<qa>  What is the primary objective of this study?Purpose: The purpose of this study is to evaluate the effect of zoledronic acid and physical activity on preventing bone loss in women aged 40 - 55 who are receiving chemotherapy for breast cancer. The primary objective is to compare the percent change in the lumbar spine bone mineral density BMD from baseline to 12 months for women who are randomized to either: Group A intravenous zoledronic acid, oral calcium carbonate, and vitamin D, or Group B a prescribed physical activity program, oral calcium carbonate and vitamin D. Secondary objectives are to compare the percent change between the groups in total hip BMD, the incidence of vertebral fractures, fatigue, functional status, and other cancer-related symptoms between the two groups. 