The benefits of being self-determined in promoting physical activity and affective well-being among women recently treated for breast cancer.

Purpose: In this study, changes in motivational regulations in women following treatment for breast cancer were described. Changes in motivational regulations as predictors of subsequent change in light and moderate-to-vigorous physical activity (PA) and affect were also examined.

Methods: Women [n = 150; M(age) = 54.41 (SD = 10.87) years] completed self-report questionnaires and wore an accelerometer for 7 days at Time 1 [M = 3.94 (SD = 3.08) months following primary treatment], as well as 3 (Time 2) and 6 (Time 3) months later. Data were analyzed using repeated-measures analysis of variance and path analysis using residual change scores.

Results: Identified regulation and self-determined motivation (i.e., combined intrinsic motivation and identified regulation) scores decreased over time (p < 0.05). In the path model [χ(2)(4) = 5.66, p = 0.22, root mean square error of approximation = 0.05 (90% CI: 0.0; 0.15), comparative fit index = 0.99, standardized root mean square of the residuals = 0.03], ΔTime(1-2) in external regulation was associated with ΔTime(2-3) in positive affect (β = -0.16), ΔTime(1-2) in introjected (β = 0.25) and amotivation (β = 0.19) were related to ΔTime(2-3) in negative affect, and ΔTime(1-2) in self-determined motivation was related to ΔTime(2-3) in positive affect (β = 0.40) and moderate-to-vigorous PA (β = 0.21).

Conclusions: Changes in motivational regulations were related to changes in PA and affect in the aftermath of breast cancer. Given the benefits of self-determined motivation, additional research is needed to develop and test interventions aimed at enhancing this type of motivation.