There is evidence that exercise after the diagnosis of breast cancer improves mortality, morbidity, health related quality of life, fatigue, physical functioning, muscle strength, and emotional wellbeing. Based on scientific data, breast cancer patients should participate in rehabilitation programs including aerobic and strength training. A 2016 meta-analysis study that included 2,659 breast cancer survivors compared a control group of non-exercising women with an exercising intervention group. Compared with the control group, quality of life was significantly improved in the exercise intervention group, especially in mental health and general health as well as emotion well-being and social well-being, Exercise alleviated the symptoms of depression and anxiety in the exercise group. Furthermore, exercise was also associated with positive outcomes in body mass index, lean mass, and muscle strength.

Zhu G, Zhang X, Wang Y, Xiong H, Zhao Y, Sun F (2016). Effects of exercise intervention in breast cancer survivors: a meta-analysis of 33 randomized control trials. OncoTargets Ther, 2016 Apr 13;9:2153-68. doi: 10.2147/OTT.S97864.