Olympic speed skating champion Hiroyasu Shimizu decided Friday to pull out of the single-distance national championships getting under way Saturday at M-Wave ice arena in Nagano.
Shimizu, the world record holder at 500 meters, hurt his back in training at Calgary three weeks ago and was unable to make it back to full fitness in time for the national championships.
National team doctors have advised him to rest.
"The Olympics are later this season so I'm trying to keep positive and get some good rest," said Shimizu, who set the 500-meter world record of 34.32 seconds last March in Salt Lake City, host of next February's 2002 Winter Games.