Frailty and Muscle Strength Tests in Older Adults Undergoing Major Surgery

The goal of this observational study is to learn if simple tests for frailty and muscle strength can help predict which older adults (age 65 and older) are at higher risk for problems after major abdominal surgery. The main questions it aims to answer are: * Do measures of frailty and muscle strength, taken before surgery, predict complications after surgery? * Can these tests be easily done during a routine pre-surgical visit? Participants will: * Complete brief tests measuring muscle strength, breathing strength, physical function, nutrition status, body composition, and memory during a regular pre-surgical clinic appointment. * Allow researchers to review their medical records 30 and 90 days after surgery to identify any complications or health problems.