Lay summary
Many people cannot exercise due to medical conditions or physical limitations, for example, those awaiting hip and knee joint replacement surgery. While on the waiting list, their fitness, functional capacity and quality of life deteriorate. Better fitness reduces the risk of surgical complications and improves recovery time. This project aims to test and compare two interventions: heat therapy and upper-limb high-intensity interval exercise, prior to hip and knee surgery, to enhance fitness, physical capacity and cardiovascular health, thereby improving surgical outcomes.