Shouldn't this be getting a bit old by now? Another U.S. championships, another year of Tanith Belbin and Ben Agosto atop the country's ice-dancing ranks, another world championships on the horizon in March.

Not only has their act not worn thin, it has gotten better. After winning the past four U.S. ice-dancing titles, two of the finest duo skaters in their country's history have found new ways to challenge themselves. Offseason dance lessons, a musical curveball and an increased attention to detail have kept Belbin and Agosto sharp and engaged heading into the start of the U.S. senior competition Wednesday at Xcel Energy Center.

Another title this year would tie Belbin and Agosto with four other tandems for the most national titles won by a U.S. ice-dancing team. Already, they are looking beyond that number, while paying respect to the past and working toward a stronger future for American ice dancing.

"It's been an honor every time to receive those titles," said Belbin, 23. "It means a great deal to us. I hope we can do it through the year 2010 and break the record.

"It's been an incredible season for us. I can honestly say with our skating, it's the best we've ever had. These are two of the best programs we've created, and we really put the work in this summer."

Life has settled into a comfortable rhythm for the pair from Michigan. Belbin has her U.S. citizenship and a relationship with U.S. men's champ Evan Lysacek. Agosto recently recorded the voice for a villainous character in a video game.

They have taken pains, though, to ensure things don't get too comfortable. In recent years, their packed touring schedule has prevented them from tuning up their basic skills. It's likely that audiences couldn't tell, and their results didn't reflect it.

A dominating U.S. team

The duo won the 2006 U.S. title by 30 points over Melissa Gregory and Denis Petukhov. Last year, they beat the same team by 15 points, a year after they became the first U.S. team since Colleen O'Connor and Jim Millns (1976) to win an Olympic medal in ice dancing. Belbin and Agosto's silver in Turin was only the second ice-dance medal won by an American couple.

Instead of resting on their accomplishments, Belbin and Agosto recognized how much more they could do. With a deepening group of talented couples coming up behind them, they grew more serious about their training and more adventurous in their artistry. Their two new programs this year reflect that: an original dance set to bluegrass music, and a soulful free skate to Chopin.

"This season is the culmination of almost 10 years of skating together," said Agosto, 26. "We had a desire to go back and work on the basics, the things you really want to work on every year. The last few years, we never quite had the time.

"We developed our own skating, instead of just working on the programs. We got stronger and faster, with better lines and more unison."

In addition to working on their skating, the team went through a dance "boot camp" last summer to study body movement. They put more time into fitness training and made warmups and workouts more efficient. They worked on mastering tougher lifts -- a weakness in their past performances -- and found ways to challenge themselves.

Belbin and Agosto jazzed up the opening of their original dance to engage the audience sooner. Their lyrical, emotional free skate demonstrated new depth; after skating mostly to contemporary music in the past, they felt ready to interpret classical. Their Chopin program helped them earn two gold medals in Grand Prix competition this fall, as well as a silver behind Russian pair Oksana Domnina and Maxim Shabalin at the Grand Prix Final.

World title is next goal

Agosto said he is particularly excited for nationals, because he enjoys performing for the pair's considerable fan base. They also have their sights firmly on this spring's world championships, where they hope to bring the United States its first world championship in ice dancing.

"We've become mature adults together, with one common goal in mind," said Belbin, who with Agosto has won two bronze and one silver medal in the past three world championships. "Things have finally fallen into place. We're in tune with what we need to do to get to the top."

And, perhaps, help others to gain the same. Belbin noted that the pair has trained with Naomi Lang/Peter Tchernyshev and Elizabeth Punsalan/Jerrod Swallow, two of the U.S. couples who previously won five national titles. Just as they received encouragement from those pairs, they hope to give the same to those behind them.

"We are lucky to follow in the footsteps of people who paved the way for us," Agosto said. "This is a very exciting time for all ice dancers. Everyone can see it's possible, that American ice dancers can succeed."