The loneliness of the long-distance runner is legendary, so it was only a mild surprise yesterday that New Zealand's roving Internationalist, Balmerino, came onto the Laurel track under the cover of darkness at 5 a.m.

"It was light enough," exercise rider Dennis Wright declared. "The racing strip was easy to follow."

Actually, Balmerino had little choice yesterday if he was to be given any early-morning calesthenics. The 5-year-old horse was under quarantine until midmorning when the results of his blood test for equine infectious enemia were returned from Beltsville. Until then, until the U.S. Department of Agriculture extended it formal approval, Balmerino was not to mix with other thoroughbreds.

New Zealand is famous for its long-winded athletes, from Peter Snell to John Walker and Dick Quax. The South Pacific islands also are known, in racing circles, as a tremendous source for bloodines possessing stamina. But Balmerino is only the second New Zealand-bred to appear in Laurel's $200,000 classic, 1 1/2 miles on the turf. Up And Coming II finished 10th in 1959.

Balmerino has much better credentials. He figures to be the third choice to France's Exceller and the U.S.'s Majestic Light in Saturday's 26th presentation of John Schapiro's lawn party.

"I though he would win the Arc," owner Ralph Stuart said. "Balmerino had trained up to the minute. The grass course at Longchamp was perfect, a trifle soft, and he drews a good starting position in the big field . . . Then (Lester) Piggott best us with too many bloody brains."

Piggott rode Alleged, which held off Balmerino by a length and a half, Alleged led nearly all the way.

Two weeks later in Milan, Italy, Balmerion nosed out Stateff only to be placed second on a disqualification. Stateff also is in the International, with Crow and Monseigneur of France and Johnny D. Vigors and Great Contractor of the U.S.

French horses have won the last four International. Foreign invitees hold a 14-11 edge, Balmerino is a bit unusual in that he already has had considerable experience in American racing. He started four times this summer in California.

"He was the champion back home as a 3-year-old," informed the 71-year-old Stuart, a retired Auckland sheep and cattle farmer. "I bred colts for the sales and kept the fillies, but Balmerino looked so rough as a yearing I kept him out of Trentham. I didn't think I'd get back the cost of shipping him 400 miles to the sales."

Ron Hutchinson will ride Salmerino.

"I was confident of his chances here, when he left home (in England)," Stuart said. "The flight to New York was good, but the van trip from there to Laurel was hard on him. He has not eaten well here. I wish the horse could have been flown straight to Baltimore, like the French horses were."

Better, Balmerino should have accompanied Stuart to Washingtonton yesterday on the Concorde.

"Not really," Stuart said. "I like the 747 better."