Purpose: (a) to determine if 110 postmenopausal breast cancer survivors (BCS) with bone loss who participated in 24 months of strength and weight training (ST) exercises had improved muscle strength and balance and had fewer falls compared to BCS who did not exercise; and (b) to describe type and frequency of ST exercises; adverse effects of exercises; and participants' adherence to exercises at home, at fitness centers, and at 36-month follow up.
Design: Findings reported are from a federally funded multicomponent intervention study of 223 postmenopausal BCS with either osteopenia or osteoporosis who were randomly assigned to an exercise (n=110) or comparison (n=113) group.
Methods: Time points for testing outcomes were baseline, 6, 12, and 24 months into intervention. Muscle strength was tested using Biodex Velocity Spectrum Evaluation, and dynamic balance using Timed Backward Tandem Walk. Adherence to exercises was measured using self-report of number of prescribed sessions attended and participants' reports of falls.
Findings: Mean adherence over 24 months was 69.4%. Using generalized estimating equation (GEE) analyses, compared to participants not exercising, participants who exercised for 24 months had significantly improved hip flexion (p=0.011), hip extension (p=0.0006), knee flexion (p<0.0001, knee extension (p=0.0018), wrist flexion (p=0.031), and balance (p=0.010). Gains in muscle strength were 9.5% and 28.5% for hip flexion and extension, 50.0% and 19.4% for wrist flexion and extension, and 21.1% and 11.6% for knee flexion and extension. Balance improved by 39.4%. Women who exercised had fewer falls, but difference in number of falls between the two groups was not significant.
Conclusions: Many postmenopausal BCS with bone loss can adhere to a 24 month ST exercise intervention, and exercises can result in meaningful gains in muscle strength and balance.
Clinical relevance: More studies are needed for examining relationships between muscle strength and balance in postmenopausal BCS with bone loss and their incidence of falls and fractures.