Thousands of runners will be arriving on Oahu this week for Sunday's Honolulu Marathon and organizers believe they?ll infuse up to $110 million into the state?s economy.

About 23,000 runners are set to hit the streets early Sunday morning, a 1 percent increase, or about 200 more entries than last year.

"I thought the numbers would probably drop a little given the overall economy in Hawaii and the mainland United States and Japan. But the numbers are staying strong,? said Honolulu Marathon president and CEO Jim Barahal.

Barahal said entries from Hawaii, the mainland U.S. and Europe are up between 7 percent and 10 percent over last year, bringing in an additional 3,000 runners from those markets.

"Endurance sports seem to be enjoying a bit of a boom. It's something people can do without spending a lot of money as far as training and participating in local races,? Barahal said.

But the marathon's target market -- Japan -- is down 5 percent this year.

Barahal believes the drop is more the result of a lack of airline seats from Japan to Hawaii than the earthquake and tsunami back in March.

"The planes are smaller and that the planes are actually quite full. But I think it's just harder for people to get an airline seat. Since the biggest part of our race is from Japan, the drop from Japan has brought the overall numbers down to where it will be about the same time last year," Barahal said.

Organizers also expect the race to infuse $100 million to $110 million into our economy despite the drop in Japanese entries.

The Hawaii Tourism Authority's executive director Mike McCartney said Japanese expenditures are up 7 percent for the year so far, even though Japanese arrivals are down 6 percent.