Musculoskeletal changes after 1 year of exercise in older breast cancer survivors
We have previously reported that 1 year of supervised resistance + impact training stopped bone loss and built muscle strength in older breast cancer survivors. The purpose of this study was to determine whether these benefits persisted 1 year after completion of the intervention.
Sixty-seven women from the original trial completed baseline and post-intervention body composition and muscle strength tests, and 44 women were available 1 year later for follow-up assessments. Bone mineral density (grams per square centimeter) of the hip and spine, muscle mass (kilograms), and fat mass (kilograms) were measured by dual-energy X-ray absorptiometry and maximal upper and lower body strength were measured by one-repetition maximum tests (kilograms). We compared between group changes across baseline (pre-intervention), 1 (post-intervention), and 2 years (1 year follow up) on study outcomes using repeated-measures analysis of covariance, adjusting for age.
Significant group by time interactions were found for spine bone mineral density (BMD) (p < 0.01) and lower body muscle strength (p < 0.05), with a trend for upper body muscle strength (p = 0.05). Spine BMD remained stable across intervention and follow-up periods in exercisers compared with continuous losses in controls across 1- and 2-year periods. In contrast, lower body strength increased in exercisers across the intervention, but decreased to near-baseline levels during follow-up compared with no change over either time period in controls.
Our data suggest that spine BMD can be preserved in older breast cancer survivors even after formal exercise training stops; however, muscle strength is not similarly maintained and may require continued participation in a supervised exercise program.
Implications for Cancer Survivors
Exercise programs aimed at improving musculoskeletal health should be considered in the long-term care plan for breast cancer survivors.