Low-Frequency Exercise Training Improves Cardiovascular Fitness and Strength During Treatment for Breast Cancer: A Single-Arm Intervention Study

Recent guidelines recommend exercising ≥ 3 times/week during and after cancer treatment, however treatment-specific barriers may inhibit adherence. We explored the effect of a flexible exercise program on fitness, body composition, and metabolism in a group of recently diagnosed breast cancer patients. Fifty-two females ≥ 18 years with stage I-IIIB breast cancer were instructed to target 2 cardiovascular and strength training sessions/week over 12 weeks, but program length was expanded as needed to accommodate missed sessions. Pre- and post-intervention, we measured: 1) cardiovascular fitness, 2) isometric strength, 3) body composition (dual-energy X-ray absorptiometry), and 4) fasting glucose, insulin, c-peptide, and lipids. Pre-intervention, participants were 53 ± 10 years old (mean ± SD) and overweight (BMI: 27.5 ± 5.4 kg∙m − 2 , 40.1 ± 6.5% body fat). Forty participants completed the program over a median 20 weeks (range: 13–32 weeks, median frequency: 1.2 sessions/week). Final workrate during a graded exercise test improved by 13% (10[5–15] W) (delta[95% CI]), and strength increased by 7–9% (right arm: 2.3[0.1–4.5] N∙m; right leg: 7.9[2.1–13.7] N∙m; left leg: 7.8[1.9–13.7] N∙m). Body composition and metabolic markers were unchanged. An exercise frequency of 1.2 sessions/week, while below recommendations, stimulated significant improvements in fitness, and may represent a more realistic target for patients during active treatment.