Last week, the ESPN cable TV network expanded to 24-hour-a-day sportscasting. That had to be good news for anyone who thinks there isn't enough sports programming on television.

Of course anyone who thinks that has been standing out on too many golf courses during electrical storms.

After a month or so hooked up to cable TV in suburban Washington, this viewer can report that it's a great little gadget, as long as you are a sports maniac. On a recent Sunday afternoon, more than half of the available programmed channels on cable were carrying some sort of sport. By contrast, there were only two stations showing old movies, which seems a case of priorities gone berserk, but then sports has never been bigger business and TV made it so.

You'd think the Constitution guaranteed a U.S. citizen the right not to have to watch a ball game. This right gets increasingly difficult to exercise as television turns more and more sports into revenue-grabbers. We've gotten to the point where no sport is safe from being televised; with NBC's "Games People Play," everything but canasta and stickball has been given video ritualization.

Of course the definition of "sport" has to be stretched to fit television's own peculiar requirements. Recent editions of "Games People Play" included such dubious sports as falling off a log into a mud pit, and street brawling. Then there was the escape artist whose sprot was being hand-cuffed to a car filled with explosives and trying to get away before another car rammed into it and blew it up.

A long way from horseshoes in the park, that's for sure.

ESPN is a thriving enterprise that claims a 250 percent increase in viewing households since signing on a year ago. ESPN spokesmen say they expect to reach 6 million households through 875 different cable systems around the country by the end of 1980.

Of course when you're doling out sports round-the-clock, you have to relax your standards just a hair as to what constitutes vital and exciting competition. One wonders just how many millions of viewers were awake and kicking at 4:30 in the morning one day last week when ESPN carried the U.S. National Kayaking Championships.

Then there are such other big September attractions as Australian rugby (5:30 a.m. on Sept. 22, among other times), Canadian football, the Pacific Northwest Frisbee whirlaway, a Chinese children's tumbling exhibition and the Great Eastern Skeetshooting Championships.

I think it's wrong to shoot skeets. A skeet never hurt anybody.

Not everybody can get ESPN, but the airwaves have plenty of sports for them just the same. On a recent hot Friday night in the Washington-Baltimore area, of seven VHF stations in operation, three were carrying pre-season football games. Football! In the depths of August! Any year now the post-season games and the pre-season games will run right into each other and the football season will be perpetual.

No less an authority than Richard M. Nixon took note of this during one of his chair-to-chair chats with Teddy White on NBC's "Today Show" this week. "You know, I'm a football fan," Nixon said, "but I must say, when I saw the first games starting this week, the day after Labor Day, and they won't end until the Super Bowl Jan. 20, I get a little bored with it at the end."

Maybe even a little bored with it at the beginning, eh Mr. President?

Hey, you sports fans, get outta here. You deserve your diversion. But television's tendency, more of an obsession really, is to expand everything it airs beyond all reasonable limits to fill more time and sell more time (forth-coming example: "Shogun"). In sports, it gets to the point where, flipping among channels, all you can see are people doing something or other to a ball.

You turn to one channel, they're kicking a ball. You turn to another channel, they're hitting a ball. They roll a ball down a wooden alley to knock over a bunch of pins. They whack a ball with rackets or slam it against a wall. They coax it into little holes. They dribble it, they dunk it, they let it bounce off their heads.

What do the glurbs on Mars think of all this? What are those TV signals that go into outer space telling extraterrestrials about the good people of earth? If pro football players are going to be busy all year, who's going to sell used cars during the off-season?

"Monday Night Football" on ABC has returned in profusion. ABC publicists recently noted that these telecasts have "altered the lives of millions of people" and that, last year, in Dade County, Fla., a junior college launched an accredited course for women on how to appreciate the broadcasts. ABC notes proudly, too, that the cost for a 30-second commercial during the games has gone from $32,500 in 1970 to $115,000 in 1980.

Now it would be possible to look at all this sports television and find so much apparent interest in physical activity to be a healthy sign. But the interest is in watching physical activity, not doing it, and recently published figures indicate Americans are a fatter bunch of armchair coaches than ever and that obesity has reached "epidemic proportions."

It could very well be that the constant availability of passive sports watching actually discourages people from participating, rather than encouraging them.

Television's need to fill time by inventing new sports and by crowding, with old sports, hours that by right ought to go to old Warner Bros. gangster pictures and MGM musicals, make people who can take or leave sports fell unpatriotic and isolated. Even the beer commercials have taken up this competitive mania; now the beers are fighting with each other, or at least making fun of each other's commercials.

It's becoming the United Sports of America, yes it is. There must be something we are all trying to forget.