May 21, 1984

Costly and crowded health clubs, modesty and a continuing desire to remain fit have sent thousands of Americans in search of creative and effective ways to work out at home. According to industry estimates, this trend has pushed sales for the home-exercise equipment industry above the $1 billion-a-year mark with no slowdown in sight. Reaping the benefits are companies both large and small that sell - at premium prices - everything from jump ropes and small hand weights to gravity-inversion systems and multi-function gyms that can cost as much as $3,000 or more. ''I've seen a lot of fads in this business, but it's mind-boggling how this home fitness thing has taken off,'' said Robert Carr, editor and co-publisher of Sporting Goods Business, a trade publication. ''The way these things go, it should have died out by now, but there's no sign of easing on the horizon.''

The Islanders were already departed when cars lined the downtown streets in Edmonton, Alberta, and sleepy-eyed children, too young to understand the childlikeness of adults, toddled around in their No. 99 T-shirts. The Oilers won their first Stanley Cup Saturday night, and it wasn't until well into yesterday morning, with the sun ready to rise, that the raised emotions of their fans began to settle down. In New York, with their charter flight touching down well after sunrise, the Islanders drove out along the Grand Central Parkway as losers for the first time in the 1980's. They were home, ready to lounge on Jones Beach or visit friends in Canada, without the Stanley Cup. ''The thought of losing had crossed my mind, especially more vividly in the past few days,'' said Butch Goring as his teammates packed their bags following their season-ending 5-2 loss.

One monitors business credit; the other measures consumer sales. And if neither company is precisely a household word, both the Dun & Bradstreet Corporation and the A. C. Nielsen Company are part of the basic business vocabulary. The merger of the two companies, announced last week, brings together two of the largest and best-established concerns in information services. While there is little overlap between the areas they currently track, the two companies can help each other in a number of ways, according to corporate management and securities analysts. ''We both have the ability to collect a lot of data and deliver it efficiently to clients,'' said Arthur C. Nielsen Jr., who resigned earlier this month as chairman and chief executive after reaching his 65th birthday. He suggested that the new company might delve more deeply into market research for industrial products, as opposed to consumer goods and services.

Arriving in New York City on flights from Geneva or Paris, Albert Camille Gillet gave all the appearances of a prosperous European businessman. A chauffeured limousine usually waited to drive him to Manhattan, where he always stopped at fine hotels and dined at expensive restaurants. In contrast, Jose Martinez-Torres lived in a dingy, poorly furnished apartment in the Bronx, only occasionally traveling out of the city on business trips. The two men are never known to have met. Yet both, according to court records, were recently involved in the same illegal billion-dollar business: trafficking in heroin and cocaine.

The usual crowd was here this weekend. Spinsters Opposed to Nuclear Genocide, Trident Nein, Young Republicans, the Communist Workers Party, the Revolutionary Communist Party, the Libertarian Party, the United Church of Christ, saffron-robed Buddhists, the Ku Klux Klan - 500 protesters and counterprotesters marched and chanted, 300 police officers in riot gear watched over them. ''We've become the focal point for demonstrations - month after month after month,'' said Joseph E. Presslitz, the chairman of the City Council's Finance Committee. ''It begins to wear you down. And now the character of the protests has begun to change. You never know what's going to happen. The cost is enormous.''