This study aims to examine the impact of daily physical activity, specifically step count, on treatment outcomes and side effects in patients with locally advanced rectal cancer receiving total neoadjuvant therapy (chemotherapy and radiotherapy before surgery). Using Huawei Watch Fit 2 smartwatches, we will track participants' daily step counts, heart rate, and sleep quality. The primary hypothesis is that higher step counts and physical activity levels correlate with higher rates of complete pathological response at surgery. A secondary hypothesis is that increased physical activity may be associated with fewer or less severe side effects during treatment. Participants will wear a smartwatch and complete the EORTC QLQ-C30 Quality of Life Questionnaire and the Pittsburgh Sleep Quality Index at the beginning and end of treatment. Data from the smartwatch, including step count, heart rate changes, and sleep duration, will be reviewed weekly during routine visits. Approximately 200 patients with rectal cancer will participate, and each will be followed from the start of therapy until surgery (around 4-6 months). Total data collection is expected to take 12-15 months. This study could improve cancer care by identifying links between physical activity and treatment outcomes, supporting future exercise guidelines for oncology patients.