By JULIET MACUR

BOULDER, Colorado - When Donna Campiglia learned recently that a genetic test might be able to determine which sports suit the talents of her 2 1/2-year-old son, Noah, she instantly said, Where can I get it and how much does it cost?

“I could see how some people might think the test would pigeonhole your child into doing fewer sports or being exposed to fewer things, but I still think it’s good to match them with the right activity,”Ms.Campiglia, 36, said as she watched a toddler class at Boulder Indoor Soccer in which Noah struggled to take direction from the coach.

“I think it would prevent a lot of parental frustration,”she said.

In health-conscious, sports-oriented Boulder, Atlas Sports Genetics is playing into the obsessions of parents by offering a $149 test that aims to predict a child’s natural athletic strengths. The process is simple. Swab inside the child’s cheek and along the gums to collect DNA and return it to a lab for analysis of ACTN3, one gene among more than 20,000 in the human genome.

The test’s goal is to determine whether a person would be best at speed and power sports like sprinting or football, or endurance sports like distance running, or a combination of the two. A 2003 study discovered the link between ACTN3 and those athletic abilities.

DNA is being analyzed to determine predispositions to disease, but experts raise serious questions about marketing it as a first step in finding a child’s sports niche, which some parents consider the road to a college scholarship or a career as a professional athlete.

Atlas executives acknowledge that their test has limitations but say that it could provide guidelines for placing youngsters in sports. The company is focused on testing children from infancy to about 8 years old because physical tests to gauge future sports performance at that age are, at best, unreliable.

The ACTN3 test has been available through the Australian company Genetic Technologies since 2004. The company has marketed the test in Australia, Europe and Japan, but is now entering the United States through Atlas.

Dr.Stephen M.Roth, director of the functional genomics laboratory at the University of Maryland’s School of Public Health, who has studied ACTN3, said he thought the test would become popular. But he had reservations.

“The idea that it will be one or two genes that are contributing to the Michael Phelpses or the Usain Bolts of the world I think is shortsighted because it’s much more complex than that,”he said, adding that athletic performance has been found to be affected by at least 200 genes.

Dr.Roth called ACTN3 “one of the most exciting and eyebrow-raising genes out there in the sports-performance arena,” but he said that any test for the gene would be best used only on top athletes looking to tailor workouts to their body types.

The study that identified the connection between ACTN3 and elite athletic performance was published in 2003 by researchers primarily based in Australia. Those scientists looked at the gene’s combinations, one copy provided by each parent. The R variant of ACTN3 instructs the body to produce a protein, alpha-actinin-3, found specifically in fast-twitch muscles. Those muscles are capable of the forceful, quick contractions necessary in speed and power sports. The X variant prevents production of the protein.

Kevin Reilly, the president of Atlas Sports Genetics and a former weightlifting coach, expected the test to be controversial. He said some people were concerned that it would cause “a rebirth of eugenics, similar to what Hitler did in trying to create this race of perfect athletes.”