He was about to be inducted into pro football's Hall of Fame, but Gale Sayers didn't really want to talk abour that "Tell me about larry Brown," he said over the telephlne, "I'm sure I know why he gave it up. It was the legs, right?

"Yeah, I saw him run the last couple of years, and it wasn't the same.

The man took more punishment than the average back. When he was young he could handle it But when the legs go, you go. And in this game, they don't last very long.

"I was glad to see him quit, and I know just why he did it. That's why I quit, too. I could hae hung around, but I knew I could never play like I did before they cut on my knees. I had too much pride, and I know Larry did, too.

"Running the football is for the kids. You just get old too fast in this game. It's a fact of life."

It is also a fact of life in the National Football League that the average career of a running back is only three years, two years less than the expectancy for all players. and it is not difficult to understand why.

Several years ago, a physicist figured out the dollision force between a 200 pound back who runs the 100 yard dash in 10 seconds and a 240 pound lineman who doew it in 11 was enough to move 33 tons one inch.

Perhaps that is why Calvin hill says "it's kind of frightening" when he watches sound films of NFL games. "When I'm running with the ball. I don't hear anything until after tha play is over," he said. "But when you hear the sound track, I can't believe all that noise, the grunts, the sound of the hits. It's seary."

Indeed, football players are getting larger and stronger and faster every year. And few of those head-on collisions are taking place on soft. Iush grass, because artificial turf makes up more than half the NFL playing fields.

"Basically," says Bobby Mitchell, "you've got to be crazy to play running back nowadays. You're either getting hit and hit hard by somebody on every play, or you're falling on something hard.

"If you're not carrying the ball you're going to be blocking. If you're not blocking you'll be running a fake and somebody's gonna' take a shot at you to make sure you don't get the ball. And now you've got to catch a pass and go with it, too. You can't help but get beat up."

Mitchell, the Redskins director of pro scouting, says he tried to run under control to avoid getting hurt, something the great Jim Brown taught him when they were teammates in Cleveland backfield.

"There are people who will say here I come, try and stop me,' but I think that's the fool's approach," Mitchell said. "I'll do it that way on third and five, an important situation where you just have to go get those yards, but there's no reason for a confrontation on first or second down.

"That's what Brown taught me, and that was a reason for his great success. In three downs, just take one bad blow if you really have to. There's a time to be smart, and a time to be tough and crazy."

Sayers tried the same approach.

"I think in all the years I played, from grade school to the pros. I probably took a total of 50 direct, solid hits, where your head would be spinning and you had trouble getting up," Sayers said.

"The way I tried to run was to give 'em a leg, a shoulder, a jersey, but never give up your whole body. I hardly ever got hit in the gut, the groin or the head.

"Larry Brown, though, took a whole lot more punishment. Where I had maybe three or four moves to shake a guy, he had only one, and as a result, he got smacked. That was his style. I'm not criticizing it. But he got popped a lot more than I did."

Still, Sayers had only five productive years in the NFL before the constant hitting took its toll. He had three knee operations, and finally had to give it up after the 1971 season.

So why do the running backs do it? Why do they put up with the constant pain, the pressure of knowing a career could be over as quickly as the next tackle, or cut?

For the successful back, the rewards often outweigh the risks.O. J. Simpson runs in airports and is a millionaire. Jim Brown is a movie star. Larry Brown drives a $20,000 Mercedes and owns what he once described as a "mansion on the outside, ghetto on the inside" in Potomac, Md.

Big salaries, constant media attention and all the other fringe benefits that go along with being a superstar in a nation obsessed with professional football are part of the rewards.

"I knew it was a high risk profession," Sayers said, "but I also knew it was a steppingstone. It's four, five, six years in the game and then you go on to your life's work. I always knew it wasn't a long-term proposition."

Hill likes to talk about other cerebral rewards of the game, the spine-tingling emotion of a long run, a big play.

"When I first started playing, all I ever saw was blurs of color and then space where there was no color," he said. "So you went to that space."

As you get older, you see it a lot better, you see the blocks, you see the holes, you see it all. And sometimes it's like a stop-action.

"There have been times that I've been running and it looks just like it's supposed to look. It's a moment where your mind shouts to you and photographs that memory, it might be a routine play, or one that wins a ball game.

"I remember feeling that way when I scored that touchdown last year to help beat Dallas. It was just one moment that no one can ever take away from you it was a perfect play.

"Then there also are the times when you hurt so much you don't think you can play at all. I remember games in Dallas where my knees ached so much, wasn't [WORD ILLEGIBLE] myself to make a block or catch a pass. I was trying to just worry about thinks like can I run?"

"And then you go out on that field. You see the people, you hear the crowd and it's right before the game and you get the feeling you know you can run.It's a triumph. And that's when carrying the ball is really enjoyable."

When the scouts go looking for professional running back prospects, they are searching for players with size, speed, quick feet, balance, agility and change of direction. "A guy who will make that first man miss," said Mike Allman, the Redskins director of college scouting and the man who uncovered Larry Brown and Mike Thomas.

"But quickness would be the main asset. Not just speed, but a guy who can get away from people in an instant. It used to be that everybody wanted to back to be 6-foot and 200 pounds, but size isn't that important.

"It's hard to get a good lick at a guy like Mike Thomas or a Tony Dorsett. They'll squirm, they'll give you a fake, they'll button up and never take a heavy shot. And those big defensive guys are leery of the waterbugs, too. Instead of trying to kill you, they're afraid you'll duck under and slip away, so they'll arm tackle you.

"When I brought the film on Mike Thomas to Redskin Park, Bobby Mitchell looked at one play and said 'That guy can run the ball.' Mike had taken a hand off out of the I and a lineman made good penetration. Mike just gave him a hip and was right by him. That's when Mitchell said, 'Turn off the projector.'" t before hitters get them doped out.

Cincinnati's Sparky Anderson hoped for the same beginners' luck reprieve. Instead, his youngsters are getting destroyed just like the rest. The Reds may end the season the greatest 500 team in history.

The Chicago Cubs and White Sox both may have passed midseason crises of confidence and be headed all the way down to the wire. The Cubs helty Rick Reuschel (15-3) once had to endure the barbs of hitters like Mike Schmidt who called him "a walking cheeseberger." Now Schmidt says of the large one who keeps every pitch far below the Wasitline. "Well, he's a cheeseberger who can pitch."