Rob Muzzio lay face down on the trainers' table at Robertson Stadium today, a huge ice pack on his tailbone and his right elbow and left shin covered with tape.

"Are you okay?" asked a somewhat timid youngster of about 8 or 9, from outside the ropes that guard ailing athletes from inquisitive public. Assured that Muzzio would be all right, the youngster added, "Gee, I'm glad. I thought you were dead."

Muzzio, the George Mason freshman who came here with high hopes of capturing an NCAA decathlon championship, brought fear to hundreds of watching eyes when he crashed onto the pole vault runway after his pole had slipped during a plant. He lay there for some time, before he was helped up and walked shakily to the trainer's tent.

There, while he was treated for a bruised back, he turned to Ralph White, George Mason's assistant track coach, and said, "I'm sorry, coach. But I'll be back."

"I was afraid to come over, he looked so bad," said White, who dashed across the track to Muzzio's side on the vault approach.

"I heard a thump--that's what scared me," Muzzio said. "The last thing I saw was that cement. I just wasn't myself out there--my mind was saying, 'You're weak, tired and sore.' It's never done that before."

Muzzio was weary before the start of the pole vault, the eighth event in the decathlon, because of an earlier misfortune in the high hurdles, when his dreams of victory went crashing down with him at the first hurdle.

Underestimating the effects of a 9 mph following wind, Muzzio started with too much drive in the hurdles, opening event of the second day's program. He fell over the initial barrier, scraping his left knee and shin, as well as his left hand. The most painful result at that time, however, was the loss of more than 200 points.

Although he rose and finished the race without further mishap, Muzzio was timed in 17.67 seconds, for a meager 607 points.

"My lead leg went under the hurdle; you can't do that," said Muzzio, a Robinson High graduate who was the U.S. junior decathlon champion a year ago.

"He was in great shape until that spill," White said. "He was sixth, but close to the leaders, and he has a better second day than the others. He had really been competing well. That's what got him. He was too strong going into that hurdle."

Muzzio threw the discus 131 feet 8 inches for 688 points and was eighth entering the pole vault with 5,239. The leader at that stage was Kerry Zimmerman of Indiana, competing in only his third decathlon, with 5,691.

Although running the climactic 1,500 meters in the slowest time of the 10 finishers, 5:02.54, Zimmerman was good enough to total 7,810 points and win the 10-event grind by 67 points over Orville Peterson of Campbell University.

Keith Robinson of Brigham Young, in finishing fourth with 7,709, established a U.S. junior record, which Muzzio had coveted. Seventh with 7,469 was Jim Connolly of UCLA, whose title chances were ruined by a horrible discus throw of 91-4. Connolly's mother, Olga, is a onetime Olympic discus champion.

Jackie Joyner, who doubles as a basketball player at UCLA, easily retained her championship in the women's heptathlon with a collegiate record of 6,365 points for the seven events. Marlene Harmon of Cal State-Northridge covered the concluding 800 meters in 2:09.35 to jump from fourth place to second. Myrtle Chester of Tennessee and Laurel (Md.) High finished ninth with 5,591.

UCLA recorded 28 points by placing 1-5-8 to get a fast start on what is expected to be its second straight women's team title. Tennessee, considered the No. 1 challenger, is unlikely to overcome the loss of Delisa Walton-Floyd, the defending 800-meter champion who withdrew because she is six months pregnant.