Exercise Experiences and Behavioral Adaptation During the Inter-Chemotherapy Interval Among Patients With Lung Cancer Receiving Platinum-Based Chemotherapy: A Qualitative Study

BACKGROUND: Symptoms and physical capacity cycle during the inter-chemotherapy interval, yet patients' exercise experiences and behavioral adaptation remain unclear. OBJECTIVE: To explore exercise experiences, behavioral adaptation strategies, and professional support needs among patients with lung cancer during the inter-chemotherapy interval, informing cyclical exercise management. METHODS: Descriptive phenomenological study. Semi-structured interviews were conducted with 11 patients with lung cancer receiving platinum-based chemotherapy at a Shanghai teaching hospital. All interviews occurred upon return for the next chemotherapy cycle. The Health Action Process Approach guided the interview outline; Colaizzi's seven-step method was used for analysis. RESULTS: Three main themes and six subthemes emerged: (1) Physical sensations during the chemotherapy interval (negative experiences triggered by treatment-related symptoms; positive feedback from exercise); (2) The complex process of behavioral adaptation (conflict between disease fluctuation and behavior maintenance; synergy between autonomous decision-making and self-efficacy); (3) Expectations for professional support during the interval (knowledge needs; emotional needs). Although derived from inductive phenomenological analysis, these themes inherently map onto the dual-phase structure of the Health Action Process Approach model. CONCLUSIONS: The inter-chemotherapy interval is characterized by cyclical fluctuations in exercise capacity. Patients tend toward passive rest during symptom peaks and engage in autonomous, flexible activity during recovery windows. Clinical support should respect this natural rhythm. IMPLICATIONS FOR ONCOLOGY NURSING PRACTICE: Oncology nurses should assess the patient's position in the chemotherapy cycle to distinguish symptom‑peak days from recovery windows and provide stage‑specific exercise guidance. In addition, they should strengthen autonomous decision‑making and self‑efficacy to reduce conflict between disease fluctuation and behavior maintenance.