Last month, Aloma's Ruler made a remarkable recovery from a serious injury, came back from obscurity and showed that he was one of the best horses of his generation.

On Monday, the same thing happened to another thoroughbred, but in an even more dramatic fashion. Conquistador Cielo, whose infirmities had kept him out of the Kentucky Derby and the Preakness, won the prestigious Metropolitan Handicap at Belmont Park in a record-shattering performance. He will probably be entered in Saturday's Belmont Stakes, and his presence will change the whole complexion of that race.

The comebacks by these two colts are due partly to their own exceptional abilities, partly to good work by their trainers and partly to the wonders of medical science. If they should run one-two in the Belmont, the result could be dubbed the Electrotherapy Exacta.

Conquistador Cielo had shown promise at Saratoga last summer, but was hampered by serious shin problems at the time. He returned to competition in Florida this winter, but once again the shins stopped him.

"He had a saucer fracture--a little crack in the middle of the shin bone," trainer Woody Stephens said. "I'd had Dr. (William O.) Reed get this electrical device for me. I charge it up at night and then wrap it around the horse's leg for two hours every morning. This might have taken months to heal. But the horse was walking after seven days and was galloping slowly at the end of five weeks."

The device, Dr. Reed said, was developed at Columbia Presbyterian Hospital for use on humans and started to be used around the racetrack about a year ago. "It transmits a current across the injured area and supposedly assists in healing," he said, "though we have cases where there is no response at all."

But the bioelectrical device certainly didn't hurt Aloma's Ruler. After suffering a fracture in his ankle last winter, he was treated with the machine and also injected with hyaluronic acid, a substance derived from rooster combs that replaces a lost lubricant in the joint. Aloma's Ruler returned to training so quickly from this injury that trainer John Lenzini Jr. felt he was doing the wrong thing. He felt it was a mistake to rush the colt and run him in the Withers Stakes and the Preakness. But Aloma's Ruler won both, and he will be among the favorites in the Belmont Saturday.

His chances will be hurt, however, if his fellow electrotherapy patient is entered in the race. Aloma's Ruler would certainly not have the luxury of taking the lead and setting a slow pace as he did in the Preakness, for nobody is going to outrun Conquistador Cielo.

The colt made his return to competition at Pimlico in a prep race for the Preakness and won it, but Stephens judged afterwards that he wasn't ready for stakes competition just yet. So Conquistador Cielo ran next in a mile allowance race at Belmont, and blew away a field of tough older rivals by 11 lengths. Now he was ready, and on Monday he took on the best milers in New York.

He annihilated them. Jockey Eddie Maple could scarcely restrain the colt as he raced with the leaders through a half-mile in 45 seconds flat. He took command as he hit the three-quarters in 1:09, and then drew away to a seven-length victory in 1:33, breaking the track record and missing Dr. Fager's world mark by only four-fifths of a second on a racing strip that was not extraordinarily fast.

In the winner's circle after that race, owner Henryk deKwiatkowski seemed eager to try the Belmont, but Stephens sounded dubious. He acknowledged that Conquistador Cielo's breeding will not help him go a mile and one-half, and that the colt may be too fast, too uncontrollable for his own good.

This morning, however, the Hall-of-Fame trainer sounded as if he was changing his mind. "I'm going to walk him on Wednesday, gallop him on Thursday and then make up my mind," he said. He knows that Conquistador Cielo will never be sharper than he is right now, and that it might be foolish not to seize the moment.