An Intervention to Reduce Sedentary Behavior and Promote Physical Activity in Colorectal Cancer Chemotherapy

This single-group feasibility study develops and evaluates an intervention designed to reduce sedentary behavior and promote physical activity in patients with colorectal cancer undergoing chemotherapy. During chemotherapy, treatment-related symptoms such as fatigue often lead to reduced physical activity and prolonged sitting time. Replacing sedentary time with light-intensity movement is associated with improved metabolic outcomes and a lower risk of several chronic conditions, including cancer. The intervention is developed using the Capability, Opportunity, Motivation-Behavior (COM-B) model and the Behavior Change Wheel (BCW), and is delivered over 3 weeks using a smartwatch. It comprises smartwatch-based prompts to interrupt prolonged sitting, symptom assessment and symptom-management education, and feedback on physical activity and sedentary behavior. Sedentary behavior and physical activity are measured objectively by smartwatch continuously before, during, and after the 3-week intervention. The primary aim is to evaluate the feasibility of the intervention across the domains of acceptability, demand, implementation, and practicality. Secondary aims explore preliminary changes in physical activity, sedentary behavior, symptoms, health-related quality of life, and self-efficacy to reduce sedentary behavior. The findings are intended to inform the development of future interventions and nursing care to support health management in patients with cancer.

Inclusion Criteria: 1. Diagnosed with colorectal cancer (stage 2 or 3) and scheduled to receive or currently receiving chemotherapy 2. Able to use a smartwatch and respond to smartphone-based surveys 3. Able to read and understand Korean and provide written informed consent 4. ECOG performance status of 0 or 1 Exclusion Criteria: 1. Newly advised by the attending physician to restrict physical activity 2. Any injury or condition that, in the investigator's judgment, makes study participation inappropriate