Metrics of diabetes risk are only minimally improved by exercise training in postmenopausal breast cancer survivors

Abstract

Context: Insulin resistance is a risk factor for breast cancer recurrence. How exercise training changes fasting and postglucose insulin resistance in breast cancer survivors is unknown. Objective: To evaluate exercise-induced changes in postglucose ingestion insulin concentrations, insulin resistance, and their associations with cancer-relevant biomarkers in breast cancer survivors. Setting: The University of Massachusetts Kinesiology Department. Participants: 15 postmenopausal breast cancer survivors not meeting the physical activity guidelines (150 min/week of exercise). Intervention: A supervised 12-week aerobic exercise program (60 min/day, 3–4 days/week). Main outcome measures: Postglucose ingestion insulin was determined by peak insulin and area under the insulin curve (iAUC) during a 5-sample oral glucose tolerance test. Insulin sensitivity was estimated from the Matsuda composite insulin sensitivity index (C-ISI). Changes in fitness and body composition were determined from submaximal VO2peak and dual energy X-ray absorptiometry. Results: Participants averaged 156.8 ± 16.6 min/week of supervised exercise. Estimated VO2peak significantly increased (+2.8 ± 1.4 mL/kg/min, P < .05) and body weight significantly decreased (–1.1 ± 0.8 kg, P