This study aims to evaluate the effectiveness of Aquatic Therapeutic Exercise by providing a set of exercises in the reduction and / or control the volume of secondary lymphedema treatment of breast cancer in patients who are in the maintenance phase of conventional treatment. It is an experimental, randomized, unifactorial, and intersubjective study. The intervention group will be treated by guided underwater exercises while the control group will receive the same set of exercises out-of-water. The research will be based on comparing the difference on the volume of lymphedema obtained by the exercises provided aquatic environment and out-of-water exercises. The study population will be obtained from rehabilitation service Bellvitge Hospital. The goal is to evaluate the volume of lymphedema and the quality of life related to the health of patients will be evaluated before starting the treatment, at the end of the 20 sessions, when the treatment reaches 3 months and when patient is discharged.