Mary Stack returned to Ann Arbor from London this week with a fourth-place powerlifting finish in the 2012 Paralympic Games.

But she's still not entirely sure why she doesn't have the bronze medal.

In her first of three attempts, Stack successfully lifted 129 kilograms. After an unsuccessful lift of 134 kilograms, Stack went for 137 on her last try, a weight that would have earned her third place.

Stack was strong enough to lift it, but the judges ruled she had a technical flaw during her lift. Powerlifting in Paralympic competition is done on the bench press.

“I still don’t know what the technical flaw was,” Stack said. “It went up easy, I had a shot at it.”

Stack's coach, Michigan assistant director of strength and conditioning Bo Sandoval, doesn't know what her technical flaw was either. In the end, both agree Stack fell victim to the strict judging that comes with the sport's most prestigious event.

“It was arguably a good lift," Sandoval said. "The judges, they did red flag her on it, but she did indeed press the weight. There’s a little bit of subjective judging in Paralympic powerlifting in terms of the bar has to stay level, the bar has to be paused at the chest. We’re not sure what the call was on why she was red-flagged, but in terms of physically pressing the weight, she pressed it pretty handily.”

Despite going to London with high hopes for a medal, and losing out on one due to a borderline call, Stack came home satisfied with a fourth place performance in the 82.5-plus kilogram division. The result marks her best finish in the four Paralympics she's participated in.

“I will take fourth in the world,” Stack said. “It’s the best that I’ve done at a Paralympic games.”

The performance also helped exorcise some Paralympic demons for Stack. After finishing fifth in the 2000 Paralympics in Sydney, Stack was disqualified at Athens in 2004 and again at Beijing in 2008, both times for technical flaws.

In London, she went into the games knowing what to expect.

“I really felt comfortable,” Stack said. “I didn’t have to worry about all the other worries about the games. I went in there, knew what I was focused for. It was just any other competition, but the stands were full and that kind of helped pump me up for it.”

Stack said publicly before going to London that she planned on transitioning from competition to coaching. She already works in a related field, as the Sports & Recreation Coordinator at the Center for Independent Living.

But Stack's experience in London changed her mind. A change in training two years ago has her improving at a faster rate than ever, instead of slowing down as her career progresses. Instead of seeing the games as an end of a career, she’s now looking at it as a rebirth.

Sandoval said he was initially surprised by Stack's reversal, but said she's not the first competitor he's seen motivated by a near miss.

“Having worked with other Olympians and Paralympians, I’ve seen people change their minds, especially when they’re in medal contention like that," Sandoval said. "Maybe their eyes open up and they realize how special they are to being in the record books forever.

And as the second-youngest competitor in her age group, Stack, 38, can be confident her best years are ahead of her.

“I might have just hit a starting point for where things can go,” Stack said.

Stack has a genetic disease that results in shortened bones, a rounded face and a predisposition to obesity. She has been powerlifting for more than 20 years, but her career started taking off two years ago when she made a coaching change.

Since she started training with Sandoval, Stack said she’s developed a better lifting plan. Under that, she’s up 50 pounds in the last two years.

"Even for someone who’s educated, with a sports science background, to design a program for yourself is a difficult thing," Sandoval said. "Even coaches need coaches.”

And now, she’s ready to see where that trajectory takes her. Stack said she will at least compete in the world championships in two years, and she isn’t ruling out the 2016 Paralympic Games in Rio de Janiero.

“I’m going to take it one international competition at a time,” Stack said.

Kyle Austin covers sports for AnnArbor.com. He can be reached at kyleaustin@annarbor.com. Follow him on Twitter @KAustin_AA.