Frank Costello has become an expert in life on the run.

The University of Maryland track coach not only experiences motion as he trots around the field watching his team, but Costello also does some of his fastest work dashing through airports.

Costello might have to lap O.J. Simpson to complete a typically grueling itinerary this weekend. He flew to a meet in Jamaica yesterday, will return to Philadelphia for the Freedom Games Saturday, then go back to College Park for a Sunday meet, Costello had not even unpacked from a West Coast trip last weekend before he left again.

Costello, 34, has an excellent reason to hop the globe: a young man named Renaldo (Skeets) Nehemiah.

Travel is not the only demand on the coach of the world's greatest hurdler. Costello cannot even leave his business at the office because his home phone number tops the list of every meet promoter.

"Coaching Skeets has brought another phase of coaching I didn't ever think I would get into," said Costello, who was a world-class high jumper in the late 1960s. "I'm more of an agent or manager."

Costello screens phone calls from promoters and the media, as well as fans, "making sure Skeets has a private life. You couldn't name a country in the world that hasn't had a magazine or television station there request an interview."

The coach performs duties on trips that would make a Secret Service man blanch. He constantly is at Nehemiah's side.

Costello had to grab a couple of policemen to help get Nehemia off the field after a spectacular effort at this year's Penn Relays. Nehemiah cannot sign his own name in hotel registers, the better to keep a horde of adoring fans from storming his room.

"Coach Costello tries to keep me out of the middle of things," Nehemiah said. "He acts as a buffer and then refers the important things to me so I can act upon them at any discretion. I just like to have silence and keep to myself before and during competition."

Despite his frantic lifestyle on the road and at the office, Costello has tried to maintain some sanity at home.

"This has been the busiest season Frank's ever had," said his wife Nancy. "But he always comes home very happy. He finds the new things he's doing a challenge.

"I think he comes home more tired than Skeets. He says, 'I don't know how Skeets can handle it all.' Frank feels the tension more. He has no release. Skeets can release the tension by going out and running a 13-second 110 meters."

Costello's fuse runs short when his coaching tactics are questioned by meet promoters, according to Nehemiah.

The two get together each fall and map out a schedule for the eight-month track season that starts in January. There is no variation permitted.

That is why Nehemiah did not run hurdle events in the first few outdoor meets this spring. Costello was entering him in sprints to improve his strength.

"Coach is extremely short-tempered when he gets flak from meet directors if I don't run the hurdles," Nehemiah said. "They approach him as if he doesn't know what is best for me. But we don't go out of our schedule to satisfy anybody. We agreed in the fall on a schedule and shook on it. The most important thing is to prepare me for the key meets."

Nehemiah came out of high school in Scotch Plains, N.J., as a blue-chipper. The fact put added pressure on his coach in terms of the technical aspects of coaching.

"He's a phenomenal athlete to start with," Costello said. "Sometimes a phenom is difficult to coach because you don't want to ruin him by doing anything wrong. The main thing I needed to do was set up his workouts right."

Costello added that there is no resentment by other Terp team members of the time the coach spends with his superstar.

"Maybe it takes away from the other athletes some," Costello said. "But I taught school for awhile. If you're showing why an ice cube melts and a kid in the back row is making an atomic bomb, you have to give that kid more time."

Nehemiah, who said that one of the reasons he chose Maryland was Costello's age, "so I could relate to him in 20th-century terms," has grown close to the coach.

"He's almost like a next of kin." Nehemiah said. "He thinks my image is the most important part. It's like we are combining forces to create a self." CAPTION: Picture, Renaldo Nehemiah (left) and Frank Costello are eating lots of meals in the air these days