Effects of a structured exercise program on motivational outcomes in patients with colon cancer

Background
Colon Health and Life-Long Exercise Change (CHALLENGE) was the first phase 3 trial to examine the effects of exercise on cancer-related survival and, therefore, required a substantial and sustained increase in moderate-to-vigorous physical activity (MVPA) that had not been achieved in previous trials. Here, we report the effects of the intervention on the social cognitive beliefs that were targeted to achieve long-term exercise behavior change.

Methods
Patients with resected colon cancer who had completed chemotherapy were randomized to health education materials (HEM) or a structured exercise program (SEP) consisting of 48 behavioral support sessions delivered over a 3-year period. Social cognitive constructs from the Theory of Planned Behavior were assessed by single items using 5-point scales at baseline and every 6 months during the 3-year intervention. Regression models for repeated measurements were used to estimate the least square means and robust standard errors (SEs) for each randomized group at each time point.

Results
Between 2009 and 2024, 889 patients were randomized to SEP (n = 445) or HEM (n = 444). SEP compared to HEM reported significantly more favorable social cognitive beliefs about exercise at almost all time points. Average intervention effects (AIE) across the 3-year intervention favored SEP for perceived benefit (AIE = 0.29; P < .001), enjoyment (AIE = 0.40; P < .001), difficulty (AIE = −0.18; P = .003), confidence (AIE = 0.28; P < .001), support (AIE = 0.59; P < .001), motivation (AIE = 0.47; P < .001), opportunity (AIE = 0.31; P < .001), and planning (AIE = 0.82; P < .001). All social cognitive variables were significantly associated with self-reported MVPA at all time points.

Conclusions
The SEP intervention in the CHALLENGE trial successfully targeted the social cognitive beliefs that were associated with sustained MVPA. NCT00819208.