Independent-samples t tests were used to assess for group differences at baseline. Separate 2-factor mixed-model analyses of variance (ANOVAs) (2 groups by 2 time points), with time as the repeated factor, were used to determine the effects of the intervention program on all outcome variables (baseline to the end of the 8-week intervention). If a significant interaction was observed, paired t tests were used to determine whether the exercise or control group changed over time. Paired t tests were used to determine whether self-reported pain and health status in those patients assigned to the exercise group at baseline differed from those at the 6-month postintervention time point. Parametric tests were justified, based on the data being normally distributed and the variance being equal between groups. All statistical analyses were conducted with SPSS software (IBM Corporation, Armonk, NY), using a significance level of P.05. Data are presented as mean SD.