RESUMEN
Interventions offering peer mentoring programmes promoting moderate-to-vigorous physical activity (MVPA) have shown improvements in MVPA and well-being from baseline; however, research is limited. The purpose of this study was to compare the physical activity (PA) levels and psychosocial well-being of coaches and participants at baseline and following a 12-week intervention. Breast cancer survivors (<5 years) were recruited and randomised into either exercise (Reach-to-Recovery (RTR) + PA) or control (RTR Control). Participants in both groups were individually assigned one of the 18 available coaches who delivered either the MVPA intervention or the control condition via telephone. PA (7-Day PA Recall), psychosocial well-being, fatigue and mood were assessed at baseline and intervention completion. Seventy-six breast cancer survivors (average age = 55.62 (±9.55)) were randomised. At baseline, all participants showed significantly lower MVPA (p = .001) and well-being (p < .05) as compared to coaches. However, post-intervention showed significant improvement in PA and well-being in RTR + PA, so that they were no longer significantly different from the coaches. Post-intervention, MVPA (p < .01), quality of life (p < .05) and fatigue (p < .05) remained significantly lower in RTR Controls compared to coaches. Future interventions should consider the behavioural patterns not only of the participants, but also of those who deliver the interventions.