For the last two years, Stephen Holmquist has had his share of success in the pool, but back problems had kept him from realizing his full potential.

Not anymore. The Wilton 16-year-old showed what he can be at last week’s YMCA Long Course National Swimming championships — a national champion.

Holmquist, swimming for the Wilton Y Wahoos, turned in an eye-opening performance in the 800-meter freestyle, dropping 14 seconds off his seed time to win the event in a time of 8:23.37. That broke the 15/16 Connecticut resident and Wahoo team record of 8:27.27, held since 1996 by Tomasz Drejer.

He had entered the event as the seventh seed with a best time of 8:37.95.

“I was quite surprised to realize I had won. It felt really good,” said Holmquist, a rising junior at Wilton High School. “I was just hoping to push hard for some best times, so I was very pleased.”

Holmquist also had a remarkable performance in the 1500-meter freestyle, finishing second with a time of 16:07.02 that broke another long-standing Connecticut resident record, 16:08.98, set by former Wahoo standout Dan Shevchik in 1997.

He also dropped about 21 seconds off his seed time, as he entered the event seeded seventh with a time of 16:28.88.

In the 400-meter individual medley, Holmquist was seeded ninth with a time of 4:40.12, but wound up dropping more than five seconds to place fourth in a time of 4:34.70.

He was also 12th in the 400-meter freestyle with a time of 4:04.10, a drop of nearly seven seconds off his seed time of 4:10.99.

Holmquist accomplished his primary goal by achieving Junior National times in all four events.

He also helped the Wahoo men’s team win the national title.

Holmquist credited the success with the fact that Wahoos coach Randy Erlenbach has been pushing his swimmers harder, and to the fact that his body is able to handle it.

“My coach has really amped up the yardage and the intervals. He’s been focusing on forcing us to go faster,” he said. “This is the first season where I‘ve been almost 100% the majority of the time.”

Two years ago, Holmquist found out that he had fractured his spine in two places, for reasons doctors weren’t able to determine.

He missed more then half of that winter season, and even when the injury had healed he was plagued by back spasms that made training difficult.

“I got back spasms from time to time, so it was hard to stay in the water,” he said. “Periodically, I would have to get out of the water and stretch a little.”

Eventually, Holmquist was able to withstand a more rigorous training regimen, although he still needs to go to physical therapy for the back spasms.

Last week’s Y nationals, held at the Georgia Tech Aquatic Center in Atlanta, were the high point of a year that has seen plenty of impressive performances by Holmquist.

Earlier this summer, he was named the Long Course High Point Distance Men's Champion at the Connecticut state championships after four top-five finishes.

In April, he helped the Wahoo men’s team win the YMCA Short Course Swimming National Championship in Greensboro, N.C., with several medal-winning efforts — including a seventh-place finish in the 400 IM in which he achieved  a National standard cut with a time of 3:57.11.

Swimming for the Wilton High boys swimming team, he was the Class L state champ in the 500 meters.

However, his performance last week went beyond anything he had done before.

“I didn’t expect to drop my times as much as I did.  I was very surprised about the finishes,” he said.

In the 800 freestyle, Holmquist swam just behind the leaders for most of the race, before passing Kevin George of Countryside, Ohio, at about the 600-meter mark. He turned in four of his best splits down the final 200 meters to win by  nearly three seconds.

“During the race I felt really smooth.  I decided to go hard for the finish,” said Holmquist, who was stunned when he saw that he had surpassed his personal best time by 14 seconds.

“I was shocked. I didn’t realize that I was going that fast. Fourteen seconds for anything is incredible.”

And no word better summed up Holmquist’s achievements than that: Incredible.