Upper-body morbidity associated with treatment for breast cancer is typically characterized by the presence of symptoms, such as pain, weakness and tightness, as well alterations in the use and function of the upper-body. Arguably, lymphedema (swelling) is regarded as the most feared and problematic upper-body concern post-breast cancer. Upper-body morbidity during and following treatment for breast cancer is common, with between 10-64% of women reporting specific upper-body symptoms, and approximately 20% of women developing lymphedema post-breast cancer. Upper-body morbidity remains common into longer-term survivorship, and although lymphedema may be transient for some, those who present with mild lymphedema are at increased risk of developing moderate to severe lymphedema. Epidemiological evidence suggests a relationship between physical activity levels and upper-body morbidity with those engaging in 150+ minutes of physical activity each week being less likely to report upper-body concerns, compared with those who are insufficiently active or sedentary. Further, severity of upper-body morbidity is less for those engaging in sufficient levels of weekly physical activity. There is also a consistent body of intervention evidence demonstrating that progressive, supervised exercise during and following breast cancer treatment can prevent and/or attenuate upper-body morbidity, including lymphedema. As such, promoting national physical activity guidelines and encouraging participation in appropriately-prescribed exercise during and beyond treatment for breast cancer is important for the prevention and management of upper-body morbidity.