Thirty-four children were enrolled in this study, 18 with CP and 16 with TD. Participants
with CP were recruited through the CP clinic at Shriners Hospital for Children in
Philadelphia, PA and through other local rehabilitation facilities. Participants with TD were
recruited from siblings of the participants with CP, children of people known to the
investigators, and from a local day care center. All procedures were approved by the IRB of
Temple University Hospital (for Shriners Hospital) and also the IRBs of additional data
collection sites as needed. Parental consent was obtained prior to participation. Assent of a
minor was obtained from any participant 7 years of age or older.
Inclusion and exclusion criteria are listed in Table 1. Children with CP were able to walk
with a hand held assistive device if it did not restrict movement of the trunk or pelvis. The
selection of months of walking experience rather than age as a primary inclusion criterion
was chosen based on reports that experience is a stronger predictor of walking and balance
skill than age in early walkers [Adolph et al., 2003; Sundermier et al., 2001]. The onset of
walking was operationally defined as the age in months at which an infant or child was able
to take at least 3 continuous independent steps on a consistent basis [Roncesvalles et al.,
2001; Wu et al., 2007]. Walking experience, in months, was calculated as the difference in
the participant’s current age and the age of onset of walking.