BOSTON — Half a mile out from Hopkinton, Byrne Decker trotted up behind fellow Mainer Joan Benoit Samuelson and tapped her on the shoulder.

“I heard you’re fit, Byrne,” Samuelson said to the 47-year-old resident of Yarmouth, who last ran this route seven years ago. “Go!”

Decker did as he was told, as he had trained in his noon training runs that began on Commercial Street in Portland, and wound up with the fastest time of any Maine runner Monday in the 118th running of the Boston Marathon.

Cautiously at first, reaching the halfway mark behind four other Maine runners, then proceeding to Boylston Street at a slightly faster pace, just under six minutes per mile.

“I was really trying to conserve,” said Decker, who made sure to slap hands with the Wellesley College students lining the course before tackling the hills of Newton. “I’ve run this so many times while dying at the end, and I was not going to let that happen.”

Running his second half six seconds faster than his first, Decker crossed the finish line near the Old South Church in 2 hours, 33 minutes, 36 seconds – good for third in his five-year age group and 124th overall. A year ago he was with his son, Ben, a senior at Yarmouth High, between college visits to Tufts and Amherst. They watched from Boylston Street, between the sites of the two bomb blasts, but left after seeing the elite runners finish.

“That sort of got me thinking,” Decker said. “Time to do another one. I decided shortly thereafter and put a good training plan together.”

Erica Jesseman, 24, of Scarborough actually beat Decker to the line. She started with the elite women 28 minutes ahead of the first wave of runners but faltered in the second half, which took her nearly eight minutes longer than the first.

“From (Mile) 13 on, I was in a really bad place,” Jesseman said. “When the group I was with took off I started thinking, ‘I can’t do this. I’m not strong enough.’ ”

The record crowds and the approach of men’s leader Meb Keflezighi – “That was so inspirational!” – gave Jesseman the energy she needed to complete her race in 2:42:32, good for 29th overall and eight seconds ahead of Sheri Piers of Falmouth.

Piers, 42, was the fourth female master and 31st woman. She caught up to Jesseman at Mile 24 and they ran in together.

“I couldn’t have done those last couple of miles without her,” Jesseman said. “I wanted to drop out. I was hurting.”

As was Piers, who left her family at home this year after bringing them, for the first time, to cheer her on at Boston a year ago, when the two bomb blasts on Boylston Street sent a city and a nation into shock.

“I have to tell you, I’m proud of myself because I went to a lot of rough places in my head,” Piers said. “The old, ‘Well, I’m getting old.’ Then I started thinking about all the Boston people … if they could go through the pain that they went through, then I could get through this.”

When Keflezighi surged past her, with the attendant helicopter and hoopla, and crowds cheering for the first American man to win Boston since Greg Meyer in 1983, Piers felt herself swept up in the excitement.

“I got chills all through my body,” she said. “It gave me a burst of energy. To see an American out there (in front), that got me through (the rest). That was so exciting.”

Longtime training partner Kristin Barry of Scarborough, returning to Boston to run for the first time since 2003, finished in 2:51:23 in her masters debut, finishing sixth among women 40 or over.

“It was rough but you know what? I had to be here this year, regardless,” Barry said. “It was emotional. It definitely had a different vibe, where like, your time almost didn’t matter.”

Samuelson, at 56, was only two places behind Barry’s 56th, in 2:52:11. Daughter Abby and son Anders also ran Monday, while husband Scott waited in the grandstand rather than try to navigate the heavy security by stopping at various points along the course as in years past.

“We went to the start together and then we went our separate ways,” Samuelson said. “There was just far more energy and bigger crowds that I can remember.”

Samuelson spent much of the previous four days in Boston visiting with different survivors of last year’s bombings.

“We are on the road to recovery,” she said. “We are strong. It was a beautiful day to celebrate the perseverance of the survivors and the perseverance of the runners.”

Spencer McElwain, a Caribou native and University of Maine graduate, led the Maine contingent through 21 miles before his right hamstring seized up and he was forced to walk for two miles before jogging in to a 2:37:58. Josh Zolla of Freeport had similar hamstring issues and also got passed by Decker, as did Adam Goode of Bangor and Claton Conrad of Portland.

“I’ve never had a muscle cramp in my hamstring,” McElwain said. “I was ready to take the (subway) but I didn’t have any money.”

Zolla, running his fourth Boston, said the support for runners was palpable.

“I was stuck on the side of the road, my hamstring seizing,” he said. “People would go by you and just touch you. And just that simple touch is so motivational, that we’re all out here together.”

Glenn Jordan can be contacted at 791-6425 or at:

Gjordan@pressherald.com

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