Breast Cancer and Physical Activity Level (BC-PAL) Trial

Abstract

Regular physical activity (PA) participation can improve recovery and survival following a breast cancer diagnosis. Current guidelines focus on moderate-vigorous intensity PA participation (50-85% heart rate reserve; HRR). However, approximately 85% of breast cancer survivors do not meet PA guidelines and may prefer lighter-intensity PA (≈40- 60% HRR). PURPOSE: We assessed the effects of prescribing different PA intensities, compared to no additional PA, on cardiorespiratory fitness (VO2peak), anthropometry and body composition in breast cancer survivors. METHODS: The Breast Cancer and Physical Activity Level (BC-PAL) Trial is a three-arm, 12-week randomized controlled trial. Forty-five inactive (≤60 minutes of moderate- vigorous PA/wk and ≤10,000 steps/day) breast cancer survivors recruited for pilot data collection were randomized to one of three groups: no additional PA prescribed (CON), 300 min/wk of lighter-intensity PA (LIPA; 40-60% HRR) and 150 min/wk of higher-intensity PA (HIPA; 60-80% HRR). VO2peak (maximal Balke protocol), anthropometric measures (height, weight, waist and hip circumferences) and body composition (DXA) were assessed at baseline and end of study. Participants in both PA groups received written resources on PA, an activity tracker (Polar A360®) to record heart rate and PA time, and a diary to record PA goals, facilitators and barriers throughout the intervention. In-person/telephone meetings occurred every three weeks to review activity tracker data, reinforce adherence and discuss barriers to achieving the prescribed PA goals. RESULTS: Statistical differences in VO2peak between groups were noted. Specifically, increases in VO2peak were noted in HIPA vs. CON (5.9±6.4 vs. 0.5±3.0 ml/kg/min; P = 0.01) and LIPA vs. CON (4.2±4.9 vs. 0.5±3.0 ml/kg/min; P = 0.03). No significant changes in BMI (0.3±0.9, -0.1±0.8, -0.0±1.4 kg/m2; P = 0.6), waist (1.2±4.2, -1.1±3.3, -1.1±3.8 cm; P = 0.2) and hip (0.8±1.7, -0.2±2.7, -0.2±2.1 cm; P = 0.4) circumferences, body fat (0.1±1.4, -0.4±1.9, -1.1±2.3 kg; P = 0.3) and lean (0.4±0.8, -0.1±1.4, 0.7±1.5 kg; P = 0.3) mass were observed between CON, LIPA and HIPA, respectively. CONCLUSIONS: Pilot results indicate that improvements in cardiorespiratory fitness can be achieved with both higher- and lower-intensity PA in breast cancer survivors.