Marvin Mandell is a man who has lived with personal crisis. He weathered a messy divorce from his wife of 33 years.He survived indictment and massive investigation into his private life, seldom showing emotion. He barely flinched at testimony during his political corruption trial that portrayed him as a public official on the take.

But the past 16 days have gotten to Maryland's governor, according to those know him best. He had had to endure a public parade of intimate details about his mysterious brain ailment while imprisoned in a sparse hospital room isolated from the political events he normally controls.

"My impression is that this is probably the worst thing he's gone through," his top legislative aide, Alan M. Wilner, said the other day after visiting the Maryland governor, "He's bedridden. He isn't at the vortex of things for the first time in years."

It's mainly a question of self esteem. Small in stature, Mandel has always prided himself on his physical stamina. He is a hunter, a sportsman, a former jogger and boxer, who set up an exercise room with a running machine in te governor's mansion.

"He has a Hemingway, macho, bravura view of life. In his head, exercise is a cure-all for everything. Hunting and sports are what masculinity is all about," says his former press spokesman and chief of staff, Frank DeFilippo. ". . . I think he'd look at this as a time of physical weakness That's different from political weakness Political weaknesses you can always do something about"

Thus, the idea of doctors giving out almost daily statements about his physical condition (revealing a disbetic condition Mnadel has always kept to himself, for example), is more of a blow to his self image than all the words and pictures over the last few years about his love life and allegations of political corruption.

"He's a very private person, a calculated enigma," said one close acquaintance. "For his private life to be paraded in a courtroom was bad enough, but now to have his physical condition made public . . . contains a fair degree of pathos."

Mandell appearde anxious to counter the reports of weakness during a 75-minute visit to his hospital room yesterday by House Speaker John Hanson Briscoe and Senate President Steny H Hoyer.

"He offered us a hardy handshake," Briscoe said.

He told the legislators he is regaining his strength by exercising.He displayed his barbells and squeezed a clay ball to show the power in his hand. But Mandel also acknowledged that he was "frustrated" by the hospitalization.

As a streetwise politician, he could handle the embarrassing courtroom scenes and gossip about his love affair with a southern Maryland divorcee whom he later married. Part of his political genius has been the ability to "understand what will fly and what won't," in Hoyer's words.

"But to be physically enfeebled," said an associate, "is the destruction of his self-image . . . an unraveling of the fabric of inscrutability."

What emerges then in conversations with those who have known Mandel for years is a portrait of the ailing governor at low ebb. It is a protrait of a masterful politican and skillful wheeler-dealer caught up in events he can't control, growing increasingly frustrated and restless in his hospital room, isolated from the power and political cronies he has spent his life accumulating.

"We're talking about a guy whose whole life has been one of controlling events, and here's an event he can't do anything about," says DeFilippo, now a Baltimore advertising executive.

When Mandel was hospitalized April 5, some skeptics suspected that the governor was still trying to control his destiny, that he was somehow faking ilness to avoid his second political corruption trial, then scheduled to begin eight days later. "My diagnosis is a bad case of the time. Six doctors have refuted this.

Mandel's life in recent years has been a continuing melodrama, the stuff of a good romantic novel, or a bad soap opera.

He's plunged from one bizarre crisis to another, always somehow maneuvering out of each one only to be met with another.

A lesser politician might have been doomed by any of them: a post-midnight auto accident Dec. 5, 1971 in which a bowie man was killed and Mandel could not adequately explain where he was coming from; his decision to leave his wife Barbara in 1973 followed by an ugly public feud between the two; a federal investigation in 1975, his indictment in November, 1975; his trial in September, 1976 which ended in a mistrial after two jury-tampering incidents and now, an illness of undertermined origin and severity.

He had won re-election in 1974 by an overwhelming margin. He built a reputation as an effective administrator, a governor other governors looked to for leadership in their national conclaves.

His batting average with the General Assembly was impressive and even as late as 18 months ago, he talked of running for the U.S. Senate.

It all didn't really begin to unravel until January, 1975, the beginning of his second term, when he and his wife flew to Jamaica for a vacation aboard a corporate jet owned by Steuart Petroleum Co. which was seeking state permission to build a controversial refinery in Southern Maryland. He at first claimed the trip was financed by raffle winnings, and was later caught in a bald-faced lie by the media.

In retrospect, the trip was foolhearty. Marvin Mandel was riding high at the time. He had scored a landslide re-election victory a few months before. He was personally happy, finally living with the woman he had risked his political career to wed.

It was, however, his third trip in three months. He had spent 20 days in Europe and Israel that November, then gone to Florida for 10 days in December. Later, he admitted at a press conference, that it had been a "public relations mistake."

But its repercussions were wideranging. It showed Mandel's tendency to lie, or aides called it "the lawyer's habit of shaving the truth," and his newly acquired taste for high living.

Events snowballed after that. And his administration has lived under an almost constant state of siege since.

"I don't feel comfortable complaining about his scale of moral values," Lt. Gov. Blair Lee III said this week. "I don't think he's done anything not done by a lot of governors in other states. He just happens to have done them at the wrong time. But I'd have a different scale."

For all outward appearances, Mandel never gave a hint that anything was wrong. He was forever calm, never losing his temper, seldom raising his voice in anger. Even during his 13-month criminal trial last fall, he seldom changed his sphinx-like expression. He listened to the bad and good with equal dispassion.

His attorneys would leap to their feet shouting protests, his wife would stamp out of the courtroom in anger, but Mandel just sat there, toying with his ever-present pipe.

Only when the most embarrassing testimony was delivered - tales of accepting free trips, jewelry and clothing - did Mandel react. And then, he merely slipped down in his big swive chair, so that he nearly went out of sight to spectators.

W. Dale Hess, a close friend and codefendant of the governor wasn't surprised that Mandel kept his cool. "Marvin is used to strain and stress," he said. "He seldom relaxes. He's a hard worker, never lazy. He gets up early and goes to bed late."

Hess and others were surprised at how bad Mandel looked when he appeared at the wedding of one of Hess' sons April 2, three days before he was taken to Prince George's General Hospital complaining of fatigue. Hess recalls his wife say, "My God, the governor looked bad."

Once in the hospital, new details about the private life of Marvin Mandel emerged: that he had a secret diabetic condition that he tried to hide even from his doctors; that he was an insomniac, who stayed up until the wee hours of the morning watching television and wandering about the governor's mansion; that he suffered severe headaches; and had momentarily lost his memory testifying before a congressional committee.

Until this week, the only visitors Mandel was permitted were members of his family. In theory, he ran the state by remote control. Each morning, key staff members sent him detailed memos, delivered to his ninth floor room by his wife, Jeanne, or state troopers.

He jealousy guarded his title and powers, only reluctantly transferring minor authority to his lieutenant governor, communicating with the State House through his wife, who described herself as "the governors' eyes and ears, arms and legs."

It wasn't until Wednesday that any word came that his condition was improving, and that he would be transfered to John Hopkins University Hospital in Baltimore for one final test.

Hoyer and Briscoe agreed that Mandel looked good yesterday. "His spirits were good, he was lucid and jovial, and he looked well rested," Briscoe said.

"He looked as good physically and mentally as he did two days before he went to the hospital," a said Hoyer.

Briscoe attributed part of the governor's impatience with the hospitalization to the fact that "he has not experienced much sickness for a man 57 years old."