1. Purpose The purpose of this study is to investigate whether performing a single bout of exercise 24 hours prior to receiving infusions of the anthracycline chemotherapy agent doxorubicin for breast cancer can prevent some of the damaging cardiac effects. Currently, doxorubicin is the most effective chemotherapy agent for breast cancer but is also the most damaging. As such, increased risk of cardiovascular disease is a growing concern in doxorubicin-treated patients. Current strategies for minimizing cardiac injury are dose reduction and discontinuation of therapy, which compromise the effectiveness of the treatment. Interventions that can minimize the cardiac injury associated with doxorubicin could reduce cancer-related and cardiovascular disease-related mortality in women diagnosed with breast cancer.