The goal of total knee arthroplasty (TKA) is to reduce pain and gain a better quality of life. With the increasing number of patients with TKA younger than 60 years old, the expectation of continuing in sports and high physical activity level after TKA is also increasing. In this chapter, we focus on physical activity, especially in return to sport after TKA. The minimum time needed for a return to sports (RTS) is 3 months to recover, but TKA patients will usually be more comfortable doing it 6 months after surgery. But no recommendation is well established in deciding the level of physical activity after TKA, mainly based on expert opinion. Lack of motivation, the desire to maintain the prosthesis in good condition, the presence of other comorbid conditions, and pain or other physical limitations of the knee are some barrier factors for patients to do sports. Choosing activities or sports that suit the lifestyle of patients after TKA surgery and managing patients’ expectations are important. Therefore, evidence regarding the best standard of care for patients receiving knee arthroplasty with high RTS expectations is needed.