Objectively Quantified Doses of Activity and Inactivity and Subjective Well-Being in Breast Cancer Survivors

Abstract

INTRODUCTION: Physically active breast cancer (BC) survivors have higher quality of life (QOL) compared to those who are sedentary. However, exercise programs may introduce compensatory responses to total daily physical activity (PA) and sedentary time (ST) that could undermine the expected benefits of exercise training. The primary aim of this study was to evaluate changes in daily PA and ST following the implementation of an exercise training program in BC survivors. A secondary aim was to examine the relationship between PA/ST and fatigue/QOL. Methods: 12 postmenopausal BC survivors wore an ActiGraph GT3X monitor on the right hip for 7 consecutive days and completed the EORTC QOL questionnaire and Piper Fatigue Scale prior to and during the final week of a supervised 12-wk exercise training program (45-60 min/day, 2-4 days/wk). The activity data were categorized using the Freedson 1998 cut-points and are presented as a percentage of wear-time spent in each intensity category. RESULTS: The table presents PA, ST, perceived fatigue and QOL scores.Table: No title available.Note: Data are presented as mean (SD); * indicates significant change from baseline (p<0.05) By post-intervention these women replaced ST with light intensity activity. The EORTC score was significantly correlated with ST at baseline (R2=0.33, p=0.05), but this relationship was not significant at post-intervention. There were no significant relationships found between the Piper Fatigue Score and ST. DISCUSSION: These findings suggest participants did not reduce PA or increase ST during the exercise program. It has been reported that exercise training may lead to compensatory declines in habitual PA and/or increases in ST but our results do not support this. It is possible that as BC survivors increase purposeful exercise, they are able to substitute low levels of PA for ST. The relationship found between QOL and ST suggests that reductions in ST could be a potential target for interventions that aim to improve QOL in BC survivors.