[ No headline ]

Alaska's 1,000-mile sled race; The Last Great Race, by Tim Jones. Seattle: Madrona Publishers (2116 Western Avenue, 98121). 266 pp. $14.95.

And you probably thought the word ''mush'' was all it took to get a dog sled moving. In Alaska's annual Iditarod Trail Sled Dog Race from Anchorage to Nome, it also takes tons of dog food, months of training, and enough sweat to start a small glacier.

The Iditarod is a grueling test of man and dog: 1,049-plus miles of snowy trails which wind through dangerous mountain passes, across frozen rivers, and over wind-wiped tundra. So far no one has ever made it in less than 12 days, and sometimes the last finalist comes in 12 days after the winner.

Author Tim Jones offers a fascinating glimpse of this race and the attitudes and competition behind it. My only complaint is that he followed the race at checkpoints; the story would have held more immediacy had Jones actually experienced the trail.