The Neo-ACT assesses the primary endpoint pathological complete response (pCR) and the secondary endpoints Residual Cancer Burden (RCB), objective tumour response (RECIST), all-cause, breast cancer-specific, and recurrence-free survival at 2, 5 and 10 years, health-related quality of life assessed by the EORTC QLQ-C30 and BR23 questionnaires, self-reported physical activity (Modified Godin Leisure Time Physical activity questionnaire), toxicity-related outcomes (chemotherapy completion rates, number of unplanned hospital admissions during NACT, objective cognitive dysfunction (Amsterdam Cognition Scan), cardiac toxicity and sick leave), device-measured physical activity level (Fitbit activity tracker), muscle strength (handgrip strength test and hypothetical 1-RM maximal leg muscle strength tests), and cardiorespiratory fitness (Ekblom-Bak submaximal cycle test).
Participants randomized to the exercise group will complete 120 min exercise sessions per week from initiation of NACT to surgery (approx. five months):
* Progressive home exercise program by an individualised mobile phone application, supported by local physiotherapists
* Initial exercise intensity individually tailored to each patient's fitness at baseline and rate of perceived exertion during the program and adapted if required
* Sessions will begin with a 3-minute moderate intensity (12-13 on Borg's Rate of Perceived Exertion (RPE) scale) warm-up.
