Variability in physical function for patients living with breast cancer during a 12-week exercise program

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University of New Brunswick


OBJECTIVES: The objectives of this study were to describe the variability during weekly performance on common physical function tests during a 12-week exercise intervention for breast cancer patients; to test if the weekly variation surpasses the minimally clinically important difference (MCID) of each test; and to explore if the self-perceived fatigue and energy were associated with weekly physical function performance. DESIGN: Twenty-five breast cancer patients were recruited in the 12-week individualized exercise program offered in a community-based fitness facility. Physical function was assessed weekly using the 6-minute walk test (6MWT) and the chair stand test before one of the two weekly sessions. A MCID value of 50 meters was used for the 6MWT and two repetitions for the chair-stand test. RESULTS: A significant average improvement was observed in the 6MWT (p=.006) and the chair-stand test (p<.01) after the intervention. Individual confidence intervals were wide across all testing measures with only 28% and 8% of participants met or surpassed the MCID for the 6MWT and chair stand test respectively. Correlations between self-perceived energy and fatigue were not significantly associated with the average score of each test during the trial p >0.24. CONCLUSION: Despite a significant improvement in physical function during the 12-week exercise intervention, the majority of patients did not reach the MCID; could be due to large variability such as treatment-related side effect or measurement bias, but not self-perceived energy and fatigue.