The changes may not be obvious to the runners and walkers winding through town Sunday morning, but Honolulu Marathon organizers are implementing measures to enhance security for the 41st annual race.

Honolulu Marathon president Jim Barahal said race officials reviewed security in light of April’s bombing at the Boston Marathon. Along with other measures, traffic and security cameras will be in use and there will be an increase in police numbers for the race.

"Of course, this year the big issue for all big marathons was security issues from what happened in Boston," Barahal said.

"I don’t think the average runner or spectator will really notice anything much different, but there’s been a fair amount going on behind the scenes. So we’re very confident it’ll be a very safe and secure event."

Some 29,562 had signed up for the marathon when online registration ended late last month and Barahal anticipates entries breaking the 30,000 mark for the second straight year.

Walk-up registration begins Wednesday with the opening of the Honolulu Marathon Expo at the Hawaii Convention Center. Late registration will be open until Saturday.

"Last year we grew so much with 31,000 entries, this year the goal was to try to keep it at that level, which we have," said Barahal.

Three past Honolulu Marathon champions and a highly decorated veteran are slated to lead the throng on the 26.2-mile course.

The race will again start at 5 a.m. Sunday on Ala Moana Boulevard. The course will take the runners through downtown Honolulu and Waikiki on the way out to Hawaii Kai, where they’ll loop back toward the finish line at Kapiolani Park.

Valentina Galimova returns to defend her the women’s title in a field that includes 2011 champion Woynishet Girma. Galimova edged Girma with a surge in the last mile to win last year’s race.

The men’s field is headlined by Martin Lel, a three-time winner of the London Marathon and two-time New York City Marathon champion who will be making his Honolulu Marathon debut. Nicholas Chelimo, the 2010 and ’11 champion, will run for a shot at his third title.

Wilson Kipsang, last year’s men’s champion, is not entered in Sunday’s race after setting a world record at the Berlin Marathon in October.

Barahal is also keeping a close watch on the weather forecast for the weekend and wasn’t complaining about the wet weather that just passed through.

"We were pretty happy that storm came in yesterday and not next Sunday," Barahal said.