Musculoskeletal changes after 1 year of exercise in older breast cancer survivors

Abstract

We have previously reported that 1year 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 1year 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 1year 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 2years (1year 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. Exercise programs aimed at improving musculoskeletal health should be considered in the long-term care plan for breast cancer survivors.