Effects of Exercise Therapy Dosing Schedule on Impaired Cardiorespiratory Fitness in Patients With Primary Breast Cancer A Randomized Controlled Trial

Background: Current exercise guidelines for clinical populations recommend an exercise therapy (ET) prescription of fixed intensity (moderate), duration (40-50 minutes per session), and volume (120-160 min/wk). A critical overarching element of exercise programming that has received minimal attention is dose scheduling. We investigated the tolerability and efficacy of 2 exercise training dose regimens on cardiorespiratory fitness and patient-reported outcomes in patients with posttreatment primary breast cancer. Methods: Using a parallel-group randomized trial, we randomly allocated 174 postmenopausal patients (2.8 years after adjuvant therapy) with impaired peak oxygen consumption (VO(2)peak) to 1 of 2 supervised exercise training interventions delivered with a standard linear (LET) (fixed dose intensity per session for 160 min/wk) or nonlinear (NLET) (variable dose intensity per session for approximate to 120 min/wk) schedule compared with a stretching attention control group for 16 consecutive weeks. Stretching was matched to exercise dosing arms on the basis of location, frequency, duration, and treatment length. The primary end point was change in VO(2)peak (mL O-2 center dot kg(-1)center dot min(-1)) from baseline to after intervention. Secondary end points were patient-reported outcomes, tolerability, and safety. Results: No serious adverse events were observed. Mean attendance was 64%, 75%, and 80% for attention control, LET, and NLET, respectively. In intention-to-treat analysis, VO(2)peak increased 0.6 +/- 1.7 mL O-2 center dot kg(-1)center dot min(-1) (P=0.05) and 0.8 +/- 1.8 mL O-2 center dot kg(-1)center dot min(-1) (P=0.07) in LET and NLET, respectively, compared with attention control. Change in VO(2)peak ranged from -2.7 to 4.1 mL O-2 center dot kg(-1)center dot min(-1) and from -3.6 to 5.1 mL O-2 center dot kg(-1)center dot min(-1) in LET and NLET, respectively. Approximately 40% of patients in both exercise dosing regimens were classified as VO(2)peak responders (ie, Delta >= 1.32 mL O-2 center dot kg(-1)center dot min(-1)). NLET improved all patient-reported outcomes compared with attention control. Conclusions: Short-term exercise training, independently of dosing schedule, is associated with modest improvements in cardiorespiratory fitness in patients previously treated for early-stage breast cancer.