Exercise volume load in women with breast cancer: Study protocol for the ABRACE randomized clinical trial

Background: An increased number of breast cancer patients are challenged by acute and persistent treatment side effects. Oncology guidelines have been establishing physical exercise to counteract several treatment-related toxicities throughout cancer care. However, evidence regarding the optimal dose-response, feasibility, and the minimal resistance exercise volume and/or intensity remains unclear. The ABRACE Study will assess the impact of different resistance training volumes (i.e., single or multiple sets) combined with aerobic exercise on physical and psychological outcomes of breast cancer patients undergoing primary treatment. Methods: This study is a randomized, controlled, three-armed parallel trial. A total of 84 participants, aged >= 18 years, with breast cancer stages I-III, initiating adjuvant or neoadjuvant chemotherapy (<= 50% of sessions completed) will be randomized to multiple sets resistance training plus aerobic training group, single set resis-tance training plus aerobic training group or control group. Neuromuscular and cancer-related fatigue (primary outcomes), muscle strength, muscle thickness, muscle quality by echo intensity, body composition, cardiore-spiratory capacity, functional performance, upper-body endurance and quality of life will be measured before and after the 12-week intervention. Our analysis will follow the intention-to-treat approach and per-protocol criteria, with additional sub-group analysis. Discussion: Findings support prescribing exercise during chemotherapy for breast cancer and elucidate the po-tential role of different resistance training volumes as a management strategy for physical and psychological impairments in women with early-stage breast cancer. Our main hypothesis is for superiority in physical and psychological outcomes for both training groups compared to the control group, with no difference between single or multiple sets groups. Trial registration: Clinical trials NCT03314168.