No special uniforms are required for Hoover-ball. No manufacturer has developed a Hoover-ball shoe. But, though the sport is not expected to dominate prime-time television, Hoover-ball is gaining in popularity.

In its second year of revitalization, Hoover-ball boasts a national championship, and recreational competitions throughout Iowa.

After a 57-year absence, the sport returns to Washington when the first Capital Classic Hoover-ball tournament begins at 10 a.m. today on the volleyball courts east of the National Air and Space Museum. More than 15 teams are expected to participate, with men's, women's and co-ed divisions.

A game developed by Admiral Joel T. Boone in 1929 for President Herbert Hoover during his four-year stint in the White House, Hoover-ball disappeared almost as quickly as it appeared. President Hoover was not re-elected in 1932 and the sport disappeared.

In the summer of 1988, the Hoover Presidential Library Association in West Branch, Iowa, decided to try to revive the sport. Blending elements of tennis and volleyball, it consists of two teams of three players hurling a six-pound medicine ball over an eight-foot net.

The game is scored like tennis: love, 15, 30, 40, advantage in and advantage out. The ball must be caught on the fly and returned without being passed to a teammate. There is no easy way of getting the ball over the net. The game requires strength and stamina. Unlike volleyball, spiking is not allowed. Each team's court is divided in half and a ball caught in the front half, the half closest to the net, must be returned to the back half of the opponent's court.