Michigan:
As a fitness coach in Grand Rapids, Michigan, Doreen Bolhuis has a passion for developing exercises for children. The younger, it seems, the better. "With the babies in our family," she said, "I start working them out in the hospital."
Ms. Bolhuis turned her exercises into a company, Gymtrix, that offers a library of videos starting with training for babies as young as 6 months. There is no lying in the crib playing with toes.
Infant athletes, accompanied by doting parents on the videos, do a lot of jumping, kicking and, in one exercise, something that looks like baseball batting practice.
"We hear all the time from families that have been with us, 'Our kids are superstars when they're in middle school and they get into sports,' " Ms. Bolhuis said.
Future Robinson Canos and Sidney Crosbys are getting their start in sports earlier than ever. Kindergartners play in soccer leagues and at an annual T-Ball World Series in Milton, Fla. But now children are being groomed as athletes before they can walk.
The growing competition in marketing baby sports DVDs includes companies with names like athleticBaby and Baby Goes Pro. Even experts in youth sports seem startled that the age of entry has dipped so low.
"That's really amazing. What's next?" said Dr. Lyle Micheli, an orthopedic surgeon and founder of the first pediatric sports medicine clinic in the United States at Children's Hospital in Boston.
Dr. Micheli said he did not see any great advantages in exposing babies to sports. "I don't know of any evidence that training at this infancy stage accelerates coordination," he said.
One of his concerns, he said, is "the potential for even younger ages of overuse injury."
Bob Bigelow, a former National Basketball Association player and a critic of competitive sports for young children, is also skeptical.
"This is Baby Mozart stuff; you play Mozart for the baby in utero and it comes out some sort of fine arts major," he said. "There are millions of American parents worried to death that their children might fall behind somebody else's kid. So the emphasis in youth sports has become more, more, more, younger, younger, younger."
The Little Gym, based in Scottsdale, Ariz., begins classes for children at 4 months old. Bob Bingham, the company's chief executive, said that about 20,000 youngsters under 2 -- about a quarter of the total enrollment -- were signed up for classes at locations in the United States, Canada and Puerto Rico. That is a sizable increase from last year, he said. The company, which has gyms in 20 countries, plans to open 100 locations in China over the next five years.
My Gym, based in Sherman Oaks, Calif., said 55 percent of those who attend classes at its 200 locations -- 157 in the United States -- were 2 ½ or younger.
The entrepreneurs behind these businesses -- gym teachers, accountants and former professional athletes among them -- make no claims about turning today's babies into tomorrow's Super Bowl star.
In the past, marketing claims for products geared toward babies have caused trouble for companies. Disney, which owned the popular Baby Einstein brand, dropped the term "educational" after a children's-rights group objected to contentions that babies who watched "Baby Einstein" were learning. Disney also offered refunds.
Most sports-video entrepreneurs promote their products as early intervention for combating childhood obesity. Others say they provide time that parents and children can spend together.
"We're not suggesting your kid will turn pro; we have to be careful about that," said Gigi Fernandez, a former professional tennis player, who is one of the founders of Baby Goes Pro.
Ms. Fernandez and a business partner started the company this year. A women's doubles star in the 1990s and a new member of the International Tennis Hall of Fame, she said she got the idea after an unsuccessful search for a DVD she could play for her twins, Madison and Karson, who will turn 2 in April.
"There was one introducing kids to golf that I didn't care for," Ms. Fernandez said. "It was kids running around a golf course whacking balls. They had a driver on the putting green."
Baby Goes Pro's "Discover Sports" video would not likely excite ESPN die-hards, but there is a lot for a baby. The $10.95 DVD covers five sports -- baseball, basketball, golf, soccer and tennis -- touches on rules and equipment, and features an animated monkey named Emkei.
When she plays the DVD for her toddlers, Ms. Fernandez said, she lays sports equipment, like rackets and softballs, around the room. When she comes back, she finds them swinging away, she said.
Someday, Ms. Fernandez predicted, this could give them an edge -- a small one, perhaps. "The first time they go to a baseball field or tennis court, they'll have a clue," she said.
Sports doctors question whether very young children gain from watching the DVDs or attending sports classes. It is common for such programs to accept students before they have turned 2.
Lisa Mullen said she was not concerned about whether her toddler developed into a baseball or soccer star. She recently visited several children's gyms in the Baltimore area in hopes of finding "a physical outlet for our high-energy son."
The one she settled on for 16-month-old Michael was appealing for its low-key atmosphere and varied activities. During the first class, Michael and his two classmates swung from a bar and walked on a low balance beam. They also banged drumsticks.
Other programs can appear more serious. At Lil' Kickers, a soccer academy with franchises in 28 states, parents can enroll their children at 18 months old; about 55 percent of the 100,000 children signed up this year are 3 years or younger. In beginner classes, toddlers run and kick. Lil' Kickers also hands out improbably small soccer jerseys.
But the program, which was developed by child-development experts, is relaxed, said its chief executive, Don Crowe.
"Our emphasis is on the child, not trying to turn them into the next Pelé," he said.
That's not enough to sell Dr. Micheli on the idea of sports classes for tykes. Before rushing off to a day of treating injured athletes, he said, "We won't be putting their brochures in our clinic."