This is good news because children with Down's syndrome generally have to work harder to control their muscles, says Ulrich (who also plans to try the treadmill on infants with cerebral palsy). The babies begin training as soon as they can sit upright. At first, they take just a few steps while their parents hold them up. "She'll do a little double step and then let her feet dangle," said Randy Russo, when his daughter, Isabelle, was 10 months. Two months later, Russo is delighted with his daughter's progress. "She's doing exceptionally well," he says. "She has a little push-toy that she holds onto as she walks around."