This single-center prospective cohort study is designed to evaluate whether preoperative physical activity measured by a wearable accelerometer is associated with cardiovascular autonomic function and whether it can help predict post-induction hypotension in elderly patients undergoing elective non-cardiac surgery. Patients aged 65 years or older scheduled for general anesthesia with tracheal intubation will undergo preoperative physical activity monitoring using an ActiGraph wearable accelerometer. Activity-related parameters, including sedentary time, light-, moderate-, and vigorous-intensity activity, daily step count, and sleep duration, will be recorded. Cardiovascular autonomic function will be assessed perioperatively using noninvasive continuous hemodynamic monitoring, with baroreflex sensitivity-related indices derived from continuous blood pressure and beat-to-beat timing data. The primary outcome is post-induction hypotension. Secondary outcomes include early intraoperative hypotension, postoperative complications, and 30-day mortality. This study aims to clarify the relationship between habitual physical activity and autonomic regulation in older surgical patients and to provide evidence supporting future prehabilitation strategies.