Astronauts Jack R. Lousma and C. Gordon Fullerton ate and slept so little their first day in space last month they were hard-pressed to keep pace with their flight plan their second day in space.

"I ran out of gas the next day," a candid Fullerton revealed yesterday at a news conference at Houston's Johnson Space Center to discuss their eight-day flight aboard the space shuttle Columbia. "Every 10 minutes, I felt like I'd just run a four-minute mile."

Fullerton and Lousma attributed their one-day exhaustion to space nausea, the side effects of a drug they took to combat motion sickness that took away their appetite and their inability to sleep their first night in Earth orbit.

Lousma was kept awake by high-frequency static from Soviet radar, while space rookie Fullerton was so bothered by the weightlessness of space during his first night in orbit that he couldn't get comfortable enough to fall asleep.

"I couldn't figure out what to do with my head, I wanted to lay it down on something, but I couldn't figure out which way was down," Fullerton said. "Even the muscles you use to go to sleep are confused up there."

The drug combination of scopolamine and Dexedrine they took to ward off motion sickness killed their appetites. "We had no desire to eat and we didn't. That was probably the root cause of how we felt the second day," Fullerton said.

"That second day was a low point in our morale," he continued. "We discovered missing tiles on the nose, the wrist camera on Columbia's robot arm failed and we had a temporary problem with the payload bay door latches. But by the third day we were raring to go, ready to enjoy the whole thing."

Enjoy it, they obviously did. About their launch from Cape Canaveral, Fullerton said, "There was this tremendous feeling of power under you, a relentless push that adds up to the ride of a lifetime."

"We knew we had a tiger by the tail," Lousma said.

Once they began eating and sleeping, Lousma and Fullerton said they were able to work fast enough to catch up with their flight plan. One of their main objectives was to operate the 50-foot mechanical arm in the shuttle's cargo bay, which they said they did with surprising ease.

"We moved that arm night and day," Fullerton said. "When the sun went down we used our payload bay lights to help us, and we were able to operate the arm just fine."

Lousma and Fullerton, whose time in space exceeded that of the first two shuttle flights combined, showed a film that demonstrated the new exercises shuttle astronauts will use to keep limber in weightlessness.

Mostly, they used a new type of treadmill to jog in space, but they also demonstrated how they locked their feet in stirrups to do "no-hands" push-ups and how they strapped pillows on their heads to bang them against the walls of the shuttle. "That's if you really get frustrated," Lousma said.

Landing the DC9-sized spaceliner at White Sands Missile Range in New Mexico proved Columbia's versatility, Lousma said, since the shuttle had been targeted to land at Edwards Air Force Base in California.

He said he brought the shuttle into a strong west wind, then "crabbed" the craft to the right and then to the left to line it up with the runway at White Sands before touching down less than 100 feet from a black diamond that marked the aim point on the White Sands runway.

"I had plenty of runway, so I just let it roll," Lousma said, "doing the nose-wheel steering test, moving the nose wheel from left to right when we were still doing 50 knots on the ground. I may have landed a little faster than I wanted to, but I never felt the need to do more than tiptoe braking to slow it down once we were rolling on the ground."