If they lived in ancient Rome, Chris Lockett and Irvin Grant might be envisioned in a giant coliseum, charging toward each other on horses with swords. It is this type of duel that has characterized the two pole vaulters in the past two months.

Lockett, a Woodbridge junior, and Grant, a Warren County senior, have recently reached the height of competition in track and field's most mystifying and unusual event, a sport in which an athlete catapults himself into the air with a thin pole.

The two vaulters met for the first time Dec. 8 in Lynchburg, where each failed to clear the opening height. Then at the Episcopal Relays on Dec. 15, Lockett and Grant each cleared 13 feet 6 inches, but Lockett was awarded the victory because of fewer misses. Less than a week later at the trials of the George Mason Invitational, Grant vaulted 14-0, a personal best, and beat Lockett by six inches.

In the George Mason finals on Jan. 5, the margin of difference was again six inches, but this time, it was Lockett who vaulted a personal best and meet-record 14-0. Grant cleared 13-6.

''I like the competition,'' said Grant, who is 5 feet 8, 125 pounds. ''The stronger the competition, the better. Chris is a great competitor.''

''I love the competition with Grant,'' said Lockett, whose 6-foot, 169-pound frame is considered large for his event. ''This year, it's kind of hard because the closest guy on the team vaults only 10-6, but when I get into the meet, the adrenalin is flowing.''

To succeed in the pole vault, an athlete needs the speed of a sprinter, the strength of a weightlifter, and the timing, balance and body control of a gymnast. This precise combination makes the vault the toughest event to master in track and field.

Lockett has the strength, Grant the speed. Both of them have the agility and body control, both have the attitude and disposition needed for a sport as dangerous and challenging as the pole vault.

''Dangerous?'' said Lockett, whose first vault as a freshman was 10-6. ''You have to be crazy anyway. I think it's fun. The exhiliration comes from the bend in the pole and the uniqueness of the sport. When I know I'm over the height, it feels great coming down.''

''It's like with every jump, you're on the edge,'' said Grant, whose first vault was a 7-6 in eighth grade. ''The greatest part of the vault is that you can't go just halfway.''

Pole vaulters are always asked about the risk of injury. Sometimes the pole breaks while the vaulter is ascending and sometimes the vaulter misses the mats on the way down. These miscues can lead to serious injury, but Lockett and Grant have been lucky.

''The closest I have come to injury,'' said Lockett, also a linebacker on the Vikings' football team, ''was when I was vaulting at Blacksburg last year. I didn't quite make it over the bar and I started falling back. I fell backward to the ground and right on the back of one of our shot putters. She had turned and tried to run, but I was falling too fast and I landed on her.''

Grant's only serious injury occurred on a freak accident when he was a freshman. ''I broke my knee,'' he said. ''I was running down the runway and before I even took off, the knee just broke.''

Woodbridge Coach Ron Helmer said that pole vaulters must possess ''a prima donna attitude about what they do. They need to combine this with the recklessness -- the thinking that 'I don't care about the weather, I don't care how the pole is handling today.'

''On one hand, they need to be as high as a kite and on the other they need to have nerves of steel,'' Helmer said. ''It's a difficult mix to have. For example, Chris works outside every day. Last year, it was 27 degrees and between sleet and snow and I looked outside and I saw Chris jump over 13 feet.

''He's a prototype field-events man. He has the ego, has has that desire for success, and he has a way of dealing with the pressure when all the spectators' eyes are on him.''

Lockett became interested in the pole vault after watching 1976 decathlon gold-medal champion Bruce Jenner in the vault. Lockett placed sixth in the Commonwealth District outdoor meet as a freshman. He vaulted indoors for the first time last year and cleared 12-6 for fifth in the state meet. In the state outdoor meet last year, he made 13-0 and took sixth.

Grant started vaulting ''because I didn't have the speed to be sprinter. I had a dream to jump 13 feet by the end of high school (now he shoots for 15 feet).'' In his junior year, Grant won the Northwestern District meet, placed third in the Northwestern Region, and captured the Virginia AA state outdoor title.

This is the first year Grant has jumped indoors. According to his coach, John Blanton, he has no indoor facility to practice vaulting so he competes in as many meets as he can for the experience.

Lockett has no indoor facility either, but he practices outdoors, even last Thursday during the snowstorm when he said he ''took a snow shovel and cleared off the runway.''

Lockett and Grant each hope to vault in college. While Grant wants to go to North Carolina State next year, Lockett will be back attempting to be the first high school athlete in Virginia to clear 16 feet and taking a ribbing about being a pole vaulter.

''If I say something stupid in class,'' Lockett said, ''a guy in the class will say that the high altitude must be messing with my brain.''