Every few years when the Olympics would roll around, the unmistakable pangs Jen Castellano knew were coming but was powerless to stop would hit. Of chalk on her hands. The beam underneath her feet.

Growing up, 33-year-old Annie Lugo-Walsh always wanted to take gymnastics lessons. "I always took the gymnastics unit really seriously in P.E. class," she recalled. "I remember we got to choreograph a ...