? I'm glad he made the decision the way he did.

"Look at him over there, shaking hands with everybody. Right now there's a smile on his face. But I know what's in his heart. I'm looking over the hill right now, and it's like I'm looking at a reflection of myself.

"How good a back was he? Well, when you talk about running backs, you only talk four people - Jim Brown, Gale Sayers, O.J. Larry Brown. A lot of backs had the ability to do what Larry did, but very few of them had the desire.

"The greatest game I ever saw Larry play was in New York in 1972. They tore his hands up, he was bleeding everywhere, people were throwing stuff at him from the stands. But he still gained 191 yards that day. The man was just determined. You could see it in his eyes. He always had that look when he played. When we were down, he'd always fire us up. He was that kind of guy, and he's going to be missed."

"He could block, he could run, and he could run great patterns and catch the ball," added Kilmer. "You never find a back who can do all of that. He was just a great, great back. For me, he was the best back I ever played with. I just wish him well, and I'm glad he'll still be a part of the organization."

Bob Brunet came to the Redskins a year before Brown's rookie season, and Brown was the man who kept him out of the starting lineup for years. Still, Brunnet said today, 'you can't have any regrets playing behind a back as talented as he was.'

"Larry paid his dues, believe me. He was just reckless. He didn't have any respect for his body in practice or the games when his knees were all right. I know people always say he got that from Lombardi, but I don't think he got that from anyone. He got it from where he grew up. He was hungry. Larry did it all himself.

"He was such a great blocker. He blocked with the same intensity as he ran with the ball. Everything he did, he did with intensity - running, blocking and catching the ball."

"That's what always impressed me about Larry, his determination," said Calvin Hill, who beat out Brown for rookie of the Year honors in 1969. "They talk about O.J. and his speed and his acceleration. They talk about Mike Thomas and his quickness. But determination is the word you use to describe Larry.

"It makes me feel kind of funny. We came in together as rookies the same year. But Larry did what he had to do and he got out. I really admire the guy."

Over the past three seasons, Brown probably spent more time in the training room than he did on the practice field. But last season, Allen made him a team captain and often used him in critical third-down passing situations.

It was on just such a play that Brown carried the football for the last time a year ago in the first quarter of the Redskin playoff loss to the Minnesota Vikings. The official play-by-play describes it as a dump over the middle, a "delay pass," one of Brown's bread-and-butter patterns.

On that day, however, he caught the ball and was hit immediately for no gain.

The Redskins have several candidates to backup fullback John Riggins, the role Brown would have filled this season. Willie Spencer, a free agent signed in the offseason, has been impressive in early workouts, and Allen may use Brunet at fullback.

But when Allen was asked to talk today about possible replacements for Brown he simply refused. "This is Larry's day, Larry's show," Allen said. "There won't be many Larry Browns in our lifetime."