One result of parental worries about childhood obesity -- and there own -- is the rise of group exercise at gyms for children 5 and under. For a fee, albeit sometimes a very steep one, toddlers as young as 2 can be left in the hands of fitness instructors to do gymnastics while the parents work out in another room.

Exercise programs designed for toddlers have been around for years, but only recently have adult health clubs started adding these programs.

According to the International Health, Racquet and Sportsclub Association, children age 6 to 17 is already the second-fastest-growing member demographic at gyms, with 4.1 million belonging to gyms in 2006.