The only problem has been that when the biggest meets of the season come along - either the World Championship, the World Cup or the Olympics, depending on the year - one of Murphy's laws typically goes into effect.

Quickly, the sordid details: At the World Championships Marsh has run into the final barrier with the race won (1983), and he has come down with mononucleosis on the eve of the event (1979). At World Cups he has finished first and then been disqualified for being pushed around a barrier (1981). And at the Olympics he was boycotted out of the 1980 Moscow Games, when he was the favorite, and at Los Angeles in 1984 a virus slowed him to fourth place at the finish line, where he collapsed unconscious.

A lot of people thought that, at 30, that might be Marsh's last Olympics and/or major world championship. Others have tossed in the towel in the face of a lot less adversity. But Marsh wasn't one of them. He came back in 1985 to not only win another national championship but to record his 8:09.17, the fastest steeplechase ever run by an American. It was a great comeback year . . . except at the World Cup, where Marsh went to sleep on the backstretch and lost to a Kenyan who wasn't supposed to be much of a threat.

He's stayed competitive since then, winning his share, keeping fit, intrigued by the chance to compete in another Olympics. Which not only brings us to Seoul, but brings up the rather obvious, but, still, well, rather tentative question:

"Say, uh, Henry . . . how do you feel?"

Marsh was sitting outside the Olympic Stadium, where the first steeplechase heat of the Seoul Games is set for Monday. He answered in a kind of just-between-you-and-me voice, as if he wasn't about to offend the fates.

"I feel good. I think I'm in the best shape of my life," he said.

"I know I'm not projected to medal," he went on. "I haven't seen one publication that picks me. But I've made all the mistakes I could (in the past). I've had all the bad luck. Maybe there's nothing else that can go wrong. Maybe it's my turn for something good. Maybe the bad stuff will happen to somebody else."

Plus, there's the not so inconsequential fact that in the past two weeks Marsh has been breaking all sorts of records - his own records.

He's 34 years old and has never run so fast at so many distances. At various training sessions he's set PRs (personal records) at 600 meters, 800 meters, 1,200 meters, 1,500 meters and 3,000 meters. He ran a 3:42.75 to win the 1,500-meter race last week in the Olympic Stadium in a tune-up meet to test the timing equipment. That time is the equiv alent of a 3:58.9 mile _ only the second sub-four-minute mile for Marsh ever. His other came just before he set the American steeplechase record in 1985.

"I haven't felt this good for three years," he said. "I've been able to do my workouts and bounce back."

He had an inkling things were really coming around at his last workout on the BYU track before leaving for the Orient. In a pre-race routine Marsh typically uses as a gauge to see where he stands _ it involves running a 400, 1,200, 800, 400 and 200, mostly over hurdles _ he ran a 3:06 for the 1,200-meter distance. He had never done better than a 3:08 before. Ever.

He had nearly written off the Olympics earlier in the year after fighting off a viral pneumonia three different times and running the worst races of his life.

But he went to a biologist in Pleasant Grove named Mark Johnson, who works with a chiropractor and diagnoses the body's electrical impulses. Johnson suggested that a virus called Epstein-Barr was the one that was plaguing Marsh and that his adrenal glands, probably because of all the competition over the past decade, were not working properly.

Marsh went on medication for the virus and took adrenalin supplements. He also took some aerobic stabilizer pills a friend sent from Dallas.

He's got the aerobic stablizer pills and the adrenal drops here in Seoul.

"There are some great runners entered in the steeplechase," he said. "I may have to run the fastest I've ever run . . . but I'm here, and I'm ready for whatever happens.'

Maybe this time it will happen to somebody else.