Breaking away from the pack after 25 kilometres, Jairus Chanchima of Kenya won the 18th Nagano Marathon, an IAAF Bronze Label Road Race, clocking 2:15:31 on Sunday (17).
Both Chanchima and Ethiopian Shasho Insermu, who won the women&rsquo;s race in 2:34:14, battled&nbsp;strong winds that heavily impacted the finishing times, resulting in the race's slowest and second-slowest winning performances, respectively.
In the men&rsquo;s contest, the real racing began after 28km when Chanchima surged away from the leaders to leave behind a chase pack of six: Fabiano Joseph, Laban Mutai, Ser-Od Bat-Ochir of Mongolia, Taiga Ito, Kazuya Ishida and Shoji Takada. Two kilometres later Chanchima led by 38 seconds, one he extended to nearly a minute and a half by 35km.
Bat-Ochir closed part of that gap to finish in 2:15:31, 25 seconds adrift with Taiga third, clocking 2:16:32.
Joseph, who was expected to make a breakthrough, finished a distant fifth in 2:17:35.
Chanchima, who dropped out of the race last year, became the ninth Kenyan to win at Nagano.
In the women&rsquo;s race, Insermu came from behind after 40km to seal her victory, 40 seconds clear of Peruvian Gladys Tejeda who clocked 2:34:54. Insermu became the third Ethiopian woman to win in Nagano after Elfnesh Alemu in 2000 and Fatuma Roba in 2004.
The race also went out slow, but by 5km (18:12) only five runners remained in contention: Insermu, Tejada, Helen Mugo, Winfridah Kebaso and Kaori Yoshida.
Tejada made the first move, breaking away from Insermu at 20km to lead by six seconds, and extending it to nearly a minute by 30km (1:46:48).
But Insermu regrouped and began to chip away at the gap, reducing it to 19 seconds by 40km before securing the victory in the final kilometre.
Yoshida, who also ran a strong final 10km, finished third in 2:35:14.
Ken Nakamura for the IAAF

Breaking away from the pack after 25 kilometres, Jairus Chanchima of Kenya won the 18th Nagano Marathon, an IAAF Bronze Label Road Race, clocking 2:15:31 on Sunday (17).

Chanchima and Insermu victorious in windy Nagano

The 18th edition of the Nagano Marathon, an IAAF Bronze Label Road Race, sees Kenya&rsquo;s Jairus Chanchima as the fastest man in the field but the big question is whether Tanzania&rsquo;s talented Fabiano Joseph will fulfil his potential on Sunday (17).
Chanchima has a best of 2:07:43 from the 2012 Seoul Marathon but this is the only time he has cracked 2:10:00 and his last marathon was at the 2014 Seoul Marathon where he was only 12th with 2:14:53.
The favorite&rsquo;s role consequently falls to the second-fastest runner in the field, his compatriot Laban Mutai, who recorded his personal best of 2:08:01 at the 2012 Koln Marathon. He also won the 2014 Linz Marathon with 2:08:03.
His latest marathon was in Valencia last November, where he was sixth with 2:09:55, still showing consistent form under 2:10:00.
However, the most intriguing runner in the field is Joseph.&nbsp;
Now 30, Joseph has run five marathons in his career but his marathon best is only 2:13:24 from 2006, when he made his debut at the Amsterdam Marathon. He was only 11th at the 2014 Commonwealth Games and 42nd at the IAAF World Championships Beijing 2015 but his credentials at shorter distances are quite impressive.
He won the 2005 IAAF World Half Marathon Championships and finished second at the 2003 and 2004 editions. His half marathon best is 59:56 and he has good track times to his name, although most were set almost a decade ago.
Theoretically, Joseph should be able to run a much faster marathon. How much faster is one of the intriguing questions on Sunday.
The third fastest runner in the field is Mongolia&rsquo;s Ser-Od Bat-Ochir who recorded the best of 2:08:50 in the 2014 Fukuoka Marathon. He is one of the most prolific elite runners in the world and Bat-Ochir has run at least four marathons every year since 2010. Nagano will be his second marathon of the year but he was a dismal 92nd in Lake Biwa Marathon last month and he may not be close to his best shape.&nbsp;
The best domestic runners in the field are Hiroki Kadota, who has a best of 2:10:46 from the 2015 Beppu-Oita Marathon, Taiga Ito, who has a best of 2:11:15 from the 2013 Tokyo Marathon and was fifth at the Nagano Marathon with 2:12:04, and Kazuya Ishida, who has a best of 2:11:57 from the 2012 Nobeoka Marathon.&nbsp;&nbsp;
The fastest woman in the race is Hellen Mugo, who recorded her best of 2:27:16 at the 2010 Carpi Marathon. But she has not broken 2:30:00 for the marathon since the 2012 Kosice Marathon.
By contrast, Peru&rsquo;s Gladys Tejeda recorded her best of 2:28:12 at the 2015 Rotterdam Marathon, and comes to Nagano in good form after finishing ninth at the IAAF World Half Marathon Championships last month.
Another woman to look out for is Kenya&rsquo;s Windfridah Kebaso, who runs for a Japanese corporate team.
Kebaso has run only one marathon, the 2015 Saitama Marathon, where she finished fifth with 2:32:08, but her half marathon best is 1:09:59 and her 10,000m best on the track is an impressive 31:19.92.
The top domestic runner is Kaori Yoshida, who has the best of 2:28:43 from 2015 Saitama Marathon.
In addition, a number of former great runners have been invited as guests this year. Among them is Japan&rsquo;s 2000 Olympic champion Naoko Takahashi and Kenya&rsquo;s two-time Olympic medallist Eric Wainaina as well as local star Yoshimi Ozaki, the 2009 world silver medallist.
Ken Nakamura for the IAAF

The 18th edition of the Nagano Marathon, an IAAF Bronze Label Road Race, sees Kenya’s Jairus Chanchima as the fastest man in the field but the big question is whether Tanzania’s talented Fabiano Joseph will fulfil his potential on Sunday (17).

Chanchima and Insermu victorious in windy Nagano

Joseph aims to fulfil his marathon potential in Nagano