Joan Samuelson’s Chicago Marathon performance last fall seemed off-key for her. It was slower than her usual stellar marathons, and not close to her once-conceivable sub-3:00-at-60 goal. She finished Chicago in 3:12:13. Was Samuelson slowing down? Too many miles and too many hard marathons on her body?

Nah. At today’s Boston Marathon, Samuelson, who turns 62 next month, bounced back with another of her customarily-extraordinary races. She finished Boston in 3:04:00 (3:05:18 gun time) to break the known world record for a 61-year-old woman, previously held by Japan’s Kimi Ushiroda (3:06:36). Samuelson smashed the Boston record in the 60–64 division, set by Barbara Miller (3:11:57 in 2000).

To do it, she had to scramble backwards in the start corrals in Hopkinton from the elite spot she is always granted. First she wriggled from one corral to the next. That proved slow and awkward, so she crawled under the snow fencing, and scampered back at a faster pace—trying to get back into a group more appropriate to her pace today.

She was still moving back when she heard the start gun. It was time to turn toward Boston and tackle the famously challenging Boston Marathon course. Few have done it better than Samuelson, or more often. This year was no exception.

“I still went out a little too fast, but I kept telling everyone who passed me to be patient, and I did the same myself,” she explained later. “I got a calf cramp on the downhill into Lower Newton Falls, so I had to run cautiously through the hills. After that I tried to push to the finish.”

Samuelson first won Boston 40 years ago, wearing a Boston Red Sox cap. She said she wanted to run no more than 40 minutes slower this year than her time in 1979: 2:35:15. Mission accomplished! With plenty of room to spare. She wore a Bowdoin College singlet similar to her apparel in 1979. “The fan support was fantastic, especially through the hills,” she said. “They yelled first for the singlet and then for me, when they recognized me.”

Samuelson admitted she was in better shape for Boston than for her Chicago race last October: She got in four or five 20-milers in training vs. just one before Chicago. But she said it might have been a winter filled with nordic skiing that did the trick. “I’m not a very efficient skier, so I have to work really hard when I go skiing,” she said. “It helps build my fitness and upper body strength, and does it without any pounding on the legs.”

In recent years, Samuelson has used the power of “story” to keep herself motivated. She said it can work for anyone, noting that every runner has a story, in part because all have faced obstacles along the marathon road of life. At Boston, she got excited by the 40-minutes-40-years-later story.

“I was supposed to stop running competitive marathons after 2008 when I squeaked under 2:50 at age 50,” she said. “I thought I would walk off into the sunset. But I’ve kept coming up with different stories since then.

“I can’t believe it’s been 40 years since 1979. I don’t feel 40 years older, though I have to admit that I do feel older.”

Older, yes. Who isn’t? But Joan Benoit Samuelson is still out there, still pushing back marathon barriers that seemed impossible before she entered the sport.