Women aged 50 and older are disproportionately affected by breast cancer, not only in terms of new diagnoses, but also in terms of survivorship. Approximately 85% of women who receive a first diagnosis of breast cancer are aged 50 and over, thus older women constitute the largest group of breast cancer survivors. Yet, few studies have focused on evaluating whether physical activity and exercise interventions affect long-term symptoms, physical fitness and function, and body composition of older breast cancer survivors. Due to the combined effects of breast cancer, related treatments and aging it is likely that exercise is even more beneficial for older breast cancer survivors than for younger survivors. Along with the cancer-related symptom of fatigue common to cancer survivors, older survivors face age-related declines in bone and muscle mass, muscle strength, bone health and physical function (gait and balance) that are likely exacerbated by reduced physical activity in survivorship and side effects of adjuvant cancer treatment. All women, regardless of age, are at risk for breast cancer recurrence. Recent epidemiologic evidence suggests a link between exercise and reduced risk of cancer recurrence in breast cancer survivors. Strength training is specifically suited to reverse or slow age-related declines in bone, muscle, strength and function and has shown promise to reduce cancer-related fatigue. However, no controlled trials of strength training in older breast cancer survivors have been conducted.

Inclusion Criteria:

• Diagnosed with early stage breast cancer at age of 50 or older
• Completed adjuvant therapy, radiation +/- chemotherapy but selective estrogen receptor modulators (SERMS), (aromatase inhibitors (AIs) ok) at least 1 year prior to enrollment

Exclusion Criteria:

• Cognitive difficulties that preclude answering the survey questions, participating in performance testing or giving informed consent
• Diagnosed osteoporosis
• Current regular participation in planned impact activities or resistance training (more than 2 times a week for 30 minutes at a time)
• Medication that contraindicates participation in moderate intensity strength training or previous use of medications known to affect bone metabolism
• Movement or neurologic disorder, not including chemo-induced peripheral neuropathy