EXERT-BC: A prospective study of an exercise regimen designed to improve functional mobility, body composition, and strength after treatment for breast cancer.

494 Background: Few studies have assessed dose-escalated resistance training in breast cancer (BC) patients utilizing compound movements and linear progression to impact body composition, strength, balance, and functional capacity. Methods: Women treated for BC underwent this 3 month, 3 times a week, observed exercise regimen in an exercise oncology facility with continual monitoring of strength. Pre- and post-workout assessment of body composition, functional mobility and balance, activity levels and quality of life were measured. Results: 20 women completed the IRB-approved protocol on interim analysis, with mean age of 57 years (range 41-74), weight of 173.2 lbs. (range 123.4-274.6), and body fat percent of 36.5% (range 18.7-50.6). Concurrent therapies included anti-estrogen therapy (73%), chemotherapy (14%), and radiotherapy (23%). 27% of women endorsed prior exercise. Subjects missed an average 1.75 classes (range 0-7) and adherence was >75%. No injuries or adverse events were reported besides muscle soreness and 2 days of knee pain. Significant differences in body composition at completion included reduced body fat on bioimpedance analysis (BIA) (38.2% vs 36.7%, p=0.003), increased muscle mass on BIA (33.1% vs 37.1%, p<0.001), reduced body fat on ultrasound (US, 37.2% vs. 32.7%, p < 0.001), increase fat free mass on US (28.7% vs. 31.7%, p = 0.011), improved functional mobility screen (FMS, 9.82 vs 11.73, p=0.018), and improved Y-balance scores (Y-B, left: 72.4 vs 85.3, p=0.001; right: 70.3 vs 85.2. p<0.001). Significant increases in load were demonstrated for split squat (p<0.001), trap bar deadlift (p=0.035), inclined dumbbell press (p<0.001), and bird dog rows (p<0.001). Conclusions: A dose-escalated resistance training regimen in women with BC and limited exercise background is safe and feasible with good adherence, resulting in significant improvements in body composition, balance, strength, muscle mass and decreases in adipose tissue and fall risk. Studies utilizing this exercise regimen and model and its potential impact on quality of life and cost of care savings are underway. Clinical trial information: NCT05747209 .[Table: see text]